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MONDO

MONDO:0010026 SHORT syndrome

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Inheritance

1

Autosomal dominant inheritance HP:0000006

Heterozygous PIK3R1 variants segregate in an autosomal dominant manner. Both de novo and inherited variants are reported, and the recurrent p.Arg649Trp allele has been observed to segregate with the phenotype in multigenerational families as well as arising de novo. Penetrance is recorded as INCOMPLETE on the strength of a single documented asymptomatic carrier: a novel frameshift variant found in a child with APDS2 and mild SHORT features was also present in the mother, who was clinically unaffected. That is one family, and it concerns a variant at the APDS2 end of the PIK3R1 spectrum rather than a classic cSH2 SHORT allele, so it should not be read as a penetrance estimate for p.Arg649Trp.

Autosomal dominant inheritance Penetrance: INCOMPLETE

Show evidence (3 references)

PMID:35789397 SUPPORT Human Clinical

"The same variant was also identified in the patient's hitherto asymptomatic mother, implicating an incomplete penetrance."

The only penetrance observation in this literature: an unaffected carrier parent. It is a single family and the authors themselves state the inference rather than quantifying it.

PMID:23980586 SUPPORT Human Clinical

"SHORT syndrome (OMIM 269880) is a rare autosomal-dominant disorder"

States the mode of inheritance directly.

PMID:23810378 SUPPORT Human Clinical

"Overall, we identified in nine affected individuals from eight families de novo or inherited PIK3R1 mutations"

Records that both de novo and inherited heterozygous alleles occur, which is what makes the dominant transmission observable across families.

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Discussions and Knowledge Gaps

3

How do PIK3R1 variants that reduce PI3K-AKT signalling (SHORT syndrome) and PIK3R1 variants that increase p110-delta activity (APDS2) coexist in the same patients, and what determines which phenotype a given allele produces?

OPEN QUESTION OPEN pik3r1_allelic_direction

Attached to

pathophysiology#Reduced PI3K-AKT Signal Transduction pathophysiology#PIK3R1 C-terminal SH2 Domain Variant

The two PIK3R1 diseases are usually described as having opposite effects on the pathway, which makes their co-occurrence in one individual mechanistically awkward rather than merely unusual. Reported overlap cases show it is not a theoretical concern: two further patients with both phenotypes were described in 2017, taking the total beyond the single previously known case, and the authors concluded the association may not be rare. Resolving this matters for curation because it determines whether the two entries can keep independent pathographs or whether a shared allele-to-phenotype model is needed.

Show evidence (4 references)

PMID:28302518 SUPPORT Human Clinical

"47 patients with APDS2 have been reported to date, only one of them sharing both PIK3R1-related phenotypes."

Quantifies how exceptional the overlap was thought to be before this report.

PMID:28302518 SUPPORT Human Clinical

"Here we describe two more patients affected by APDS2 and SHORT syndrome, which highlights that this association may not be so infrequent."

The observation that reopens the question: the overlap is more common than the single prior case suggested.

PMID:32778990 SUPPORT Human Clinical

"This pathogenic variant had been previously associated with APDS2; however, it had not been associated with SHORT syndrome. The exact mechanisms linking both conditions are yet to be identified."

The sharpest form of the problem: one splice allele, previously an APDS2 allele, producing SHORT syndrome features in this patient. Cited here because it is the strongest published case against the split this entry maintains, and the authors state plainly that the mechanism is unknown.

+ 1 more reference

If the C-terminal PIK3R1 variants impair insulin signalling only in some cellular contexts, what determines which tissues are affected, and is a single "reduced PI3K-AKT signalling" node the right way to model this disease?

OPEN QUESTION OPEN context_dependent_signalling

Attached to

pathophysiology#Reduced PI3K-AKT Signal Transduction pathophysiology#Dissociation of Insulin Resistance from Dyslipidaemia

The pathograph in this entry routes everything through one node in which PI3K-AKT signalling is reduced, and that is how the founding papers framed it. The 2016 study that established the dyslipidaemia dissociation complicates the picture in two ways. First, it states outright that these mutations impair insulin signalling only in some cellular contexts. Second, in cells from one patient carrying the p.Tyr657X allele, the mutant p85-alpha failed to associate with IRS1 while downstream signalling was normal - a binding defect that did not propagate. Taken together these say the lesion is not a uniform dial turned down across every tissue, which is what the single node implies. The tissue selectivity would also explain the dissociation directly: hepatic lipogenesis is spared while glucose disposal is not. Nothing cited here identifies what makes a given cell type sensitive or resistant, so the node is kept as one and this question records the qualification rather than splitting the pathograph on speculation.

Show evidence (2 references)

PMID:27766312 SUPPORT Human Clinical

"PIK3R1 C-terminal mutations impair insulin signaling only in some cellular contexts"

The authors' explicit statement of context-dependence, which is what this question is about.

PMID:27766312 SUPPORT In Vitro

"showed severely reduced insulin-stimulated association of mutant but not WT p85α with IRS1, but normal downstream signaling"

A measured case where the binding defect did not propagate downstream. This is the single most direct challenge to the simple linear reading of the pathograph, and is recorded here rather than omitted because it is inconvenient.

By what developmental route does reduced PI3K-AKT signalling produce anterior segment dysgenesis (Rieger anomaly) in SHORT syndrome?

KNOWLEDGE GAP OPEN anterior_segment_mechanism_gap

Attached to

pathophysiology#Anterior Segment Dysgenesis

The gap here is narrower than it looks, and narrower than an earlier draft of this entry claimed. Sufficiency is established: the heterozygous R649W allele produces iris hypoplasia with an enlarged irregular pupil in the knock-in mouse, and the same allele produces Rieger anomaly in human carriers, so the p85-alpha lesion demonstrably reaches anterior segment development in vivo. What is missing is everything between. The anterior segment derives from periocular neural crest, and no cited source identifies which crest population, which developmental window, or which PI3K-dependent process is affected - nor why the mouse stops at the iris while humans go on to goniosynechiae, cataract and glaucoma. That species difference is itself a clue nobody has followed up. The pathophysiology node is connected to the upstream signalling node with unknown intermediates, which is the honest encoding of "we know it gets there, we do not know how".

Show evidence (2 references)

PMID:28632845 SUPPORT Model Organism

"A dominant-negative mutation in the p85α regulatory subunit of PI3K affects development of the iris, and contributes to changes consistent with anterior segment dysgenesis in both humans and mice."

Establishes sufficiency, which is the half of the question that is answered.

PMID:28632845 SUPPORT Model Organism

"While overall eye development was normal with clear cornea and lens, normal anterior chamber volume, normal intraocular pressure, and no changes in the retinal structure, OCT images of the knock-in mouse eyes revealed a significant decrease in thickness and width of the iris"

The selectivity of the mouse phenotype - iris only, everything else normal - which is the observation any mechanistic account would have to explain and none does.

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Pathophysiology

10

PIK3R1 C-terminal SH2 Domain Variant

Heterozygous PIK3R1 variants cluster in exon 14, which encodes the C-terminal SH2 domain of the p85-alpha regulatory subunit. The reported allele spectrum comprises missense, frameshift and nonsense changes, all of which spare the N-terminal half of the protein, and c.1945C>T (p.Arg649Trp) recurs across unrelated families as a mutational hotspot. PIK3R1 also encodes the p55-alpha and p50-alpha subunits, so a single allele perturbs the regulatory arm of every class IA PI3K holoenzyme in which those subunits participate.

PIK3R1 hgnc:8979

p85-alpha PI3K regulatory subunit activity GO:0035014 ⚠ ABNORMAL

Downstream

Impaired p85-alpha Binding to IRS-1 The variant SH2 domain is the surface through which p85-alpha docks onto tyrosine-phosphorylated IRS-1, so a change in this domain acts directly on that interaction.

Show evidence (3 references)

PMID:23810382 SUPPORT Human Clinical

"Whole-exome sequencing in a family trio of an affected child and unaffected parents identified a de novo frameshift insertion, c.1906_1907insC"

The exome finding that identified PIK3R1 as the SHORT syndrome gene, and the first of the exon 14 alleles.

PMID:23810378 SUPPORT Human Clinical

"we identified in nine affected individuals from eight families de novo or inherited PIK3R1 mutations, including a mutational hotspot"

Establishes p.Arg649Trp as a recurrent allele across unrelated families.

PMID:23810378 SUPPORT Human Clinical

"PIK3R1 encodes the p85α, p55α, and p50α regulatory subunits of class IA phosphatidylinositol 3 kinases (PI3Ks), which are known to play a key role in insulin signaling."

States which gene products are affected and why a regulatory-subunit defect reaches insulin signalling.

Impaired p85-alpha Binding to IRS-1

Recruitment of class IA PI3K to the activated insulin receptor depends on the p85-alpha SH2 domains engaging phosphotyrosine motifs on IRS-1. The SHORT syndrome hotspot variant impairs that interaction, so the catalytic p110 subunit is not brought to its membrane substrate after insulin stimulation. This is the step that makes the disease a post-receptor defect: the insulin receptor itself is intact.

p85-alpha binding to IRS-1 GO:0043560 ↓ DECREASED

Downstream

Reduced PI3K-AKT Signal Transduction Failure to recruit the holoenzyme to IRS-1 is the immediate cause of reduced downstream AKT and S6 phosphorylation.

Show evidence (1 reference)

PMID:23810379 SUPPORT In Vitro

"This mutation led to impaired interaction between p85α and IRS-1 and reduced AKT-mediated insulin signaling in fibroblasts from affected subjects and in reconstituted Pik3r1-knockout preadipocytes."

Demonstrates the binding defect in both patient fibroblasts and a reconstituted preadipocyte system.

Reduced PI3K-AKT Signal Transduction

Downstream of the failed IRS-1 interaction, phosphorylation of AKT and of the more distal S6 target is reduced in patient-derived cells. The defect is not confined to one branch of the cascade: proximal and distal PI3K-dependent signalling are both impaired, which is why one molecular lesion produces a phenotype spanning growth, adipose tissue and glucose metabolism.

patient-derived dermal fibroblast CL:0000057

PI3K-AKT signal transduction GO:0043491 ↓ DECREASED

Animal models

Pik3r1 R649W knock-in mouse Mouse recapitulates The model demonstrates the signalling defect in vivo, across the three tissues that matter for the human phenotype, rather than only in cultured patient cells.

Downstream

Post-receptor Insulin Resistance Reduced PI3K-dependent signalling downstream of an intact insulin receptor is what post-receptor insulin resistance consists of at the cellular level.

Impaired Adipocyte Differentiation PI3K activity is required for adipose differentiation, so the same reduction in signalling that impairs insulin action also constrains adipogenesis.

Impaired Insulin Secretion and Incretin Response PI3K signalling operates in the beta cell as well as in insulin target tissues, so the secretory defect seen in the knock-in mouse plausibly shares this upstream lesion. The intervening steps in the islet are not established.

Progeroid Craniofacial and Dental Development The craniofacial and dental features segregate with PIK3R1 variants and are, on systematic appraisal, the most consistent part of the phenotype. No developmental mechanism connecting reduced PI3K signalling to them is established, so the edge is drawn with unknown intermediates rather than omitted.

Anterior Segment Dysgenesis The anterior chamber phenotype is attributed to the same signalling defect because it segregates with PIK3R1 variants, but no developmental route from reduced PI3K signalling to neural-crest-derived anterior segment formation is established. The edge is drawn with unknown intermediates rather than left disconnected, because leaving it disconnected would imply an independent cause the evidence does not support.

Impaired Growth Signalling The PI3K-AKT-mTOR axis drives cell growth and proliferation, so its downregulation is the proposed route from the variant to the growth phenotype.

Show evidence (1 reference)

PMID:23810382 SUPPORT Human Clinical

"Our findings show that PIK3R1 mutations are the major cause of SHORT syndrome and suggest that the molecular mechanism of disease might involve downregulation of the PI3K-AKT-mTOR pathway."

The authors' own summary of the proposed mechanism. Note the hedge in the original ("might involve") is preserved here rather than upgraded.

Post-receptor Insulin Resistance

Insulin resistance in SHORT syndrome arises below the receptor, in the PI3K arm of the cascade. Clinically this presents as severe insulin resistance with compensatory hyperinsulinaemia, progressing in some patients to diabetes, typically in the second decade.

insulin receptor signaling pathway GO:0008286 ↓ DECREASED

Downstream

Insulin resistance The cellular signalling defect is the mechanism of the clinical insulin resistance.

Diabetes mellitus Sustained severe insulin resistance is the route to diabetes in this disorder.

Dissociation of Insulin Resistance from Dyslipidaemia The insulin resistance of SHORT syndrome does not carry the metabolic company it usually keeps. This is not an absence of findings but a positive, discriminating feature.

Polycystic ovaries Hyperinsulinaemia secondary to insulin resistance is the conventional route to the ovarian phenotype; the cited source reports the association, not the intervening steps.

Show evidence (2 references)

PMID:23980586 SUPPORT Human Clinical

"teething delay, partial lipodystrophy, insulin resistance and facial dysmorphic signs"

Lists insulin resistance among the defining features of the syndrome.

PMID:35110500 SUPPORT Other

"conditions such as SHORT syndrome caused by abnormalities of PIK3R1, which encodes a regulatory subunit of phosphatidylinositol 3-kinase"

A national diabetes society's formal classification placing SHORT syndrome among the genetic insulin resistance syndromes, which is the citation behind this entry's "Syndromic insulin resistance" parent. Graded OTHER as an expert-consensus classification document rather than a study.

Dissociation of Insulin Resistance from Dyslipidaemia

Obesity-related insulin resistance travels with fatty liver, dyslipidaemia and low adiponectin. Insulin resistance from insulin-receptor dysfunction travels with none of them, and insulin resistance from AKT2 dysfunction phenocopies the obesity pattern. SHORT syndrome sits with the receptor group: four of five studied patients had extreme insulin resistance without dyslipidaemia or hepatic steatosis, and adiponectin was preserved in three of those four. Because PIK3R1 acts between the receptor and AKT, that placement is informative about where in the cascade the lesion sits, and it makes the metabolic profile a discriminating clinical feature rather than an incidental one.

Animal models

Pik3r1 R649W knock-in mouse Mouse recapitulates Challenged with a high-fat diet or crossed onto an obese background, the mutant mice are protected from obesity and hepatic steatosis while becoming more diabetic. That is the mouse form of the human dissociation, and it separates the two effects experimentally in a way patient observation cannot.

Downstream

Hypertriglyceridemia The other half of the dissociation, and recorded the same way: an expected feature that is characteristically absent.

Hepatic steatosis Recorded as an expected feature that is characteristically absent. The phenotype entry carries REFUTE evidence rather than asserting its presence.

Show evidence (2 references)

PMID:27766312 SUPPORT Human Clinical

"Obesity-related insulin resistance is associated with fatty liver, dyslipidemia, and low plasma adiponectin. Insulin resistance due to insulin receptor (INSR) dysfunction is associated with none of these"

The comparison that gives the dissociation its meaning: which group SHORT syndrome resembles is a statement about where in the cascade the lesion is.

PMID:27766312 SUPPORT Human Clinical

"PIK3R1 C-terminal mutations impair insulin signaling only in some cellular contexts and produce a subphenotype of insulin resistance resembling INSR dysfunction but unlike AKT2 dysfunction"

The authors' own conclusion, including the qualification that the signalling defect is context-dependent rather than global. That qualification is carried into the discussions rather than dropped.

Impaired Insulin Secretion and Incretin Response

A second, beta-cell arm of the metabolic phenotype, demonstrated only in the knock-in mouse: the mutation impairs insulin secretion and the action of GLP-1 on islets, in vivo and in vitro. If it holds in patients it means the diabetes is not purely a resistance phenomenon, which would matter for treatment choice. No equivalent human measurement is cited, so this node is model-derived throughout.

insulin secretion GO:0030073 ↓ DECREASED

Downstream

Diabetes mellitus A secretory defect on top of resistance would lower the threshold for overt hyperglycaemia. Marked indirect because the secretory defect is shown in mouse and the diabetes is a human phenotype.

Show evidence (1 reference)

PMID:26974159 SUPPORT Model Organism

"In addition, mutant mice displayed defective insulin secretion and GLP-1 action on islets in vivo and in vitro."

The observation this node records, stated as a mouse result.

Impaired Adipocyte Differentiation

PI3K signalling is required for preadipocytes to differentiate into mature adipocytes. The hotspot variant reduces AKT-mediated insulin signalling in reconstituted Pik3r1-knockout preadipocytes, and the resulting failure of adipose differentiation is the proposed basis of the partial lipodystrophy, which characteristically affects the face, chest and upper extremities while sparing the buttocks and legs.

preadipocyte CL:0002334 adipocyte CL:0000136

fat cell differentiation GO:0045444 ↓ DECREASED

Animal models

Pik3r1 R649W knock-in mouse Mouse recapitulates Partial lipodystrophy is reproduced, alongside the reduced body weight and length.

Downstream

Triangular face Facial lipoatrophy is a major contributor to the progeroid facial gestalt. It is not the whole of it - frontal bossing and micrognathia are skeletal - but the loss of facial fat is what gives the aged appearance.

Deeply set eye Loss of periorbital fat contributes to the ocular depression that gives the acronym its "O".

Lipoatrophy Failure of adipose differentiation produces the regional loss of subcutaneous fat that defines the lipodystrophy.

Show evidence (2 references)

PMID:23810379 SUPPORT In Vitro

"reduced AKT-mediated insulin signaling in fibroblasts from affected subjects and in reconstituted Pik3r1-knockout preadipocytes"

The preadipocyte model in which the signalling defect relevant to adipogenesis was demonstrated.

PMID:23810379 SUPPORT In Vitro

"the mutated PIK3R1 therefore provides a unique link among lipodystrophy, growth, and insulin signaling"

The authors' framing of one lesion producing the three arms of the phenotype, which is the structure this pathograph encodes.

Impaired Growth Signalling

Growth restriction in SHORT syndrome begins prenatally and continues after birth. It is attributed to downregulation of the PI3K-AKT-mTOR axis, which drives cell growth and proliferation. This attribution rests on the pathway's known role rather than on a direct measurement in growth-plate tissue from patients.

Downstream

Intrauterine growth retardation The prenatal arm of the growth phenotype.

Short stature The postnatal arm of the same growth phenotype.

Show evidence (3 references)

PMID:23810382 SUPPORT INDIRECT Human Clinical

"plays an important role in cell growth, proliferation, and survival"

The pathway property the growth phenotype is attributed to. Cited as the basis for the inference, not as a measurement of growth-plate signalling.

PMID:24886349 SUPPORT Human Clinical

"the patients usually present a low birth weight and height, lipodystrophy, delayed bone age, hernias, low body mass index and a progeroid appearance"

Establishes that the growth deficit is present from birth and is accompanied by delayed skeletal maturation, which is what makes it a growth-signalling phenotype rather than a nutritional one.

PMID:36401775 SUPPORT Other

"PI3K malfunction is associated with insulin resistance, decreased lipogenesis, increased energy expenditure, and possible IGF1 resistance."

Names three candidate routes to the growth phenotype that are more specific than "the pathway drives growth": IGF1 resistance, increased energy expenditure, and decreased lipogenesis. The review hedges on the IGF1 arm ("possible"), and that hedge is retained. Graded OTHER as a narrative review.

Progeroid Craniofacial and Dental Development

A distinct progeroid craniofacial appearance - triangular face, frontal bossing, hypoplastic or thin alae nasi, large low-set ears, mandibular retrognathia - together with a dental phenotype broader than the acronym's "teething delay": microdontia, hypodontia and enamel hypoplasia are all reported. Systematic appraisal found the facial dysmorphism to be the *most* consistent feature of the syndrome, ahead of the eponymous ocular and dental signs, which makes it the best recognition cue and not a minor detail. The facial fat loss contributes to the appearance and is modelled separately from the adipose node; the skeletal and dental components have no established mechanism, which is why this node carries no upstream molecular detail.

Downstream

Frontal bossing A skeletal component of the gestalt.

Micrognathia Mandibular retrognathia, a skeletal component of the gestalt.

Low-set ears Large low-set ears, a component of the gestalt.

Underdeveloped nasal alae Hypoplastic or thin alae nasi.

Delayed eruption of teeth The "T" of the acronym, part of the dental phenotype.

Hypodontia Reduced tooth number.

Microdontia Small teeth.

Enamel hypoplasia Defective enamel formation.

Show evidence (1 reference)

PMID:34212753 SUPPORT Human Clinical

"Facial dysmorphism including ocular depression, triangular shaped face, frontal bossing, large low-set ears, and micrognathia were the most consistent features followed by lipodystrophy, insulin resistance, and intrauterine growth restriction."

The finding that reorders the syndrome's own acronym: facial dysmorphism is more consistent than the eponymous features. This is why the craniofacial phenotype gets its own node rather than being scattered across unattached phenotype entries.

Anterior Segment Dysgenesis

Maldevelopment of the anterior segment of the eye produces the Rieger anomaly and related findings (posterior embryotoxon, glaucoma) that give the syndrome its "R". The developmental route from reduced PI3K signalling to anterior chamber dysgenesis has not been worked out; this node records the tissue-level lesion without asserting an intervening mechanism.

Animal models

Pik3r1 R649W knock-in mouse Mouse recapitulates The same knock-in line was examined ophthalmologically alongside two human R649W subjects. The mice have significantly thinner and narrower irides with enlarged, irregular pupils, and the human subjects have the corresponding Rieger anomaly with thin irides and irregular pupils. This is the evidence that the ocular arm of the syndrome follows from the p85-alpha lesion rather than from an unrelated cause, and it is what makes a single heterozygous allele sufficient for anterior segment dysgenesis in vivo.

Downstream

Glaucoma Raised intraocular pressure follows from maldevelopment of the drainage structures of the anterior chamber.

Posterior embryotoxon An anteriorly displaced Schwalbe line is part of the same anterior segment maldevelopment.

Hypoplasia of the iris Thinning of the iris stroma, the component of the anterior segment phenotype that the knock-in mouse reproduces and that is measurable by OCT.

Abnormal pupil morphology The irregular, enlarged pupil follows from the iris hypoplasia rather than being an independent defect.

Anterior synechiae of the anterior chamber Goniosynechiae, adhesions across the iridocorneal angle. Present in the human subjects and absent from the mouse, which is part of why the model is graded as reproducing the iris defect rather than the whole anterior segment phenotype.

Cataract Early cataract in the human subjects. Whether it is a direct consequence of the anterior segment maldevelopment or secondary to the glaucoma and its treatment is not addressed by the source.

Rieger anomaly Anterior segment maldevelopment is what the Rieger anomaly consists of.

Show evidence (1 reference)

PMID:23810382 SUPPORT Human Clinical

"SHORT syndrome is a rare, multisystem disease characterized by short stature, anterior-chamber eye anomalies, characteristic facial features, lipodystrophy, hernias, hyperextensibility, and delayed dentition."

Establishes anterior chamber anomalies as a core feature of the disease.

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Pathograph

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Phenotypes

29

Digestive 2

Inguinal hernia HP:0000023

Show evidence (1 reference)

PMID:26497935 SUPPORT Human Clinical

"hyperextensibility of joints and inguinal hernia"

Inguinal hernia among the minor features.

Hepatic steatosis HP:0001397

Show evidence (1 reference)

PMID:27766312 REFUTE Human Clinical

"Four of 5 patients had extreme insulin resistance without dyslipidemia or hepatic steatosis."

Directly contradicts the presence of hepatic steatosis in four of five studied patients, which is why this item is graded REFUTE rather than SUPPORT.

Ear 2

Sensorineural hearing impairment HP:0000407

Show evidence (1 reference)

PMID:26497935 SUPPORT Human Clinical

"thin wrinkled skin, speech delay, sensorineural deafness"

Sensorineural deafness among the minor features.

Low-set ears FREQUENT HP:0000369

Show evidence (1 reference)

PMID:34212753 SUPPORT Human Clinical

"frontal bossing, large low-set ears, and micrognathia were the most consistent features"

Large low-set ears among the most consistent features.

Endocrine 1

Diabetes mellitus OCCASIONAL HP:0000819

Show evidence (2 references)

PMID:33129256 SUPPORT Human Clinical

"Severe insulin resistance may also lead to an early onset of type 2 diabetes, typically occurring in the second decade of life"

Establishes diabetes as a consequence and gives its usual age of onset. The hedged "may" in the source is why the frequency band is conservative.

PMID:26497935 SUPPORT Human Clinical

"Given the high risk of diabetes mellitus, regular monitoring of glucose metabolism is warranted."

The cohort study's own risk assessment, which is what justifies surveillance.

Eye 4

Glaucoma HP:0000501

Show evidence (1 reference)

PMID:23980586 SUPPORT Human Clinical

"ophthalmic anomalies (Rieger anomaly, posterior embryotoxon, glaucoma)"

Names glaucoma among the ophthalmic features. No frequency is recorded because none of the cited sources gives one.

Posterior embryotoxon HP:0000627

Show evidence (1 reference)

PMID:23980586 SUPPORT Human Clinical

"ophthalmic anomalies (Rieger anomaly, posterior embryotoxon, glaucoma)"

Names posterior embryotoxon among the ophthalmic features.

Deeply set eye HP:0000490

Show evidence (1 reference)

PMID:23980586 SUPPORT Human Clinical

"short stature, hyperextensibility of joints, hernias, ocular depression"

Ocular depression as a defining acronym feature.

Cataract HP:0000518

Show evidence (1 reference)

PMID:28632845 SUPPORT Human Clinical

"goniosynechiae, early cataract formation, and glaucoma"

Early cataract in the two human subjects.

Genitourinary 1

Polycystic ovaries VERY_FREQUENT HP:0000147

Show evidence (1 reference)

PMID:33129256 SUPPORT Human Clinical

"almost all postpubertal women affected present polycystic ovary syndrome"

"Almost all" is the basis for the VERY_FREQUENT band, which applies to the postpubertal female subgroup rather than to all patients.

Head and Neck 7

Triangular face FREQUENT HP:0000325

Show evidence (2 references)

PMID:33129256 SUPPORT Human Clinical

"a characteristic facial gestalt (e.g. triangular face with a small thin, thin lip, downturned mouth, low-set posteriorly rotated ears, prominent forehead, underdeveloped or thin nasal alae as well as wrinkles)"

Spells out the components of the facial gestalt, of which the triangular face is the bindable element.

PMID:26497935 SUPPORT Human Clinical

"lipoatrophy and the characteristic facial gestalt"

The facial gestalt among the commonly observed features of the confirmed cohort.

Delayed eruption of teeth HP:0000684

Show evidence (1 reference)

PMID:26497935 SUPPORT Human Clinical

"The less specific, or minor features of SHORT syndrome include teething delay, thin wrinkled skin, speech delay, sensorineural deafness, hyperextensibility of joints and inguinal hernia."

Places teething delay among the minor features. No frequency band is recorded because the source grades specificity, not prevalence.

Frontal bossing FREQUENT HP:0002007

Show evidence (1 reference)

PMID:34212753 SUPPORT Human Clinical

"Facial dysmorphism including ocular depression, triangular shaped face, frontal bossing, large low-set ears, and micrognathia were the most consistent features followed by lipodystrophy, insulin resistance, and intrauterine growth restriction."

Places frontal bossing within the most consistent feature group, and gives the ordering that the frequency bands in this entry follow.

Micrognathia FREQUENT HP:0000347

Show evidence (1 reference)

PMID:34212753 SUPPORT Human Clinical

"triangular shaped face, frontal bossing, large low-set ears, and micrognathia were the most consistent features"

Micrognathia among the most consistent features.

Hypodontia HP:0000668

Show evidence (1 reference)

PMID:34212753 SUPPORT Human Clinical

"Teething delay, microdontia, hypodontia, and enamel hypoplasia have all been reported."

Establishes the wider dental phenotype. The source says "have all been reported" without frequencies, so no band is recorded.

Microdontia HP:0000691

Show evidence (1 reference)

PMID:34212753 SUPPORT Human Clinical

"Teething delay, microdontia, hypodontia, and enamel hypoplasia have all been reported."

Microdontia among the reported dental findings.

Enamel hypoplasia HP:0006297

Show evidence (1 reference)

PMID:34212753 SUPPORT Human Clinical

"microdontia, hypodontia, and enamel hypoplasia have all been reported"

Enamel hypoplasia among the reported dental findings.

Metabolism 2

Insulin resistance FREQUENT HP:0000855

Show evidence (1 reference)

PMID:26497935 SUPPORT Human Clinical

"Anterior chamber defects and insulin resistance or diabetes were also observed but were not as prevalent."

Establishes the feature and, explicitly, that it is less prevalent than the growth and lipoatrophy features. The band is set below those features on that basis rather than from a reported percentage.

Hypertriglyceridemia HP:0002155

Show evidence (1 reference)

PMID:27766312 REFUTE Human Clinical

"Four of 5 patients had extreme insulin resistance without dyslipidemia or hepatic steatosis."

Contradicts the presence of dyslipidaemia in four of five studied patients. The binding is to the hypertriglyceridaemia term because that is the specific lipid abnormality the obesity-related pattern would predict.

Musculoskeletal 1

Joint hypermobility HP:0001382

Show evidence (1 reference)

PMID:26497935 SUPPORT Human Clinical

"speech delay, sensorineural deafness, hyperextensibility of joints and inguinal hernia"

Hyperextensibility among the minor features.

Nervous System 1

Delayed speech and language development HP:0000750

Show evidence (2 references)

PMID:26497935 SUPPORT Human Clinical

"thin wrinkled skin, speech delay, sensorineural deafness"

Speech delay among the minor features.

PMID:33129256 SUPPORT Human Clinical

"Intelligence is within normal range and most patients can have normal educational achievements"

Establishes that the speech delay is not part of a global intellectual disability, which is the clinically important qualification.

Growth 2

Intrauterine growth retardation FREQUENT HP:0001511

Show evidence (1 reference)

PMID:26497935 SUPPORT Human Clinical

"The commonly observed clinical features of SHORT syndrome seen in the cohort included intrauterine growth restriction (IUGR) <10th percentile, postnatal growth restriction, lipoatrophy and the characteristic facial gestalt."

"Commonly observed" in a 32-patient molecularly confirmed cohort. The source gives no percentage, so FREQUENT is the widest band consistent with the wording rather than a reported figure.

Short stature FREQUENT HP:0004322

Show evidence (1 reference)

PMID:26497935 SUPPORT Human Clinical

"included intrauterine growth restriction (IUGR) <10th percentile, postnatal growth restriction"

Postnatal growth restriction listed among the commonly observed features.

Other 6

Lipoatrophy FREQUENT HP:0100578

Show evidence (2 references)

PMID:26497935 SUPPORT Human Clinical

"postnatal growth restriction, lipoatrophy and the characteristic facial gestalt"

Lipoatrophy among the commonly observed features of the confirmed cohort.

PMID:33129256 SUPPORT Human Clinical

"Lipodystrophy, characterized by selective loss of adipose tissue, is another typical feature of the syndrome."

Describes the nature of the fat loss.

Rieger anomaly OCCASIONAL HP:0000558

Show evidence (2 references)

PMID:26497935 SUPPORT Human Clinical

"Anterior chamber defects and insulin resistance or diabetes were also observed but were not as prevalent."

Anterior chamber defects present but explicitly less prevalent than the core growth and adipose features.

PMID:23810379 SUPPORT Human Clinical

"short stature, progeroid face, and Rieger anomaly (SHORT syndrome)"

Rieger anomaly as a defining feature in the families in which the hotspot variant was identified.

Underdeveloped nasal alae FREQUENT HP:0000430

Show evidence (1 reference)

PMID:34212753 SUPPORT Human Clinical

"Individuals have a distinct progeroid craniofacial appearance with a triangular face, frontal bossing, hypoplastic or thin alae nasi, large low-set ears, and mandibular retrognathia."

Names the components of the progeroid craniofacial appearance, including the alae nasi.

Hypoplasia of the iris HP:0007676

Show evidence (1 reference)

PMID:28632845 SUPPORT Human Clinical

"Both human subjects had Rieger anomaly with similar defects including thin irides and irregular pupils"

Thin irides in both human subjects carrying the hotspot allele. Two patients, so no frequency band is recorded.

Abnormal pupil morphology HP:0000615

Show evidence (1 reference)

PMID:28632845 SUPPORT Human Clinical

"thin irides and irregular pupils, as well as a prominent ring of Schwalbe"

Irregular pupils in the human subjects, alongside the posterior embryotoxon this entry already curates as the prominent Schwalbe ring.

Anterior synechiae of the anterior chamber HP:0011483

Show evidence (1 reference)

PMID:28632845 SUPPORT Human Clinical

"as well as a prominent ring of Schwalbe, goniosynechiae, early cataract formation, and glaucoma"

Goniosynechiae in both human subjects, reported together with the glaucoma.

🧬

Genetic Associations

1

PIK3R1 pathogenic variants (Causative)

Gene: PIK3R1 hgnc:8979 relationship_type: CAUSATIVE

Show evidence (4 references)

PMID:23810382 SUPPORT Human Clinical

"Heterozygous mutations in exon 14 of PIK3R1 were subsequently identified by Sanger sequencing in three additional affected individuals and two affected family members."

Establishes the exon 14 clustering across multiple affected individuals.

PMID:23810382 SUPPORT Human Clinical

"The other mutation, a de novo truncating mutation"

A truncating allele in the same region, showing the spectrum is not restricted to missense changes.

PMID:23980586 SUPPORT Human Clinical

"Eight of these families had a recurrent missense mutation (c.1945C>T; p.Arg649Trp)."

Quantifies the recurrence of the hotspot allele across reported families.

+ 1 more reference

Variants (3)

PIK3R1 c.1945C>T (p.Arg649Trp) Pathogenic

Gene: PIK3R1 hgnc:8979 MISSENSE

The recurrent hotspot allele, accounting for the majority of reported cases. It substitutes an arginine in the C-terminal SH2 domain of p85-alpha. Two lines of functional work place it as dominant negative rather than simply hypomorphic: overexpression of the mutant subunit in preadipocytes attenuates insulin-induced AKT phosphorylation and adipocyte differentiation, and the knock-in mouse carrying one copy reproduces the human phenotype.

Functional effects

p85-alpha binding to IRS-1

Impairs insulin-stimulated association of p85-alpha with IRS-1, so class IA PI3K is not recruited to the activated receptor complex.

Show evidence (2 references)

PMID:29724723 SUPPORT Model Organism

"A heterozygous missense mutation (R649W) in the p85α regulatory subunit gene of PI3K (PIK3R1) has been identified in patients with SHORT"

Identifies the allele. The paper's own title characterises it as dominant negative, which is the basis for that reading in the description.

PMID:27766312 SUPPORT In Vitro

"In 3T3-L1 preadipocytes, mutant p85α overexpression attenuated insulin-induced AKT phosphorylation and adipocyte differentiation."

A dominant-negative effect demonstrated by overexpression against a wild-type background, which is the functional evidence for that mechanism.

PIK3R1 c.1906_1907insC (p.Asn636Thrfs*18) Pathogenic

Gene: PIK3R1 hgnc:8979 FRAMESHIFT

A frameshift insertion in exon 14, the allele in the trio whose exome sequencing identified PIK3R1 as the SHORT syndrome gene.

Show evidence (1 reference)

PMID:23810382 SUPPORT Human Clinical

"Whole-exome sequencing in a family trio of an affected child and unaffected parents identified a de novo frameshift insertion, c.1906_1907insC"

The gene-discovery allele, established as de novo in a trio.

PIK3R1 c.1971T>G (p.Tyr657*) Pathogenic

Gene: PIK3R1 hgnc:8979 NONSENSE

A de novo truncating allele in the same region. Cells from a patient carrying it express abundant truncated PIK3R1 products, which is the observation behind the dominant-negative reading rather than a simple loss of the subunit.

Show evidence (1 reference)

PMID:27766312 SUPPORT In Vitro

"Cells studied from one patient with the p.Tyr657X PIK3R1 mutation expressed abundant truncated PIK3R1 products and showed severely reduced insulin-stimulated association of mutant but not WT p85α with IRS1"

Establishes that the truncated product is made and that it fails to bind IRS-1, while the wild-type allele's product still does.

💊

Medical Actions

5

Metformin and SGLT2 inhibitor for insulin-resistant diabetes

Action: Pharmacotherapy NCIT:C15986

Agent: metformin CHEBI:6801 canagliflozin CHEBI:73274

Once diabetes is overt, the reported regimen is an insulin sensitiser plus an insulin-independent glucose-lowering agent. In the documented case, metformin with canagliflozin brought HbA1c from 9.2% to around 7% and, notably, corrected both the daytime hyperglycaemia and the nocturnal hypoglycaemia. The rationale for an SGLT2 inhibitor here is mechanistic as well as empirical: it lowers glucose by a renal route that does not depend on the impaired PI3K arm of insulin signalling.

Target Phenotypes: Diabetes mellitus HP:0000819 Insulin resistance HP:0000855

Show evidence (2 references)

PMID:32879144 SUPPORT Human Clinical

"She was treated with metformin and canagliflozin (a sodium glucose co-transporter 2 (SGLT2) inhibitor), which ameliorated overt diurnal hyperglycemia and mild nocturnal hypoglycemia and reduced her blood HbA1c around 7%."

The regimen and its measured effect in the one reported case. A single case, which is why this is recorded as reported practice rather than as established therapy.

PMID:32879144 SUPPORT Human Clinical

"a usefulness of SGLT2 inhibitor in the treatment of IRDM"

The authors' own conclusion about the drug class.

Multi-agent oral antidiabetic therapy

Action: Pharmacotherapy NCIT:C15986

Agent: metformin CHEBI:6801 pioglitazone CHEBI:8228 sulfonylurea NCIT:C97936 thiazolidinedione NCIT:C98241

Where a single agent is not enough, published practice is to stack oral agents with complementary mechanisms rather than move to insulin - which matters here, because insulin resistance of this severity makes injected insulin both unattractive and only partly effective. In the reported case, metformin, an SGLT-2 inhibitor, a sulfonylurea, a thiazolidinedione and a GLP-1 agonist together took HbA1c from 14% to 8.8% in six months and then to 7.4%, and deferred insulin. Two of those classes are worth identifying separately: the SGLT-2 inhibitor lowers glucose by a renal route that does not depend on the impaired PI3K arm at all, and the GLP-1 agonist acts on the incretin axis that the knock-in mouse shows to be defective in this disease.

Mechanism Target:

Impaired Insulin Secretion and Incretin Response — A GLP-1 agonist acts directly on the incretin axis this pathograph records as defective. The link is mechanistically motivated rather than demonstrated: the incretin defect is a mouse finding, and the case report does not attribute the patient's response to any one agent in the combination.

Show evidence (1 reference)

PMID:41459015 SUPPORT INDIRECT Human Clinical

"By utilizing a combination of oral anti-glycemic agents with complementary mechanisms of action (metformin, sodium-glucose co-transporter 2 (SGLT-2) inhibitors, sulfonylureas, thiazolidinediones, and GLP-1 agonists), insulin therapy was delayed."

Names the GLP-1 agonist among the agents used. That an incretin-directed drug is used in a disease with a documented incretin defect is the reason for this link; the source does not isolate its contribution.

Target Phenotypes: Diabetes mellitus HP:0000819

Show evidence (5 references)

PMID:41459015 SUPPORT Human Clinical

"The patient's blood glucose levels improved significantly, with HbA1c decreased from 14% to 8.8% within 6 months of starting the multi-agent regimen"

The measured response, with its timescale. A single case.

PMID:41459015 SUPPORT Human Clinical

"Currently, there are no established guidelines for the treatment of diabetes in SHORT syndrome patients."

States the evidence base this and every other treatment entry here rests on: case reports, not guidelines.

PMID:33742773 SUPPORT Human Clinical

"our treatment plans, including lifestyle intervention combined with metformin and pioglitazone, were carried out for this patient. After the intervention, insulin resistance and hyperinsulinemia in this patient were significantly decreased during a 6-month follow up"

An independent case using a metformin plus thiazolidinedione combination, with the same direction of response over the same interval.

+ 2 more references

Growth hormone therapy

Action: Hormone therapy Ontology label: Pharmacotherapy NCIT:C15986

Long treated as contraindicated because growth hormone is diabetogenic and these patients are already severely insulin resistant. The reported evidence complicates that: growth response was poor in the one documented case, and the literature review in the same paper found insulin-resistant diabetes in 10 of 15 untreated patients aged 12 or over and in none of three treated or six untreated patients aged 10 or under - an age effect, not a treatment effect. So the case against growth hormone here rests on lack of benefit more securely than on causing the diabetes.

Target Phenotypes: Short stature HP:0004322

Show evidence (2 references)

PMID:32879144 SUPPORT Human Clinical

"GH dosage was increased from 0.23 to 0.36 mg/kg/week, but statural response to GH therapy remained poor."

The growth outcome, which is the clearest argument against the intervention in this disorder.

PMID:32879144 REFUTE Human Clinical

"These findings imply a critical role of pubertal development and/or advanced age rather than GH therapy in the development of IRDM"

Graded REFUTE because it contradicts the claim this treatment entry might otherwise be read as making - that growth hormone causes the diabetes. The authors attribute the diabetes to puberty instead.

Metabolic surveillance and management of insulin resistance

Action: Supportive Care NCIT:C15747

There is no disease-modifying therapy. Management centres on surveillance for and treatment of the metabolic consequences: because the risk of diabetes is high, regular monitoring of glucose metabolism is recommended, with treatment of hyperglycaemia when it develops.

Target Phenotypes: Insulin resistance HP:0000855 Diabetes mellitus HP:0000819

Show evidence (1 reference)

PMID:26497935 SUPPORT Human Clinical

"Given the high risk of diabetes mellitus, regular monitoring of glucose metabolism is warranted."

The explicit management recommendation from the cohort review.

Multisystem surveillance

Action: Supportive Care NCIT:C15747

Cardiac, ophthalmological and audiological assessment are recommended alongside the metabolic monitoring, reflecting the cardiac, anterior chamber and sensorineural components of the phenotype.

Target Phenotypes: Rieger anomaly HP:0000558 Glaucoma HP:0000501 Sensorineural hearing impairment HP:0000407

Show evidence (1 reference)

PMID:26497935 SUPPORT Human Clinical

"An echocardiogram, ophthalmological and hearing assessments are also recommended."

The surveillance recommendation this treatment entry implements.

🔬

Diagnosis

2

Clinical recognition with PIK3R1 sequencing

The diagnosis is suspected from the combination of intrauterine and postnatal growth restriction, lipoatrophy and the facial gestalt, and confirmed by finding a heterozygous PIK3R1 variant. Relying on the acronym as a checklist under-diagnoses the condition: in a molecularly confirmed cohort only about half of patients had four or more of the five classic features, so the acronym should not be treated as a diagnostic threshold.

Show evidence (2 references)

PMID:26497935 SUPPORT Human Clinical

"The major features described in the SHORT acronym were not universally seen and only half (52%) had four or more of the classic features."

The quantitative basis for not using the acronym as a diagnostic threshold.

PMID:26497935 SUPPORT Human Clinical

"Knowledge of the molecular etiology of SHORT syndrome has permitted a reassessment of the clinical phenotype."

States that molecular confirmation is what allowed the clinical definition to be revised, which is the argument for gene-first testing.

Immunological assessment for coexisting APDS2

Because PIK3R1 variants cause both SHORT syndrome and activated PI3K-delta syndrome 2, and because individuals manifesting both have been reported, patients with a PIK3R1 variant warrant assessment by clinical immunology as well as clinical genetics.

Show evidence (1 reference)

PMID:28302518 SUPPORT Human Clinical

"We recommend that patients with mutations in PIK3R1 gene should be assessed by both clinical immunologists and clinical geneticists."

The recommendation this diagnostic step implements, stated by the authors who reported the overlapping cases.

📈

Progression

2

Pubertal emergence of insulin-resistant diabetes

The metabolic phenotype has a clear temporal structure. Insulin resistance is detectable in childhood, but overt diabetes characteristically appears around or after puberty. In the literature review accompanying the case report, insulin-resistant diabetes had developed in 10 of 15 growth-hormone-untreated patients aged 12 or over, and in none of the three treated or six untreated patients aged 10 or under. That contrast is what separates an age effect from a treatment effect, and it sets the surveillance interval: glucose monitoring matters most from puberty onward.

Show evidence (1 reference)

PMID:32879144 SUPPORT Human Clinical

"Subsequent literature review for patients with molecularly confirmed SHORT syndrome revealed the development of IRDM in 10 of 15 GH-untreated patients aged ≥12 years but in none of three GH-treated and six GH-untreated patients aged ≤10 years."

The age-stratified counts, with the inequalities that make them a claim about puberty: every affected patient was 12 or older, and none of the nine aged 10 or under had developed diabetes regardless of growth hormone exposure.

Diabetes onset in the second decade

Consistent with the age-stratified counts, narrative reviews place the onset of type 2 diabetes in the second decade of life.

Show evidence (1 reference)

PMID:33129256 SUPPORT Human Clinical

"Severe insulin resistance may also lead to an early onset of type 2 diabetes, typically occurring in the second decade of life"

An independent statement of the same timing.

📊

Prevalence

1

Worldwide

Point Prevalence <1 in 1,000,000

An upper bound rather than an estimate. The cited source states explicitly that the prevalence is unclear and gives only a ceiling, so no point rate is recorded here. Cohort sizes in the literature are consistent with an ultra-rare disorder: the largest systematically phenotyped series comprised 32 individuals with a confirmed PIK3R1 variant.

Show evidence (2 references)

PMID:33129256 SUPPORT Human Clinical

"A few cases have been reported in the literature, but the prevalence of SHORT syndrome remains unclear"

The source declines to give a point estimate; only the ceiling that follows in the same sentence is quantitative, which is why this record carries a class and no rate.

PMID:26497935 SUPPORT Human Clinical

"The detailed phenotypes of 32 individuals with SHORT syndrome and PIK3R1 mutation, including eight newly ascertained individuals, were studied to fully define the syndrome and the indications for PIK3R1 testing."

The size of the largest systematically phenotyped molecularly confirmed cohort, which bounds how much is known about the disorder's occurrence.

🔀

Differential Diagnoses

2

Conditions with similar clinical presentations that must be differentiated from SHORT Syndrome:

Silver-Russell syndrome

Overlapping Features The differential that matters most in practice. A child presenting with intrauterine growth restriction, postnatal short stature and a triangular face fits both, and SRS is far commoner. The distinguishing features are the ones SRS lacks: the anterior segment anomaly, the partial lipodystrophy, and the severe insulin resistance that emerges at puberty. SHORT syndrome is recognised in the SRS literature as a differential precisely because of that phenotypic overlap.

Show evidence (1 reference)

PMID:32546215 SUPPORT Human Clinical

"our data confirmed IGF1R abnormality, SHORT syndrome, and Floating-Harbor syndrome are differential diagnoses of SRS because of the shared phenotypes among these syndromes and SRS"

States the differential relationship directly, from a cohort of 92 patients with an SRS phenotype and no identified cause.

Activated PI3K-delta syndrome 2

Overlapping Features The other PIK3R1-related disease. It is caused by a different class of variant in the same gene, acting in the opposite direction on PI3K signalling, and presents as a primary immunodeficiency. The two are not mutually exclusive: individuals with both phenotypes have been reported, so finding a PIK3R1 variant does not settle which disease a patient has.

Show evidence (1 reference)

PMID:28302518 SUPPORT Human Clinical

"Mutations in PIK3R1 gene have been associated to two different conditions: a primary immunodeficiency, called APDS2, of recent description and SHORT syndrome."

Establishes that one gene underlies both entities.

🐁

Animal Models

1

Pik3r1 R649W knock-in mouse

A heterozygous knock-in of the human hotspot allele, and the load-bearing model for this disease. It reproduces the growth, adipose and metabolic phenotype together, which is what allows the three arms of the human phenotype to be attributed to one signalling lesion rather than to three coincident ones.

Species

Mouse

Genotype

Pik3r1 Arg649Trp heterozygous knock-in

Publication

PMID:26974159

Pathograph links

Reduced PI3K-AKT Signal Transduction recapitulates fidelity: high The model demonstrates the signalling defect in vivo, across the three tissues that matter for the human phenotype, rather than only in cultured patient cells.

Limitations: A mouse carrying one human allele. The dental component of the human syndrome is not reported for this model. The ocular component is reported, in a separate study of the same line, and is curated as its own link below.

Readouts

Insulin and growth-factor-stimulated PI3K activation in liver, muscle and fat

Direction: DECREASED

Interpretation: The in vivo counterpart of the reduced AKT and S6 phosphorylation measured in patient cells.

Show evidence (1 reference)

PMID:26974159 SUPPORT Model Organism

"These derangements were associated with a reduced capacity of insulin and other growth factors to activate PI3K in liver, muscle, and fat"

The tissue-level measurement behind this readout.

Show evidence (1 reference)

PMID:26974159 SUPPORT Model Organism

"These data demonstrate the ability of this heterozygous mutation to alter PI3K activity in vivo and the central role of PI3K in insulin/growth factor action, adipocyte function, and glucose metabolism."

The authors' summary of what the model establishes.

Impaired Adipocyte Differentiation recapitulates fidelity: high Partial lipodystrophy is reproduced, alongside the reduced body weight and length.

Limitations: Regional distribution of the fat loss is not reported in the same terms as the human facial and upper-limb pattern, so the correspondence is at the level of "partial lipodystrophy" rather than of its anatomy.

Readouts

Body weight, length and adipose mass

Direction: DECREASED

Interpretation: The growth and adipose phenotype in the model.

Show evidence (1 reference)

PMID:26974159 SUPPORT Model Organism

"Similar to the patients, mutant mice exhibited a reduction in body weight and length, partial lipodystrophy, and systemic insulin resistance."

The three-way phenotypic correspondence with patients.

Show evidence (1 reference)

PMID:26974159 SUPPORT Model Organism

"Similar to the patients, mutant mice exhibited a reduction in body weight and length, partial lipodystrophy, and systemic insulin resistance."

Establishes the model's fidelity for the adipose arm.

Anterior Segment Dysgenesis recapitulates fidelity: high The same knock-in line was examined ophthalmologically alongside two human R649W subjects. The mice have significantly thinner and narrower irides with enlarged, irregular pupils, and the human subjects have the corresponding Rieger anomaly with thin irides and irregular pupils. This is the evidence that the ocular arm of the syndrome follows from the p85-alpha lesion rather than from an unrelated cause, and it is what makes a single heterozygous allele sufficient for anterior segment dysgenesis in vivo.

Limitations: The mouse phenotype is milder than the human one and is confined to the iris: overall eye development, cornea, lens, anterior chamber volume, intraocular pressure and retinal structure were all normal in the mice, whereas the human subjects also had goniosynechiae, early cataract and glaucoma. So the model establishes that the lesion reaches iris development, not that it reproduces the full human anterior segment phenotype. It also says nothing about the intervening developmental steps.

Readouts

Iris thickness and width on optical coherence tomography

Direction: DECREASED

Interpretation: Thinner and narrower iris with a consequently enlarged, irregular pupil - the structural measurement that grounds the ocular claim.

Show evidence (1 reference)

PMID:28632845 SUPPORT Model Organism

"OCT images of the knock-in mouse eyes revealed a significant decrease in thickness and width of the iris resulting in increased pupil area and irregularity of shape."

The imaging measurement behind this readout, in the same knock-in line curated above.

Show evidence (1 reference)

PMID:28632845 SUPPORT Model Organism

"A dominant-negative mutation in the p85α regulatory subunit of PI3K affects development of the iris, and contributes to changes consistent with anterior segment dysgenesis in both humans and mice."

The authors' conclusion, drawn from the mouse and the human subjects together, that this mutation is what drives the anterior segment phenotype.

Dissociation of Insulin Resistance from Dyslipidaemia recapitulates fidelity: moderate Challenged with a high-fat diet or crossed onto an obese background, the mutant mice are protected from obesity and hepatic steatosis while becoming more diabetic. That is the mouse form of the human dissociation, and it separates the two effects experimentally in a way patient observation cannot.

Limitations: The mouse experiments impose obesogenic challenges that patients are not subjected to, so the protection is demonstrated under conditions with no human counterpart. The direction of the dissociation matches; its magnitude in unchallenged animals is not reported here.

Readouts

Adiposity and hepatic steatosis under obesogenic challenge

Direction: DECREASED

Interpretation: Less fat and less fatty liver despite worse glycaemia, which is the dissociation.

Show evidence (1 reference)

PMID:29724723 SUPPORT Model Organism

"the ob/ob mice carrying the heterozygous R649W mutation were protected from obesity and hepatic steatosis but developed a severe diabetic state"

The clearest statement of the dissociation, in the genetically obese cross.

Show evidence (1 reference)

PMID:29724723 SUPPORT Model Organism

"despite the lower level of adiposity, the HFD knock-in mice are more hyperglycemic and more insulin-resistant than HFD-fed control mice"

The dissociation under dietary challenge: less adiposity, worse glycaemia.

{ }

Source YAML

click to show

name: SHORT Syndrome
creation_date: "2026-09-01T14:07:00Z"
description: >-
  SHORT syndrome is a rare autosomal dominant multisystem disorder caused by
  heterozygous variants in PIK3R1, which encodes the p85-alpha, p55-alpha and
  p50-alpha regulatory subunits of class IA phosphatidylinositol 3-kinase. The
  causal variants cluster in exon 14, in the C-terminal SH2 domain, with a
  recurrent p.Arg649Trp hotspot; they impair the interaction between p85-alpha and
  IRS-1 and reduce AKT-mediated insulin signalling, so the disease is a
  post-receptor defect of PI3K-AKT signal transduction rather than of the insulin
  receptor itself. The acronym records short stature, hyperextensibility of joints
  and/or inguinal hernia, ocular depression, Rieger anomaly and teething delay, but
  systematic phenotyping of a PIK3R1-confirmed cohort showed that these classic
  features are not universally present; intrauterine and postnatal growth
  restriction, lipoatrophy and a characteristic facial gestalt are the features
  most consistently seen, with anterior chamber defects and insulin resistance or
  diabetes less prevalent. Because the same gene also causes activated PI3K-delta
  syndrome 2 through a different class of variant with the opposite effect on
  signalling, PIK3R1 genotype alone does not predict which phenotype a patient will
  have, and rare individuals manifest both.
synonyms:
- Short stature, hyperextensibility of joints, ocular depression, Rieger anomaly and teething delay
- Lipodystrophy, partial, with Rieger anomaly and short stature
- Rieger anomaly-partial lipodystrophy syndrome
- Aarskog-Ose-Pande syndrome
- PIK3R1-related SHORT syndrome
category: Mendelian
disease_term:
  preferred_term: SHORT syndrome
  term:
    id: MONDO:0010026
    label: SHORT syndrome
mappings:
  mondo_mappings:
  - term:
      id: MONDO:0010026
      label: SHORT syndrome
    mapping_predicate: skos:exactMatch
    mapping_source: MONDO
parents:
- Hereditary lipodystrophy
- Syndromic insulin resistance
inheritance:
- name: Autosomal dominant inheritance
  penetrance: INCOMPLETE
  inheritance_term:
    preferred_term: Autosomal dominant inheritance
    term:
      id: HP:0000006
      label: Autosomal dominant inheritance
  description: >-
    Heterozygous PIK3R1 variants segregate in an autosomal dominant manner. Both de
    novo and inherited variants are reported, and the recurrent p.Arg649Trp allele
    has been observed to segregate with the phenotype in multigenerational families
    as well as arising de novo. Penetrance is recorded as INCOMPLETE on the strength of a
    single documented asymptomatic carrier: a novel frameshift variant found in a child
    with APDS2 and mild SHORT features was also present in the mother, who was clinically
    unaffected. That is one family, and it concerns a variant at the APDS2 end of the
    PIK3R1 spectrum rather than a classic cSH2 SHORT allele, so it should not be read as a
    penetrance estimate for p.Arg649Trp.
  evidence:
  - reference: PMID:35789397
    reference_title: Clinical and immunological assessment of APDS2 with features of the SHORT syndrome related to a novel mutation in PIK3R1 with reduced penetrance.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      The same variant was also identified in the patient's hitherto asymptomatic mother,
      implicating an incomplete penetrance.
    explanation: >-
      The only penetrance observation in this literature: an unaffected carrier parent. It
      is a single family and the authors themselves state the inference rather than
      quantifying it.
  - reference: PMID:23980586
    reference_title: PIK3R1 mutations in SHORT syndrome.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      SHORT syndrome (OMIM 269880) is a rare autosomal-dominant disorder
    explanation: >-
      States the mode of inheritance directly.
  - reference: PMID:23810378
    reference_title: PIK3R1 mutations cause syndromic insulin resistance with lipoatrophy.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Overall, we identified in nine affected individuals from eight families de
      novo or inherited PIK3R1 mutations
    explanation: >-
      Records that both de novo and inherited heterozygous alleles occur, which is
      what makes the dominant transmission observable across families.
prevalence:
- population: Worldwide
  measure_type: POINT_PREVALENCE
  prevalence_class: BELOW_1_IN_1000000
  notes: >-
    An upper bound rather than an estimate. The cited source states explicitly that
    the prevalence is unclear and gives only a ceiling, so no point rate is
    recorded here. Cohort sizes in the literature are consistent with an ultra-rare
    disorder: the largest systematically phenotyped series comprised 32 individuals
    with a confirmed PIK3R1 variant.
  evidence:
  - reference: PMID:33129256
    reference_title: "A novel PIK3R1 mutation of SHORT syndrome in a Chinese female with diffuse thyroid disease: a case report and review of literature."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      A few cases have been reported in the literature, but the prevalence of SHORT
      syndrome remains unclear
    explanation: >-
      The source declines to give a point estimate; only the ceiling that follows in
      the same sentence is quantitative, which is why this record carries a class
      and no rate.
  - reference: PMID:26497935
    reference_title: "Clinical reappraisal of SHORT syndrome with PIK3R1 mutations: toward recommendation for molecular testing and management."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      The detailed phenotypes of 32 individuals with SHORT syndrome and PIK3R1
      mutation, including eight newly ascertained individuals, were studied to fully
      define the syndrome and the indications for PIK3R1 testing.
    explanation: >-
      The size of the largest systematically phenotyped molecularly confirmed cohort,
      which bounds how much is known about the disorder's occurrence.
pathophysiology:
- name: PIK3R1 C-terminal SH2 Domain Variant
  biological_scale: MOLECULAR
  description: >-
    Heterozygous PIK3R1 variants cluster in exon 14, which encodes the C-terminal
    SH2 domain of the p85-alpha regulatory subunit. The reported allele spectrum
    comprises missense, frameshift and nonsense changes, all of which spare the
    N-terminal half of the protein, and c.1945C>T (p.Arg649Trp) recurs across
    unrelated families as a mutational hotspot. PIK3R1 also encodes the p55-alpha
    and p50-alpha subunits, so a single allele perturbs the regulatory arm of every
    class IA PI3K holoenzyme in which those subunits participate.
  genes:
  - preferred_term: PIK3R1
    term:
      id: hgnc:8979
      label: PIK3R1
  molecular_functions:
  - preferred_term: p85-alpha PI3K regulatory subunit activity
    term:
      id: GO:0035014
      label: phosphatidylinositol 3-kinase regulator activity
    modifier: ABNORMAL
  downstream:
  - target: Impaired p85-alpha Binding to IRS-1
    causal_link_type: DIRECT
    description: >-
      The variant SH2 domain is the surface through which p85-alpha docks onto
      tyrosine-phosphorylated IRS-1, so a change in this domain acts directly on
      that interaction.
    evidence:
    - reference: PMID:23810379
      reference_title: SHORT syndrome with partial lipodystrophy due to impaired phosphatidylinositol 3 kinase signaling.
      supports: SUPPORT
      evidence_source: IN_VITRO
      snippet: >-
        This mutation led to impaired interaction between p85α and IRS-1 and reduced
        AKT-mediated insulin signaling in fibroblasts from affected subjects
      explanation: >-
        Directly links the hotspot variant to loss of the p85-alpha/IRS-1 interaction.
  evidence:
  - reference: PMID:23810382
    reference_title: Mutations in PIK3R1 cause SHORT syndrome.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Whole-exome sequencing in a family trio of an affected child and unaffected
      parents identified a de novo frameshift insertion, c.1906_1907insC
    explanation: >-
      The exome finding that identified PIK3R1 as the SHORT syndrome gene, and the
      first of the exon 14 alleles.
  - reference: PMID:23810378
    reference_title: PIK3R1 mutations cause syndromic insulin resistance with lipoatrophy.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      we identified in nine affected individuals from eight families de novo or
      inherited PIK3R1 mutations, including a mutational hotspot
    explanation: >-
      Establishes p.Arg649Trp as a recurrent allele across unrelated families.
  - reference: PMID:23810378
    reference_title: PIK3R1 mutations cause syndromic insulin resistance with lipoatrophy.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      PIK3R1 encodes the p85α, p55α, and p50α regulatory subunits of class IA
      phosphatidylinositol 3 kinases (PI3Ks), which are known to play a key role in
      insulin signaling.
    explanation: >-
      States which gene products are affected and why a regulatory-subunit defect
      reaches insulin signalling.
- name: Impaired p85-alpha Binding to IRS-1
  biological_scale: MOLECULAR
  description: >-
    Recruitment of class IA PI3K to the activated insulin receptor depends on the
    p85-alpha SH2 domains engaging phosphotyrosine motifs on IRS-1. The SHORT
    syndrome hotspot variant impairs that interaction, so the catalytic p110 subunit
    is not brought to its membrane substrate after insulin stimulation. This is the
    step that makes the disease a post-receptor defect: the insulin receptor itself
    is intact.
  molecular_functions:
  - preferred_term: p85-alpha binding to IRS-1
    term:
      id: GO:0043560
      label: insulin receptor substrate binding
    modifier: DECREASED
  downstream:
  - target: Reduced PI3K-AKT Signal Transduction
    causal_link_type: DIRECT
    description: >-
      Failure to recruit the holoenzyme to IRS-1 is the immediate cause of reduced
      downstream AKT and S6 phosphorylation.
    evidence:
    - reference: PMID:23810382
      reference_title: Mutations in PIK3R1 cause SHORT syndrome.
      supports: SUPPORT
      evidence_source: IN_VITRO
      snippet: >-
        Functional studies on lymphoblastoid cells with the PIK3R1 c.1906_1907insC
        mutation showed decreased phosphorylation of the downstream S6 target of the
        PI3K-AKT-mTOR pathway.
      explanation: >-
        Measures the downstream consequence in patient-derived cells.
  evidence:
  - reference: PMID:23810379
    reference_title: SHORT syndrome with partial lipodystrophy due to impaired phosphatidylinositol 3 kinase signaling.
    supports: SUPPORT
    evidence_source: IN_VITRO
    snippet: >-
      This mutation led to impaired interaction between p85α and IRS-1 and reduced
      AKT-mediated insulin signaling in fibroblasts from affected subjects and in
      reconstituted Pik3r1-knockout preadipocytes.
    explanation: >-
      Demonstrates the binding defect in both patient fibroblasts and a reconstituted
      preadipocyte system.
- name: Reduced PI3K-AKT Signal Transduction
  biological_scale: CELLULAR
  description: >-
    Downstream of the failed IRS-1 interaction, phosphorylation of AKT and of the
    more distal S6 target is reduced in patient-derived cells. The defect is not
    confined to one branch of the cascade: proximal and distal PI3K-dependent
    signalling are both impaired, which is why one molecular lesion produces a
    phenotype spanning growth, adipose tissue and glucose metabolism.
  cell_types:
  - preferred_term: patient-derived dermal fibroblast
    term:
      id: CL:0000057
      label: fibroblast
  biological_processes:
  - preferred_term: PI3K-AKT signal transduction
    term:
      id: GO:0043491
      label: phosphatidylinositol 3-kinase/protein kinase B signal transduction
    modifier: DECREASED
  downstream:
  - target: Post-receptor Insulin Resistance
    causal_link_type: DIRECT
    description: >-
      Reduced PI3K-dependent signalling downstream of an intact insulin receptor is
      what post-receptor insulin resistance consists of at the cellular level.
    evidence:
    - reference: PMID:23810378
      reference_title: PIK3R1 mutations cause syndromic insulin resistance with lipoatrophy.
      supports: SUPPORT
      evidence_source: IN_VITRO
      snippet: >-
        Functional data from fibroblasts derived from individuals with PIK3R1
        mutations showed severe insulin resistance for both proximal and distal
        PI3K-dependent signaling.
      explanation: >-
        Shows the signalling defect is present at both proximal and distal levels of
        the cascade in patient cells.
  - target: Impaired Adipocyte Differentiation
    causal_link_type: DIRECT
    description: >-
      PI3K activity is required for adipose differentiation, so the same reduction in
      signalling that impairs insulin action also constrains adipogenesis.
    evidence:
    - reference: PMID:23810379
      reference_title: SHORT syndrome with partial lipodystrophy due to impaired phosphatidylinositol 3 kinase signaling.
      supports: SUPPORT
      evidence_source: IN_VITRO
      snippet: >-
        Normal PI3K activity is critical for adipose differentiation and insulin
        signaling
      explanation: >-
        States the dependency of adipose differentiation on PI3K activity that this
        edge asserts.
  - target: Impaired Insulin Secretion and Incretin Response
    causal_link_type: INDIRECT_UNKNOWN_INTERMEDIATES
    description: >-
      PI3K signalling operates in the beta cell as well as in insulin target tissues, so
      the secretory defect seen in the knock-in mouse plausibly shares this upstream
      lesion. The intervening steps in the islet are not established.
    evidence:
    - reference: PMID:26974159
      reference_title: PI3-kinase mutation linked to insulin and growth factor resistance in vivo.
      supports: SUPPORT
      evidence_source: MODEL_ORGANISM
      snippet: >-
        These data demonstrate the ability of this heterozygous mutation to alter PI3K
        activity in vivo and the central role of PI3K in insulin/growth factor action,
        adipocyte function, and glucose metabolism.
      explanation: >-
        Places the secretory defect within the same in vivo PI3K lesion. The islet
        mechanism itself is not resolved, hence unknown intermediates.
      directness: INDIRECT
  - target: Progeroid Craniofacial and Dental Development
    causal_link_type: INDIRECT_UNKNOWN_INTERMEDIATES
    description: >-
      The craniofacial and dental features segregate with PIK3R1 variants and are, on
      systematic appraisal, the most consistent part of the phenotype. No developmental
      mechanism connecting reduced PI3K signalling to them is established, so the edge is
      drawn with unknown intermediates rather than omitted.
    evidence:
    - reference: PMID:34212753
      reference_title: "SHORT Syndrome: Systematic Appraisal of the Medical and Dental Phenotype."
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: >-
        Facial dysmorphism including ocular depression, triangular shaped face, frontal
        bossing, large low-set ears, and micrognathia were the most consistent features
      explanation: >-
        Establishes the craniofacial gestalt as the most consistent element of the
        syndrome, which is what makes it worth a node despite the missing mechanism.
      directness: INDIRECT
  - target: Anterior Segment Dysgenesis
    causal_link_type: INDIRECT_UNKNOWN_INTERMEDIATES
    description: >-
      The anterior chamber phenotype is attributed to the same signalling defect because
      it segregates with PIK3R1 variants, but no developmental route from reduced PI3K
      signalling to neural-crest-derived anterior segment formation is established. The
      edge is drawn with unknown intermediates rather than left disconnected, because
      leaving it disconnected would imply an independent cause the evidence does not
      support.
    evidence:
    - reference: PMID:23810379
      reference_title: SHORT syndrome with partial lipodystrophy due to impaired phosphatidylinositol 3 kinase signaling.
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: >-
        in two unrelated families affected by partial lipodystrophy, low body mass index,
        short stature, progeroid face, and Rieger anomaly (SHORT syndrome)
      explanation: >-
        Rieger anomaly segregates with the same variant as the metabolic and growth
        features, which is the basis for placing it downstream of the shared signalling
        lesion. It is co-segregation, not a demonstrated developmental mechanism.
      directness: INDIRECT
  - target: Impaired Growth Signalling
    causal_link_type: DIRECT
    description: >-
      The PI3K-AKT-mTOR axis drives cell growth and proliferation, so its
      downregulation is the proposed route from the variant to the growth phenotype.
    evidence:
    - reference: PMID:23810382
      reference_title: Mutations in PIK3R1 cause SHORT syndrome.
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: >-
        PIK3R1 is involved in the phosphatidylinositol 3 kinase (PI3K) signaling
        cascade and, as such, plays an important role in cell growth, proliferation,
        and survival.
      explanation: >-
        The authors' statement of the pathway's growth role, which is the basis for
        attributing the growth restriction to pathway downregulation. This is an
        inference about the pathway rather than a measurement in growth plate tissue.
      directness: INDIRECT
  evidence:
  - reference: PMID:23810382
    reference_title: Mutations in PIK3R1 cause SHORT syndrome.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Our findings show that PIK3R1 mutations are the major cause of SHORT syndrome
      and suggest that the molecular mechanism of disease might involve
      downregulation of the PI3K-AKT-mTOR pathway.
    explanation: >-
      The authors' own summary of the proposed mechanism. Note the hedge in the
      original ("might involve") is preserved here rather than upgraded.
- name: Post-receptor Insulin Resistance
  biological_scale: ORGANISM
  description: >-
    Insulin resistance in SHORT syndrome arises below the receptor, in the PI3K arm
    of the cascade. Clinically this presents as severe insulin resistance with
    compensatory hyperinsulinaemia, progressing in some patients to diabetes,
    typically in the second decade.
  biological_processes:
  - preferred_term: insulin receptor signaling pathway
    term:
      id: GO:0008286
      label: insulin receptor signaling pathway
    modifier: DECREASED
  downstream:
  - target: Insulin resistance
    causal_link_type: DIRECT
    description: >-
      The cellular signalling defect is the mechanism of the clinical insulin
      resistance.
    evidence:
    - reference: PMID:23810378
      reference_title: PIK3R1 mutations cause syndromic insulin resistance with lipoatrophy.
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: >-
        Our findings extend the genetic causes of severe insulin-resistance syndromes
      explanation: >-
        Places SHORT syndrome among the severe insulin-resistance syndromes.
  - target: Diabetes mellitus
    causal_link_type: DIRECT
    description: >-
      Sustained severe insulin resistance is the route to diabetes in this disorder.
    evidence:
    - reference: PMID:33129256
      reference_title: "A novel PIK3R1 mutation of SHORT syndrome in a Chinese female with diffuse thyroid disease: a case report and review of literature."
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: >-
        Severe insulin resistance may also lead to an early onset of type 2 diabetes,
        typically occurring in the second decade of life
      explanation: >-
        States both the causal step and its usual timing.
  - target: Dissociation of Insulin Resistance from Dyslipidaemia
    causal_link_type: DIRECT
    description: >-
      The insulin resistance of SHORT syndrome does not carry the metabolic company it
      usually keeps. This is not an absence of findings but a positive, discriminating
      feature.
    evidence:
    - reference: PMID:27766312
      reference_title: Insulin resistance uncoupled from dyslipidemia due to C-terminal PIK3R1 mutations.
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: >-
        Four of 5 patients had extreme insulin resistance without dyslipidemia or hepatic
        steatosis.
      explanation: >-
        The counted observation that defines this node.
  - target: Polycystic ovaries
    causal_link_type: INDIRECT_KNOWN_INTERMEDIATES
    description: >-
      Hyperinsulinaemia secondary to insulin resistance is the conventional route to
      the ovarian phenotype; the cited source reports the association, not the
      intervening steps.
    evidence:
    - reference: PMID:33129256
      reference_title: "A novel PIK3R1 mutation of SHORT syndrome in a Chinese female with diffuse thyroid disease: a case report and review of literature."
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: >-
        almost all postpubertal women affected present polycystic ovary syndrome
      explanation: >-
        Records the near-universal ovarian phenotype in postpubertal affected women.
        The quote establishes the association; the insulin-mediated mechanism is the
        curator's inference and is why this edge is marked INDIRECT.
      directness: INDIRECT
  evidence:
  - reference: PMID:23980586
    reference_title: PIK3R1 mutations in SHORT syndrome.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      teething delay, partial lipodystrophy, insulin resistance and facial dysmorphic
      signs
    explanation: >-
      Lists insulin resistance among the defining features of the syndrome.
  - reference: PMID:35110500
    reference_title: New classification and diagnostic criteria for insulin resistance syndrome.
    supports: SUPPORT
    evidence_source: OTHER
    snippet: >-
      conditions such as SHORT syndrome caused by abnormalities of PIK3R1, which encodes a
      regulatory subunit of phosphatidylinositol 3-kinase
    explanation: >-
      A national diabetes society's formal classification placing SHORT syndrome among the
      genetic insulin resistance syndromes, which is the citation behind this entry's
      "Syndromic insulin resistance" parent. Graded OTHER as an expert-consensus
      classification document rather than a study.
- name: Dissociation of Insulin Resistance from Dyslipidaemia
  biological_scale: ORGANISM
  description: >-
    Obesity-related insulin resistance travels with fatty liver, dyslipidaemia and low
    adiponectin. Insulin resistance from insulin-receptor dysfunction travels with none of
    them, and insulin resistance from AKT2 dysfunction phenocopies the obesity pattern.
    SHORT syndrome sits with the receptor group: four of five studied patients had extreme
    insulin resistance without dyslipidaemia or hepatic steatosis, and adiponectin was
    preserved in three of those four. Because PIK3R1 acts between the receptor and AKT,
    that placement is informative about where in the cascade the lesion sits, and it makes
    the metabolic profile a discriminating clinical feature rather than an incidental one.
  downstream:
  - target: Hypertriglyceridemia
    causal_link_type: DIRECT
    description: >-
      The other half of the dissociation, and recorded the same way: an expected feature
      that is characteristically absent.
    evidence:
    - reference: PMID:27766312
      reference_title: Insulin resistance uncoupled from dyslipidemia due to C-terminal PIK3R1 mutations.
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: >-
        Four of 5 patients had extreme insulin resistance without dyslipidemia or hepatic
        steatosis.
      explanation: >-
        Establishes the absence of dyslipidaemia, which is the claim the linked phenotype
        records.
  - target: Hepatic steatosis
    causal_link_type: DIRECT
    description: >-
      Recorded as an expected feature that is characteristically absent. The phenotype
      entry carries REFUTE evidence rather than asserting its presence.
    evidence:
    - reference: PMID:27766312
      reference_title: Insulin resistance uncoupled from dyslipidemia due to C-terminal PIK3R1 mutations.
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: >-
        Four of 5 patients had extreme insulin resistance without dyslipidemia or hepatic
        steatosis.
      explanation: >-
        Establishes the absence, which is the claim the linked phenotype records.
  evidence:
  - reference: PMID:27766312
    reference_title: Insulin resistance uncoupled from dyslipidemia due to C-terminal PIK3R1 mutations.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Obesity-related insulin resistance is associated with fatty liver, dyslipidemia, and
      low plasma adiponectin. Insulin resistance due to insulin receptor (INSR) dysfunction
      is associated with none of these
    explanation: >-
      The comparison that gives the dissociation its meaning: which group SHORT syndrome
      resembles is a statement about where in the cascade the lesion is.
  - reference: PMID:27766312
    reference_title: Insulin resistance uncoupled from dyslipidemia due to C-terminal PIK3R1 mutations.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      PIK3R1 C-terminal mutations impair insulin signaling only in some cellular contexts
      and produce a subphenotype of insulin resistance resembling INSR dysfunction but
      unlike AKT2 dysfunction
    explanation: >-
      The authors' own conclusion, including the qualification that the signalling defect
      is context-dependent rather than global. That qualification is carried into the
      discussions rather than dropped.
- name: Impaired Insulin Secretion and Incretin Response
  biological_scale: ORGANISM
  description: >-
    A second, beta-cell arm of the metabolic phenotype, demonstrated only in the knock-in
    mouse: the mutation impairs insulin secretion and the action of GLP-1 on islets, in
    vivo and in vitro. If it holds in patients it means the diabetes is not purely a
    resistance phenomenon, which would matter for treatment choice. No equivalent human
    measurement is cited, so this node is model-derived throughout.
  biological_processes:
  - preferred_term: insulin secretion
    term:
      id: GO:0030073
      label: insulin secretion
    modifier: DECREASED
  downstream:
  - target: Diabetes mellitus
    causal_link_type: INDIRECT_KNOWN_INTERMEDIATES
    description: >-
      A secretory defect on top of resistance would lower the threshold for overt
      hyperglycaemia. Marked indirect because the secretory defect is shown in mouse and
      the diabetes is a human phenotype.
    evidence:
    - reference: PMID:26974159
      reference_title: PI3-kinase mutation linked to insulin and growth factor resistance in vivo.
      supports: SUPPORT
      evidence_source: MODEL_ORGANISM
      snippet: >-
        mutant mice displayed defective insulin secretion and GLP-1 action on islets in
        vivo and in vitro
      explanation: >-
        The secretory and incretin defect in the knock-in model.
      directness: INDIRECT
  evidence:
  - reference: PMID:26974159
    reference_title: PI3-kinase mutation linked to insulin and growth factor resistance in vivo.
    supports: SUPPORT
    evidence_source: MODEL_ORGANISM
    snippet: >-
      In addition, mutant mice displayed defective insulin secretion and GLP-1 action on
      islets in vivo and in vitro.
    explanation: >-
      The observation this node records, stated as a mouse result.
- name: Impaired Adipocyte Differentiation
  biological_scale: CELLULAR
  description: >-
    PI3K signalling is required for preadipocytes to differentiate into mature
    adipocytes. The hotspot variant reduces AKT-mediated insulin signalling in
    reconstituted Pik3r1-knockout preadipocytes, and the resulting failure of
    adipose differentiation is the proposed basis of the partial lipodystrophy, which
    characteristically affects the face, chest and upper extremities while sparing
    the buttocks and legs.
  cell_types:
  - preferred_term: preadipocyte
    term:
      id: CL:0002334
      label: preadipocyte
  - preferred_term: adipocyte
    term:
      id: CL:0000136
      label: adipocyte
  biological_processes:
  - preferred_term: fat cell differentiation
    term:
      id: GO:0045444
      label: fat cell differentiation
    modifier: DECREASED
  downstream:
  - target: Triangular face
    causal_link_type: INDIRECT_KNOWN_INTERMEDIATES
    description: >-
      Facial lipoatrophy is a major contributor to the progeroid facial gestalt. It is not
      the whole of it - frontal bossing and micrognathia are skeletal - but the loss of
      facial fat is what gives the aged appearance.
    evidence:
    - reference: PMID:33129256
      reference_title: "A novel PIK3R1 mutation of SHORT syndrome in a Chinese female with diffuse thyroid disease: a case report and review of literature."
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: >-
        causing an aged appearance of the patients suffering from the SHORT syndrome
      explanation: >-
        States the causal contribution of the facial fat loss to the appearance. The
        skeletal components of the gestalt are not covered by this edge.
      directness: INDIRECT
  - target: Deeply set eye
    causal_link_type: INDIRECT_KNOWN_INTERMEDIATES
    description: >-
      Loss of periorbital fat contributes to the ocular depression that gives the acronym
      its "O".
    evidence:
    - reference: PMID:33129256
      reference_title: "A novel PIK3R1 mutation of SHORT syndrome in a Chinese female with diffuse thyroid disease: a case report and review of literature."
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: >-
        Lipodystrophy, characterized by selective loss of adipose tissue, is another
        typical feature of the syndrome. It is displayed mainly in the face
      explanation: >-
        Establishes facial adipose loss. The specific attribution of ocular depression to
        periorbital fat loss is the curator's reading, which is why the edge is indirect.
      directness: INDIRECT
  - target: Lipoatrophy
    causal_link_type: DIRECT
    description: >-
      Failure of adipose differentiation produces the regional loss of subcutaneous
      fat that defines the lipodystrophy.
    evidence:
    - reference: PMID:33129256
      reference_title: "A novel PIK3R1 mutation of SHORT syndrome in a Chinese female with diffuse thyroid disease: a case report and review of literature."
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: >-
        It is displayed mainly in the face, chest and upper extremities, often sparing
        the buttocks and legs
      explanation: >-
        The regional distribution of the fat loss, which is what makes it partial
        rather than generalised.
  evidence:
  - reference: PMID:23810379
    reference_title: SHORT syndrome with partial lipodystrophy due to impaired phosphatidylinositol 3 kinase signaling.
    supports: SUPPORT
    evidence_source: IN_VITRO
    snippet: >-
      reduced AKT-mediated insulin signaling in fibroblasts from affected subjects and
      in reconstituted Pik3r1-knockout preadipocytes
    explanation: >-
      The preadipocyte model in which the signalling defect relevant to adipogenesis
      was demonstrated.
  - reference: PMID:23810379
    reference_title: SHORT syndrome with partial lipodystrophy due to impaired phosphatidylinositol 3 kinase signaling.
    supports: SUPPORT
    evidence_source: IN_VITRO
    snippet: >-
      the mutated PIK3R1 therefore provides a unique link among lipodystrophy, growth,
      and insulin signaling
    explanation: >-
      The authors' framing of one lesion producing the three arms of the phenotype,
      which is the structure this pathograph encodes.
- name: Impaired Growth Signalling
  biological_scale: ORGANISM
  description: >-
    Growth restriction in SHORT syndrome begins prenatally and continues after birth.
    It is attributed to downregulation of the PI3K-AKT-mTOR axis, which drives cell
    growth and proliferation. This attribution rests on the pathway's known role
    rather than on a direct measurement in growth-plate tissue from patients.
  downstream:
  - target: Intrauterine growth retardation
    causal_link_type: DIRECT
    description: >-
      The prenatal arm of the growth phenotype.
    evidence:
    - reference: PMID:26497935
      reference_title: "Clinical reappraisal of SHORT syndrome with PIK3R1 mutations: toward recommendation for molecular testing and management."
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: >-
        The commonly observed clinical features of SHORT syndrome seen in the cohort
        included intrauterine growth restriction (IUGR)
      explanation: >-
        Establishes IUGR as one of the consistently observed features in the
        molecularly confirmed cohort.
  - target: Short stature
    causal_link_type: DIRECT
    description: >-
      The postnatal arm of the same growth phenotype.
    evidence:
    - reference: PMID:26497935
      reference_title: "Clinical reappraisal of SHORT syndrome with PIK3R1 mutations: toward recommendation for molecular testing and management."
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: >-
        postnatal growth restriction, lipoatrophy and the characteristic facial
        gestalt
      explanation: >-
        Lists postnatal growth restriction among the consistently observed features.
  evidence:
  - reference: PMID:23810382
    reference_title: Mutations in PIK3R1 cause SHORT syndrome.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      plays an important role in cell growth, proliferation, and survival
    explanation: >-
      The pathway property the growth phenotype is attributed to. Cited as the basis
      for the inference, not as a measurement of growth-plate signalling.
    directness: INDIRECT
  - reference: PMID:24886349
    reference_title: Exome sequencing identifies a novel mutation in PIK3R1 as the cause of SHORT syndrome.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      the patients usually present a low birth weight and height, lipodystrophy, delayed
      bone age, hernias, low body mass index and a progeroid appearance
    explanation: >-
      Establishes that the growth deficit is present from birth and is accompanied by
      delayed skeletal maturation, which is what makes it a growth-signalling phenotype
      rather than a nutritional one.
  - reference: PMID:36401775
    reference_title: "SHORT Syndrome: an Update on Pathogenesis and Clinical Spectrum."
    supports: SUPPORT
    evidence_source: OTHER
    snippet: >-
      PI3K malfunction is associated with insulin resistance, decreased lipogenesis,
      increased energy expenditure, and possible IGF1 resistance.
    explanation: >-
      Names three candidate routes to the growth phenotype that are more specific than "the
      pathway drives growth": IGF1 resistance, increased energy expenditure, and decreased
      lipogenesis. The review hedges on the IGF1 arm ("possible"), and that hedge is
      retained. Graded OTHER as a narrative review.
- name: Progeroid Craniofacial and Dental Development
  biological_scale: TISSUE
  description: >-
    A distinct progeroid craniofacial appearance - triangular face, frontal bossing,
    hypoplastic or thin alae nasi, large low-set ears, mandibular retrognathia - together
    with a dental phenotype broader than the acronym's "teething delay": microdontia,
    hypodontia and enamel hypoplasia are all reported. Systematic appraisal found the
    facial dysmorphism to be the *most* consistent feature of the syndrome, ahead of the
    eponymous ocular and dental signs, which makes it the best recognition cue and not a
    minor detail. The facial fat loss contributes to the appearance and is modelled
    separately from the adipose node; the skeletal and dental components have no
    established mechanism, which is why this node carries no upstream molecular detail.
  downstream:
  - target: Frontal bossing
    causal_link_type: DIRECT
    description: A skeletal component of the gestalt.
    evidence:
    - reference: PMID:34212753
      reference_title: "SHORT Syndrome: Systematic Appraisal of the Medical and Dental Phenotype."
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: >-
        Individuals have a distinct progeroid craniofacial appearance with a triangular
        face, frontal bossing, hypoplastic or thin alae nasi, large low-set ears, and
        mandibular retrognathia.
      explanation: Names frontal bossing as a component of the craniofacial appearance.
  - target: Micrognathia
    causal_link_type: DIRECT
    description: Mandibular retrognathia, a skeletal component of the gestalt.
    evidence:
    - reference: PMID:34212753
      reference_title: "SHORT Syndrome: Systematic Appraisal of the Medical and Dental Phenotype."
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: >-
        a triangular face, frontal bossing, hypoplastic or thin alae nasi, large low-set
        ears, and mandibular retrognathia
      explanation: Names mandibular retrognathia as a component.
  - target: Low-set ears
    causal_link_type: DIRECT
    description: Large low-set ears, a component of the gestalt.
    evidence:
    - reference: PMID:34212753
      reference_title: "SHORT Syndrome: Systematic Appraisal of the Medical and Dental Phenotype."
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: >-
        hypoplastic or thin alae nasi, large low-set ears, and mandibular retrognathia
      explanation: Names the ear finding as a component.
  - target: Underdeveloped nasal alae
    causal_link_type: DIRECT
    description: Hypoplastic or thin alae nasi.
    evidence:
    - reference: PMID:34212753
      reference_title: "SHORT Syndrome: Systematic Appraisal of the Medical and Dental Phenotype."
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: >-
        a triangular face, frontal bossing, hypoplastic or thin alae nasi
      explanation: Names the alae nasi finding as a component.
  - target: Delayed eruption of teeth
    causal_link_type: DIRECT
    description: The "T" of the acronym, part of the dental phenotype.
    evidence:
    - reference: PMID:34212753
      reference_title: "SHORT Syndrome: Systematic Appraisal of the Medical and Dental Phenotype."
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: >-
        Teething delay, microdontia, hypodontia, and enamel hypoplasia have all been
        reported.
      explanation: Groups the teething delay with the wider dental phenotype.
  - target: Hypodontia
    causal_link_type: DIRECT
    description: Reduced tooth number.
    evidence:
    - reference: PMID:34212753
      reference_title: "SHORT Syndrome: Systematic Appraisal of the Medical and Dental Phenotype."
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: >-
        Teething delay, microdontia, hypodontia, and enamel hypoplasia have all been
        reported.
      explanation: Hypodontia among the reported dental findings.
  - target: Microdontia
    causal_link_type: DIRECT
    description: Small teeth.
    evidence:
    - reference: PMID:34212753
      reference_title: "SHORT Syndrome: Systematic Appraisal of the Medical and Dental Phenotype."
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: >-
        microdontia, hypodontia, and enamel hypoplasia have all been reported
      explanation: Microdontia among the reported dental findings.
  - target: Enamel hypoplasia
    causal_link_type: DIRECT
    description: Defective enamel formation.
    evidence:
    - reference: PMID:34212753
      reference_title: "SHORT Syndrome: Systematic Appraisal of the Medical and Dental Phenotype."
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: >-
        hypodontia, and enamel hypoplasia have all been reported
      explanation: Enamel hypoplasia among the reported dental findings.
  evidence:
  - reference: PMID:34212753
    reference_title: "SHORT Syndrome: Systematic Appraisal of the Medical and Dental Phenotype."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Facial dysmorphism including ocular depression, triangular shaped face, frontal
      bossing, large low-set ears, and micrognathia were the most consistent features
      followed by lipodystrophy, insulin resistance, and intrauterine growth restriction.
    explanation: >-
      The finding that reorders the syndrome's own acronym: facial dysmorphism is more
      consistent than the eponymous features. This is why the craniofacial phenotype gets
      its own node rather than being scattered across unattached phenotype entries.
- name: Anterior Segment Dysgenesis
  biological_scale: TISSUE
  description: >-
    Maldevelopment of the anterior segment of the eye produces the Rieger anomaly and
    related findings (posterior embryotoxon, glaucoma) that give the syndrome its
    "R". The developmental route from reduced PI3K signalling to anterior chamber
    dysgenesis has not been worked out; this node records the tissue-level lesion
    without asserting an intervening mechanism.
  downstream:
  - target: Glaucoma
    causal_link_type: DIRECT
    description: >-
      Raised intraocular pressure follows from maldevelopment of the drainage structures
      of the anterior chamber.
    evidence:
    - reference: PMID:23980586
      reference_title: PIK3R1 mutations in SHORT syndrome.
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: >-
        ophthalmic anomalies (Rieger anomaly, posterior embryotoxon, glaucoma)
      explanation: >-
        Groups glaucoma with the other anterior segment findings as one ophthalmic
        phenotype.
  - target: Posterior embryotoxon
    causal_link_type: DIRECT
    description: >-
      An anteriorly displaced Schwalbe line is part of the same anterior segment
      maldevelopment.
    evidence:
    - reference: PMID:23980586
      reference_title: PIK3R1 mutations in SHORT syndrome.
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: >-
        ophthalmic anomalies (Rieger anomaly, posterior embryotoxon, glaucoma)
      explanation: >-
        Posterior embryotoxon among the anterior segment findings.
  - target: Hypoplasia of the iris
    causal_link_type: DIRECT
    description: >-
      Thinning of the iris stroma, the component of the anterior segment phenotype that
      the knock-in mouse reproduces and that is measurable by OCT.
    evidence:
    - reference: PMID:28632845
      reference_title: Iris Malformation and Anterior Segment Dysgenesis in Mice and Humans With a Mutation in PI 3-Kinase.
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: >-
        Both human subjects had Rieger anomaly with similar defects including thin irides
        and irregular pupils
      explanation: >-
        The thin iris in human R649W carriers, matching the mouse finding.
  - target: Abnormal pupil morphology
    causal_link_type: INDIRECT_KNOWN_INTERMEDIATES
    description: >-
      The irregular, enlarged pupil follows from the iris hypoplasia rather than being an
      independent defect.
    evidence:
    - reference: PMID:28632845
      reference_title: Iris Malformation and Anterior Segment Dysgenesis in Mice and Humans With a Mutation in PI 3-Kinase.
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: >-
        Both human subjects had Rieger anomaly with similar defects including thin irides
        and irregular pupils
      explanation: >-
        Irregular pupils in human carriers. The mouse data in the same paper make the
        dependence on iris thinning explicit, which is why the link is indirect.
      directness: INDIRECT
  - target: Anterior synechiae of the anterior chamber
    causal_link_type: DIRECT
    description: >-
      Goniosynechiae, adhesions across the iridocorneal angle. Present in the human
      subjects and absent from the mouse, which is part of why the model is graded as
      reproducing the iris defect rather than the whole anterior segment phenotype.
    evidence:
    - reference: PMID:28632845
      reference_title: Iris Malformation and Anterior Segment Dysgenesis in Mice and Humans With a Mutation in PI 3-Kinase.
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: >-
        as well as a prominent ring of Schwalbe, goniosynechiae, early cataract formation,
        and glaucoma
      explanation: >-
        The additional human anterior segment findings, which include the angle adhesions.
  - target: Cataract
    causal_link_type: INDIRECT_UNKNOWN_INTERMEDIATES
    description: >-
      Early cataract in the human subjects. Whether it is a direct consequence of the
      anterior segment maldevelopment or secondary to the glaucoma and its treatment is not
      addressed by the source.
    evidence:
    - reference: PMID:28632845
      reference_title: Iris Malformation and Anterior Segment Dysgenesis in Mice and Humans With a Mutation in PI 3-Kinase.
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: >-
        goniosynechiae, early cataract formation, and glaucoma
      explanation: >-
        Early cataract in both human R649W subjects.
  - target: Rieger anomaly
    causal_link_type: DIRECT
    description: >-
      Anterior segment maldevelopment is what the Rieger anomaly consists of.
    evidence:
    - reference: PMID:23980586
      reference_title: PIK3R1 mutations in SHORT syndrome.
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: >-
        ophthalmic anomalies (Rieger anomaly, posterior embryotoxon, glaucoma)
      explanation: >-
        Names the anterior segment findings that characterise the syndrome.
  evidence:
  - reference: PMID:23810382
    reference_title: Mutations in PIK3R1 cause SHORT syndrome.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      SHORT syndrome is a rare, multisystem disease characterized by short stature,
      anterior-chamber eye anomalies, characteristic facial features, lipodystrophy,
      hernias, hyperextensibility, and delayed dentition.
    explanation: >-
      Establishes anterior chamber anomalies as a core feature of the disease.
phenotypes:
- name: Intrauterine growth retardation
  category: Clinical
  description: >-
    Prenatal growth restriction, generally below the 10th percentile, and one of the
    features most consistently present in molecularly confirmed patients.
  phenotype_term:
    preferred_term: Intrauterine growth retardation
    term:
      id: HP:0001511
      label: Intrauterine growth retardation
  frequency: FREQUENT
  evidence:
  - reference: PMID:26497935
    reference_title: "Clinical reappraisal of SHORT syndrome with PIK3R1 mutations: toward recommendation for molecular testing and management."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      The commonly observed clinical features of SHORT syndrome seen in the cohort
      included intrauterine growth restriction (IUGR) <10th percentile, postnatal
      growth restriction, lipoatrophy and the characteristic facial gestalt.
    explanation: >-
      "Commonly observed" in a 32-patient molecularly confirmed cohort. The source
      gives no percentage, so FREQUENT is the widest band consistent with the wording
      rather than a reported figure.
- name: Short stature
  category: Clinical
  description: >-
    Postnatal growth restriction, continuous with the prenatal deficit; the "S" of
    the acronym.
  phenotype_term:
    preferred_term: Short stature
    term:
      id: HP:0004322
      label: Short stature
  frequency: FREQUENT
  evidence:
  - reference: PMID:26497935
    reference_title: "Clinical reappraisal of SHORT syndrome with PIK3R1 mutations: toward recommendation for molecular testing and management."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      included intrauterine growth restriction (IUGR) <10th percentile, postnatal
      growth restriction
    explanation: >-
      Postnatal growth restriction listed among the commonly observed features.
- name: Lipoatrophy
  category: Clinical
  description: >-
    Partial lipodystrophy with selective loss of subcutaneous adipose tissue,
    predominantly of the face, chest and upper limbs, characteristically sparing the
    buttocks and legs; it contributes to the progeroid facial appearance.
  phenotype_term:
    preferred_term: Lipoatrophy
    term:
      id: HP:0100578
      label: Lipoatrophy
  frequency: FREQUENT
  evidence:
  - reference: PMID:26497935
    reference_title: "Clinical reappraisal of SHORT syndrome with PIK3R1 mutations: toward recommendation for molecular testing and management."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      postnatal growth restriction, lipoatrophy and the characteristic facial gestalt
    explanation: >-
      Lipoatrophy among the commonly observed features of the confirmed cohort.
  - reference: PMID:33129256
    reference_title: "A novel PIK3R1 mutation of SHORT syndrome in a Chinese female with diffuse thyroid disease: a case report and review of literature."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Lipodystrophy, characterized by selective loss of adipose tissue, is another
      typical feature of the syndrome.
    explanation: >-
      Describes the nature of the fat loss.
- name: Insulin resistance
  category: Biochemical
  description: >-
    Severe post-receptor insulin resistance with compensatory hyperinsulinaemia,
    often detectable on oral glucose tolerance testing before fasting glucose becomes
    abnormal.
  phenotype_term:
    preferred_term: Insulin resistance
    term:
      id: HP:0000855
      label: Insulin resistance
  frequency: FREQUENT
  evidence:
  - reference: PMID:26497935
    reference_title: "Clinical reappraisal of SHORT syndrome with PIK3R1 mutations: toward recommendation for molecular testing and management."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Anterior chamber defects and insulin resistance or diabetes were also observed
      but were not as prevalent.
    explanation: >-
      Establishes the feature and, explicitly, that it is less prevalent than the
      growth and lipoatrophy features. The band is set below those features on that
      basis rather than from a reported percentage.
- name: Diabetes mellitus
  category: Clinical
  description: >-
    Diabetes arising from sustained severe insulin resistance, with onset typically in
    the second decade. The reported risk is high enough that the systematic cohort
    review recommends routine glucose monitoring.
  phenotype_term:
    preferred_term: Diabetes mellitus
    term:
      id: HP:0000819
      label: Diabetes mellitus
  frequency: OCCASIONAL
  evidence:
  - reference: PMID:33129256
    reference_title: "A novel PIK3R1 mutation of SHORT syndrome in a Chinese female with diffuse thyroid disease: a case report and review of literature."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Severe insulin resistance may also lead to an early onset of type 2 diabetes,
      typically occurring in the second decade of life
    explanation: >-
      Establishes diabetes as a consequence and gives its usual age of onset. The
      hedged "may" in the source is why the frequency band is conservative.
  - reference: PMID:26497935
    reference_title: "Clinical reappraisal of SHORT syndrome with PIK3R1 mutations: toward recommendation for molecular testing and management."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Given the high risk of diabetes mellitus, regular monitoring of glucose
      metabolism is warranted.
    explanation: >-
      The cohort study's own risk assessment, which is what justifies surveillance.
- name: Rieger anomaly
  category: Clinical
  description: >-
    Anterior segment dysgenesis of the Axenfeld-Rieger type; the "R" of the acronym.
    Associated anterior chamber findings include posterior embryotoxon and glaucoma.
  phenotype_term:
    preferred_term: Rieger anomaly
    term:
      id: HP:0000558
      label: Rieger anomaly
  frequency: OCCASIONAL
  evidence:
  - reference: PMID:26497935
    reference_title: "Clinical reappraisal of SHORT syndrome with PIK3R1 mutations: toward recommendation for molecular testing and management."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Anterior chamber defects and insulin resistance or diabetes were also observed
      but were not as prevalent.
    explanation: >-
      Anterior chamber defects present but explicitly less prevalent than the core
      growth and adipose features.
  - reference: PMID:23810379
    reference_title: SHORT syndrome with partial lipodystrophy due to impaired phosphatidylinositol 3 kinase signaling.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      short stature, progeroid face, and Rieger anomaly (SHORT syndrome)
    explanation: >-
      Rieger anomaly as a defining feature in the families in which the hotspot
      variant was identified.
- name: Glaucoma
  category: Clinical
  description: >-
    Raised intraocular pressure and glaucoma, a recognised consequence of the anterior
    chamber dysgenesis and the reason ophthalmological assessment is recommended.
  phenotype_term:
    preferred_term: Glaucoma
    term:
      id: HP:0000501
      label: Glaucoma
  evidence:
  - reference: PMID:23980586
    reference_title: PIK3R1 mutations in SHORT syndrome.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      ophthalmic anomalies (Rieger anomaly, posterior embryotoxon, glaucoma)
    explanation: >-
      Names glaucoma among the ophthalmic features. No frequency is recorded because
      none of the cited sources gives one.
- name: Posterior embryotoxon
  category: Clinical
  description: >-
    A prominent, anteriorly displaced Schwalbe line, part of the anterior segment
    phenotype.
  phenotype_term:
    preferred_term: Posterior embryotoxon
    term:
      id: HP:0000627
      label: Posterior embryotoxon
  evidence:
  - reference: PMID:23980586
    reference_title: PIK3R1 mutations in SHORT syndrome.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      ophthalmic anomalies (Rieger anomaly, posterior embryotoxon, glaucoma)
    explanation: >-
      Names posterior embryotoxon among the ophthalmic features.
- name: Deeply set eye
  category: Clinical
  description: >-
    Ocular depression, the "O" of the acronym, and part of the characteristic facial
    gestalt.
  phenotype_term:
    preferred_term: Deeply set eye
    term:
      id: HP:0000490
      label: Deeply set eye
  evidence:
  - reference: PMID:23980586
    reference_title: PIK3R1 mutations in SHORT syndrome.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      short stature, hyperextensibility of joints, hernias, ocular depression
    explanation: >-
      Ocular depression as a defining acronym feature.
- name: Triangular face
  category: Clinical
  description: >-
    Part of the characteristic facial gestalt, together with a small chin, thin lips,
    a downturned mouth and low-set posteriorly rotated ears. The gestalt is one of the
    features most consistently present in molecularly confirmed patients.
  phenotype_term:
    preferred_term: Triangular face
    term:
      id: HP:0000325
      label: Triangular face
  frequency: FREQUENT
  evidence:
  - reference: PMID:33129256
    reference_title: "A novel PIK3R1 mutation of SHORT syndrome in a Chinese female with diffuse thyroid disease: a case report and review of literature."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      a characteristic facial gestalt (e.g. triangular face with a small thin, thin
      lip, downturned mouth, low-set posteriorly rotated ears, prominent forehead,
      underdeveloped or thin nasal alae as well as wrinkles)
    explanation: >-
      Spells out the components of the facial gestalt, of which the triangular face is
      the bindable element.
  - reference: PMID:26497935
    reference_title: "Clinical reappraisal of SHORT syndrome with PIK3R1 mutations: toward recommendation for molecular testing and management."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      lipoatrophy and the characteristic facial gestalt
    explanation: >-
      The facial gestalt among the commonly observed features of the confirmed cohort.
- name: Delayed eruption of teeth
  category: Clinical
  description: >-
    Teething delay, the "T" of the acronym; classified by the cohort review as one of
    the less specific, minor features.
  phenotype_term:
    preferred_term: Delayed eruption of teeth
    term:
      id: HP:0000684
      label: Delayed eruption of teeth
  evidence:
  - reference: PMID:26497935
    reference_title: "Clinical reappraisal of SHORT syndrome with PIK3R1 mutations: toward recommendation for molecular testing and management."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      The less specific, or minor features of SHORT syndrome include teething delay,
      thin wrinkled skin, speech delay, sensorineural deafness, hyperextensibility of
      joints and inguinal hernia.
    explanation: >-
      Places teething delay among the minor features. No frequency band is recorded
      because the source grades specificity, not prevalence.
- name: Joint hypermobility
  category: Clinical
  description: >-
    Hyperextensibility of joints, the "H" of the acronym; graded by the cohort review
    as a minor feature.
  phenotype_term:
    preferred_term: Joint hypermobility
    term:
      id: HP:0001382
      label: Joint hypermobility
  evidence:
  - reference: PMID:26497935
    reference_title: "Clinical reappraisal of SHORT syndrome with PIK3R1 mutations: toward recommendation for molecular testing and management."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      speech delay, sensorineural deafness, hyperextensibility of joints and inguinal
      hernia
    explanation: >-
      Hyperextensibility among the minor features.
- name: Inguinal hernia
  category: Clinical
  description: >-
    The alternative "H" of the acronym; graded as a minor feature.
  phenotype_term:
    preferred_term: Inguinal hernia
    term:
      id: HP:0000023
      label: Inguinal hernia
  evidence:
  - reference: PMID:26497935
    reference_title: "Clinical reappraisal of SHORT syndrome with PIK3R1 mutations: toward recommendation for molecular testing and management."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      hyperextensibility of joints and inguinal hernia
    explanation: >-
      Inguinal hernia among the minor features.
- name: Sensorineural hearing impairment
  category: Clinical
  description: >-
    Sensorineural deafness, a minor feature but one that drives a specific
    surveillance recommendation.
  phenotype_term:
    preferred_term: Sensorineural hearing impairment
    term:
      id: HP:0000407
      label: Sensorineural hearing impairment
  evidence:
  - reference: PMID:26497935
    reference_title: "Clinical reappraisal of SHORT syndrome with PIK3R1 mutations: toward recommendation for molecular testing and management."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      thin wrinkled skin, speech delay, sensorineural deafness
    explanation: >-
      Sensorineural deafness among the minor features.
- name: Delayed speech and language development
  category: Clinical
  description: >-
    Speech delay is recognised as a minor feature. It occurs against a background of
    generally normal intelligence.
  phenotype_term:
    preferred_term: Delayed speech and language development
    term:
      id: HP:0000750
      label: Delayed speech and language development
  evidence:
  - reference: PMID:26497935
    reference_title: "Clinical reappraisal of SHORT syndrome with PIK3R1 mutations: toward recommendation for molecular testing and management."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      thin wrinkled skin, speech delay, sensorineural deafness
    explanation: >-
      Speech delay among the minor features.
  - reference: PMID:33129256
    reference_title: "A novel PIK3R1 mutation of SHORT syndrome in a Chinese female with diffuse thyroid disease: a case report and review of literature."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Intelligence is within normal range and most patients can have normal
      educational achievements
    explanation: >-
      Establishes that the speech delay is not part of a global intellectual
      disability, which is the clinically important qualification.
- name: Polycystic ovaries
  category: Clinical
  description: >-
    Polycystic ovary syndrome in postpubertal affected women, attributed to
    hyperinsulinaemia secondary to the insulin resistance.
  phenotype_term:
    preferred_term: Polycystic ovaries
    term:
      id: HP:0000147
      label: Polycystic ovaries
  frequency: VERY_FREQUENT
  evidence:
  - reference: PMID:33129256
    reference_title: "A novel PIK3R1 mutation of SHORT syndrome in a Chinese female with diffuse thyroid disease: a case report and review of literature."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      almost all postpubertal women affected present polycystic ovary syndrome
    explanation: >-
      "Almost all" is the basis for the VERY_FREQUENT band, which applies to the
      postpubertal female subgroup rather than to all patients.
- name: Frontal bossing
  category: Clinical
  description: >-
    A prominent forehead, part of the progeroid craniofacial gestalt that the systematic
    review found to be the most consistent feature of the syndrome.
  phenotype_term:
    preferred_term: Frontal bossing
    term:
      id: HP:0002007
      label: Frontal bossing
  frequency: FREQUENT
  evidence:
  - reference: PMID:34212753
    reference_title: "SHORT Syndrome: Systematic Appraisal of the Medical and Dental Phenotype."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Facial dysmorphism including ocular depression, triangular shaped face, frontal
      bossing, large low-set ears, and micrognathia were the most consistent features
      followed by lipodystrophy, insulin resistance, and intrauterine growth restriction.
    explanation: >-
      Places frontal bossing within the most consistent feature group, and gives the
      ordering that the frequency bands in this entry follow.
- name: Micrognathia
  category: Clinical
  description: >-
    Mandibular retrognathia, a skeletal rather than adipose component of the facial
    gestalt.
  phenotype_term:
    preferred_term: Mandibular retrognathia
    term:
      id: HP:0000347
      label: Micrognathia
  frequency: FREQUENT
  evidence:
  - reference: PMID:34212753
    reference_title: "SHORT Syndrome: Systematic Appraisal of the Medical and Dental Phenotype."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      triangular shaped face, frontal bossing, large low-set ears, and micrognathia were
      the most consistent features
    explanation: >-
      Micrognathia among the most consistent features.
- name: Low-set ears
  category: Clinical
  description: >-
    Large, low-set ears, part of the facial gestalt.
  phenotype_term:
    preferred_term: Large low-set ears
    term:
      id: HP:0000369
      label: Low-set ears
  frequency: FREQUENT
  evidence:
  - reference: PMID:34212753
    reference_title: "SHORT Syndrome: Systematic Appraisal of the Medical and Dental Phenotype."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      frontal bossing, large low-set ears, and micrognathia were the most consistent
      features
    explanation: >-
      Large low-set ears among the most consistent features.
- name: Underdeveloped nasal alae
  category: Clinical
  description: >-
    Hypoplastic or thin alae nasi, a recurrent component of the progeroid craniofacial
    appearance.
  phenotype_term:
    preferred_term: Hypoplastic alae nasi
    term:
      id: HP:0000430
      label: Underdeveloped nasal alae
  frequency: FREQUENT
  evidence:
  - reference: PMID:34212753
    reference_title: "SHORT Syndrome: Systematic Appraisal of the Medical and Dental Phenotype."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Individuals have a distinct progeroid craniofacial appearance with a triangular
      face, frontal bossing, hypoplastic or thin alae nasi, large low-set ears, and
      mandibular retrognathia.
    explanation: >-
      Names the components of the progeroid craniofacial appearance, including the alae
      nasi.
- name: Hypodontia
  category: Clinical
  description: >-
    Reduced tooth number, one of the dental findings the systematic appraisal set out to
    characterise. The dental phenotype of this syndrome is broader than the acronym's
    "teething delay" implies.
  phenotype_term:
    preferred_term: Hypodontia
    term:
      id: HP:0000668
      label: Hypodontia
  evidence:
  - reference: PMID:34212753
    reference_title: "SHORT Syndrome: Systematic Appraisal of the Medical and Dental Phenotype."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Teething delay, microdontia, hypodontia, and enamel hypoplasia have all been
      reported.
    explanation: >-
      Establishes the wider dental phenotype. The source says "have all been reported"
      without frequencies, so no band is recorded.
- name: Microdontia
  category: Clinical
  description: >-
    Small teeth, reported alongside the hypodontia and enamel defects.
  phenotype_term:
    preferred_term: Microdontia
    term:
      id: HP:0000691
      label: Microdontia
  evidence:
  - reference: PMID:34212753
    reference_title: "SHORT Syndrome: Systematic Appraisal of the Medical and Dental Phenotype."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Teething delay, microdontia, hypodontia, and enamel hypoplasia have all been
      reported.
    explanation: >-
      Microdontia among the reported dental findings.
- name: Enamel hypoplasia
  category: Clinical
  description: >-
    Defective enamel formation, completing the dental phenotype.
  phenotype_term:
    preferred_term: Enamel hypoplasia
    term:
      id: HP:0006297
      label: Enamel hypoplasia
  evidence:
  - reference: PMID:34212753
    reference_title: "SHORT Syndrome: Systematic Appraisal of the Medical and Dental Phenotype."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      microdontia, hypodontia, and enamel hypoplasia have all been reported
    explanation: >-
      Enamel hypoplasia among the reported dental findings.
- name: Hepatic steatosis
  category: Clinical
  description: >-
    Characteristically ABSENT. This entry records the phenotype in order to record its
    absence, because that absence is diagnostically useful: extreme insulin resistance
    without fatty liver points away from obesity-related insulin resistance and towards a
    proximal receptor-to-PI3K lesion. Recorded with REFUTE evidence rather than omitted,
    so that a query for "does this disease cause fatty liver" gets an answer rather than
    silence.
  phenotype_term:
    preferred_term: Hepatic steatosis
    term:
      id: HP:0001397
      label: Hepatic steatosis
  evidence:
  - reference: PMID:27766312
    reference_title: Insulin resistance uncoupled from dyslipidemia due to C-terminal PIK3R1 mutations.
    supports: REFUTE
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Four of 5 patients had extreme insulin resistance without dyslipidemia or hepatic
      steatosis.
    explanation: >-
      Directly contradicts the presence of hepatic steatosis in four of five studied
      patients, which is why this item is graded REFUTE rather than SUPPORT.
- name: Hypertriglyceridemia
  category: Biochemical
  description: >-
    Characteristically ABSENT, for the same reason as the hepatic steatosis and recorded
    the same way.
  phenotype_term:
    preferred_term: Dyslipidaemia
    term:
      id: HP:0002155
      label: Hypertriglyceridemia
  evidence:
  - reference: PMID:27766312
    reference_title: Insulin resistance uncoupled from dyslipidemia due to C-terminal PIK3R1 mutations.
    supports: REFUTE
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Four of 5 patients had extreme insulin resistance without dyslipidemia or hepatic
      steatosis.
    explanation: >-
      Contradicts the presence of dyslipidaemia in four of five studied patients. The
      binding is to the hypertriglyceridaemia term because that is the specific lipid
      abnormality the obesity-related pattern would predict.
- name: Hypoplasia of the iris
  category: Clinical
  description: >-
    Thin iris stroma. Directly measured by OCT in the knock-in mouse and observed in human
    R649W carriers, it is the most precisely characterised component of the anterior
    segment phenotype and the only one with a quantitative animal readout.
  phenotype_term:
    preferred_term: Thin iris
    term:
      id: HP:0007676
      label: Hypoplasia of the iris
  evidence:
  - reference: PMID:28632845
    reference_title: Iris Malformation and Anterior Segment Dysgenesis in Mice and Humans With a Mutation in PI 3-Kinase.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Both human subjects had Rieger anomaly with similar defects including thin irides and
      irregular pupils
    explanation: >-
      Thin irides in both human subjects carrying the hotspot allele. Two patients, so no
      frequency band is recorded.
- name: Abnormal pupil morphology
  category: Clinical
  description: >-
    Irregular and enlarged pupil, secondary to the iris hypoplasia.
  phenotype_term:
    preferred_term: Irregular pupil
    term:
      id: HP:0000615
      label: Abnormal pupil morphology
  evidence:
  - reference: PMID:28632845
    reference_title: Iris Malformation and Anterior Segment Dysgenesis in Mice and Humans With a Mutation in PI 3-Kinase.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      thin irides and irregular pupils, as well as a prominent ring of Schwalbe
    explanation: >-
      Irregular pupils in the human subjects, alongside the posterior embryotoxon this entry
      already curates as the prominent Schwalbe ring.
- name: Anterior synechiae of the anterior chamber
  category: Clinical
  description: >-
    Goniosynechiae. Clinically important because adhesions across the iridocorneal angle
    obstruct aqueous outflow, which is the route from anterior segment dysgenesis to the
    glaucoma this entry also curates.
  phenotype_term:
    preferred_term: Goniosynechiae
    term:
      id: HP:0011483
      label: Anterior synechiae of the anterior chamber
  evidence:
  - reference: PMID:28632845
    reference_title: Iris Malformation and Anterior Segment Dysgenesis in Mice and Humans With a Mutation in PI 3-Kinase.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      as well as a prominent ring of Schwalbe, goniosynechiae, early cataract formation, and
      glaucoma
    explanation: >-
      Goniosynechiae in both human subjects, reported together with the glaucoma.
- name: Cataract
  category: Clinical
  description: >-
    Early cataract formation, reported in both human R649W subjects examined
    ophthalmologically.
  phenotype_term:
    preferred_term: Early cataract
    term:
      id: HP:0000518
      label: Cataract
  evidence:
  - reference: PMID:28632845
    reference_title: Iris Malformation and Anterior Segment Dysgenesis in Mice and Humans With a Mutation in PI 3-Kinase.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      goniosynechiae, early cataract formation, and glaucoma
    explanation: >-
      Early cataract in the two human subjects.
genetic:
- name: PIK3R1 pathogenic variants
  gene_term:
    preferred_term: PIK3R1
    term:
      id: hgnc:8979
      label: PIK3R1
  association: Causative
  relationship_type: CAUSATIVE
  notes: >-
    Reported alleles are heterozygous and cluster in exon 14, encoding the C-terminal
    SH2 domain of p85-alpha; they include missense (recurrently c.1945C>T,
    p.Arg649Trp), frameshift (c.1906_1907insC, p.Asn636Thrfs*18) and nonsense
    (c.1971T>G, p.Tyr657*; c.1960C>T, p.Gln654*) changes. The domain clustering is the
    clinically load-bearing observation: variants elsewhere in the same gene, notably
    splice-site changes affecting the inter-SH2 region, cause activated PI3K-delta
    syndrome 2 instead, which has the opposite effect on PI3K signalling. This entry
    does not assign a `functional_impact_category`: the reported functional data
    establish that pathway signalling is reduced, but none of the cited sources
    distinguishes haploinsufficiency from a dominant-negative action of the mutant
    subunit, and the recurrent missense hotspot in a heterozygous state is compatible
    with either.
  evidence:
  - reference: PMID:23810382
    reference_title: Mutations in PIK3R1 cause SHORT syndrome.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Heterozygous mutations in exon 14 of PIK3R1 were subsequently identified by
      Sanger sequencing in three additional affected individuals and two affected
      family members.
    explanation: >-
      Establishes the exon 14 clustering across multiple affected individuals.
  - reference: PMID:23810382
    reference_title: Mutations in PIK3R1 cause SHORT syndrome.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      The other mutation, a de novo truncating mutation
    explanation: >-
      A truncating allele in the same region, showing the spectrum is not restricted
      to missense changes.
  - reference: PMID:23980586
    reference_title: PIK3R1 mutations in SHORT syndrome.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Eight of these families had a recurrent missense mutation (c.1945C>T;
      p.Arg649Trp).
    explanation: >-
      Quantifies the recurrence of the hotspot allele across reported families.
  - reference: PMID:33129256
    reference_title: "A novel PIK3R1 mutation of SHORT syndrome in a Chinese female with diffuse thyroid disease: a case report and review of literature."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Sequencing result indicated c.1960C > T of PIK3R1 gene a novel nonsense
      mutation, leading to the termination of protein translation
    explanation: >-
      An additional nonsense allele in the same region.
  variants:
  - name: PIK3R1 c.1945C>T (p.Arg649Trp)
    description: >-
      The recurrent hotspot allele, accounting for the majority of reported cases. It
      substitutes an arginine in the C-terminal SH2 domain of p85-alpha. Two lines of
      functional work place it as dominant negative rather than simply hypomorphic:
      overexpression of the mutant subunit in preadipocytes attenuates insulin-induced
      AKT phosphorylation and adipocyte differentiation, and the knock-in mouse carrying
      one copy reproduces the human phenotype.
    gene:
      preferred_term: PIK3R1
      term:
        id: hgnc:8979
        label: PIK3R1
    type: MISSENSE
    clinical_significance: PATHOGENIC
    functional_effects:
    - function: p85-alpha binding to IRS-1
      description: >-
        Impairs insulin-stimulated association of p85-alpha with IRS-1, so class IA PI3K
        is not recruited to the activated receptor complex.
    evidence:
    - reference: PMID:29724723
      reference_title: Mice Carrying a Dominant-Negative Human PI3K Mutation Are Protected From Obesity and Hepatic Steatosis but Not Diabetes.
      supports: SUPPORT
      evidence_source: MODEL_ORGANISM
      snippet: >-
        A heterozygous missense mutation (R649W) in the p85α regulatory subunit gene of
        PI3K (PIK3R1) has been identified in patients with SHORT
      explanation: >-
        Identifies the allele. The paper's own title characterises it as dominant
        negative, which is the basis for that reading in the description.
    - reference: PMID:27766312
      reference_title: Insulin resistance uncoupled from dyslipidemia due to C-terminal PIK3R1 mutations.
      supports: SUPPORT
      evidence_source: IN_VITRO
      snippet: >-
        In 3T3-L1 preadipocytes, mutant p85α overexpression attenuated insulin-induced
        AKT phosphorylation and adipocyte differentiation.
      explanation: >-
        A dominant-negative effect demonstrated by overexpression against a wild-type
        background, which is the functional evidence for that mechanism.
  - name: PIK3R1 c.1906_1907insC (p.Asn636Thrfs*18)
    description: >-
      A frameshift insertion in exon 14, the allele in the trio whose exome sequencing
      identified PIK3R1 as the SHORT syndrome gene.
    gene:
      preferred_term: PIK3R1
      term:
        id: hgnc:8979
        label: PIK3R1
    type: FRAMESHIFT
    clinical_significance: PATHOGENIC
    evidence:
    - reference: PMID:23810382
      reference_title: Mutations in PIK3R1 cause SHORT syndrome.
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: >-
        Whole-exome sequencing in a family trio of an affected child and unaffected
        parents identified a de novo frameshift insertion, c.1906_1907insC
      explanation: >-
        The gene-discovery allele, established as de novo in a trio.
  - name: PIK3R1 c.1971T>G (p.Tyr657*)
    description: >-
      A de novo truncating allele in the same region. Cells from a patient carrying it
      express abundant truncated PIK3R1 products, which is the observation behind the
      dominant-negative reading rather than a simple loss of the subunit.
    gene:
      preferred_term: PIK3R1
      term:
        id: hgnc:8979
        label: PIK3R1
    type: NONSENSE
    clinical_significance: PATHOGENIC
    evidence:
    - reference: PMID:27766312
      reference_title: Insulin resistance uncoupled from dyslipidemia due to C-terminal PIK3R1 mutations.
      supports: SUPPORT
      evidence_source: IN_VITRO
      snippet: >-
        Cells studied from one patient with the p.Tyr657X PIK3R1 mutation expressed
        abundant truncated PIK3R1 products and showed severely reduced insulin-stimulated
        association of mutant but not WT p85α with IRS1
      explanation: >-
        Establishes that the truncated product is made and that it fails to bind IRS-1,
        while the wild-type allele's product still does.
diagnosis:
- name: Clinical recognition with PIK3R1 sequencing
  description: >-
    The diagnosis is suspected from the combination of intrauterine and postnatal
    growth restriction, lipoatrophy and the facial gestalt, and confirmed by finding a
    heterozygous PIK3R1 variant. Relying on the acronym as a checklist under-diagnoses
    the condition: in a molecularly confirmed cohort only about half of patients had
    four or more of the five classic features, so the acronym should not be treated as
    a diagnostic threshold.
  evidence:
  - reference: PMID:26497935
    reference_title: "Clinical reappraisal of SHORT syndrome with PIK3R1 mutations: toward recommendation for molecular testing and management."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      The major features described in the SHORT acronym were not universally seen and
      only half (52%) had four or more of the classic features.
    explanation: >-
      The quantitative basis for not using the acronym as a diagnostic threshold.
  - reference: PMID:26497935
    reference_title: "Clinical reappraisal of SHORT syndrome with PIK3R1 mutations: toward recommendation for molecular testing and management."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Knowledge of the molecular etiology of SHORT syndrome has permitted a
      reassessment of the clinical phenotype.
    explanation: >-
      States that molecular confirmation is what allowed the clinical definition to be
      revised, which is the argument for gene-first testing.
- name: Immunological assessment for coexisting APDS2
  description: >-
    Because PIK3R1 variants cause both SHORT syndrome and activated PI3K-delta
    syndrome 2, and because individuals manifesting both have been reported, patients
    with a PIK3R1 variant warrant assessment by clinical immunology as well as
    clinical genetics.
  evidence:
  - reference: PMID:28302518
    reference_title: "Mutations in PIK3R1 can lead to APDS2, SHORT syndrome or a combination of the two."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      We recommend that patients with mutations in PIK3R1 gene should be assessed by
      both clinical immunologists and clinical geneticists.
    explanation: >-
      The recommendation this diagnostic step implements, stated by the authors who
      reported the overlapping cases.
treatments:
- name: Metformin and SGLT2 inhibitor for insulin-resistant diabetes
  description: >-
    Once diabetes is overt, the reported regimen is an insulin sensitiser plus an
    insulin-independent glucose-lowering agent. In the documented case, metformin with
    canagliflozin brought HbA1c from 9.2% to around 7% and, notably, corrected both the
    daytime hyperglycaemia and the nocturnal hypoglycaemia. The rationale for an SGLT2
    inhibitor here is mechanistic as well as empirical: it lowers glucose by a renal route
    that does not depend on the impaired PI3K arm of insulin signalling.
  therapeutic_modality: SMALL_MOLECULE
  treatment_term:
    preferred_term: Pharmacotherapy
    term:
      id: NCIT:C15986
      label: Pharmacotherapy
    therapeutic_agent:
    - preferred_term: metformin
      term:
        id: CHEBI:6801
        label: metformin
    - preferred_term: canagliflozin
      term:
        id: CHEBI:73274
        label: canagliflozin
  target_phenotypes:
  - preferred_term: Diabetes mellitus
    term:
      id: HP:0000819
      label: Diabetes mellitus
  - preferred_term: Insulin resistance
    term:
      id: HP:0000855
      label: Insulin resistance
  evidence:
  - reference: PMID:32879144
    reference_title: "Insulin resistant diabetes mellitus in SHORT syndrome: case report and literature review."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      She was treated with metformin and canagliflozin (a sodium glucose co-transporter 2
      (SGLT2) inhibitor), which ameliorated overt diurnal hyperglycemia and mild nocturnal
      hypoglycemia and reduced her blood HbA1c around 7%.
    explanation: >-
      The regimen and its measured effect in the one reported case. A single case, which is
      why this is recorded as reported practice rather than as established therapy.
  - reference: PMID:32879144
    reference_title: "Insulin resistant diabetes mellitus in SHORT syndrome: case report and literature review."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      a usefulness of SGLT2 inhibitor in the treatment of IRDM
    explanation: >-
      The authors' own conclusion about the drug class.
- name: Multi-agent oral antidiabetic therapy
  description: >-
    Where a single agent is not enough, published practice is to stack oral agents with
    complementary mechanisms rather than move to insulin - which matters here, because
    insulin resistance of this severity makes injected insulin both unattractive and only
    partly effective. In the reported case, metformin, an SGLT-2 inhibitor, a sulfonylurea,
    a thiazolidinedione and a GLP-1 agonist together took HbA1c from 14% to 8.8% in six
    months and then to 7.4%, and deferred insulin. Two of those classes are worth
    identifying separately: the SGLT-2 inhibitor lowers glucose by a renal route that does
    not depend on the impaired PI3K arm at all, and the GLP-1 agonist acts on the incretin
    axis that the knock-in mouse shows to be defective in this disease.
  therapeutic_modality: SMALL_MOLECULE
  treatment_term:
    preferred_term: Pharmacotherapy
    term:
      id: NCIT:C15986
      label: Pharmacotherapy
    therapeutic_agent:
    - preferred_term: metformin
      term:
        id: CHEBI:6801
        label: metformin
    - preferred_term: pioglitazone
      term:
        id: CHEBI:8228
        label: pioglitazone
    - preferred_term: sulfonylurea
      term:
        id: NCIT:C97936
        label: Sulfonylurea Antidiabetic Agent
    - preferred_term: thiazolidinedione
      term:
        id: NCIT:C98241
        label: Thiazolidinedione Antidiabetic Agent
  target_mechanisms:
  - target: Impaired Insulin Secretion and Incretin Response
    description: >-
      A GLP-1 agonist acts directly on the incretin axis this pathograph records as
      defective. The link is mechanistically motivated rather than demonstrated: the
      incretin defect is a mouse finding, and the case report does not attribute the
      patient's response to any one agent in the combination.
    evidence:
    - reference: PMID:41459015
      reference_title: "Diabetes mellitus in SHORT syndrome managed with multi-agent oral therapies: a case report and literature review."
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: >-
        By utilizing a combination of oral anti-glycemic agents with complementary
        mechanisms of action (metformin, sodium-glucose co-transporter 2 (SGLT-2)
        inhibitors, sulfonylureas, thiazolidinediones, and GLP-1 agonists), insulin therapy
        was delayed.
      explanation: >-
        Names the GLP-1 agonist among the agents used. That an incretin-directed drug is
        used in a disease with a documented incretin defect is the reason for this link; the
        source does not isolate its contribution.
      directness: INDIRECT
  target_phenotypes:
  - preferred_term: Diabetes mellitus
    term:
      id: HP:0000819
      label: Diabetes mellitus
  evidence:
  - reference: PMID:41459015
    reference_title: "Diabetes mellitus in SHORT syndrome managed with multi-agent oral therapies: a case report and literature review."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      The patient's blood glucose levels improved significantly, with HbA1c decreased from
      14% to 8.8% within 6 months of starting the multi-agent regimen
    explanation: >-
      The measured response, with its timescale. A single case.
  - reference: PMID:41459015
    reference_title: "Diabetes mellitus in SHORT syndrome managed with multi-agent oral therapies: a case report and literature review."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Currently, there are no established guidelines for the treatment of diabetes in SHORT
      syndrome patients.
    explanation: >-
      States the evidence base this and every other treatment entry here rests on: case
      reports, not guidelines.
  - reference: PMID:33742773
    reference_title: "Novel PIK3R1 mutation of SHORT syndrome: A case report with a 6-month follow up."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      our treatment plans, including lifestyle intervention combined with metformin and
      pioglitazone, were carried out for this patient. After the intervention, insulin
      resistance and hyperinsulinemia in this patient were significantly decreased during a
      6-month follow up
    explanation: >-
      An independent case using a metformin plus thiazolidinedione combination, with the
      same direction of response over the same interval.
  - reference: PMID:39735640
    reference_title: "Atypical diabetes arising from SHORT syndrome: a case report."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      we implemented a comprehensive treatment plan, including lifestyle interventions,
      metformin, and voglibose for glucose control. After 6 months of continuous observation,
      the patient's blood glucose levels and insulin resistance improved significantly.
    explanation: >-
      A third independent case, in a patient carrying the same c.1945C>T hotspot allele this
      entry curates, using metformin with an alpha-glucosidase inhibitor.
  - reference: PMID:32602265
    reference_title: "SHORT syndrome in two Chinese girls: A case report and review of the literature."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      We report two Chinese girls with SHORT syndrome who presented with growth retardation,
      dysmorphic features, insulin resistance, and diabetes.
    explanation: >-
      Two further patients in whom metformin was the chosen agent. Cited as part of the case
      series behind metformin being the consistent first agent across every published report,
      which is the only sense in which this literature supports a first-line choice.
- name: Growth hormone therapy
  description: >-
    Long treated as contraindicated because growth hormone is diabetogenic and these
    patients are already severely insulin resistant. The reported evidence complicates
    that: growth response was poor in the one documented case, and the literature review
    in the same paper found insulin-resistant diabetes in 10 of 15 untreated patients aged
    12 or over and in none of three treated or six untreated patients aged 10 or under -
    an age effect, not a treatment effect. So the case against growth hormone here rests
    on lack of benefit more securely than on causing the diabetes.
  therapeutic_modality: PROTEIN_REPLACEMENT
  treatment_term:
    preferred_term: Hormone therapy
    term:
      id: NCIT:C15986
      label: Pharmacotherapy
  target_phenotypes:
  - preferred_term: Short stature
    term:
      id: HP:0004322
      label: Short stature
  evidence:
  - reference: PMID:32879144
    reference_title: "Insulin resistant diabetes mellitus in SHORT syndrome: case report and literature review."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      GH dosage was increased from 0.23 to 0.36 mg/kg/week, but statural response to GH
      therapy remained poor.
    explanation: >-
      The growth outcome, which is the clearest argument against the intervention in this
      disorder.
  - reference: PMID:32879144
    reference_title: "Insulin resistant diabetes mellitus in SHORT syndrome: case report and literature review."
    supports: REFUTE
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      These findings imply a critical role of pubertal development and/or advanced age
      rather than GH therapy in the development of IRDM
    explanation: >-
      Graded REFUTE because it contradicts the claim this treatment entry might otherwise
      be read as making - that growth hormone causes the diabetes. The authors attribute
      the diabetes to puberty instead.
- name: Metabolic surveillance and management of insulin resistance
  description: >-
    There is no disease-modifying therapy. Management centres on surveillance for and
    treatment of the metabolic consequences: because the risk of diabetes is high,
    regular monitoring of glucose metabolism is recommended, with treatment of
    hyperglycaemia when it develops.
  therapeutic_modality: OTHER
  treatment_term:
    preferred_term: Supportive Care
    term:
      id: NCIT:C15747
      label: Supportive Care
  target_phenotypes:
  - preferred_term: Insulin resistance
    term:
      id: HP:0000855
      label: Insulin resistance
  - preferred_term: Diabetes mellitus
    term:
      id: HP:0000819
      label: Diabetes mellitus
  evidence:
  - reference: PMID:26497935
    reference_title: "Clinical reappraisal of SHORT syndrome with PIK3R1 mutations: toward recommendation for molecular testing and management."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Given the high risk of diabetes mellitus, regular monitoring of glucose
      metabolism is warranted.
    explanation: >-
      The explicit management recommendation from the cohort review.
- name: Multisystem surveillance
  description: >-
    Cardiac, ophthalmological and audiological assessment are recommended alongside
    the metabolic monitoring, reflecting the cardiac, anterior chamber and
    sensorineural components of the phenotype.
  therapeutic_modality: OTHER
  treatment_term:
    preferred_term: Supportive Care
    term:
      id: NCIT:C15747
      label: Supportive Care
  target_phenotypes:
  - preferred_term: Rieger anomaly
    term:
      id: HP:0000558
      label: Rieger anomaly
  - preferred_term: Glaucoma
    term:
      id: HP:0000501
      label: Glaucoma
  - preferred_term: Sensorineural hearing impairment
    term:
      id: HP:0000407
      label: Sensorineural hearing impairment
  evidence:
  - reference: PMID:26497935
    reference_title: "Clinical reappraisal of SHORT syndrome with PIK3R1 mutations: toward recommendation for molecular testing and management."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      An echocardiogram, ophthalmological and hearing assessments are also
      recommended.
    explanation: >-
      The surveillance recommendation this treatment entry implements.
progression:
- phase: Pubertal emergence of insulin-resistant diabetes
  notes: >-
    The metabolic phenotype has a clear temporal structure. Insulin resistance is
    detectable in childhood, but overt diabetes characteristically appears around or after
    puberty. In the literature review accompanying the case report, insulin-resistant
    diabetes had developed in 10 of 15 growth-hormone-untreated patients aged 12 or over,
    and in none of the three treated or six untreated patients aged 10 or under. That
    contrast is what separates an age effect from a treatment effect, and it sets the
    surveillance interval: glucose monitoring matters most from puberty onward.
  evidence:
  - reference: PMID:32879144
    reference_title: "Insulin resistant diabetes mellitus in SHORT syndrome: case report and literature review."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Subsequent literature review for patients with molecularly confirmed SHORT syndrome
      revealed the development of IRDM in 10 of 15 GH-untreated patients aged ≥12 years
      but in none of three GH-treated and six GH-untreated patients aged ≤10 years.
    explanation: >-
      The age-stratified counts, with the inequalities that make them a claim about
      puberty: every affected patient was 12 or older, and none of the nine aged 10 or
      under had developed diabetes regardless of growth hormone exposure.
- phase: Diabetes onset in the second decade
  notes: >-
    Consistent with the age-stratified counts, narrative reviews place the onset of type 2
    diabetes in the second decade of life.
  evidence:
  - reference: PMID:33129256
    reference_title: "A novel PIK3R1 mutation of SHORT syndrome in a Chinese female with diffuse thyroid disease: a case report and review of literature."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Severe insulin resistance may also lead to an early onset of type 2 diabetes,
      typically occurring in the second decade of life
    explanation: >-
      An independent statement of the same timing.
animal_models:
- name: Pik3r1 R649W knock-in mouse
  species: Mouse
  genotype: Pik3r1 Arg649Trp heterozygous knock-in
  publication: PMID:26974159
  description: >-
    A heterozygous knock-in of the human hotspot allele, and the load-bearing model for
    this disease. It reproduces the growth, adipose and metabolic phenotype together, which
    is what allows the three arms of the human phenotype to be attributed to one signalling
    lesion rather than to three coincident ones.
  modeled_mechanisms:
  - target: Reduced PI3K-AKT Signal Transduction
    relationship: RECAPITULATES
    fidelity: HIGH
    description: >-
      The model demonstrates the signalling defect in vivo, across the three tissues that
      matter for the human phenotype, rather than only in cultured patient cells.
    limitations: >-
      A mouse carrying one human allele. The dental component of the human syndrome is
      not reported for this model. The ocular component is reported, in a separate study
      of the same line, and is curated as its own link below.
    readouts:
    - name: Insulin and growth-factor-stimulated PI3K activation in liver, muscle and fat
      target: Reduced PI3K-AKT Signal Transduction
      direction: DECREASED
      interpretation: >-
        The in vivo counterpart of the reduced AKT and S6 phosphorylation measured in
        patient cells.
      evidence:
      - reference: PMID:26974159
        reference_title: PI3-kinase mutation linked to insulin and growth factor resistance in vivo.
        supports: SUPPORT
        evidence_source: MODEL_ORGANISM
        snippet: >-
          These derangements were associated with a reduced capacity of insulin and other
          growth factors to activate PI3K in liver, muscle, and fat
        explanation: >-
          The tissue-level measurement behind this readout.
    evidence:
    - reference: PMID:26974159
      reference_title: PI3-kinase mutation linked to insulin and growth factor resistance in vivo.
      supports: SUPPORT
      evidence_source: MODEL_ORGANISM
      snippet: >-
        These data demonstrate the ability of this heterozygous mutation to alter PI3K
        activity in vivo and the central role of PI3K in insulin/growth factor action,
        adipocyte function, and glucose metabolism.
      explanation: >-
        The authors' summary of what the model establishes.
  - target: Impaired Adipocyte Differentiation
    relationship: RECAPITULATES
    fidelity: HIGH
    description: >-
      Partial lipodystrophy is reproduced, alongside the reduced body weight and length.
    limitations: >-
      Regional distribution of the fat loss is not reported in the same terms as the human
      facial and upper-limb pattern, so the correspondence is at the level of "partial
      lipodystrophy" rather than of its anatomy.
    readouts:
    - name: Body weight, length and adipose mass
      target: Impaired Adipocyte Differentiation
      direction: DECREASED
      interpretation: >-
        The growth and adipose phenotype in the model.
      evidence:
      - reference: PMID:26974159
        reference_title: PI3-kinase mutation linked to insulin and growth factor resistance in vivo.
        supports: SUPPORT
        evidence_source: MODEL_ORGANISM
        snippet: >-
          Similar to the patients, mutant mice exhibited a reduction in body weight and
          length, partial lipodystrophy, and systemic insulin resistance.
        explanation: >-
          The three-way phenotypic correspondence with patients.
    evidence:
    - reference: PMID:26974159
      reference_title: PI3-kinase mutation linked to insulin and growth factor resistance in vivo.
      supports: SUPPORT
      evidence_source: MODEL_ORGANISM
      snippet: >-
        Similar to the patients, mutant mice exhibited a reduction in body weight and
        length, partial lipodystrophy, and systemic insulin resistance.
      explanation: >-
        Establishes the model's fidelity for the adipose arm.
  - target: Anterior Segment Dysgenesis
    relationship: RECAPITULATES
    fidelity: HIGH
    description: >-
      The same knock-in line was examined ophthalmologically alongside two human R649W
      subjects. The mice have significantly thinner and narrower irides with enlarged,
      irregular pupils, and the human subjects have the corresponding Rieger anomaly with
      thin irides and irregular pupils. This is the evidence that the ocular arm of the
      syndrome follows from the p85-alpha lesion rather than from an unrelated cause, and
      it is what makes a single heterozygous allele sufficient for anterior segment
      dysgenesis in vivo.
    limitations: >-
      The mouse phenotype is milder than the human one and is confined to the iris: overall
      eye development, cornea, lens, anterior chamber volume, intraocular pressure and
      retinal structure were all normal in the mice, whereas the human subjects also had
      goniosynechiae, early cataract and glaucoma. So the model establishes that the lesion
      reaches iris development, not that it reproduces the full human anterior segment
      phenotype. It also says nothing about the intervening developmental steps.
    readouts:
    - name: Iris thickness and width on optical coherence tomography
      target: Anterior Segment Dysgenesis
      direction: DECREASED
      interpretation: >-
        Thinner and narrower iris with a consequently enlarged, irregular pupil - the
        structural measurement that grounds the ocular claim.
      evidence:
      - reference: PMID:28632845
        reference_title: Iris Malformation and Anterior Segment Dysgenesis in Mice and Humans With a Mutation in PI 3-Kinase.
        supports: SUPPORT
        evidence_source: MODEL_ORGANISM
        snippet: >-
          OCT images of the knock-in mouse eyes revealed a significant decrease in thickness
          and width of the iris resulting in increased pupil area and irregularity of shape.
        explanation: >-
          The imaging measurement behind this readout, in the same knock-in line curated
          above.
    evidence:
    - reference: PMID:28632845
      reference_title: Iris Malformation and Anterior Segment Dysgenesis in Mice and Humans With a Mutation in PI 3-Kinase.
      supports: SUPPORT
      evidence_source: MODEL_ORGANISM
      snippet: >-
        A dominant-negative mutation in the p85α regulatory subunit of PI3K affects
        development of the iris, and contributes to changes consistent with anterior segment
        dysgenesis in both humans and mice.
      explanation: >-
        The authors' conclusion, drawn from the mouse and the human subjects together, that
        this mutation is what drives the anterior segment phenotype.
  - target: Dissociation of Insulin Resistance from Dyslipidaemia
    relationship: RECAPITULATES
    fidelity: MODERATE
    description: >-
      Challenged with a high-fat diet or crossed onto an obese background, the mutant mice
      are protected from obesity and hepatic steatosis while becoming more diabetic. That
      is the mouse form of the human dissociation, and it separates the two effects
      experimentally in a way patient observation cannot.
    limitations: >-
      The mouse experiments impose obesogenic challenges that patients are not subjected
      to, so the protection is demonstrated under conditions with no human counterpart. The
      direction of the dissociation matches; its magnitude in unchallenged animals is not
      reported here.
    readouts:
    - name: Adiposity and hepatic steatosis under obesogenic challenge
      target: Dissociation of Insulin Resistance from Dyslipidaemia
      direction: DECREASED
      interpretation: >-
        Less fat and less fatty liver despite worse glycaemia, which is the dissociation.
      evidence:
      - reference: PMID:29724723
        reference_title: Mice Carrying a Dominant-Negative Human PI3K Mutation Are Protected From Obesity and Hepatic Steatosis but Not Diabetes.
        supports: SUPPORT
        evidence_source: MODEL_ORGANISM
        snippet: >-
          the ob/ob mice carrying the heterozygous R649W mutation were protected from
          obesity and hepatic steatosis but developed a severe diabetic state
        explanation: >-
          The clearest statement of the dissociation, in the genetically obese cross.
    evidence:
    - reference: PMID:29724723
      reference_title: Mice Carrying a Dominant-Negative Human PI3K Mutation Are Protected From Obesity and Hepatic Steatosis but Not Diabetes.
      supports: SUPPORT
      evidence_source: MODEL_ORGANISM
      snippet: >-
        despite the lower level of adiposity, the HFD knock-in mice are more hyperglycemic
        and more insulin-resistant than HFD-fed control mice
      explanation: >-
        The dissociation under dietary challenge: less adiposity, worse glycaemia.
differential_diagnoses:
- name: Silver-Russell syndrome
  description: >-
    The differential that matters most in practice. A child presenting with intrauterine
    growth restriction, postnatal short stature and a triangular face fits both, and SRS is
    far commoner. The distinguishing features are the ones SRS lacks: the anterior segment
    anomaly, the partial lipodystrophy, and the severe insulin resistance that emerges at
    puberty. SHORT syndrome is recognised in the SRS literature as a differential precisely
    because of that phenotypic overlap.
  evidence:
  - reference: PMID:32546215
    reference_title: "Contribution of gene mutations to Silver-Russell syndrome phenotype: multigene sequencing analysis in 92 etiology-unknown patients."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      our data confirmed IGF1R abnormality, SHORT syndrome, and Floating-Harbor syndrome are
      differential diagnoses of SRS because of the shared phenotypes among these syndromes
      and SRS
    explanation: >-
      States the differential relationship directly, from a cohort of 92 patients with an SRS
      phenotype and no identified cause.
- name: Activated PI3K-delta syndrome 2
  description: >-
    The other PIK3R1-related disease. It is caused by a different class of variant in
    the same gene, acting in the opposite direction on PI3K signalling, and presents as
    a primary immunodeficiency. The two are not mutually exclusive: individuals with
    both phenotypes have been reported, so finding a PIK3R1 variant does not settle
    which disease a patient has.
  evidence:
  - reference: PMID:28302518
    reference_title: "Mutations in PIK3R1 can lead to APDS2, SHORT syndrome or a combination of the two."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Mutations in PIK3R1 gene have been associated to two different conditions: a
      primary immunodeficiency, called APDS2, of recent description and SHORT
      syndrome.
    explanation: >-
      Establishes that one gene underlies both entities.
discussions:
- discussion_id: pik3r1_allelic_direction
  kind: OPEN_QUESTION
  status: OPEN
  prompt: >-
    How do PIK3R1 variants that reduce PI3K-AKT signalling (SHORT syndrome) and
    PIK3R1 variants that increase p110-delta activity (APDS2) coexist in the same
    patients, and what determines which phenotype a given allele produces?
  attaches_to:
  - pathophysiology#Reduced PI3K-AKT Signal Transduction
  - pathophysiology#PIK3R1 C-terminal SH2 Domain Variant
  rationale: >-
    The two PIK3R1 diseases are usually described as having opposite effects on the
    pathway, which makes their co-occurrence in one individual mechanistically
    awkward rather than merely unusual. Reported overlap cases show it is not a
    theoretical concern: two further patients with both phenotypes were described in
    2017, taking the total beyond the single previously known case, and the authors
    concluded the association may not be rare. Resolving this matters for curation
    because it determines whether the two entries can keep independent pathographs or
    whether a shared allele-to-phenotype model is needed.
  evidence:
  - reference: PMID:28302518
    reference_title: "Mutations in PIK3R1 can lead to APDS2, SHORT syndrome or a combination of the two."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      47 patients with APDS2 have been reported to date, only one of them sharing both
      PIK3R1-related phenotypes.
    explanation: >-
      Quantifies how exceptional the overlap was thought to be before this report.
  - reference: PMID:28302518
    reference_title: "Mutations in PIK3R1 can lead to APDS2, SHORT syndrome or a combination of the two."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Here we describe two more patients affected by APDS2 and SHORT syndrome, which
      highlights that this association may not be so infrequent.
    explanation: >-
      The observation that reopens the question: the overlap is more common than the
      single prior case suggested.
  - reference: PMID:32778990
    reference_title: APDS2 and SHORT Syndrome in a Teenager with PIK3R1 Pathogenic Variant.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      This pathogenic variant had been previously associated with APDS2; however, it had not
      been associated with SHORT syndrome. The exact mechanisms linking both conditions are
      yet to be identified.
    explanation: >-
      The sharpest form of the problem: one splice allele, previously an APDS2 allele,
      producing SHORT syndrome features in this patient. Cited here because it is the
      strongest published case against the split this entry maintains, and the authors state
      plainly that the mechanism is unknown.
  - reference: PMID:35789397
    reference_title: Clinical and immunological assessment of APDS2 with features of the SHORT syndrome related to a novel mutation in PIK3R1 with reduced penetrance.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      LOF variants in an intronic splice site (c.1425+1G.C/A/T) in the PI3KR1 gene have been
      identified in patients affected with both APDS2 and SHORT syndrome.
    explanation: >-
      Identifies the specific intronic splice site where the overlap alleles cluster, which
      is what makes the overlap look like a property of a variant class rather than a
      coincidence.
- discussion_id: context_dependent_signalling
  kind: OPEN_QUESTION
  status: OPEN
  prompt: >-
    If the C-terminal PIK3R1 variants impair insulin signalling only in some cellular
    contexts, what determines which tissues are affected, and is a single "reduced
    PI3K-AKT signalling" node the right way to model this disease?
  attaches_to:
  - pathophysiology#Reduced PI3K-AKT Signal Transduction
  - pathophysiology#Dissociation of Insulin Resistance from Dyslipidaemia
  rationale: >-
    The pathograph in this entry routes everything through one node in which PI3K-AKT
    signalling is reduced, and that is how the founding papers framed it. The 2016 study
    that established the dyslipidaemia dissociation complicates the picture in two ways.
    First, it states outright that these mutations impair insulin signalling only in some
    cellular contexts. Second, in cells from one patient carrying the p.Tyr657X allele,
    the mutant p85-alpha failed to associate with IRS1 while downstream signalling was
    normal - a binding defect that did not propagate. Taken together these say the lesion
    is not a uniform dial turned down across every tissue, which is what the single node
    implies. The tissue selectivity would also explain the dissociation directly: hepatic
    lipogenesis is spared while glucose disposal is not. Nothing cited here identifies
    what makes a given cell type sensitive or resistant, so the node is kept as one and
    this question records the qualification rather than splitting the pathograph on
    speculation.
  evidence:
  - reference: PMID:27766312
    reference_title: Insulin resistance uncoupled from dyslipidemia due to C-terminal PIK3R1 mutations.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      PIK3R1 C-terminal mutations impair insulin signaling only in some cellular contexts
    explanation: >-
      The authors' explicit statement of context-dependence, which is what this question is
      about.
  - reference: PMID:27766312
    reference_title: Insulin resistance uncoupled from dyslipidemia due to C-terminal PIK3R1 mutations.
    supports: SUPPORT
    evidence_source: IN_VITRO
    snippet: >-
      showed severely reduced insulin-stimulated association of mutant but not WT p85α with
      IRS1, but normal downstream signaling
    explanation: >-
      A measured case where the binding defect did not propagate downstream. This is the
      single most direct challenge to the simple linear reading of the pathograph, and is
      recorded here rather than omitted because it is inconvenient.
- discussion_id: anterior_segment_mechanism_gap
  kind: KNOWLEDGE_GAP
  status: OPEN
  prompt: >-
    By what developmental route does reduced PI3K-AKT signalling produce anterior
    segment dysgenesis (Rieger anomaly) in SHORT syndrome?
  attaches_to:
  - pathophysiology#Anterior Segment Dysgenesis
  rationale: >-
    The gap here is narrower than it looks, and narrower than an earlier draft of this
    entry claimed. Sufficiency is established: the heterozygous R649W allele produces
    iris hypoplasia with an enlarged irregular pupil in the knock-in mouse, and the same
    allele produces Rieger anomaly in human carriers, so the p85-alpha lesion demonstrably
    reaches anterior segment development in vivo. What is missing is everything between.
    The anterior segment derives from periocular neural crest, and no cited source
    identifies which crest population, which developmental window, or which PI3K-dependent
    process is affected - nor why the mouse stops at the iris while humans go on to
    goniosynechiae, cataract and glaucoma. That species difference is itself a clue nobody
    has followed up. The pathophysiology node is connected to the upstream signalling node
    with unknown intermediates, which is the honest encoding of "we know it gets there, we
    do not know how".
  evidence:
  - reference: PMID:28632845
    reference_title: Iris Malformation and Anterior Segment Dysgenesis in Mice and Humans With a Mutation in PI 3-Kinase.
    supports: SUPPORT
    evidence_source: MODEL_ORGANISM
    snippet: >-
      A dominant-negative mutation in the p85α regulatory subunit of PI3K affects
      development of the iris, and contributes to changes consistent with anterior segment
      dysgenesis in both humans and mice.
    explanation: >-
      Establishes sufficiency, which is the half of the question that is answered.
  - reference: PMID:28632845
    reference_title: Iris Malformation and Anterior Segment Dysgenesis in Mice and Humans With a Mutation in PI 3-Kinase.
    supports: SUPPORT
    evidence_source: MODEL_ORGANISM
    snippet: >-
      While overall eye development was normal with clear cornea and lens, normal anterior
      chamber volume, normal intraocular pressure, and no changes in the retinal structure,
      OCT images of the knock-in mouse eyes revealed a significant decrease in thickness and
      width of the iris
    explanation: >-
      The selectivity of the mouse phenotype - iris only, everything else normal - which is
      the observation any mechanistic account would have to explain and none does.
notes: >-
  Entity scope. This entry covers SHORT syndrome as the PIK3R1-related growth,
  lipodystrophy and anterior-segment disorder. It is deliberately kept separate from
  the existing `Activated_PI3K-delta_Syndrome` entry even though both are PIK3R1
  diseases, because the variant classes, the direction of effect on PI3K signalling,
  and the affected systems differ. MONDO's `MONDO:1060136` ("PIK3R1-related
  immunodeficiency and SHORT syndrome") lumps the two; that lumping is not adopted
  here, and the overlap between them is recorded as an open question rather than as a
  merged pathograph.

  Frequency bands. Two cohorts inform them and they agree on ordering. The 32-patient
  molecularly confirmed cohort grades features qualitatively ("commonly observed", "not as
  prevalent", "less specific, or minor") and gives only one percentage, for the
  acronym-completeness figure. The later systematic appraisal of 19 individuals from 11
  families puts facial dysmorphism first, ahead of lipodystrophy, insulin resistance and
  intrauterine growth restriction, and ahead of the eponymous ocular and dental signs.
  Bands here are anchored to that ordering rather than to reported prevalences, and each
  phenotype's evidence explanation says which wording it rests on. Where the sources
  support no ordering at all, no `frequency` is recorded.

  Reference consumption. Every reference cached by this PR is cited except one:
  `PMID:24033310` is a three-line commentary whose cached body contains only a list of the
  three 2013 gene-discovery papers, with no abstract and nothing quotable. It is kept in the
  cache because the deep-research report cites it and the cache should match the report's
  reference set, but there is no claim it can support.

  GeneReviews. There is no GeneReviews chapter for SHORT syndrome. A PubMed title search
  (`SHORT syndrome[TI] AND GeneReviews[TI]`) returns zero records, and the deep-research run
  surfaced none across its 19 references. Recorded here so the question does not have to be
  re-asked. The systematic appraisal (PMID:34212753) is the nearest equivalent and is the
  source most of this entry's frequency ordering rests on.

  Pathograph connectivity. Four phenotypes are deliberately left with no incoming edge:
  joint hypermobility, inguinal hernia, sensorineural hearing impairment and speech delay.
  These are exactly the features the cohort study grades as "less specific, or minor", and
  no cited source proposes a route from the signalling defect to any of them. Drawing an
  edge would assert a mechanism nobody has; leaving them attached to nothing is the
  accurate representation. Every other phenotype in the entry is reachable from the
  PIK3R1 variant node.

  Mechanism, and one qualification carried rather than dropped. The pathograph routes the
  three arms of the phenotype - growth, adipose, metabolic - through a single node in
  which PI3K-AKT signalling is reduced, which is how the founding papers framed it and
  what the knock-in mouse supports across liver, muscle and fat. The 2016 dissociation
  study qualifies that: it states the mutations impair insulin signalling only in some
  cellular contexts, and reports one patient's cells in which the binding defect did not
  propagate downstream. That qualification is recorded as an open question rather than
  resolved by splitting the node, because nothing cited identifies what makes a tissue
  sensitive.

  Two phenotypes are recorded in order to record their absence. Hepatic steatosis and
  dyslipidaemia carry REFUTE evidence, because their absence alongside extreme insulin
  resistance is diagnostically useful - it points away from obesity-related insulin
  resistance and towards a proximal receptor-to-PI3K lesion. Omitting them would make the
  entry silent on a question clinicians actually ask.

  Not asserted. The gene-level `genetic:` entry carries no `functional_impact_category`,
  since the schema places that slot on variant-level records; the variants themselves are
  curated with their functional effects, and the dominant-negative reading of p.Arg649Trp
  is evidenced from the preadipocyte overexpression experiment and the mouse paper's own
  framing rather than asserted from the heterozygous state alone. Growth hormone therapy
  is recorded with REFUTE evidence against the claim that it causes the diabetes: the
  cited review attributes that to puberty instead, and the case against growth hormone in
  this disorder rests on lack of statural benefit.
references:
- reference: PMID:34212753
  title: "SHORT Syndrome: Systematic Appraisal of the Medical and Dental Phenotype."
  found_in:
  - SHORT_Syndrome-deep-research-openscientist.md
- reference: PMID:36401775
  title: "SHORT Syndrome: an Update on Pathogenesis and Clinical Spectrum."
  found_in:
  - SHORT_Syndrome-deep-research-openscientist.md
- reference: PMID:26974159
  title: PI3-kinase mutation linked to insulin and growth factor resistance in vivo.
  found_in:
  - SHORT_Syndrome-deep-research-openscientist.md
- reference: PMID:27766312
  title: Insulin resistance uncoupled from dyslipidemia due to C-terminal PIK3R1 mutations.
  found_in:
  - SHORT_Syndrome-deep-research-openscientist.md
- reference: PMID:28632845
  title: Iris Malformation and Anterior Segment Dysgenesis in Mice and Humans With a Mutation in PI 3-Kinase.
  found_in:
  - SHORT_Syndrome-deep-research-openscientist.md
datasets: []

📚

References & Deep Research

References

5

PMID:34212753

SHORT Syndrome: Systematic Appraisal of the Medical and Dental Phenotype.

No top-level findings curated for this source.

PMID:36401775

SHORT Syndrome: an Update on Pathogenesis and Clinical Spectrum.

No top-level findings curated for this source.

PMID:26974159

PI3-kinase mutation linked to insulin and growth factor resistance in vivo.

No top-level findings curated for this source.

PMID:27766312

Insulin resistance uncoupled from dyslipidemia due to C-terminal PIK3R1 mutations.

No top-level findings curated for this source.

PMID:28632845

Iris Malformation and Anterior Segment Dysgenesis in Mice and Humans With a Mutation in PI 3-Kinase.

No top-level findings curated for this source.

Deep Research

1

OpenScientist ▸

SHORT Syndrome — Comprehensive Disease Characteristics Report

openscientist-autonomous 19 citations 2026-09-01T15:27:03.690229

SHORT Syndrome — Comprehensive Disease Characteristics Report

Disease: SHORT Syndrome Category: Mendelian (monogenic) Key identifiers: OMIM #269880 · Orphanet ORPHA:3163 · MONDO:0009159 · ICD-10 Q87.1 · MeSH — indexed under lipodystrophy/insulin-resistance syndromes (no dedicated descriptor) Causal gene: PIK3R1 (HGNC:8979; OMIM *171833), encoding the p85α regulatory subunit of class IA phosphatidylinositol 3-kinase (PI3K)

Summary

SHORT syndrome is a rare autosomal dominant multisystem disorder whose name is an acronym for its cardinal features: Short stature, Hyperextensibility of joints, Ocular depression (deep-set eyes), Rieger anomaly (anterior-segment dysgenesis), and Teething (delayed dental eruption). It is caused by heterozygous loss-of-function / dominant-negative mutations in PIK3R1, the gene encoding the p85α regulatory subunit of class IA PI3K. Three concurrent 2013 exome-sequencing studies established causality, and the recurrent C-terminal hotspot missense variant c.1945C>T (p.Arg649Trp) accounts for the majority of cases (PMID: 24886349, PMID: 23980586, PMID: 24033310).

The unifying mechanism is impaired proximal insulin/growth-factor PI3K–AKT signaling. Mutations cluster in the C-terminal SH2 (cSH2)/inter-SH2 (iSH2) substrate-recognition region of p85α; the mutant subunit fails to relieve p110 catalytic inhibition and fails to transmit receptor-generated phosphotyrosine signals. The downstream consequences—intrauterine growth restriction (IUGR) and postnatal short stature, partial (facial/limb) lipodystrophy, a distinctive severe insulin resistance, progeroid craniofacial dysmorphism, and Rieger anomaly—map onto tissues that depend on PI3K signaling. A Pik3r1 Arg649Trp knock-in mouse recapitulates the human disease and directly demonstrates reduced PI3K activation as the mechanism (PMID: 26974159).

A distinctive metabolic signature separates SHORT syndrome from common obesity-related insulin resistance: the insulin resistance is uncoupled from dyslipidemia and hepatic steatosis, biochemically resembling primary insulin-receptor dysfunction and localizing the lesion to a proximal receptor→PI3K node (PMID: 27766312). Diabetes typically becomes overt around puberty (PMID: 32879144). Management is supportive—insulin-sensitizing and glucose-lowering drugs (metformin, SGLT2 inhibitors), with growth hormone used cautiously. Notably, PIK3R1 is a dual-disorder gene: loss-of-function C-terminal variants cause SHORT syndrome, while splice variants that hyperactivate p110δ cause the gain-of-function immunodeficiency APDS2, with occasional phenotypic overlap (PMID: 32778990).

Section 1 — Disease Information

Overview. SHORT syndrome is a rare, congenital, autosomal dominant multisystem disorder characterized by pre- and post-natal growth failure, a recognizable progeroid facial gestalt, partial lipodystrophy, anterior-segment eye dysgenesis (Rieger anomaly), delayed dental eruption, joint hyperextensibility, and a highly characteristic insulin-resistant diabetes that emerges around puberty. The SHORT acronym only partially captures the phenotype; systematic review has shown that facial dysmorphism is actually the most consistent feature, ahead of the eponymous ocular and dental signs (PMID: 34212753).

Key identifiers. | Resource | Identifier | |---|---| | OMIM | #269880 (SHORT syndrome) | | Orphanet | ORPHA:3163 | | MONDO | MONDO:0009159 | | ICD-10 | Q87.1 | | Gene (HGNC) | PIK3R1, HGNC:8979 | | Gene (OMIM) | *171833 |

Synonyms / alternative names. SHORT syndrome; Short stature–hyperextensibility–ocular depression–Rieger anomaly–teething delay syndrome; Rieger anomaly–partial lipodystrophy syndrome; Aarskog-Ose-Pande syndrome; lipodystrophy–Rieger anomaly–diabetes syndrome.

Evidence source. Information is derived from aggregated disease-level resources (OMIM, Orphanet), individual case reports and small case series, and one systematic review of 19 individuals from 11 families (PMID: 34212753). There is no large EHR-derived cohort; the total reported literature comprises on the order of tens of families.

Section 2 — Etiology

Primary cause — genetic. SHORT syndrome is a monogenic disorder caused by heterozygous pathogenic variants in PIK3R1. It is not infectious or primarily environmental. Inheritance is autosomal dominant; both inherited (parent-to-child) and de novo mutations are reported, with several case reports documenting confirmed de novo origin (parents and siblings unaffected and mutation-negative) — e.g., PMID: 33129256, PMID: 32602265.

Genetic risk factors. The causal variants are the PIK3R1 C-terminal cSH2/iSH2 mutations (see Section 4). The recurrent c.1945C>T (p.Arg649Trp) is the single largest contributor. No independent susceptibility loci or common modifier alleles have been established; because the disorder is highly penetrant and monogenic, the "risk factor" is essentially carriage of the pathogenic allele.

Environmental risk factors. None established as causal. Age/puberty acts as a temporal modifier of the metabolic phenotype—insulin-resistant diabetes appears around/after puberty rather than in early childhood (PMID: 32879144). Sex does not appear to strongly modify prevalence, though several prominent case reports are female.

Protective factors. No genetic or environmental protective variants are described. In mouse models, the mutation itself confers apparent "protection" from obesity and hepatic steatosis (a consequence of reduced lipogenesis), but this is a manifestation of the disease mechanism rather than a protective factor for the patient (PMID: 29724723).

Gene–environment interactions. The principal documented interaction is genotype × pubertal/hormonal milieu: the diabetogenic insulin resistance is latent in childhood and unmasked around puberty. Growth hormone (an iatrogenic/therapeutic exposure) is diabetogenic and can aggravate the metabolic phenotype (PMID: 32879144).

Section 3 — Phenotypes

SHORT syndrome is a multisystem disorder. Phenotype frequencies below draw on the systematic review of 19 individuals (PMID: 34212753) and multiple case reports.

Phenotype	Type	Onset	Frequency	Suggested HPO term
Intrauterine growth restriction	Physical manifestation	Prenatal/congenital	Very common	HP:0001511
Short stature / postnatal growth failure	Clinical sign	Congenital–childhood	Common	HP:0004322
Facial dysmorphism (triangular face, frontal bossing)	Physical manifestation	Congenital	Most consistent	HP:0000271 / HP:0000268
Deep-set eyes / ocular depression	Physical manifestation	Congenital	Common	HP:0000490
Large, low-set ears	Physical manifestation	Congenital	Common	HP:0000369 / HP:0000368
Micrognathia / mandibular retrognathia	Physical manifestation	Congenital	Common	HP:0000347
Thin/hypoplastic alae nasi	Physical manifestation	Congenital	Common	HP:0000430
Progeroid / aged appearance	Physical manifestation	Childhood	Common	HP:0005104
Partial lipodystrophy (facial/limb lipoatrophy)	Physical manifestation	Childhood	Common	HP:0009125
Insulin resistance	Laboratory abnormality	Childhood–puberty	Common (metabolic hallmark)	HP:0000855
Insulin-resistant diabetes mellitus	Laboratory/clinical	~Puberty onward	~10/15 untreated ≥12 y	HP:0000831 / HP:0000857
Acanthosis nigricans	Clinical sign	Childhood	Reported	HP:0000956
Rieger anomaly / anterior-segment dysgenesis	Clinical sign	Congenital	Common (eponymous)	HP:0000554 / HP:0000539
Glaucoma	Clinical sign	Childhood–adult	Reported	HP:0000501
Delayed tooth eruption	Clinical sign	Childhood	Common (eponymous)	HP:0000684
Joint hyperextensibility	Clinical sign	Congenital–childhood	Common (eponymous)	HP:0001382
Inguinal hernia	Clinical sign	Childhood	Reported	HP:0000023
Sensorineural hearing loss	Clinical sign	Variable	Reported	HP:0000407

Characteristics. Craniofacial features are congenital, stable, and the most penetrant. Metabolic features are progressive and age-dependent: insulin resistance is often subclinical in early childhood, then diabetes develops around puberty (PMID: 32879144). Severity is variable even within the recurrent hotspot genotype, indicating variable expressivity. Intelligence is typically normal.

Quality-of-life impact. No formal EQ-5D/SF-36 studies exist. Practically, QoL is affected by (i) chronic metabolic disease requiring lifelong glucose management, (ii) visual morbidity from glaucoma/anterior-segment disease (risk of vision loss), (iii) short stature and dysmorphism with psychosocial impact, and (iv) dental complications. Cognition and lifespan appear largely preserved.

Section 4 — Genetic / Molecular Information

Causal gene. PIK3R1 (HGNC:8979; OMIM 171833), chromosome 5q13.1, encoding the p85α regulatory subunit* of class IA PI3K.

Pathogenic variants. Most mutations cluster in the region encoding the C-terminal SH2 (cSH2) / inter-SH2 (iSH2) substrate-recognition domain. Documented variants:

Variant (cDNA)	Protein	Type	Note
c.1945C>T	p.Arg649Trp	Missense	Recurrent hotspot — majority of cases (8/14 families in one series)
c.1929_1933delTGGCA	p.Asp643Aspfs*8	Frameshift	Novel truncating variant
c.1960C>T	p.Gln654*	Nonsense	De novo; first Chinese case with thyroid disease
c.2008delT	—	Frameshift	Truncating
c.1615_1617del	in-frame del	Small deletion	Chinese case series

Classification (ACMG/AMP). The recurrent c.1945C>T (p.Arg649Trp) and the reported truncating variants are classified pathogenic/likely pathogenic in ClinVar. Truncating and dominant-negative missense variants converge on the same C-terminal region.

Allele frequency. These are private/ultra-rare disease variants essentially absent from gnomAD control populations, consistent with severe monogenic disease.

Origin. Germline (constitutional). Both inherited and de novo germline events occur. No somatic contribution to SHORT syndrome.

Functional consequence. Loss of function with a dominant-negative component. The mutant p85α fails to relieve inhibition of the p110 catalytic subunit and fails to couple to receptor phosphotyrosines, reducing PI3K activation. Because p85α is a shared regulatory subunit, the mutant subunit dominantly interferes with signaling (heterozygous, autosomal dominant) — PMID: 26974159.

Modifier genes / epigenetics / chromosomal abnormalities. No specific modifier genes, epigenetic signatures, or large chromosomal rearrangements are established for SHORT syndrome. It is a single-nucleotide/small-indel monogenic disorder; chromosomal microarray is typically normal.

Section 5 — Environmental Information

SHORT syndrome is a genetic disorder with no established environmental etiology. There are no causal toxins, radiation exposures, occupational factors, dietary triggers, or infectious agents. The only clinically relevant "environmental"/exogenous modifier is growth hormone therapy, which—being diabetogenic—can worsen the metabolic phenotype and is regarded with caution (PMID: 32879144). Pubertal hormonal changes act as an endogenous temporal modifier of diabetes onset.

Section 6 — Mechanism / Pathophysiology

Ordered causal chain

A heterozygous PIK3R1 mutation (most often c.1945C>T, p.Arg649Trp) in the C-terminal cSH2/iSH2 region produces a defective p85α regulatory subunit.
The mutant p85α fails to relieve inhibition of the p110 catalytic subunit and fails to engage activated receptor phosphotyrosines → results in reduced recruitment/activation of class IA PI3K at the insulin/IGF-1/growth-factor receptor complex.
Because p85α is heterozygously mutated and dominant-negative, PI3K activation is reduced across insulin-responsive tissues (liver, muscle, adipose) → leads to diminished generation of PIP₃ and blunted downstream AKT (PKB) signaling (demonstrated in the knock-in mouse: reduced capacity of insulin and other growth factors to activate PI3K in liver, muscle, and fat — PMID: 26974159).
Reduced PI3K–AKT signaling branches into the disease phenotypes:
Metabolic branch: impaired insulin action → systemic insulin resistance → compensatory hyperinsulinemia → (around puberty) insulin-resistant diabetes mellitus (PMID: 32879144). Because the lesion is proximal (receptor→PI3K), the insulin resistance is uncoupled from hepatic lipogenesis → no fatty liver, no dyslipidemia, preserved/high adiponectin (PMID: 27766312).
Adipose branch: impaired PI3K-dependent adipocyte development/maintenance → partial lipodystrophy → reduced lipid buffering, further aggravating insulin resistance (inferred).
Growth branch: reduced PI3K/IGF-1 signaling (possible IGF-1 resistance) → IUGR and postnatal short stature (inferred from clinical + IGF resistance data; PMID: 36401775).
Ocular/developmental branch: reduced PI3K signaling during anterior-segment development → iris hypoplasia and anterior-segment dysgenesis → Rieger anomaly — a demonstrated developmental iris defect, independent of diabetes (PMID: 28632845).
Craniofacial/dental branch: reduced PI3K signaling in craniofacial/dental development → progeroid dysmorphism and delayed tooth eruption (inferred).

Molecular / cellular detail

Molecular pathway: class IA PI3K–AKT–mTOR signaling downstream of insulin/IGF-1 and other growth-factor receptor tyrosine kinases (KEGG hsa04151 PI3K-Akt; KEGG hsa04910 insulin signaling). SHORT syndrome represents haploinsufficient/dominant-negative attenuation of this axis—the mirror image of gain-of-function PI3K activation.
Protein dysfunction: p85α cSH2/iSH2 substrate-recognition domain defect → failure of the regulatory subunit to bind phosphotyrosine motifs and to properly regulate p110 (loss-of-function with dominant-negative behavior).
Metabolic changes: decreased lipogenesis, increased energy expenditure, insulin resistance, and possible IGF-1 resistance (PMID: 36401775).
Classification: formally a genetic (monogenic) insulin resistance syndrome within the PI3K signaling axis, grouped with INSR (type A/Donohue/Rabson–Mendenhall) and AKT2/TBC1D4/PRKCE disorders (PMID: 35110500).

Suggested ontology terms

GO biological process: phosphatidylinositol 3-kinase signaling (GO:0014065); insulin receptor signaling pathway (GO:0008286); regulation of glucose import (GO:0046324); positive regulation of cell growth (GO:0030307).
GO cellular component / molecular function: phosphatidylinositol 3-kinase complex (GO:0005942); 1-phosphatidylinositol-3-kinase regulator activity (GO:0046935).
Cell types (CL): adipocyte (CL:0000136); hepatocyte (CL:0000182); skeletal muscle cell (CL:0000188); iris pigment/stromal cells and neural-crest-derived anterior-segment cells.

Section 7 — Anatomical Structures Affected

Organ / system level. - Endocrine/metabolic: pancreas (islet dysfunction/insulin secretion defect in mouse), adipose tissue, liver, skeletal muscle — insulin target tissues (UBERON:0002107 liver; UBERON:0001013 adipose tissue; UBERON:0001134 skeletal muscle; UBERON:0000006 islet of Langerhans). - Eye: anterior segment — iris (UBERON:0001769), cornea/angle structures; Rieger anomaly with goniosynechiae, prominent ring of Schwalbe, glaucoma, early cataract. - Craniofacial skeleton and teeth: face, mandible, dental structures (delayed eruption). - Musculoskeletal: joints (hyperextensibility); overall stature/growth. - Skin: acanthosis nigricans (secondary to insulin resistance).

Tissue/cell level. Adipocytes (lipodystrophy), hepatocytes and myocytes (insulin resistance), pancreatic β-cells (insulin secretion), and neural-crest-derived anterior-segment cells (iris hypoplasia). The mouse model localizes the ocular defect specifically to a decrease in iris thickness and width with increased pupil area/irregularity, cornea/lens/retina otherwise normal (PMID: 28632845).

Subcellular level. Signaling defect at the plasma membrane / cytoplasmic receptor-signaling complex (PI3K complex; GO:0005942); PIP₃ generation at the inner leaflet of the plasma membrane.

Localization / lateralization. Systemic and generally bilateral/symmetric; ocular involvement is bilateral.

Section 8 — Temporal Development

Onset: Congenital. IUGR is prenatal; dysmorphism, ocular, and dental features are present from birth/early childhood.
Progression: Craniofacial features are stable. The metabolic phenotype is progressive and age-dependent: insulin resistance is often subclinical in early childhood, with insulin-resistant diabetes typically emerging around puberty — diabetes in 10/15 untreated patients aged ≥12 y versus none aged ≤10 y (PMID: 32879144).
Course: Chronic, lifelong. No spontaneous remission of the underlying disorder; metabolic parameters can be improved with treatment.
Critical period / intervention window: Peripubertal transition is the key window for metabolic surveillance and early intervention; anterior-segment/glaucoma monitoring is lifelong to preserve vision.

Section 9 — Inheritance and Population

Epidemiology: Ultra-rare. Prevalence is not precisely established; Orphanet lists it as <1/1,000,000, with only tens of families reported worldwide. No reliable incidence figure exists.
Inheritance: Autosomal dominant (PMID: 23980586, PMID: 24033310).
Penetrance: High for the overall syndrome; age-dependent penetrance for the diabetes component (largely post-pubertal).
Expressivity: Variable, even among carriers of the recurrent p.Arg649Trp allele.
De novo vs inherited: Both occur; multiple confirmed de novo cases (parents/siblings unaffected and mutation-negative).
Anticipation / mosaicism / founder effects: No genetic anticipation (not a repeat-expansion disorder). No established founder effect; the recurrence of c.1945C>T reflects a mutational hotspot rather than a founder haplotype. Germline mosaicism not specifically documented.
Consanguinity: Not relevant (dominant disorder).
Population demographics: Reported across multiple ethnicities (European, Chinese, Filipino, etc.); no strong ethnic predilection. Sex ratio not clearly skewed. Age distribution spans childhood to adulthood.

Section 10 — Diagnostics

Genetic testing (definitive). Diagnosis is confirmed by identifying a heterozygous pathogenic PIK3R1 variant. Recommended approaches: - Single-gene testing / targeted variant analysis for PIK3R1 (especially the c.1945C>T hotspot) when the phenotype is classic. - Whole-exome sequencing (WES) is the most common route to diagnosis in the reported literature and is high-yield when the phenotype is atypical or overlaps with Silver–Russell syndrome (PMID: 32546215). - Gene panels for lipodystrophy/insulin-resistance/growth-failure that include PIK3R1. - Whole-genome sequencing (WGS) is useful for splice/structural variants (relevant given the allelic APDS2 splice variants). Chromosomal microarray/karyotype are typically normal and not diagnostic.

Clinical/laboratory tests. - Metabolic: fasting glucose, HbA1c, fasting insulin/C-peptide, OGTT with insulin — reveal severe insulin resistance and hyperinsulinemia; adiponectin is characteristically preserved/high (PMID: 27766312). Lipid panel and liver imaging are characteristically normal (no dyslipidemia/steatosis), a distinguishing feature. - Ophthalmologic: slit-lamp/gonioscopy and OCT identify Rieger anomaly, iris thinning, goniosynechiae, prominent ring of Schwalbe, cataract, and glaucoma (PMID: 28632845). - Auxological/imaging: growth charts documenting IUGR/short stature; dental radiographs for eruption delay.

Clinical criteria / differential diagnosis. No formal consensus criteria; diagnosis is based on the recognizable gestalt plus molecular confirmation. Key differentials: - Silver–Russell syndrome (shared IUGR, triangular face, growth failure) — distinguished by 11p15 LOM/upd(7)mat and by SHORT’s lipodystrophy/insulin resistance (PMID: 32546215). - Other congenital/partial lipodystrophies (e.g., FPLD) — distinguished by the SHORT gestalt, Rieger anomaly, and the dyslipidemia-uncoupled insulin resistance. - APDS2 (allelic; immunodeficiency phenotype) — distinguished by recurrent sinopulmonary infection and hypogammaglobulinemia and by the splice-site GOF variant (PMID: 32778990).

Screening. Cascade genetic testing of at-risk relatives once a familial variant is known. No population newborn screening.

Section 11 — Outcome / Prognosis

Survival / life expectancy: No evidence of substantially reduced lifespan; the disorder is compatible with adult life. There is no reported disease-specific mortality figure.
Morbidity: Driven by (i) chronic insulin-resistant diabetes and its long-term complications, (ii) ophthalmologic morbidity (glaucoma → potential vision loss), and (iii) growth/dysmorphism-related psychosocial impact. Notably, two patients with >30 years of diabetes had no diabetic retinopathy, suggesting the ocular phenotype is developmental rather than microvascular (PMID: 28632845).
Disease course: Chronic, lifelong, non-remitting at the genetic level; metabolic control is achievable pharmacologically.
Prognostic factors: Age/puberty (diabetes onset), adequacy of glycemic management, and intraocular pressure control (vision). Preserved adiponectin and absent dyslipidemia may confer relative protection from atherogenic complications compared with obesity-related insulin resistance.
Data gaps: Long-term natural-history and outcome data are sparse (PMID: 36401775).

Section 12 — Treatment

No formal treatment guidelines exist; management is supportive and organ-directed, drawn from case reports.

Pharmacotherapy for insulin resistance / diabetes (NCIT: metformin C61793; SGLT2 inhibitors; thiazolidinediones): - Metformin (± pioglitazone) improved insulin resistance and hyperinsulinemia (PMID: 33742773); metformin effective in early treatment of two Chinese girls (PMID: 32602265). - SGLT2 inhibitor (canagliflozin) ameliorated overt diurnal hyperglycemia and mild nocturnal hypoglycemia (PMID: 32879144). - Multi-agent oral therapy (metformin + voglibose/DPP-4/SGLT2 combinations) improved glucose and insulin resistance over months (PMID: 39735640, PMID: 41459015). - Lifestyle intervention (diet, exercise) is a consistent adjunct.

Growth hormone — relatively contraindicated. GH gives a poor statural response and, being diabetogenic, can worsen glucose metabolism; it has been regarded as contraindicated. However, Masunaga et al. concluded that pubertal development/age—not GH per se—drives diabetes onset, nuancing this caution (PMID: 32879144).

Ophthalmologic / surgical: glaucoma management (IOP-lowering therapy, surgery as needed), cataract surgery, and anterior-segment care. Dental management for eruption delay/anomalies.

Advanced/experimental therapeutics: No approved gene, cell, RNA-based, or targeted molecular therapy exists for SHORT syndrome. Because the defect is loss-of-PI3K-signaling, PI3K/AKT-pathway inhibitors (used in the opposite, gain-of-function conditions) are inappropriate; conceptually, pathway-restorative strategies would be required. No registered SHORT-syndrome-specific interventional trials identified.

Pharmacogenomics / personalized approach: Genotype-guided care is essentially "diagnosis-guided"—confirming PIK3R1 etiology reframes the insulin resistance as a proximal signaling defect, supporting insulin-sensitizer-based strategies and cautious GH use.

Section 13 — Prevention

SHORT syndrome cannot be prevented (congenital monogenic disorder). Preventive strategy focuses on secondary and tertiary prevention: - Genetic counseling: autosomal dominant 50% transmission risk; discussion of de novo occurrence and variable expressivity. Prenatal / preimplantation genetic testing is feasible when the familial variant is known. - Cascade genetic screening of at-risk relatives. - Secondary prevention (early detection): peripubertal metabolic surveillance (glucose/insulin/HbA1c) to detect and treat diabetes early; regular ophthalmologic monitoring (IOP, gonioscopy) to detect glaucoma before vision loss. - Tertiary prevention: optimize glycemic control to limit diabetic complications; manage IOP to preserve vision; dental follow-up. Avoid/limit diabetogenic exposures (e.g., cautious GH use). - No immunization or public-health/environmental interventions are applicable.

Section 14 — Other Species / Natural Disease

Taxonomy: No naturally occurring SHORT syndrome is described in companion animals or wildlife; OMIA has no established entry. SHORT syndrome is essentially a human-defined disorder studied via engineered animal models.
Orthologous gene: Pik3r1 is highly conserved (mouse Pik3r1, NCBI Gene ID 18708; human PIK3R1, NCBI Gene ID 5295). The Arg649 residue and the C-terminal SH2/iSH2 region are conserved between human and mouse, enabling faithful knock-in modeling.
Comparative biology: The conserved PI3K–AKT insulin-signaling axis means the mouse model reproduces core human features, supporting strong evolutionary conservation of the disease mechanism.
Zoonotic potential: Not applicable (non-infectious genetic disorder).

Section 15 — Model Organisms

Mouse models (mammalian) are the principal system.

Model	Genotype	Key phenotype	Reference
Pik3r1 Arg649Trp knock-in	Heterozygous KI (homolog of human hotspot)	Reduced body weight/length, partial lipodystrophy, systemic insulin resistance; reduced PI3K activation in liver/muscle/fat; defective insulin secretion; impaired GLP-1 action on islets	PMID: 26974159
Dominant-negative human PI3K (R649W) mouse	Knock-in	Protected from obesity and hepatic steatosis but not diabetes	PMID: 29724723
R649W knock-in (ocular)	Knock-in	Decreased iris thickness/width, increased pupil area/irregularity; cornea/lens/retina normal — recapitulates Rieger anomaly	PMID: 28632845

Phenotype recapitulation. The knock-in mice reproduce the core human phenotype—growth restriction, partial lipodystrophy, insulin resistance, and (independently) the iris/anterior-segment defect—and provide direct mechanistic proof that reduced PI3K activation underlies the disease.

Model limitations. Some human features (full craniofacial gestalt, dental eruption delay, joint hyperextensibility) are not comprehensively modeled; the obesity-protection phenotype reflects species/dietary context. No invertebrate, zebrafish, or organoid/iPSC SHORT-syndrome models are prominent in the reviewed literature.

Resources: MGI (Pik3r1), IMPC/KOMP for engineered alleles.

Key Findings (with statistical evidence)

F1. PIK3R1 loss-of-function/dominant-negative mutations cause SHORT syndrome

Three concurrent 2013 exome studies (Thauvin-Robinet, Chudasama, Dyment; AJHG 93:141–166) established heterozygous PIK3R1 mutations as causal, with the recurrent hotspot c.1945C>T (p.Arg649Trp) in 8 of 14 families and additional frameshift/nonsense variants clustering in the C-terminal cSH2/iSH2 domain. "We report the finding of a novel mutation in PIK3R1 (c.1929_1933delTGGCA; p.Asp643Aspfs*8), as well as a recurrent mutation c.1945C > T (p.Arg649Trp) in this gene" (PMID: 24886349); "Eight of these families had a recurrent missense mutation (c.1945C>T; p.Arg649Trp)" (PMID: 23980586); PMID: 24033310.

F2. A knock-in mouse confirms reduced PI3K activation as the mechanism

"mutant mice exhibited a reduction in body weight and length, partial lipodystrophy, and systemic insulin resistance... associated with a reduced capacity of insulin and other growth factors to activate PI3K in liver, muscle, and fat" (PMID: 26974159). A second model was "Protected From Obesity and Hepatic Steatosis but Not Diabetes" (PMID: 29724723).

F3. Craniofacial dysmorphism is the most consistent feature; diabetes is puberty-onset

Systematic review of 19 individuals: "Facial dysmorphism including ocular depression, triangular shaped face, frontal bossing, large low-set ears, and micrognathia were the most consistent features followed by lipodystrophy, insulin resistance, and intrauterine growth restriction" (PMID: 34212753). Diabetes is age-dependent: "IRDM in 10 of 15 GH-untreated patients aged ≥12 years but in none of three GH-treated and six GH-untreated patients aged ≤10 years" (PMID: 32879144).

F4. Management: insulin sensitizers/SGLT2 inhibitors; GH relatively contraindicated

Metformin ± pioglitazone reduced insulin resistance (PMID: 33742773); canagliflozin "ameliorated overt diurnal hyperglycemia and mild nocturnal hypoglycemia" (PMID: 32879144).

F5. Rieger anomaly is a PI3K-dependent developmental iris defect

"OCT images of the knock-in mouse eyes revealed a significant decrease in thickness and width of the iris... Both human subjects had Rieger anomaly with similar defects including thin irides and irregular pupils, as well as a prominent ring of Schwalbe, goniosynechiae, early cataract formation, and glaucoma" (PMID: 28632845).

F6. PIK3R1 is a dual-disorder gene (SHORT LOF vs APDS2 GOF)

"APDS type 2 is caused by mutations in the PIK3R1 gene affecting the p85α regulatory subunit... The primary causes of SHORT syndrome are heterozygous loss-of-function mutations in the PIK3R1 gene." A splice variant "c.1425 + 1G > C... previously associated with APDS2" was found in a patient with SHORT features (PMID: 32778990); overlap also reported by PMID: 35789397.

F7. Insulin resistance uncoupled from dyslipidemia (distinctive signature)

"Insulin resistance due to insulin receptor (INSR) dysfunction is associated with none of these, but when due to dysfunction of the downstream kinase AKT2 phenocopies obesity-related insulin resistance. We report 5 patients with SHORT syndrome and C-terminal mutations" — placing the p85α defect at a proximal receptor→PI3K node, resembling INSR dysfunction (no fatty liver, no dyslipidemia, high adiponectin) (PMID: 27766312).

F8. Formally classified as a genetic insulin resistance syndrome

The Japan Diabetes Society working group classifies "SHORT syndrome caused by abnormalities of PIK3R1... conditions caused by abnormalities of AKT2, TBC1D4, or PRKCE" within genetic insulin resistance syndromes (PMID: 35110500).

Mechanistic Model / Interpretation

   PIK3R1 mutation (C-terminal cSH2/iSH2; e.g. p.Arg649Trp)
    │
defective p85α regulatory subunit
    │  (fails to relieve p110 inhibition;
    │   fails to engage receptor phosphotyrosines)
    ▼
↓ class IA PI3K activation  →  ↓ PIP3  →  ↓ AKT signaling
    │
   ┌────────────┬───┴─────────┬──────────────┬───────────────┐
   ▼            ▼             ▼              ▼               ▼
 Metabolic    Adipose      Growth        Ocular          Craniofacial/
 branch       branch       branch        (development)   dental branch
   │            │             │              │               │
 insulin      partial      IUGR /         iris          progeroid
 resistance   lipodys-     short          hypoplasia →  dysmorphism;
   │          trophy       stature        Rieger        delayed
 (proximal →                (± IGF-1      anomaly       tooth eruption
 no dyslipid-  ─────────►   resistance)   (NOT diabetic
 emia/NAFLD;               ◄──────────    retinopathy)
 high adipo-   aggravates IR
 nectin)
   │
 peri-pubertal → insulin-resistant diabetes mellitus

The model’s central insight is that a single proximal signaling lesion (attenuated PI3K activation) produces a pleiotropic phenotype by acting in multiple PI3K-dependent developmental and metabolic programs. The proximal location of the defect (receptor→PI3K, upstream of the branch controlling hepatic lipogenesis) explains the syndrome’s most discriminating laboratory signature—severe insulin resistance without dyslipidemia or fatty liver—which mirrors INSR dysfunction rather than downstream AKT2 dysfunction. This positions SHORT syndrome as a "clean" human experiment of nature isolating proximal PI3K signaling, and it is the loss-of-function mirror image of APDS2/gain-of-function PI3K disease at the same gene.

Evidence Base

PMID	Title (abbrev.)	Contribution
24886349	Exome identifies novel PIK3R1 mutation	Hotspot + frameshift variants; causality
23980586	PIK3R1 mutations in SHORT	AD inheritance; Arg649Trp in 8/14 families
24033310	Autosomal dominant PIK3R1 cause	Landmark 2013 discovery
26974159	PI3K mutation → insulin/GF resistance in vivo	Knock-in mouse; mechanism
29724723	Dominant-negative PI3K mouse	Protected from obesity/steatosis, not diabetes
34212753	Systematic medical/dental phenotype	Frequency ranking; facial dysmorphism most consistent
32879144	IRDM in SHORT syndrome	Pubertal onset of diabetes; SGLT2i; GH caution
28632845	Iris malformation/anterior-segment dysgenesis	Rieger anomaly as developmental iris defect
32778990	APDS2 + SHORT in a teenager	Dual-disorder gene; phenotypic overlap
27766312	IR uncoupled from dyslipidemia	Distinctive proximal metabolic signature
35110500	New IR-syndrome classification	Formal classification of SHORT syndrome
33742773	Novel variant, 6-mo follow-up	Metformin/pioglitazone efficacy
32602265	Two Chinese girls	Metformin early efficacy; de novo variants
33129256	Chinese female + thyroid disease	Novel p.Gln654* nonsense; expanding spectrum
36401775	Pathogenesis/clinical-spectrum update	Decreased lipogenesis, energy expenditure, IGF1 resistance
32546215	SRS multigene analysis	SHORT syndrome as SRS differential
39735640	Atypical diabetes in SHORT	Multi-agent oral therapy
35789397	APDS2 with SHORT features	Overlap; novel mutation

Evidence-type mix: human clinical (case reports, series, systematic review), model organism (knock-in mice), and in vitro/mechanistic (PI3K activation assays). Most clinical evidence is Level IV (case reports/series); the mechanistic conclusions are strengthened by convergent mouse-model data.

Limitations and Knowledge Gaps

Small evidence base: Only tens of families reported; no large cohorts, no natural-history registry, and no formal QoL (EQ-5D/SF-36) or long-term outcome/mortality data.
No treatment guidelines: Therapy is extrapolated from individual case reports; comparative efficacy of metformin vs SGLT2 inhibitors vs thiazolidinediones is untested in trials.
Genotype–phenotype correlation incomplete: Variable expressivity even within the p.Arg649Trp genotype is unexplained; modifier genes are unidentified.
Mechanistic gaps: Precise contributions of PI3K attenuation to craniofacial and dental phenotypes are inferred, not experimentally demonstrated; the degree of IGF-1 resistance is not fully quantified.
Model gaps: No non-mammalian, organoid, or iPSC models; some human features not recapitulated in mice.
APDS2 overlap: The mechanistic basis by which certain PIK3R1 variants produce both loss- and gain-of-function features requires further study.

Proposed Follow-up Experiments / Actions

Establish an international patient registry for SHORT syndrome to define prevalence, natural history, long-term outcomes, and standardized QoL measures.
Prospective metabolic trial comparing insulin-sensitizing regimens (metformin, SGLT2 inhibitors, TZDs) with peripubertal surveillance protocols to build an evidence-based treatment algorithm.
Deep phenotype–genotype study across all reported PIK3R1 variants (missense vs truncating vs splice) to map variant class to LOF/GOF behavior and clinical severity, and to search for modifier loci.
Mechanistic dissection of craniofacial/dental and IGF-1-resistance branches using conditional/tissue-specific Pik3r1 knock-in mice and patient iPSC-derived tissues (adipocytes, β-cells, anterior-segment/neural-crest models).
Pathway-restorative therapeutic exploration: evaluate whether partial, tissue-selective potentiation of PI3K/AKT signaling can safely correct the metabolic phenotype without recapitulating APDS2-like overactivation.
Cross-screening protocol: systematically test SHORT-syndrome patients for immunologic features (and vice-versa for APDS2) given the shared gene, to detect overlap cases early.

Report compiled from an autonomous, literature-grounded investigation (5 iterations, 8 confirmed findings, 22 papers reviewed). All mechanistic and clinical claims are cited to primary literature by PMID.

Artifacts

Reference Validation

Checked with linkml-reference-validator 0.2.1.

Outcome	Count
References checked	19
Resolved	19
Unresolved (possible confabulation)	0
Unverifiable	0
References weighed for topical relevance	19
On topic	19
Off topic	0

All extracted references resolved successfully.

Term Validation

Checked with linkml-term-validator 0.4.5, through the ols: adapter.

Outcome	Count
Terms checked	39
Resolved	35
Unresolved (possible confabulation)	0
Obsolete	2
Unverifiable	2
Terms whose name was checked	13
Terms named correctly	0
Terms named as a different term	11
Terms whose name is worth a second look	2

Terms the report names something else

These identifiers resolve, so nothing about them looks wrong, and the ontology calls them something unrelated to what the report calls them. That usually means the identifier is not the one the sentence needs:

MONDO:0009159 (2 mentions) - the report calls it "MONDO"; MONDO calls it Ehlers-Danlos syndrome, cardiac valvular type
HP:0001511 (1 mention) - the report calls it "Very common"; HP calls it Intrauterine growth retardation
HP:0004322 (1 mention) - the report calls it "Common"; HP calls it Short stature
HP:0000490 (1 mention) - the report calls it "Common"; HP calls it Deeply set eye
HP:0000347 (1 mention) - the report calls it "Common"; HP calls it Micrognathia
HP:0000430 (1 mention) - the report calls it "Common"; HP calls it Underdeveloped nasal alae
HP:0005104 (1 mention) - the report calls it "Common"; HP calls it Hypoplastic nasal septum
HP:0009125 (1 mention) - the report calls it "Common"; HP calls it Lipodystrophy
HP:0000855 (1 mention) - the report calls it "Common (metabolic hallmark)"; HP calls it Insulin resistance
HP:0000684 (1 mention) - the report calls it "Common (eponymous)"; HP calls it Delayed eruption of teeth
HP:0001382 (1 mention) - the report calls it "Common (eponymous)"; HP calls it Joint hypermobility

Obsolete terms

These terms are real but deprecated. Citing one is not a fabrication; it does mean the report is naming something the ontology has retired:

HP:0000368 (obsolete Low-set, posteriorly rotated ears) (1 mention) - replaced by HP:0000358
GO:0014065 (obsolete phosphatidylinositol 3-kinase signaling) (1 mention) - replaced by GO:0043491

Terms whose name is worth a second look

The report's name for these is recognisably related to the term's own name without being one of them. A loose paraphrase reads the same way as a citation of the wrong sibling term - and so does a related synonym, which the ontology records precisely because it names something adjacent rather than the same thing - so these are listed rather than judged:

GO:0014065 (1 mention) - the report calls it "GO biological process: phosphatidylinositol 3-kinase signaling"; GO calls it obsolete phosphatidylinositol 3-kinase signaling**
UBERON:0001769 (1 mention) - the report calls it "Eye: anterior segment — iris"; UBERON calls it iris**, and lists "anterior uvea" among its other names

Prefixes with no resolver

Terms carrying these prefixes were not checked either way, because no configured ontology covers them. An unrecognised prefix may name an ontology this run could not reach as easily as one that does not exist, so nothing here is evidence of fabrication: ORPHA.

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Mappings

Inheritance

Discussions and Knowledge Gaps

Pathophysiology

Pathograph

Phenotypes

Genetic Associations

Medical Actions

Diagnosis

Progression

Prevalence

Differential Diagnoses

Animal Models

Source YAML

References & Deep Research

References

Deep Research

SHORT Syndrome — Comprehensive Disease Characteristics Report

Summary

Section 1 — Disease Information

Section 2 — Etiology

Section 3 — Phenotypes

Section 4 — Genetic / Molecular Information

Section 5 — Environmental Information

Section 6 — Mechanism / Pathophysiology

Ordered causal chain

Molecular / cellular detail

Suggested ontology terms

Section 7 — Anatomical Structures Affected

Section 8 — Temporal Development

Section 9 — Inheritance and Population

Section 10 — Diagnostics

Section 11 — Outcome / Prognosis

Section 12 — Treatment

Section 13 — Prevention

Section 14 — Other Species / Natural Disease

Section 15 — Model Organisms

Key Findings (with statistical evidence)

F1. PIK3R1 loss-of-function/dominant-negative mutations cause SHORT syndrome

F2. A knock-in mouse confirms reduced PI3K activation as the mechanism

F3. Craniofacial dysmorphism is the most consistent feature; diabetes is puberty-onset

F4. Management: insulin sensitizers/SGLT2 inhibitors; GH relatively contraindicated

F5. Rieger anomaly is a PI3K-dependent developmental iris defect

F6. PIK3R1 is a dual-disorder gene (SHORT LOF vs APDS2 GOF)

F7. Insulin resistance uncoupled from dyslipidemia (distinctive signature)

F8. Formally classified as a genetic insulin resistance syndrome

Mechanistic Model / Interpretation

Evidence Base

Limitations and Knowledge Gaps

Proposed Follow-up Experiments / Actions

Artifacts

Reference Validation

Term Validation

Terms the report names something else

Obsolete terms

Terms whose name is worth a second look

Prefixes with no resolver