Mulibrey Nanism

Mendelian MONDO:0009664 Pathograph 23 Show in embeddings browser Inborn Genetic Disease Primordial Dwarfism Tumor Predisposition Syndrome

Mulibrey nanism is an autosomal recessive, prenatal-onset growth disorder caused by biallelic loss-of-function variants in TRIM37, which encodes a RING-B-box-coiled-coil (RBCC/TRIM) protein carrying a C-terminal TRAF domain and RING-dependent ubiquitin ligase activity. The name is an acronym for the tissues involved — muscle, liver, brain, eye — all of mesodermal origin, which was the original argument for a single highly pleiotropic gene. The disease is enriched in Finland through a founder frameshift allele ("Finn major") and is rare elsewhere. Clinically the constant findings are severe growth failure of prenatal onset without postnatal catch-up, and a characteristic craniofacial appearance (scaphocephaly, facial triangularity, high broad forehead, low nasal bridge) present in over 90% of patients. Constrictive pericarditis with consequent hepatomegaly is the feature that dominates outcome. Yellowish dots in the ocular fundi, a high-pitched voice, cutaneous naevi flammei, fibrous dysplasia of long bones, and mild muscular hypotonia complete the picture, but organ manifestations vary considerably in early childhood. The mechanistic link from TRIM37 loss to this phenotype is genuinely unresolved, and this entry is curated to say so rather than to pick a side. Two non-exclusive models have authoritative primary support. TRIM37 was localised to peroxisomes, which led to Mulibrey nanism being classified as a new peroxisomal disorder — but the same study found that patient fibroblasts stain normally for peroxisomal matrix and membrane markers, so peroxisome biogenesis is apparently intact and the peroxisomal classification does not on its own explain the disease. Separately, TRIM37 is a centrosomal ubiquitin ligase that restrains PLK4 self-assembly and controls CEP192, so its loss permits ectopic microtubule-organising condensates and disturbs mitotic fidelity; that work was done in a cancer-vulnerability context rather than in patient tissue, so its application to Mulibrey nanism is an inference. What is directly observed in patients is disturbed organ architecture with ectopic tissues and a high frequency of benign and malignant tumours, which is at least consistent with a mitotic-fidelity mechanism.

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1
Inheritance
8
Pathophys.
2
Histopath.
21
Phenotypes
3
Gaps
23
Pathograph
1
Genes
3
Medical Actions
1
Models
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Deep Research
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Inheritance

1
Autosomal recessive inheritance HP:0000007
Mulibrey nanism follows autosomal recessive inheritance. In Finland most patients are homozygous for the Finn major TRIM37 frameshift allele.
Autosomal recessive inheritance
Show evidence (2 references)
PMID:14757854 SUPPORT DIRECT Human Clinical
"Mulibrey nanism (MUL) is an autosomal recessive disease caused by mutations in the TRIM37 gene encoding the peroxisomal TRIM37 protein of unknown function."
States the inheritance pattern and the causal gene in the cohort that defined the diagnostic criteria.
PMID:10888877 SUPPORT DIRECT Human Clinical
"Mulibrey nanism (for muscle-liver-brain-eye nanism, MUL; MIM 253250) is an autosomal recessive disorder that involves several tissues of mesodermal origin, implying a defect in a highly pleiotropic gene."
The positional cloning paper states the recessive inheritance and the mesodermal, pleiotropic character of the disorder.
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Discussions and Knowledge Gaps

3
Does loss of peroxisomal TRIM37 produce any measurable peroxisomal dysfunction in patients, or is the peroxisomal localisation incidental to the disease mechanism?
KNOWLEDGE GAP peroxisomal_classification_unsupported
Attached to
pathophysiology#Peroxisomal TRIM37 Depletion
Mulibrey nanism was classified as a peroxisomal disorder on the strength of TRIM37's localisation, and that classification has propagated widely. But the same paper reported that patient fibroblasts stain normally for both peroxisomal matrix and membrane markers, i.e. biogenesis appears intact, and no study has demonstrated the biochemical signature of a peroxisomal disorder — raised very-long-chain fatty acids, reduced plasmalogens — in Mulibrey nanism patients. Secondary sources routinely present the peroxisomal chain as if it were established; it is a localisation result plus an inference. Resolving this matters because it decides whether peroxisomal metabolites are useful biomarkers here at all.
By what route does TRIM37 loss cause pericardial fibrosis and constriction?
KNOWLEDGE GAP pericardial_fibrosis_mechanism_unknown
Attached to
pathophysiology#Pericardial Constriction
Pericardial constriction is the feature that determines survival and the main indication for surgery, yet no mechanism connects it to the TRIM37 lesion. Neither the peroxisomal model nor the centrosomal/mitotic model predicts a fibrotic pericardium specifically, and no animal or cellular model of the pericardial phenotype has been reported. This is the largest single gap in the entry: the clinically dominant manifestation has no upstream edge that can be evidenced.
Does the TRIM37-PLK4 centrosomal mechanism, established in RPE1 and cancer cell lines, operate in the tissues affected in Mulibrey nanism?
HUMAN MODEL MISMATCH centrosomal_mechanism_not_shown_in_patients
Attached to
pathophysiology#Centrosomal Ubiquitin Ligase Deficiency
The centrosomal work is the most mechanistically satisfying account of TRIM37 and is the one that plausibly explains both disturbed organ architecture and tumour predisposition. But it was done to explain a cancer-specific therapeutic vulnerability, in immortalised and transformed cell lines, and the cancer-relevant direction is TRIM37 amplification and over-expression, whereas Mulibrey nanism is loss of function. The loss-of-function arm was studied, so the direction is covered, but nothing has been shown in patient-derived cells or in a TRIM37-null organism with the human phenotype. Every edge in this entry that depends on this mechanism is therefore graded INDIRECT.
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Pathophysiology

8
TRIM37 Loss of Function
Biallelic TRIM37 variants abolish or mislocalise the TRIM37 RING-B-box-coiled-coil ubiquitin ligase. This is the initiating lesion; every node below is downstream of it.
Genetic context allele_type: SNV variant_origin: GERMLINE zygosity: HOMOZYGOUS functional_impact_category: LOSS_OF_FUNCTION
TRIM37 ubiquitin protein ligase activity GO:0061630 Gene Ontology (GO) Relation: this pathophysiological event involves this molecular function This pathophysiological event involves TRIM37 ubiquitin protein ligase activity, annotated with ubiquitin protein ligase activity (GO:0061630), qualified as loss of function. GO:0061630 is a molecular function from the Gene Ontology. ⇓ LOSS OF FUNCTION
Downstream
Prenatal-Onset Growth Failure Growth failure is the most consistent finding in the disorder and must be downstream of the germline lesion, but nothing is known about the route. The intermediates are recorded as unknown rather than guessed: the knockout mouse, which reproduces the infertility and the cardiac and hepatic phenotypes, does not reproduce the growth failure at all.
Mesodermal Ocular Involvement The choroidal lesion is downstream of the germline lesion by elimination, since every feature of the syndrome is, but no step between TRIM37 loss and choroidal hypoplasia has been described in any source cited here.
Gonadal Failure and Insulin Resistance The endocrine and metabolic axis. Typed as having unknown intermediates because the mouse localises the lesion to the gonad itself — germ cell aplasia with Leydig cell hyperplasia — without establishing what TRIM37 does there, and nothing at all connects the lesion to the insulin-resistance arm.
Peroxisomal TRIM37 Depletion TRIM37 is a peroxisomal protein and the major Finnish mutant fails to reach the peroxisome, so the germline lesion removes TRIM37 from that compartment.
Centrosomal Ubiquitin Ligase Deficiency TRIM37 also acts at the centrosome, where it restrains PLK4 self-assembly, so loss of the ligase removes that restraint.
Show evidence (1 reference)
PMID:10888877 SUPPORT DIRECT Human Clinical
"MUL is ubiquitously expressed and encodes a new member of the RING-B-box-Coiled-coil (RBCC) family of zinc-finger proteins, whose members are involved in diverse cellular functions such as developmental patterning and oncogenesis."
Establishes the protein family and the ubiquitous expression that makes a multisystem phenotype plausible.
Peroxisomal TRIM37 Depletion
Endogenous TRIM37 is a peroxisomal protein of ~130 kD, and its loss from that compartment is what led to Mulibrey nanism being classified as a peroxisomal disorder. The node is deliberately named for the depletion of TRIM37 from the peroxisome rather than for peroxisomal failure: patient fibroblasts stain normally for peroxisomal matrix and membrane markers, so biogenesis is apparently intact and no downstream metabolic consequence has been demonstrated in patients. See the knowledge gap attached to this node.
peroxisome GO:0005777 Gene Ontology (GO) Relation: this pathophysiological event involves this cellular component This pathophysiological event involves peroxisome (GO:0005777). GO:0005777 is a cellular component from the Gene Ontology.
Animal models
Trim37 knockout mouse Mouse fails to recapitulate Liver peroxisome number and morphology are normal in the null mouse, which is the same negative that patient fibroblasts give.
Show evidence (2 references)
PMID:11938494 SUPPORT DIRECT In Vitro
"We show that the human TRIM37 cDNA encodes a peroxisomal protein with an apparent molecular weight of 130 kD."
Establishes the peroxisomal localisation of the TRIM37 protein.
PMID:11938494 REFUTE DIRECT In Vitro
"Fibroblasts derived from patients with mulibrey nanism lack C-terminal TRIM37 immunoreactivity but stain normally for both peroxisomal matrix and membrane markers, suggesting apparently normal peroxisome biogenesis in patient fibroblasts."
Refutes the stronger reading of this node as a peroxisome biogenesis defect. The same paper that established the peroxisomal localisation reports intact biogenesis in patient cells, so the two items are split by quoted sentence rather than merged.
Centrosomal Ubiquitin Ligase Deficiency
TRIM37 normally prevents PLK4 from self-assembling into centrosome-independent condensates and controls levels of the centrosomal component CEP192. In its absence, ectopic PLK4 condensates form and can act as microtubule-organising centres, altering spindle assembly. This is the strongest current candidate for a mechanism that would produce both the developmental and the neoplastic features, but it has not been shown in Mulibrey nanism patient tissue.
centriole replication GO:0007099 Gene Ontology (GO) Relation: this pathophysiological event involves this biological process This pathophysiological event involves abnormal centriole replication (GO:0007099). GO:0007099 is a biological process from the Gene Ontology. ⚠ ABNORMAL mitotic spindle assembly GO:0090307 Gene Ontology (GO) Relation: this pathophysiological event involves this biological process This pathophysiological event involves abnormal mitotic spindle assembly (GO:0090307). GO:0090307 is a biological process from the Gene Ontology. ⚠ ABNORMAL
Downstream
Disturbed Organ Architecture and Tumor Predisposition Loss of mitotic fidelity in proliferating tissue is the proposed route to the ectopic tissues and the excess of benign and malignant tumours seen in patients. The link is an inference from cell-line work to patient pathology, not a demonstrated chain.
Show evidence (1 reference)
PMID:32908304 SUPPORT INDIRECT In Vitro
"Low TRIM37 levels accelerate acentrosomal spindle assembly and improve proliferation following PLK4 inhibition, whereas high TRIM37 levels inhibit acentrosomal spindle assembly, leading to mitotic failure and cessation of proliferation."
Shows the loss-of-function direction relevant to Mulibrey nanism has a measurable mitotic phenotype. INDIRECT for the same reason as above.
Disturbed Organ Architecture and Tumor Predisposition
Patients show disturbed organ architecture with ectopic tissues, together with a high frequency of both benign and malignant tumours across internal organs. This is an observed patient-level finding, independent of which upstream mechanism proves correct.
Downstream
Wilms tumor Wilms tumour is the commonest malignancy in this predisposition.
Show evidence (2 references)
PMID:19334051 SUPPORT DIRECT Human Clinical
"The results show that the MUL patients have disturbed architecture with ectopic tissues and a high frequency of both benign and malignant tumours detectable in several internal organs."
The national cohort establishes both the architectural disturbance and the tumour excess directly in patients.
PMID:19334051 SUPPORT DIRECT Human Clinical
"A total of 210 tumorous lesions were detected in 66/89 patients (74%)."
Quantifies the tumour burden in the 89-patient national cohort.
Gonadal Failure and Insulin Resistance
The endocrine and metabolic arm of the disease, and the one that emerges latest. In males the gonad fails progressively after a normal pubertal onset, giving hypergonadotropic hypogonadism and near-universal infertility; in females the ovarian stroma instead produces sex cord-stromal tumours. Insulin resistance runs alongside and ends in early type 2 diabetes. Curated as one node because the knockout mouse shows the gonadal and glycaemic abnormalities together and neither has been shown to cause the other.
Animal models
Trim37 knockout mouse Mouse recapitulates Infertility in both sexes with germ cell aplasia and Leydig cell hyperplasia, raised FSH and LH with preserved testosterone, and raised fasting glucose. The most consistent phenotype in the model.
Downstream
Hypergonadotropic hypogonadism The clinical expression of the testicular failure in adult males.
Type 2 diabetes mellitus Through the insulin resistance recorded as its own phenotype. The intermediate is known and named but is not modelled as a separate node.
Show evidence (4 references)
PMID:21865362 SUPPORT DIRECT Human Clinical
"All adult MUL males have a unique disorder of testicular function with small testes, elevated FSH and LH, and low inhibin B."
The human gonadal finding, in all adult males of the national cohort.
PMID:17548484 SUPPORT DIRECT Human Clinical
"Mulibrey nanism is a monogenic disorder with prenatal-onset growth restriction, mild dysmorphic features, and a strong tendency for insulin resistance but no major neurologic handicap."
The human metabolic finding, in the largest growth cohort.
PMID:27044324 SUPPORT INDIRECT Model Organism
"Both male and female Trim37(-/-) mice were infertile, the gonads showing germ cell aplasia, hilus and Leydig cell hyperplasia and accumulation of lipids in and around Leydig cells."
Localises the gonadal lesion to the gonad itself in the null mouse, with a histological description that no human study provides.
+ 1 more reference
Pericardial Constriction
A thickened, non-compliant pericardium restricts diastolic filling, giving raised venous pressure, hepatomegaly and congestive heart failure. This is the feature that dominates outcome, and the step connecting TRIM37 loss to pericardial fibrosis is not established — see the knowledge gap attached to this node.
Downstream
Hepatomegaly Constriction raises systemic venous pressure, producing hepatic congestion and hepatomegaly.
Show evidence (1 reference)
PMID:14757854 SUPPORT DIRECT Human Clinical
"Congestive heart failure and pericardial constriction were diagnosed during infancy in 12% and 6% of the patients, respectively."
Quantifies how often the cardiac manifestations are already present in infancy in the Finnish cohort.
Prenatal-Onset Growth Failure
Growth failure begins prenatally and there is no postnatal catch-up, so the height deficit widens with age. It is the most consistent finding in the disorder and is present essentially independent of organ involvement.
Animal models
Trim37 knockout mouse Mouse fails to recapitulate The model does not reproduce the defining feature of the disease. Weight development is normal to about 12 months and long-bone length does not differ from wild-type; only skull size is reduced.
Show evidence (2 references)
PMID:14757854 SUPPORT DIRECT Human Clinical
"All except four of the patients (95%) had a prenatal onset growth failure without postnatal catch up growth."
Establishes both the prenatal onset and the absence of catch-up in the defining cohort.
PMID:14757854 SUPPORT DIRECT Human Clinical
"The mean length standard deviation score (SDS) was -3.1 and -4.0 at birth and at diagnosis, respectively."
Quantifies the deficit at birth and its widening by the time of diagnosis.
Mesodermal Ocular Involvement
Focal choroidal hypoplasia with overlying pigment disturbance produces the yellowish fundus dots that are part of the diagnostic picture. The choroid is mesodermal, which is consistent with the mesodermal framing of the syndrome as a whole.
choroid UBERON:0001776 Uberon multi-species anatomy ontology (UBERON) Relation: this pathophysiological event occurs in this anatomical location This pathophysiological event occurs in choroid, annotated with optic choroid (UBERON:0001776). UBERON:0001776 is an anatomical location from the Uberon multi-species anatomy ontology.
Show evidence (2 references)
PMID:6818830 SUPPORT DIRECT Human Clinical
"By fluorescein angiography areas of focal choroidal hypoplasia have been noted."
Identifies the choroidal lesion behind the fundus findings.
PMID:6818830 SUPPORT INDIRECT Human Clinical
"The findings do confirm the hypothesis that the choroidal changes represent one further manifestation originating from mesodermal tissues in these patients."
Supports the mesodermal framing. Graded INDIRECT because the mesodermal origin is the authors' interpretation of the histology rather than a direct observation.
✶

Histopathology

2
Peliosis, vascularised cysts and nodular lesions
The visceral lesion the disease produces, seen on imaging and confirmed histologically: strongly dilated blood vessels, vascularised cysts and nodular lesions across liver and other organs. Vascular rather than epithelial, which is what distinguishes the benign tumour burden here from ordinary adenomatous disease.
Show evidence (2 references)
PMID:19334051 SUPPORT DIRECT Human Clinical
"Tumours detected by radiology in the liver and other organs mainly comprised strongly dilated blood vessels (peliosis), vascularized cysts and nodular lesions."
Describes the composition of the benign lesions.
PMID:19334051 SUPPORT DIRECT Human Clinical
"The lesions showed strong expression of the endothelial cell markers CD34 and CD31 as well as the myocyte marker alpha-smooth muscle actin (alpha-SMA)."
The immunohistochemistry, which is what establishes the lesions as endothelial and smooth-muscle rather than epithelial.
Pericardial fibrosis
Extensive fibrosis of the pericardium, found in nearly every diseased pericardium examined. This is the tissue-level finding underlying constrictive pericarditis, the manifestation that determines outcome in this disease.
Show evidence (1 reference)
PMID:35257621 SUPPORT DIRECT Human Clinical
"Microscopic analysis of diseased pericardium almost invariably shows extensive fibrosis."
States the histological finding and that it is near-invariable in affected pericardium.
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Pathograph

Use the checkboxes to hide or show graph categories. Hover nodes for evidence and cross-linked metadata.
Pathograph: causal mechanism network for Mulibrey Nanism Interactive directed graph showing how pathophysiology mechanisms, phenotypes, genetic factors and variants, experimental models, environmental triggers, and treatments relate through causal and linked edges.
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Phenotypes

21
Cardiovascular 3
Constrictive pericarditis FREQUENT HP:0002563 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Constrictive pericarditis (HP:0002563), qualified as course progressive. HP:0002563 is a phenotype from the Human Phenotype Ontology.
Course: PROGRESSIVE
Two denominators are in play and only one of them bands this phenotype. The 6%/12% figures from the diagnostic-criteria cohort count patients diagnosed during infancy, so they describe how often the manifestation is present at presentation, not how often it occurs. The band uses the lifetime figures instead. "Up to" is a ceiling, and the sentence sits in a case report's narrative discussion summarising Lipsanen-Nyman rather than in a primary cohort table, so the band is the weaker claim of the two the source supports.
Show evidence (2 references)
PMID:14757854 SUPPORT DIRECT Human Clinical
"Congestive heart failure and pericardial constriction were diagnosed during infancy in 12% and 6% of the patients, respectively."
The infancy-onset figure: how often the manifestation was already present at diagnosis in infancy, not its lifetime frequency.
PMID:35257621 SUPPORT DIRECT Human Clinical
"The most common cardiac manifestations are CHF and constrictive pericarditis seen in up to 51% and 39% of the cases, respectively."
The lifetime figures, which is what the band is derived from.
Congestive heart failure FREQUENT HP:0001635 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Congestive heart failure (HP:0001635). HP:0001635 is a phenotype from the Human Phenotype Ontology.
Two denominators are in play and only one of them bands this phenotype. The 6%/12% figures from the diagnostic-criteria cohort count patients diagnosed during infancy, so they describe how often the manifestation is present at presentation, not how often it occurs. The band uses the lifetime figures instead. "Up to" is a ceiling, and the sentence sits in a case report's narrative discussion summarising Lipsanen-Nyman rather than in a primary cohort table, so the band is the weaker claim of the two the source supports.
Show evidence (2 references)
PMID:14757854 SUPPORT DIRECT Human Clinical
"Congestive heart failure and pericardial constriction were diagnosed during infancy in 12% and 6% of the patients, respectively."
The infancy-onset figure: how often the manifestation was already present at diagnosis in infancy, not its lifetime frequency.
PMID:35257621 SUPPORT DIRECT Human Clinical
"The most common cardiac manifestations are CHF and constrictive pericarditis seen in up to 51% and 39% of the cases, respectively."
The lifetime figures, which is what the band is derived from.
Left ventricular hypertrophy HP:0001712 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Left ventricular hypertrophy (HP:0001712). HP:0001712 is a phenotype from the Human Phenotype Ontology.
No frequency is asserted. The source characterises the echocardiographic picture without giving a proportion. Recorded because the "irrespective of previous pericardiectomy" clause bears directly on what pericardiectomy can be expected to achieve: relieving the constriction does not abolish the diastolic abnormality. For the same reason this phenotype is deliberately not made a readout of Pericardial Constriction: the source's point is that it persists once the pericardium is gone, so an edge from that node would assert the opposite of what is cited.
Show evidence (1 reference)
PMID:35257621 SUPPORT DIRECT Human Clinical
"Echocardiographic findings are characterized by left ventricular hypertrophy and diastolic dysfunction with preserved systolic function irrespective of previous pericardiectomy."
Reports the echocardiographic finding, and that it does not resolve after the pericardium is removed.
Digestive 2
Hepatomegaly FREQUENT HP:0002240 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Hepatomegaly (HP:0002240). HP:0002240 is a phenotype from the Human Phenotype Ontology.
Show evidence (1 reference)
PMID:14757854 SUPPORT DIRECT Human Clinical
"Other findings included a peculiar high-pitched voice (96%), yellowish dots in ocular fundi (79%), cutaneous naevi flammei (65%), hepatomegaly (45%), and fibrous dysplasia of long bones (25%)."
Gives the frequency of hepatomegaly in the defining cohort.
Hepatic steatosis VERY_FREQUENT HP:0001397 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Fatty liver, annotated with Hepatic steatosis (HP:0001397). HP:0001397 is a phenotype from the Human Phenotype Ontology.
Banded VERY_FREQUENT rather than OBLIGATE because "all adults and adolescents" is a narrative review's summary rather than a counted proportion, and it is asserted for adolescents and adults only — hence the context slot rather than a disease-wide band. The mouse item is kept alongside the human one because the model reproduces this phenotype, which is part of why it was proposed as a system for studying the disease.
Show evidence (2 references)
PMID:35257621 SUPPORT DIRECT Human Clinical
"Fatty liver is seen in all adults and adolescents."
The human observation, from the case report's review of hepatic involvement in this disease.
PMID:27044324 SUPPORT INDIRECT Model Organism
"At 1.5 years Trim37(-/-) mice showed non-compaction cardiomyopathy, hepatomegaly, fatty liver and various tumors."
The finding in the knockout mouse at 1.5 years. Graded MODEL_ORGANISM and INDIRECT because this is the only source in this entry reporting steatosis and it is not a human observation.
Endocrine 2
Type 2 diabetes mellitus Type II diabetes mellitus HP:0005978 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Early-onset type 2 diabetes mellitus, annotated with Type II diabetes mellitus (HP:0005978). HP:0005978 is a phenotype from the Human Phenotype Ontology.
Deliberately left unbanded. The only adult proportion available counts impaired glucose tolerance and type 2 diabetes as one endpoint, and the split between them is not reported. Banding this phenotype VERY_FREQUENT from that figure would assert diabetes in 92% of adults, which the source does not say. The age condition would also have to be carried in context, since the figure is for patients over 20.
Show evidence (2 references)
PMID:28432469 SUPPORT DIRECT Human Clinical
"MUL affects multiple organs, leading to growth retardation and early onset type 2 diabetes."
States early-onset type 2 diabetes as a consequence of the multi-organ involvement, in a 101-patient national cohort.
PMID:35257621 SUPPORT INDIRECT Human Clinical
"In contrast, at >20 years old 92% of patients had either impaired glucose tolerance or type 2 diabetes mellitus."
Establishes that dysglycaemia is close to universal in adults. Graded INDIRECT because the 92% counts impaired glucose tolerance and type 2 diabetes together, so it does not measure this phenotype on its own.
Hypergonadotropic hypogonadism OBLIGATE HP:0000815 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Progressive hypergonadotropic testicular failure, annotated with Hypergonadotropic hypogonadism (HP:0000815). HP:0000815 is a phenotype from the Human Phenotype Ontology.
Show evidence (2 references)
PMID:21865362 SUPPORT DIRECT Human Clinical
"All adult MUL males have a unique disorder of testicular function with small testes, elevated FSH and LH, and low inhibin B."
The conclusion of the 28-male national cohort. OBLIGATE because the finding was present in all adult males studied.
PMID:21865362 SUPPORT DIRECT Human Clinical
"Puberty started spontaneously at a median age of 12.6 yr (range, 11.1-15.0), and FSH, LH, T, and inhibin B levels increased adequately until midpuberty."
Establishes the timing, and is the reason this is curated as hypergonadotropic failure rather than as delayed puberty: pubertal onset is spontaneous and at a normal median age of 12.6 years.
Eye 1
Yellowish dots in ocular fundi FREQUENT Abnormal choroid morphology HP:0000610 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Yellowish dots in ocular fundi, annotated with Abnormal choroid morphology (HP:0000610). HP:0000610 is a phenotype from the Human Phenotype Ontology.
Rebound from HP:0007703 (Abnormal retinal pigmentation) to HP:0000610. The lesion this entry models is focal choroidal hypoplasia with overlying pigment disturbance, so the choroid term names the substrate while the retinal-pigmentation term named only the secondary change. The fundus dots themselves have no HPO term.
Show evidence (1 reference)
PMID:14757854 SUPPORT DIRECT Human Clinical
"Other findings included a peculiar high-pitched voice (96%), yellowish dots in ocular fundi (79%), cutaneous naevi flammei (65%), hepatomegaly (45%), and fibrous dysplasia of long bones (25%)."
Gives the frequency of the fundus finding.
Genitourinary 3
Wilms tumor Nephroblastoma HP:0002667 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Nephroblastoma (HP:0002667). HP:0002667 is a phenotype from the Human Phenotype Ontology.
Show evidence (2 references)
PMID:10888877 SUPPORT DIRECT Human Clinical
"About 4% of MUL patients develop Wilms' tumour."
The original estimate of Wilms tumour risk in this disorder.
PMID:19334051 SUPPORT DIRECT Human Clinical
"Fifteen malignancies occurred in 13 patients (15%), seven of them in the kidney (five Wilms' tumours), three in the thyroid gland, two gynaecological cancers, one gastrointestinal carcinoid tumour, one neuropituitary Langerhans cell histiocytosis and one case of acute lymphoblastic leukaemia (ALL)."
The systematically screened cohort, which gives the malignancy spectrum rather than Wilms tumour alone.
Azoospermia or severe oligoasthenozoospermia OBLIGATE HP:0000027 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Azoospermia or severe oligoasthenozoospermia, annotated with Azoospermia (HP:0000027). HP:0000027 is a phenotype from the Human Phenotype Ontology.
Bound to HP:0000027 because HPO has no term spanning azoospermia and severe oligoasthenozoospermia together; the preferred_term carries the range the source actually reports.
Show evidence (1 reference)
PMID:21865362 SUPPORT DIRECT Human Clinical
"All semen samples showed severe oligoasthenozoospermia or azoospermia."
States the semen finding in all samples.
Ovarian sex cord-stromal tumor FREQUENT HP:0031918 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Ovarian fibrothecoma-group tumour, annotated with Ovarian sex cord-stromal tumor (HP:0031918). HP:0031918 is a phenotype from the Human Phenotype Ontology.
Show evidence (1 reference)
PMID:19329943 SUPPORT DIRECT Human Clinical
"More than half of female patients with Mulibrey nanism develop benign mesenchymal tumors of ovarian sex cord-stromal origin."
Gives the more-than-half figure in female patients, which is the FREQUENT band. This is a sex-limited finding, recorded in context rather than as a disease-wide frequency.
Head and Neck 2
Facial triangularity VERY_FREQUENT Triangular face HP:0000325 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Triangular face (HP:0000325). HP:0000325 is a phenotype from the Human Phenotype Ontology.
Show evidence (1 reference)
PMID:14757854 SUPPORT DIRECT Human Clinical
"At the time of the diagnosis, characteristic craniofacial features of scaphocephaly, facial triangularity, high and broad forehead, and low nasal bridge were evident in over 90% of the patients."
Names the craniofacial features and their frequency.
Scaphocephaly VERY_FREQUENT Dolichocephaly HP:0000268 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Dolichocephaly (HP:0000268). HP:0000268 is a phenotype from the Human Phenotype Ontology.
Show evidence (1 reference)
PMID:14757854 SUPPORT DIRECT Human Clinical
"At the time of the diagnosis, characteristic craniofacial features of scaphocephaly, facial triangularity, high and broad forehead, and low nasal bridge were evident in over 90% of the patients."
Scaphocephaly is the clinical term for the long, narrow skull that HPO captures as dolichocephaly; the preferred_term keeps the source wording.
Integument 1
Cutaneous naevi flammei FREQUENT Nevus flammeus HP:0001052 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Cutaneous naevus flammeus, annotated with Nevus flammeus (HP:0001052). HP:0001052 is a phenotype from the Human Phenotype Ontology.
Show evidence (1 reference)
PMID:14757854 SUPPORT DIRECT Human Clinical
"Other findings included a peculiar high-pitched voice (96%), yellowish dots in ocular fundi (79%), cutaneous naevi flammei (65%), hepatomegaly (45%), and fibrous dysplasia of long bones (25%)."
Gives the 65% frequency, which is the FREQUENT band.
Metabolism 2
Hypoglycemia FREQUENT HP:0001943 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Hypoglycemia (HP:0001943). HP:0001943 is a phenotype from the Human Phenotype Ontology.
Deliberately not linked to a pathophysiology node. The metabolic node in this entry is scoped to the late-emerging insulin-resistance arm, and no cited source connects the childhood hypoglycaemia to it or gives it a mechanism of its own. Recording the finding without inventing an edge is the honest option; the relationship between the two ends of the glucose-handling abnormality is not established in the literature cited here.
Show evidence (1 reference)
PMID:35257621 SUPPORT DIRECT Human Clinical
"In patients younger than 10 years old, hypoglycemia was recorded half of the time."
Gives the proportion directly, for a single named finding in a stated age band.
Insulin resistance HP:0000855 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Insulin resistance (HP:0000855). HP:0000855 is a phenotype from the Human Phenotype Ontology.
Deliberately left unbanded. The two proportions the sources give are both for something wider than insulin resistance itself — 70% for metabolic syndrome, a composite diagnosis, and 92% for impaired glucose tolerance or type 2 diabetes taken together. Banding this phenotype from either would put a number on a narrower finding than the one that was counted. HP has no metabolic syndrome term, so the composite cannot be curated as a phenotype in its own right either.
Show evidence (2 references)
PMID:17548484 SUPPORT DIRECT Human Clinical
"Mulibrey nanism is a monogenic disorder with prenatal-onset growth restriction, mild dysmorphic features, and a strong tendency for insulin resistance but no major neurologic handicap."
Names insulin resistance as a defining feature of the disorder. No frequency is recorded: the paper characterises the tendency without giving a proportion.
PMID:35257621 SUPPORT INDIRECT Human Clinical
"Up to 70% of patients with MUL develop metabolic syndrome."
The scale of the metabolic axis this phenotype sits on. Graded INDIRECT because metabolic syndrome is a composite endpoint of which insulin resistance is one component, so the figure bears on this phenotype without counting it.
Musculoskeletal 2
Fibrous dysplasia of long bones OCCASIONAL Fibrous dysplasia of the bones HP:0010734 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Fibrous dysplasia of long bones, annotated with Fibrous dysplasia of the bones (HP:0010734). HP:0010734 is a phenotype from the Human Phenotype Ontology.
Show evidence (1 reference)
PMID:14757854 SUPPORT DIRECT Human Clinical
"Other findings included a peculiar high-pitched voice (96%), yellowish dots in ocular fundi (79%), cutaneous naevi flammei (65%), hepatomegaly (45%), and fibrous dysplasia of long bones (25%)."
Gives the frequency of the skeletal lesion.
Mild muscular hypotonia FREQUENT HP:0001252 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Mild muscular hypotonicity, annotated with Hypotonia (HP:0001252), qualified as severity mild. HP:0001252 is a phenotype from the Human Phenotype Ontology.
Severity: MILD
Show evidence (1 reference)
PMID:14757854 SUPPORT DIRECT Human Clinical
"Mild muscular hypotonicity (68%) was the only neurological abnormality."
Gives both the frequency and the important negative — no other neurological abnormality was found.
Nervous System 1
High-pitched voice VERY_FREQUENT Abnormally high-pitched voice HP:0001620 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Peculiar high-pitched voice, annotated with Abnormally high-pitched voice (HP:0001620). HP:0001620 is a phenotype from the Human Phenotype Ontology.
Show evidence (1 reference)
PMID:14757854 SUPPORT DIRECT Human Clinical
"Other findings included a peculiar high-pitched voice (96%), yellowish dots in ocular fundi (79%), cutaneous naevi flammei (65%), hepatomegaly (45%), and fibrous dysplasia of long bones (25%)."
Gives the 96% frequency. Banded VERY_FREQUENT rather than OBLIGATE because the figure is 96%, not 100%.
Growth 2
Prenatal-onset growth failure VERY_FREQUENT Intrauterine growth retardation HP:0001511 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Intrauterine growth retardation (HP:0001511), qualified as course progressive. HP:0001511 is a phenotype from the Human Phenotype Ontology.
Course: PROGRESSIVE
Show evidence (1 reference)
PMID:14757854 SUPPORT DIRECT Human Clinical
"All except four of the patients (95%) had a prenatal onset growth failure without postnatal catch up growth."
Gives the frequency directly.
Slender build VERY_FREQUENT HP:0001533 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Gracile habitus with thin extremities, annotated with Slender build (HP:0001533). HP:0001533 is a phenotype from the Human Phenotype Ontology.
Show evidence (1 reference)
PMID:14757854 SUPPORT DIRECT Human Clinical
"In addition, practically all patients were gracile and had thin extremities."
States the finding in practically all patients. Banded VERY_FREQUENT rather than OBLIGATE because "practically all" is not a counted proportion.
🧬

Genetic Associations

1
TRIM37
Gene: TRIM37 hgnc:7523 HUGO Gene Nomenclature Committee (hgnc) Relation: this disease-associated gene is this gene This disease-associated gene is TRIM37 (hgnc:7523). hgnc:7523 is a gene from the HUGO Gene Nomenclature Committee. relationship_type: CAUSATIVE
Show evidence (3 references)
PMID:10888877 SUPPORT DIRECT Human Clinical
"We identified a gene with four independent MUL-associated mutations that all cause a frameshift and predict a truncated protein."
Establishes TRIM37 as the causal gene by positional cloning, with a loss-of-function allele class.
PMID:15108285 SUPPORT DIRECT Human Clinical
"Here we have characterized the genomic structure of the TRIM37 gene, which has 24 exons spanning approximately 109 kb of genomic DNA."
Defines the gene structure within which the reported alleles fall.
PMID:15108285 SUPPORT DIRECT In Vitro
"The sixth mutation (c.965G>T) is the first missense mutation (p.Gly322Val) associated with Mulibrey nanism. It affects the TRAF domain of TRIM37 and results in altered subcellular localization of the mutant TRIM37 protein, further suggesting that it is pathogenic."
The only reported missense allele acts through mislocalisation, which supports subcellular targeting as part of the loss-of-function mechanism.
💊

Medical Actions

3
Pericardiectomy
Action: pericardiectomyNCI Thesaurus (NCIT) Relation: this treatment is this clinical intervention This treatment is pericardiectomy (NCIT:C51643). NCIT:C51643 is a clinical intervention from the NCI Thesaurus. Ontology label: Pericardiectomy NCIT:C51643
Platform: Surgery
Surgical decompression of the constricted pericardium is the definitive treatment for the cardiac manifestation that dominates outcome. It addresses the mechanical consequence of the pericardial lesion, not its cause.
Mechanism Target:
Pericardial Constriction — Removing the constricting pericardium restores diastolic filling and relieves the raised venous pressure that causes hepatomegaly and congestive failure.
Show evidence (2 references)
PMID:35257621 SUPPORT INDIRECT Human Clinical
"We present a case of a patient with Mulibrey nanism syndrome who underwent pericardiectomy at 12 years old and was able to live 44 years more with relatively stable and asymptomatic diastolic congestive heart failure (CHF)."
The operation's effect in this disease, from the oldest reported case: pericardiectomy at 12 followed by 44 further years with stable, asymptomatic diastolic heart failure. Graded INDIRECT because a single uncontrolled case cannot establish that the survival followed from the operation.
PMID:35257621 SUPPORT DIRECT Human Clinical
"Constrictive pericarditis and diastolic dysfunction are the most common causes of mortality."
States why the operation matters: constrictive pericarditis and diastolic dysfunction are the commonest causes of death in this disease.
Recombinant human growth hormone therapy
Action: PharmacotherapyNCI Thesaurus (NCIT) Relation: this treatment is this clinical intervention This treatment is Pharmacotherapy (NCIT:C15986). NCIT:C15986 is a clinical intervention from the NCI Thesaurus. NCIT:C15986
Agent: recombinant human growth hormone NCIT:C837 NCI Thesaurus (NCIT) Relation: this treatment uses this therapeutic agent This treatment uses recombinant human growth hormone, annotated with Somatropin (NCIT:C837). NCIT:C837 is a therapeutic agent from the NCI Thesaurus.
Platform: Peptide
Growth hormone given for the prenatal-onset growth failure, evaluated over a median of 5.7 years in 30 of 72 subjects followed to 30 years — the only long-term treatment evaluation in this disease.
Mechanism Target:
Prenatal-Onset Growth Failure — Acts on the growth deficit symptomatically. It does not address the TRIM37 lesion and, on the cohort's own numbers, does not restore normal stature.
Show evidence (3 references)
PMID:17548484 SUPPORT DIRECT Human Clinical
"Growth hormone treatment improved the prepubertal growth but had only little impact on adult height (+5 cm)."
The result, stated as the authors state it: prepubertal growth improved, adult height by about 5 cm. This is the honest headline and it is a modest one.
PMID:17548484 SUPPORT DIRECT Human Clinical
"The final adult height averaged 136 cm in girls and 150 cm in boys."
The untreated final heights, which is the baseline the 5 cm is measured against.
PMID:17548484 SUPPORT DIRECT Human Clinical
"On the contrary, the subjects who were treated with growth hormone were slimmer and had less metabolic syndrome as young adults."
The unexpected metabolic result. Growth hormone raises insulin resistance in other settings, so the concern here was that it would worsen the disease's own metabolic tendency; the treated subjects were slimmer and had less metabolic syndrome instead.
Tumour surveillance
Action: tumour surveillance imaging and clinical reviewNCI Thesaurus (NCIT) Relation: this treatment is this clinical intervention This treatment is tumour surveillance imaging and clinical review, annotated with Cancer Screening (NCIT:C15406). NCIT:C15406 is a clinical intervention from the NCI Thesaurus. Ontology label: Cancer Screening NCIT:C15406
Periodic imaging and clinical review for the tumours that occur in most patients. Wilms tumour in childhood is the reason surveillance starts early; ovarian sex cord-stromal tumours in adult women and the wider benign vascular and adenomatous burden are why it continues.
Mechanism Target:
Disturbed Organ Architecture and Tumor Predisposition — Detects the consequence rather than modifying the mechanism. Surveillance does not reduce tumour incidence; it changes the stage at which tumours are found.
Show evidence (2 references)
PMID:19334051 SUPPORT DIRECT Human Clinical
"Fifteen malignancies occurred in 13 patients (15%), seven of them in the kidney (five Wilms' tumours), three in the thyroid gland, two gynaecological cancers, one gastrointestinal carcinoid tumour, one neuropituitary Langerhans cell histiocytosis and one case of acute lymphoblastic leukaemia (ALL)."
The malignancy burden that surveillance is directed at: 15 malignancies in 13 of 89 patients, across kidney, thyroid, gynaecological and haematological sites.
PMID:19329943 SUPPORT DIRECT Human Clinical
"More than half of female patients with Mulibrey nanism develop benign mesenchymal tumors of ovarian sex cord-stromal origin."
The adult female component, which is what extends surveillance beyond the childhood Wilms tumour window.
🔬

Diagnosis

2
Clinical diagnostic criteria
Diagnosis rests on the clinical gestalt — growth failure plus the craniofacial features — with the organ manifestations variable at presentation. The defining cohort proposed formal criteria on that basis.
clinical evaluation against Mulibrey nanism diagnostic criteria NCIT:C124351 NCI Thesaurus (NCIT)
Results: Prenatal-onset growth failure without catch-up, plus scaphocephaly, facial triangularity, high broad forehead and low nasal bridge.
The criteria themselves are not reproduced here: the cached record is the abstract, which states that criteria were proposed without listing them. What is curated is the evidence base the criteria rest on, not the criteria.
Show evidence (2 references)
PMID:14757854 SUPPORT DIRECT Human Clinical
"Based on these findings, we propose new diagnostic criteria for MUL."
The paper's own statement that it proposes diagnostic criteria.
PMID:14757854 SUPPORT DIRECT Human Clinical
"At the time of the diagnosis, characteristic craniofacial features of scaphocephaly, facial triangularity, high and broad forehead, and low nasal bridge were evident in over 90% of the patients."
The craniofacial component, present in over 90% at diagnosis, which is the most consistent finding after growth failure.
TRIM37 molecular genetic testing
Confirmatory testing. Twenty-three disease-associated TRIM37 variants were known at the time of the mouse paper, with a Finnish founder allele accounting for most Finnish cases.
TRIM37 sequence analysis NCIT:C15709 NCI Thesaurus (NCIT)
Results: Biallelic loss-of-function TRIM37 variants.
📈

Progression

3
Infancy
Feeding difficulties and respiratory tract infections dominate infancy. Cardiac manifestations are already detectable in a minority.
Show evidence (1 reference)
PMID:14757854 SUPPORT DIRECT Human Clinical
"In infancy, feeding difficulties, and respiratory tract infections were the most common problems."
Characterises the infantile presentation.
Time of diagnosis
Diagnosis spans a very wide age range with a median of about two years, and the craniofacial gestalt plus growth failure are what make the diagnosis; organ manifestations are variable at this stage.
Show evidence (2 references)
PMID:14757854 SUPPORT DIRECT Human Clinical
"Mulibrey nanism (MUL) is an autosomal recessive disease caused by mutations in the TRIM37 gene encoding the peroxisomal TRIM37 protein of unknown function. In this work, we analysed the clinical characteristics of 85 Finnish patients with MUL, most of whom were homozygous for the Finn major..."
Connects diagnostic timing to Mulibrey nanism and the characteristic growth/craniofacial findings used in proposed diagnostic criteria, while retaining variability in organ involvement.
PMID:14757854 SUPPORT DIRECT Human Clinical
"The most consistent findings were growth failure and characteristic craniofacial features. However, organ manifestations varied considerably in early childhood."
States which features are reliable for diagnosis and which are variable at this stage.
Later childhood and adult life
Tumour surveillance becomes the dominant long-term concern: the national cohort spanned ages 0.7 to 76 years and found lesions in three quarters of patients.
Show evidence (1 reference)
PMID:19334051 SUPPORT DIRECT Human Clinical
"A total of 210 tumorous lesions were detected in 66/89 patients (74%)."
Establishes the lifetime tumour burden that motivates long-term surveillance.
📊

Prevalence

1
Finland
Cases In Literature Ultra Rare
Enriched in Finland by a founder effect and rare elsewhere. The national Finnish cohorts number 85 patients (2004) and 89 patients (2009).
Show evidence (2 references)
PMID:10888877 SUPPORT DIRECT Human Clinical
"MUL is enriched in the Finnish population, but is rare elsewhere."
States the Finnish enrichment and rarity elsewhere.
PMID:19334051 SUPPORT DIRECT Human Clinical
"In this work, the frequency and pathology of malignant and benign tumours were analysed in a national cohort of 89 Finnish MUL patients aged 0.7-76 years."
Gives the size of the national cohort, which is the practical bound on how many molecularly confirmed patients exist in Finland.
🐁

Animal Models

1
Trim37 knockout mouse
The only reported animal model. It reproduces the infertility, the cardiomyopathy, the fatty liver and the tumour predisposition, and reproduces none of the growth failure that names the disease.
Species
Mouse
Genotype
Trim37(-/-) congenic knock-out
Publication
PMID:27044324
Pathograph links
Gonadal Failure and Insulin Resistance recapitulates fidelity: moderate observes: organism Infertility in both sexes with germ cell aplasia and Leydig cell hyperplasia, raised FSH and LH with preserved testosterone, and raised fasting glucose. The most consistent phenotype in the model.
Limitations: The glycaemic abnormality runs the other way from the human one: the mouse has raised fasting glucose with LOW fasting insulin, whereas patients are described as insulin resistant. Testosterone is maintained in the mouse and levels off in patients. And the model is not a model of the human sex difference — female patients develop ovarian sex cord-stromal tumours, which the paper does not report.
Show evidence (2 references)
PMID:27044324 SUPPORT DIRECT Model Organism
"Both male and female Trim37(-/-) mice were infertile, the gonads showing germ cell aplasia, hilus and Leydig cell hyperplasia and accumulation of lipids in and around Leydig cells."
The gonadal phenotype with its histology, in both sexes.
+ 1 more reference
Prenatal-Onset Growth Failure fails to recapitulate fidelity: low observes: organism The model does not reproduce the defining feature of the disease. Weight development is normal to about 12 months and long-bone length does not differ from wild-type; only skull size is reduced.
Limitations: This is a negative result about the model, not about the disease. It means the growth arm of Mulibrey nanism currently has no experimental system at all, and any mechanism proposed for it cannot be tested in this mouse.
Show evidence (2 references)
PMID:27044324 SUPPORT DIRECT Model Organism
"Trim37(-/-) mice were viable and had normal weight development until approximately 12 months of age, after which they started to manifest increasing problems in wellbeing and weight loss."
Normal weight development for the first year, against severe prenatal-onset failure in patients.
+ 1 more reference
Peroxisomal TRIM37 Depletion fails to recapitulate fidelity: low observes: cellular Liver peroxisome number and morphology are normal in the null mouse, which is the same negative that patient fibroblasts give.
Limitations: Morphology is not function: normal peroxisome number and appearance do not exclude a metabolic defect that was not assayed. The result is recorded as a failure to reproduce a peroxisomal phenotype, not as proof that peroxisomal function is intact.
Show evidence (1 reference)
PMID:27044324 SUPPORT DIRECT Model Organism
"The amount and morphology of liver peroxisomes seemed normal in Trim37(-/-) mice."
The negative peroxisomal result in the model, independent of the human fibroblast result the entry already cites for the same claim.
Show evidence (1 reference)
PMID:27044324 SUPPORT DIRECT Model Organism
"Trim37(-/-) mice recapitulate several features of the human MUL disease and thus provide a good model to study disease pathogenesis related to TRIM37 deficiency, including infertility, non-alcoholic fatty liver disease, cardiomyopathy and tumorigenesis."
The authors' own statement of what the model is for, which is the scope of every link above.
{ }

Source YAML

click to show 
name: Mulibrey Nanism
category: Mendelian
creation_date: '2026-09-08T08:30:00Z'
synonyms:
- MUL
- muscle-liver-brain-eye nanism
- Perheentupa syndrome
- pericardial constriction and growth failure
- TRIM37 deficiency
description: >-
  Mulibrey nanism is an autosomal recessive, prenatal-onset growth disorder
  caused by biallelic loss-of-function variants in TRIM37, which encodes a
  RING-B-box-coiled-coil (RBCC/TRIM) protein carrying a C-terminal TRAF domain
  and RING-dependent ubiquitin ligase activity. The name is an acronym for the
  tissues involved — muscle, liver, brain, eye — all of mesodermal origin, which
  was the original argument for a single highly pleiotropic gene. The disease is
  enriched in Finland through a founder frameshift allele ("Finn major") and is
  rare elsewhere.

  Clinically the constant findings are severe growth failure of prenatal onset
  without postnatal catch-up, and a characteristic craniofacial appearance
  (scaphocephaly, facial triangularity, high broad forehead, low nasal bridge)
  present in over 90% of patients. Constrictive pericarditis with consequent
  hepatomegaly is the feature that dominates outcome. Yellowish dots in the
  ocular fundi, a high-pitched voice, cutaneous naevi flammei, fibrous dysplasia
  of long bones, and mild muscular hypotonia complete the picture, but organ
  manifestations vary considerably in early childhood.

  The mechanistic link from TRIM37 loss to this phenotype is genuinely
  unresolved, and this entry is curated to say so rather than to pick a side.
  Two non-exclusive models have authoritative primary support. TRIM37 was
  localised to peroxisomes, which led to Mulibrey nanism being classified as a
  new peroxisomal disorder — but the same study found that patient fibroblasts
  stain normally for peroxisomal matrix and membrane markers, so peroxisome
  biogenesis is apparently intact and the peroxisomal classification does not on
  its own explain the disease. Separately, TRIM37 is a centrosomal ubiquitin
  ligase that restrains PLK4 self-assembly and controls CEP192, so its loss
  permits ectopic microtubule-organising condensates and disturbs mitotic
  fidelity; that work was done in a cancer-vulnerability context rather than in
  patient tissue, so its application to Mulibrey nanism is an inference. What is
  directly observed in patients is disturbed organ architecture with ectopic
  tissues and a high frequency of benign and malignant tumours, which is at
  least consistent with a mitotic-fidelity mechanism.
disease_term:
  preferred_term: mulibrey nanism
  term:
    id: MONDO:0009664
    label: mulibrey nanism
parents:
- Inborn Genetic Disease
- Primordial Dwarfism
- Tumor Predisposition Syndrome
notes: >-
  Gene identity was checked against HGNC directly rather than taken from the
  deep-research report: TRIM37 is hgnc:7523 (tripartite motif containing 37,
  17q22). The Perplexity report used for this entry asserted "HGNC:16287", which
  is NFU1, an unrelated iron-sulfur cluster scaffold gene. See the PR and the
  history record for the other citation defects found in that report.
inheritance:
- name: Autosomal recessive inheritance
  inheritance_term:
    preferred_term: Autosomal recessive inheritance
    term:
      id: HP:0000007
      label: Autosomal recessive inheritance
  description: >-
    Mulibrey nanism follows autosomal recessive inheritance. In Finland most
    patients are homozygous for the Finn major TRIM37 frameshift allele.
  evidence:
  - reference: PMID:14757854
    reference_title: "Mulibrey nanism: clinical features and diagnostic criteria."
    supports: SUPPORT
    directness: DIRECT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Mulibrey nanism (MUL) is an autosomal recessive disease caused by mutations in the TRIM37 gene encoding the peroxisomal TRIM37 protein of unknown function.
    explanation: >-
      States the inheritance pattern and the causal gene in the cohort that
      defined the diagnostic criteria.
  - reference: PMID:10888877
    reference_title: Gene encoding a new RING-B-box-Coiled-coil protein is mutated in mulibrey nanism.
    supports: SUPPORT
    directness: DIRECT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Mulibrey nanism (for muscle-liver-brain-eye nanism, MUL; MIM 253250) is an autosomal recessive disorder that involves several tissues of mesodermal origin, implying a defect in a highly pleiotropic gene.
    explanation: >-
      The positional cloning paper states the recessive inheritance and the
      mesodermal, pleiotropic character of the disorder.
genetic:
- name: TRIM37
  gene_term:
    preferred_term: TRIM37
    term:
      id: hgnc:7523
      label: TRIM37
  relationship_type: CAUSATIVE
  notes: >-
    Biallelic loss-of-function variants in TRIM37 cause Mulibrey nanism.
    Reported alleles span frameshift, nonsense, splice-site and large genomic
    deletions, plus a single TRAF-domain missense variant. The Finnish founder
    allele is a frameshift predicting a truncated protein.
  evidence:
  - reference: PMID:10888877
    reference_title: Gene encoding a new RING-B-box-Coiled-coil protein is mutated in mulibrey nanism.
    supports: SUPPORT
    directness: DIRECT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      We identified a gene with four independent MUL-associated mutations that all cause a frameshift and predict a truncated protein.
    explanation: >-
      Establishes TRIM37 as the causal gene by positional cloning, with a
      loss-of-function allele class.
  - reference: PMID:15108285
    reference_title: Novel mutations in the TRIM37 gene in Mulibrey Nanism.
    supports: SUPPORT
    directness: DIRECT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Here we have characterized the genomic structure of the TRIM37 gene, which has 24 exons spanning approximately 109 kb of genomic DNA.
    explanation: Defines the gene structure within which the reported alleles fall.
  - reference: PMID:15108285
    reference_title: Novel mutations in the TRIM37 gene in Mulibrey Nanism.
    supports: SUPPORT
    directness: DIRECT
    evidence_source: IN_VITRO
    snippet: >-
      The sixth mutation (c.965G>T) is the first missense mutation (p.Gly322Val) associated with Mulibrey nanism. It affects the TRAF domain of TRIM37 and results in altered subcellular localization of the mutant TRIM37 protein, further suggesting that it is pathogenic.
    explanation: >-
      The only reported missense allele acts through mislocalisation, which
      supports subcellular targeting as part of the loss-of-function mechanism.
pathophysiology:
- name: TRIM37 Loss of Function
  biological_scale: MOLECULAR
  description: >-
    Biallelic TRIM37 variants abolish or mislocalise the TRIM37
    RING-B-box-coiled-coil ubiquitin ligase. This is the initiating lesion;
    every node below is downstream of it.
  genetic_context:
    variant_origin: GERMLINE
    functional_impact_category: LOSS_OF_FUNCTION
    allele_type: SNV
    zygosity: HOMOZYGOUS
  molecular_functions:
  - preferred_term: TRIM37 ubiquitin protein ligase activity
    modifier: LOSS_OF_FUNCTION
    term:
      id: GO:0061630
      label: ubiquitin protein ligase activity
  downstream:
  - target: Prenatal-Onset Growth Failure
    causal_link_type: INDIRECT_UNKNOWN_INTERMEDIATES
    description: >-
      Growth failure is the most consistent finding in the disorder and must
      be downstream of the germline lesion, but nothing is known about the
      route. The intermediates are recorded as unknown rather than guessed:
      the knockout mouse, which reproduces the infertility and the cardiac
      and hepatic phenotypes, does not reproduce the growth failure at all.
    evidence:
    - reference: PMID:27044324
      reference_title: "Trim37-deficient mice recapitulate several features of the multi-organ disorder Mulibrey nanism."
      supports: REFUTE
      directness: DIRECT
      evidence_source: MODEL_ORGANISM
      snippet: >-
        Trim37(-/-) mice were viable and had normal weight development until approximately 12 months of age, after which they started to manifest increasing problems in wellbeing and weight loss.
      explanation: >-
        Refutes any account of the growth failure that the mouse model would
        support: the null mouse has normal weight development for the first
        year. Recorded on this edge because the absence of a model is what
        leaves the intermediates unknown.
    - reference: PMID:27044324
      reference_title: "Trim37-deficient mice recapitulate several features of the multi-organ disorder Mulibrey nanism."
      supports: REFUTE
      directness: DIRECT
      evidence_source: MODEL_ORGANISM
      snippet: >-
        Assessment of skeletal parameters with computer tomography revealed significantly smaller skull size, but no difference in the lengths of long bones in Trim37(-/-) mice as compared with wild-type.
      explanation: >-
        The skeletal counterpart: skull size is reduced in the mouse but
        long-bone length is not, so the model reproduces the craniofacial
        arm of the phenotype without the linear-growth arm.
  - target: Mesodermal Ocular Involvement
    causal_link_type: INDIRECT_UNKNOWN_INTERMEDIATES
    description: >-
      The choroidal lesion is downstream of the germline lesion by
      elimination, since every feature of the syndrome is, but no step
      between TRIM37 loss and choroidal hypoplasia has been described in any
      source cited here.
  - target: Gonadal Failure and Insulin Resistance
    causal_link_type: INDIRECT_UNKNOWN_INTERMEDIATES
    description: >-
      The endocrine and metabolic axis. Typed as having unknown
      intermediates because the mouse localises the lesion to the gonad
      itself — germ cell aplasia with Leydig cell hyperplasia — without
      establishing what TRIM37 does there, and nothing at all connects the
      lesion to the insulin-resistance arm.
  - target: Peroxisomal TRIM37 Depletion
    causal_link_type: DIRECT
    description: >-
      TRIM37 is a peroxisomal protein and the major Finnish mutant fails to
      reach the peroxisome, so the germline lesion removes TRIM37 from that
      compartment.
    evidence:
    - reference: PMID:11938494
      reference_title: "The TRIM37 gene encodes a peroxisomal RING-B-box-coiled-coil protein: classification of mulibrey nanism as a new peroxisomal disorder."
      supports: SUPPORT
      directness: DIRECT
      evidence_source: IN_VITRO
      snippet: >-
        Peroxisomal localization is compromised in mutant protein representing the major Finnish TRIM37 mutation but is retained in the protein representing the minor Finnish mutation.
      explanation: >-
        Directly links the commonest disease allele to loss of TRIM37 from the
        peroxisome.
  - target: Centrosomal Ubiquitin Ligase Deficiency
    causal_link_type: DIRECT
    description: >-
      TRIM37 also acts at the centrosome, where it restrains PLK4 self-assembly,
      so loss of the ligase removes that restraint.
    evidence:
    - reference: PMID:32908304
      reference_title: TRIM37 controls cancer-specific vulnerability to PLK4 inhibition.
      supports: SUPPORT
      directness: INDIRECT
      evidence_source: IN_VITRO
      snippet: >-
        Here we show that acentrosomal spindle assembly following PLK4 inhibition depends on levels of the centrosomal ubiquitin ligase TRIM37.
      explanation: >-
        Identifies TRIM37 as a centrosomal ubiquitin ligase. Graded INDIRECT
        because the experiments were performed in cancer and RPE1 cell lines to
        study a therapeutic vulnerability, not in Mulibrey nanism patient
        material.
  evidence:
  - reference: PMID:10888877
    reference_title: Gene encoding a new RING-B-box-Coiled-coil protein is mutated in mulibrey nanism.
    supports: SUPPORT
    directness: DIRECT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      MUL is ubiquitously expressed and encodes a new member of the RING-B-box-Coiled-coil (RBCC) family of zinc-finger proteins, whose members are involved in diverse cellular functions such as developmental patterning and oncogenesis.
    explanation: >-
      Establishes the protein family and the ubiquitous expression that makes a
      multisystem phenotype plausible.
- name: Peroxisomal TRIM37 Depletion
  biological_scale: CELLULAR
  description: >-
    Endogenous TRIM37 is a peroxisomal protein of ~130 kD, and its loss from
    that compartment is what led to Mulibrey nanism being classified as a
    peroxisomal disorder. The node is deliberately named for the depletion of
    TRIM37 from the peroxisome rather than for peroxisomal failure: patient
    fibroblasts stain normally for peroxisomal matrix and membrane markers, so
    biogenesis is apparently intact and no downstream metabolic consequence has
    been demonstrated in patients. See the knowledge gap attached to this node.
  cellular_components:
  - preferred_term: peroxisome
    term:
      id: GO:0005777
      label: peroxisome
  evidence:
  - reference: PMID:11938494
    reference_title: "The TRIM37 gene encodes a peroxisomal RING-B-box-coiled-coil protein: classification of mulibrey nanism as a new peroxisomal disorder."
    supports: SUPPORT
    directness: DIRECT
    evidence_source: IN_VITRO
    snippet: >-
      We show that the human TRIM37 cDNA encodes a peroxisomal protein with an apparent molecular weight of 130 kD.
    explanation: Establishes the peroxisomal localisation of the TRIM37 protein.
  - reference: PMID:11938494
    reference_title: "The TRIM37 gene encodes a peroxisomal RING-B-box-coiled-coil protein: classification of mulibrey nanism as a new peroxisomal disorder."
    supports: REFUTE
    directness: DIRECT
    evidence_source: IN_VITRO
    snippet: >-
      Fibroblasts derived from patients with mulibrey nanism lack C-terminal TRIM37 immunoreactivity but stain normally for both peroxisomal matrix and membrane markers, suggesting apparently normal peroxisome biogenesis in patient fibroblasts.
    explanation: >-
      Refutes the stronger reading of this node as a peroxisome biogenesis
      defect. The same paper that established the peroxisomal localisation
      reports intact biogenesis in patient cells, so the two items are split by
      quoted sentence rather than merged.
- name: Centrosomal Ubiquitin Ligase Deficiency
  biological_scale: CELLULAR
  description: >-
    TRIM37 normally prevents PLK4 from self-assembling into
    centrosome-independent condensates and controls levels of the centrosomal
    component CEP192. In its absence, ectopic PLK4 condensates form and can act as
    microtubule-organising centres, altering spindle assembly. This is the
    strongest current candidate for a mechanism that would produce both the
    developmental and the neoplastic features, but it has not been shown in
    Mulibrey nanism patient tissue.
  biological_processes:
  - preferred_term: centriole replication
    modifier: ABNORMAL
    term:
      id: GO:0007099
      label: centriole replication
  - preferred_term: mitotic spindle assembly
    modifier: ABNORMAL
    term:
      id: GO:0090307
      label: mitotic spindle assembly
  downstream:
  - target: Disturbed Organ Architecture and Tumor Predisposition
    causal_link_type: INDIRECT_KNOWN_INTERMEDIATES
    description: >-
      Loss of mitotic fidelity in proliferating tissue is the proposed route to
      the ectopic tissues and the excess of benign and malignant tumours seen in
      patients. The link is an inference from cell-line work to patient
      pathology, not a demonstrated chain.
    evidence:
    - reference: PMID:32908304
      reference_title: TRIM37 controls cancer-specific vulnerability to PLK4 inhibition.
      supports: SUPPORT
      directness: INDIRECT
      evidence_source: IN_VITRO
      snippet: >-
        We find that inactivating TRIM37 improves acentrosomal mitosis because TRIM37 prevents PLK4 from self-assembling into centrosome-independent condensates that serve as ectopic microtubule-organizing centres.
      explanation: >-
        Establishes what TRIM37 loss does to centrosome biology in cultured
        cells. Graded INDIRECT: the inference to patient organ architecture is
        an added step this paper does not make.
  evidence:
  - reference: PMID:32908304
    reference_title: TRIM37 controls cancer-specific vulnerability to PLK4 inhibition.
    supports: SUPPORT
    directness: INDIRECT
    evidence_source: IN_VITRO
    snippet: >-
      Low TRIM37 levels accelerate acentrosomal spindle assembly and improve proliferation following PLK4 inhibition, whereas high TRIM37 levels inhibit acentrosomal spindle assembly, leading to mitotic failure and cessation of proliferation.
    explanation: >-
      Shows the loss-of-function direction relevant to Mulibrey nanism has a
      measurable mitotic phenotype. INDIRECT for the same reason as above.
- name: Disturbed Organ Architecture and Tumor Predisposition
  biological_scale: TISSUE
  description: >-
    Patients show disturbed organ architecture with ectopic tissues, together
    with a high frequency of both benign and malignant tumours across internal
    organs. This is an observed patient-level finding, independent of which
    upstream mechanism proves correct.
  downstream:
  - target: Wilms tumor
    causal_link_type: DIRECT
    description: Wilms tumour is the commonest malignancy in this predisposition.
  evidence:
  - reference: PMID:19334051
    reference_title: High frequency of tumours in Mulibrey nanism.
    supports: SUPPORT
    directness: DIRECT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      The results show that the MUL patients have disturbed architecture with ectopic tissues and a high frequency of both benign and malignant tumours detectable in several internal organs.
    explanation: >-
      The national cohort establishes both the architectural disturbance and the
      tumour excess directly in patients.
  - reference: PMID:19334051
    reference_title: High frequency of tumours in Mulibrey nanism.
    supports: SUPPORT
    directness: DIRECT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      A total of 210 tumorous lesions were detected in 66/89 patients (74%).
    explanation: Quantifies the tumour burden in the 89-patient national cohort.
- name: Gonadal Failure and Insulin Resistance
  biological_scale: ORGANISM
  description: >-
    The endocrine and metabolic arm of the disease, and the one that emerges
    latest. In males the gonad fails progressively after a normal pubertal
    onset, giving hypergonadotropic hypogonadism and near-universal
    infertility; in females the ovarian stroma instead produces sex
    cord-stromal tumours. Insulin resistance runs alongside and ends in early
    type 2 diabetes. Curated as one node because the knockout mouse shows
    the gonadal and glycaemic abnormalities together and neither has been
    shown to cause the other.
  downstream:
  - target: Hypergonadotropic hypogonadism
    causal_link_type: DIRECT
    description: The clinical expression of the testicular failure in adult males.
  - target: Type 2 diabetes mellitus
    causal_link_type: INDIRECT_KNOWN_INTERMEDIATES
    description: >-
      Through the insulin resistance recorded as its own phenotype. The
      intermediate is known and named but is not modelled as a separate
      node.
  evidence:
  - reference: PMID:21865362
    reference_title: "Testicular failure and male infertility in the monogenic Mulibrey nanism disorder."
    supports: SUPPORT
    directness: DIRECT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      All adult MUL males have a unique disorder of testicular function with small testes, elevated FSH and LH, and low inhibin B.
    explanation: >-
      The human gonadal finding, in all adult males of the national cohort.
  - reference: PMID:17548484
    reference_title: "Growth and growth hormone therapy in subjects with mulibrey nanism."
    supports: SUPPORT
    directness: DIRECT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Mulibrey nanism is a monogenic disorder with prenatal-onset growth restriction, mild dysmorphic features, and a strong tendency for insulin resistance but no major neurologic handicap.
    explanation: >-
      The human metabolic finding, in the largest growth cohort.
  - reference: PMID:27044324
    reference_title: "Trim37-deficient mice recapitulate several features of the multi-organ disorder Mulibrey nanism."
    supports: SUPPORT
    directness: INDIRECT
    evidence_source: MODEL_ORGANISM
    snippet: >-
      Both male and female Trim37(-/-) mice were infertile, the gonads showing germ cell aplasia, hilus and Leydig cell hyperplasia and accumulation of lipids in and around Leydig cells.
    explanation: >-
      Localises the gonadal lesion to the gonad itself in the null mouse,
      with a histological description that no human study provides.
  - reference: PMID:27044324
    reference_title: "Trim37-deficient mice recapitulate several features of the multi-organ disorder Mulibrey nanism."
    supports: SUPPORT
    directness: INDIRECT
    evidence_source: MODEL_ORGANISM
    snippet: >-
      Six-month-old Trim37(-/-) mice had elevated fasting blood glucose and low fasting serum insulin levels.
    explanation: >-
      The glycaemic abnormality in the same model, which is why the two arms
      are curated as one node rather than as unrelated findings.
  notes: >-
    Note the mouse and human metabolic phenotypes are not identical: the
    mouse has elevated fasting glucose with LOW fasting insulin, whereas the
    human literature describes insulin resistance. The direction of the
    insulin abnormality differs, and that is recorded rather than smoothed
    over.
- name: Pericardial Constriction
  biological_scale: TISSUE
  description: >-
    A thickened, non-compliant pericardium restricts diastolic filling, giving
    raised venous pressure, hepatomegaly and congestive heart failure. This is
    the feature that dominates outcome, and the step connecting TRIM37 loss to
    pericardial fibrosis is not established — see the knowledge gap attached to
    this node.
  downstream:
  - target: Hepatomegaly
    causal_link_type: DIRECT
    description: >-
      Constriction raises systemic venous pressure, producing hepatic congestion
      and hepatomegaly.
    evidence:
    - reference: PMID:10888877
      reference_title: Gene encoding a new RING-B-box-Coiled-coil protein is mutated in mulibrey nanism.
      supports: SUPPORT
      directness: DIRECT
      evidence_source: HUMAN_CLINICAL
      snippet: >-
        Characteristic features include severe growth failure of prenatal onset and constrictive pericardium with consequent hepatomegaly.
      explanation: >-
        States the causal relationship between pericardial constriction and
        hepatomegaly in this disorder.
  evidence:
  - reference: PMID:14757854
    reference_title: "Mulibrey nanism: clinical features and diagnostic criteria."
    supports: SUPPORT
    directness: DIRECT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Congestive heart failure and pericardial constriction were diagnosed during infancy in 12% and 6% of the patients, respectively.
    explanation: >-
      Quantifies how often the cardiac manifestations are already present in
      infancy in the Finnish cohort.
- name: Prenatal-Onset Growth Failure
  biological_scale: ORGANISM
  description: >-
    Growth failure begins prenatally and there is no postnatal catch-up, so the
    height deficit widens with age. It is the most consistent finding in the
    disorder and is present essentially independent of organ involvement.
  evidence:
  - reference: PMID:14757854
    reference_title: "Mulibrey nanism: clinical features and diagnostic criteria."
    supports: SUPPORT
    directness: DIRECT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      All except four of the patients (95%) had a prenatal onset growth failure without postnatal catch up growth.
    explanation: >-
      Establishes both the prenatal onset and the absence of catch-up in the
      defining cohort.
  - reference: PMID:14757854
    reference_title: "Mulibrey nanism: clinical features and diagnostic criteria."
    supports: SUPPORT
    directness: DIRECT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      The mean length standard deviation score (SDS) was -3.1 and -4.0 at birth and at diagnosis, respectively.
    explanation: >-
      Quantifies the deficit at birth and its widening by the time of diagnosis.
- name: Mesodermal Ocular Involvement
  biological_scale: TISSUE
  description: >-
    Focal choroidal hypoplasia with overlying pigment disturbance produces the
    yellowish fundus dots that are part of the diagnostic picture. The choroid
    is mesodermal, which is consistent with the mesodermal framing of the
    syndrome as a whole.
  evidence:
  - reference: PMID:6818830
    reference_title: "Mulibrey nanism, an autosomal recessive syndrome with ocular involvement."
    supports: SUPPORT
    directness: DIRECT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      By fluorescein angiography areas of focal choroidal hypoplasia have been noted.
    explanation: Identifies the choroidal lesion behind the fundus findings.
  - reference: PMID:6818830
    reference_title: "Mulibrey nanism, an autosomal recessive syndrome with ocular involvement."
    supports: SUPPORT
    directness: INDIRECT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      The findings do confirm the hypothesis that the choroidal changes represent one further manifestation originating from mesodermal tissues in these patients.
    explanation: >-
      Supports the mesodermal framing. Graded INDIRECT because the mesodermal
      origin is the authors' interpretation of the histology rather than a
      direct observation.
  locations:
  - preferred_term: choroid
    term:
      id: UBERON:0001776
      label: optic choroid
phenotypes:
- category: Growth
  name: Prenatal-onset growth failure
  description: >-
    Growth failure of prenatal onset without postnatal catch-up, present in 95%
    of the Finnish cohort.
  phenotype_term:
    preferred_term: Intrauterine growth retardation
    term:
      id: HP:0001511
      label: Intrauterine growth retardation
    clinical_course: PROGRESSIVE
  frequency: VERY_FREQUENT
  reports_on:
  - target: Prenatal-Onset Growth Failure
    relationship: READOUT_OF
  evidence:
  - reference: PMID:14757854
    reference_title: "Mulibrey nanism: clinical features and diagnostic criteria."
    supports: SUPPORT
    directness: DIRECT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      All except four of the patients (95%) had a prenatal onset growth failure without postnatal catch up growth.
    explanation: Gives the frequency directly.
- category: Cardiovascular
  name: Constrictive pericarditis
  description: >-
    Pericardial constriction restricting diastolic filling. Diagnosed in 6% of
    patients already during infancy and reported in up to 39% of cases over the
    course of the disease; it is progressive and is the principal determinant
    of outcome.
  frequency: FREQUENT
  phenotype_term:
    preferred_term: Constrictive pericarditis
    term:
      id: HP:0002563
      label: Constrictive pericarditis
    clinical_course: PROGRESSIVE
  reports_on:
  - target: Pericardial Constriction
    relationship: READOUT_OF
  evidence:
  - reference: PMID:14757854
    reference_title: "Mulibrey nanism: clinical features and diagnostic criteria."
    supports: SUPPORT
    directness: DIRECT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Congestive heart failure and pericardial constriction were diagnosed during infancy in 12% and 6% of the patients, respectively.
    explanation: >-
      The infancy-onset figure: how often the manifestation was already
      present at diagnosis in infancy, not its lifetime frequency.
  - reference: PMID:35257621
    reference_title: "The Importance of Early Pericardiectomy in Mulibrey Nanism Syndrome, a Case Report."
    supports: SUPPORT
    directness: DIRECT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      The most common cardiac manifestations are CHF and constrictive pericarditis seen in up to 51% and 39% of the cases, respectively.
    explanation: >-
      The lifetime figures, which is what the band is derived from.
  notes: >-
    Two denominators are in play and only one of them bands this phenotype.
    The 6%/12% figures from the diagnostic-criteria cohort count patients
    diagnosed during infancy, so they describe how often the manifestation is
    present at presentation, not how often it occurs. The band uses the
    lifetime figures instead. "Up to" is a ceiling, and the sentence sits in a
    case report's narrative discussion summarising Lipsanen-Nyman rather than
    in a primary cohort table, so the band is the weaker claim of the two the
    source supports.
- category: Cardiovascular
  name: Congestive heart failure
  description: >-
    Diagnosed during infancy in 12% of the Finnish cohort, and reported in up
    to 51% of cases over the course of the disease.
  frequency: FREQUENT
  phenotype_term:
    preferred_term: Congestive heart failure
    term:
      id: HP:0001635
      label: Congestive heart failure
  reports_on:
  - target: Pericardial Constriction
    relationship: READOUT_OF
  evidence:
  - reference: PMID:14757854
    reference_title: "Mulibrey nanism: clinical features and diagnostic criteria."
    supports: SUPPORT
    directness: DIRECT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Congestive heart failure and pericardial constriction were diagnosed during infancy in 12% and 6% of the patients, respectively.
    explanation: >-
      The infancy-onset figure: how often the manifestation was already
      present at diagnosis in infancy, not its lifetime frequency.
  - reference: PMID:35257621
    reference_title: "The Importance of Early Pericardiectomy in Mulibrey Nanism Syndrome, a Case Report."
    supports: SUPPORT
    directness: DIRECT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      The most common cardiac manifestations are CHF and constrictive pericarditis seen in up to 51% and 39% of the cases, respectively.
    explanation: >-
      The lifetime figures, which is what the band is derived from.
  notes: >-
    Two denominators are in play and only one of them bands this phenotype.
    The 6%/12% figures from the diagnostic-criteria cohort count patients
    diagnosed during infancy, so they describe how often the manifestation is
    present at presentation, not how often it occurs. The band uses the
    lifetime figures instead. "Up to" is a ceiling, and the sentence sits in a
    case report's narrative discussion summarising Lipsanen-Nyman rather than
    in a primary cohort table, so the band is the weaker claim of the two the
    source supports.
- category: Cardiovascular
  name: Left ventricular hypertrophy
  description: >-
    Left ventricular hypertrophy with diastolic dysfunction and preserved
    systolic function. The source states this persists irrespective of
    previous pericardiectomy, which places part of the diastolic abnormality
    in the myocardium rather than in the constricting pericardium alone.
  phenotype_term:
    preferred_term: Left ventricular hypertrophy
    term:
      id: HP:0001712
      label: Left ventricular hypertrophy
  evidence:
  - reference: PMID:35257621
    reference_title: "The Importance of Early Pericardiectomy in Mulibrey Nanism Syndrome, a Case Report."
    supports: SUPPORT
    directness: DIRECT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Echocardiographic findings are characterized by left ventricular hypertrophy and diastolic dysfunction with preserved systolic function irrespective of previous pericardiectomy.
    explanation: >-
      Reports the echocardiographic finding, and that it does not resolve
      after the pericardium is removed.
  notes: >-
    No frequency is asserted. The source characterises the echocardiographic
    picture without giving a proportion. Recorded because the
    "irrespective of previous pericardiectomy" clause bears directly on what
    pericardiectomy can be expected to achieve: relieving the constriction
    does not abolish the diastolic abnormality. For the same reason this
    phenotype is deliberately not made a readout of Pericardial Constriction:
    the source's point is that it persists once the pericardium is gone, so
    an edge from that node would assert the opposite of what is cited.
- category: Craniofacial
  name: Facial triangularity
  description: >-
    Part of the craniofacial gestalt — scaphocephaly, facial triangularity, high
    and broad forehead, low nasal bridge — evident in over 90% of patients at
    diagnosis.
  phenotype_term:
    preferred_term: Triangular face
    term:
      id: HP:0000325
      label: Triangular face
  frequency: VERY_FREQUENT
  evidence:
  - reference: PMID:14757854
    reference_title: "Mulibrey nanism: clinical features and diagnostic criteria."
    supports: SUPPORT
    directness: DIRECT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      At the time of the diagnosis, characteristic craniofacial features of scaphocephaly, facial triangularity, high and broad forehead, and low nasal bridge were evident in over 90% of the patients.
    explanation: Names the craniofacial features and their frequency.
- category: Craniofacial
  name: Scaphocephaly
  description: Part of the craniofacial gestalt present in over 90% of patients.
  frequency: VERY_FREQUENT
  phenotype_term:
    preferred_term: Dolichocephaly
    term:
      id: HP:0000268
      label: Dolichocephaly
  evidence:
  - reference: PMID:14757854
    reference_title: "Mulibrey nanism: clinical features and diagnostic criteria."
    supports: SUPPORT
    directness: DIRECT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      At the time of the diagnosis, characteristic craniofacial features of scaphocephaly, facial triangularity, high and broad forehead, and low nasal bridge were evident in over 90% of the patients.
    explanation: >-
      Scaphocephaly is the clinical term for the long, narrow skull that HPO
      captures as dolichocephaly; the preferred_term keeps the source wording.
- category: Hepatic
  name: Hepatomegaly
  description: >-
    Present in 45% of the Finnish cohort at diagnosis, and mechanistically a
    consequence of raised venous pressure from pericardial constriction rather
    than a primary liver disease.
  frequency: FREQUENT
  phenotype_term:
    preferred_term: Hepatomegaly
    term:
      id: HP:0002240
      label: Hepatomegaly
  reports_on:
  - target: Pericardial Constriction
    relationship: READOUT_OF
  evidence:
  - reference: PMID:14757854
    reference_title: "Mulibrey nanism: clinical features and diagnostic criteria."
    supports: SUPPORT
    directness: DIRECT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Other findings included a peculiar high-pitched voice (96%), yellowish dots in ocular fundi (79%), cutaneous naevi flammei (65%), hepatomegaly (45%), and fibrous dysplasia of long bones (25%).
    explanation: Gives the frequency of hepatomegaly in the defining cohort.
- category: Ocular
  name: Yellowish dots in ocular fundi
  description: >-
    Present in 79% of patients; the histological correlate is focal choroidal
    hypoplasia with pigment disturbance.
  phenotype_term:
    preferred_term: Yellowish dots in ocular fundi
    term:
      id: HP:0000610
      label: Abnormal choroid morphology
  frequency: FREQUENT
  reports_on:
  - target: Mesodermal Ocular Involvement
    relationship: READOUT_OF
  evidence:
  - reference: PMID:14757854
    reference_title: "Mulibrey nanism: clinical features and diagnostic criteria."
    supports: SUPPORT
    directness: DIRECT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Other findings included a peculiar high-pitched voice (96%), yellowish dots in ocular fundi (79%), cutaneous naevi flammei (65%), hepatomegaly (45%), and fibrous dysplasia of long bones (25%).
    explanation: Gives the frequency of the fundus finding.
  notes: >-
    Rebound from HP:0007703 (Abnormal retinal pigmentation) to HP:0000610.
    The lesion this entry models is focal choroidal hypoplasia with
    overlying pigment disturbance, so the choroid term names the substrate
    while the retinal-pigmentation term named only the secondary change. The
    fundus dots themselves have no HPO term.
- category: Skeletal
  name: Fibrous dysplasia of long bones
  description: Present in 25% of the Finnish cohort.
  frequency: OCCASIONAL
  phenotype_term:
    preferred_term: Fibrous dysplasia of long bones
    term:
      id: HP:0010734
      label: Fibrous dysplasia of the bones
  evidence:
  - reference: PMID:14757854
    reference_title: "Mulibrey nanism: clinical features and diagnostic criteria."
    supports: SUPPORT
    directness: DIRECT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Other findings included a peculiar high-pitched voice (96%), yellowish dots in ocular fundi (79%), cutaneous naevi flammei (65%), hepatomegaly (45%), and fibrous dysplasia of long bones (25%).
    explanation: Gives the frequency of the skeletal lesion.
- category: Neurologic
  name: Mild muscular hypotonia
  description: >-
    Present in 68% of patients and, notably, the only neurological abnormality
    found in the defining cohort — despite "brain" appearing in the acronym.
  frequency: FREQUENT
  phenotype_term:
    preferred_term: Mild muscular hypotonicity
    term:
      id: HP:0001252
      label: Hypotonia
    severity: MILD
  evidence:
  - reference: PMID:14757854
    reference_title: "Mulibrey nanism: clinical features and diagnostic criteria."
    supports: SUPPORT
    directness: DIRECT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Mild muscular hypotonicity (68%) was the only neurological abnormality.
    explanation: >-
      Gives both the frequency and the important negative — no other
      neurological abnormality was found.
- category: Neoplastic
  name: Wilms tumor
  description: >-
    Nephroblastoma is the commonest malignancy. The original cloning paper put
    it at about 4% of patients; the later national cohort, which screened
    systematically, found five Wilms tumours among 15 malignancies in 89
    patients.
  phenotype_term:
    preferred_term: Nephroblastoma
    term:
      id: HP:0002667
      label: Nephroblastoma
  reports_on:
  - target: Disturbed Organ Architecture and Tumor Predisposition
    relationship: READOUT_OF
  evidence:
  - reference: PMID:10888877
    reference_title: Gene encoding a new RING-B-box-Coiled-coil protein is mutated in mulibrey nanism.
    supports: SUPPORT
    directness: DIRECT
    evidence_source: HUMAN_CLINICAL
    snippet: "About 4% of MUL patients develop Wilms' tumour."
    explanation: The original estimate of Wilms tumour risk in this disorder.
  - reference: PMID:19334051
    reference_title: High frequency of tumours in Mulibrey nanism.
    supports: SUPPORT
    directness: DIRECT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Fifteen malignancies occurred in 13 patients (15%), seven of them in the kidney (five Wilms' tumours), three in the thyroid gland, two gynaecological cancers, one gastrointestinal carcinoid tumour, one neuropituitary Langerhans cell histiocytosis and one case of acute lymphoblastic leukaemia (ALL).
    explanation: >-
      The systematically screened cohort, which gives the malignancy spectrum
      rather than Wilms tumour alone.
- category: Craniofacial
  name: High-pitched voice
  frequency: VERY_FREQUENT
  description: >-
    A peculiar high-pitched voice in 96% of the Finnish cohort. One of the
    more distinctive features of the disease clinically, and the
    highest-frequency finding outside growth failure and the craniofacial gestalt.
  phenotype_term:
    preferred_term: Peculiar high-pitched voice
    term:
      id: HP:0001620
      label: Abnormally high-pitched voice
  evidence:
  - reference: PMID:14757854
    reference_title: "Mulibrey nanism: clinical features and diagnostic criteria."
    supports: SUPPORT
    directness: DIRECT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Other findings included a peculiar high-pitched voice (96%), yellowish dots in ocular fundi (79%), cutaneous naevi flammei (65%), hepatomegaly (45%), and fibrous dysplasia of long bones (25%).
    explanation: >-
      Gives the 96% frequency. Banded VERY_FREQUENT rather than OBLIGATE
      because the figure is 96%, not 100%.
- category: Dermatologic
  name: Cutaneous naevi flammei
  frequency: FREQUENT
  description: >-
    Capillary malformations of the skin in 65% of the Finnish cohort.
    Consistent with the vascular abnormality seen elsewhere in the disease,
    where visceral lesions stain strongly for the endothelial markers CD34
    and CD31.
  phenotype_term:
    preferred_term: Cutaneous naevus flammeus
    term:
      id: HP:0001052
      label: Nevus flammeus
  evidence:
  - reference: PMID:14757854
    reference_title: "Mulibrey nanism: clinical features and diagnostic criteria."
    supports: SUPPORT
    directness: DIRECT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Other findings included a peculiar high-pitched voice (96%), yellowish dots in ocular fundi (79%), cutaneous naevi flammei (65%), hepatomegaly (45%), and fibrous dysplasia of long bones (25%).
    explanation: >-
      Gives the 65% frequency, which is the FREQUENT band.
- category: Growth
  name: Slender build
  frequency: VERY_FREQUENT
  description: >-
    Gracile habitus with thin extremities, described in practically all
    patients. Recorded because it is part of what makes the gestalt
    recognisable, alongside the craniofacial features and the growth
    deficit.
  phenotype_term:
    preferred_term: Gracile habitus with thin extremities
    term:
      id: HP:0001533
      label: Slender build
  evidence:
  - reference: PMID:14757854
    reference_title: "Mulibrey nanism: clinical features and diagnostic criteria."
    supports: SUPPORT
    directness: DIRECT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      In addition, practically all patients were gracile and had thin extremities.
    explanation: >-
      States the finding in practically all patients. Banded VERY_FREQUENT
      rather than OBLIGATE because "practically all" is not a counted
      proportion.
- category: Endocrine
  name: Hypoglycemia
  context: Children under 10 years
  frequency: FREQUENT
  description: >-
    Recorded in half of patients under 10 years old. It is the childhood end
    of the same glucose-handling abnormality that presents as insulin
    resistance and type 2 diabetes in adults.
  phenotype_term:
    preferred_term: Hypoglycemia
    term:
      id: HP:0001943
      label: Hypoglycemia
  evidence:
  - reference: PMID:35257621
    reference_title: "The Importance of Early Pericardiectomy in Mulibrey Nanism Syndrome, a Case Report."
    supports: SUPPORT
    directness: DIRECT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      In patients younger than 10 years old, hypoglycemia was recorded half of the time.
    explanation: >-
      Gives the proportion directly, for a single named finding in a stated
      age band.
  notes: >-
    Deliberately not linked to a pathophysiology node. The metabolic node in
    this entry is scoped to the late-emerging insulin-resistance arm, and no
    cited source connects the childhood hypoglycaemia to it or gives it a
    mechanism of its own. Recording the finding without inventing an edge is
    the honest option; the relationship between the two ends of the
    glucose-handling abnormality is not established in the literature cited
    here.
- category: Endocrine
  name: Insulin resistance
  description: >-
    A strong tendency to insulin resistance is part of how the disease is
    characterised in the largest growth cohort, and it is the metabolic axis
    underlying the type 2 diabetes seen later.
  phenotype_term:
    preferred_term: Insulin resistance
    term:
      id: HP:0000855
      label: Insulin resistance
  reports_on:
  - target: Gonadal Failure and Insulin Resistance
    relationship: READOUT_OF
  evidence:
  - reference: PMID:17548484
    reference_title: "Growth and growth hormone therapy in subjects with mulibrey nanism."
    supports: SUPPORT
    directness: DIRECT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Mulibrey nanism is a monogenic disorder with prenatal-onset growth restriction, mild dysmorphic features, and a strong tendency for insulin resistance but no major neurologic handicap.
    explanation: >-
      Names insulin resistance as a defining feature of the disorder. No
      frequency is recorded: the paper characterises the tendency without
      giving a proportion.
  - reference: PMID:35257621
    reference_title: "The Importance of Early Pericardiectomy in Mulibrey Nanism Syndrome, a Case Report."
    supports: SUPPORT
    directness: INDIRECT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Up to 70% of patients with MUL develop metabolic syndrome.
    explanation: >-
      The scale of the metabolic axis this phenotype sits on. Graded INDIRECT
      because metabolic syndrome is a composite endpoint of which insulin
      resistance is one component, so the figure bears on this phenotype
      without counting it.
  notes: >-
    Deliberately left unbanded. The two proportions the sources give are both
    for something wider than insulin resistance itself — 70% for metabolic
    syndrome, a composite diagnosis, and 92% for impaired glucose tolerance or
    type 2 diabetes taken together. Banding this phenotype from either would
    put a number on a narrower finding than the one that was counted. HP has
    no metabolic syndrome term, so the composite cannot be curated as a
    phenotype in its own right either.
- category: Endocrine
  name: Type 2 diabetes mellitus
  description: >-
    Early-onset type 2 diabetes, the clinical endpoint of the
    insulin-resistance axis. It emerges in adolescence or adulthood rather than in
    the childhood presentation, which is why it is absent from the
    diagnostic-criteria cohort.
  phenotype_term:
    preferred_term: Early-onset type 2 diabetes mellitus
    term:
      id: HP:0005978
      label: Type II diabetes mellitus
  evidence:
  - reference: PMID:28432469
    reference_title: "Renal findings in patients with Mulibrey nanism."
    supports: SUPPORT
    directness: DIRECT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      MUL affects multiple organs, leading to growth retardation and early onset type 2 diabetes.
    explanation: >-
      States early-onset type 2 diabetes as a consequence of the multi-organ
      involvement, in a 101-patient national cohort.
  - reference: PMID:35257621
    reference_title: "The Importance of Early Pericardiectomy in Mulibrey Nanism Syndrome, a Case Report."
    supports: SUPPORT
    directness: INDIRECT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      In contrast, at >20 years old 92% of patients had either impaired glucose tolerance or type 2 diabetes mellitus.
    explanation: >-
      Establishes that dysglycaemia is close to universal in adults. Graded
      INDIRECT because the 92% counts impaired glucose tolerance and type 2
      diabetes together, so it does not measure this phenotype on its own.
  notes: >-
    Deliberately left unbanded. The only adult proportion available counts
    impaired glucose tolerance and type 2 diabetes as one endpoint, and the
    split between them is not reported. Banding this phenotype VERY_FREQUENT
    from that figure would assert diabetes in 92% of adults, which the source
    does not say. The age condition would also have to be carried in context,
    since the figure is for patients over 20.
- category: Endocrine
  name: Hypergonadotropic hypogonadism
  context: Adult males
  frequency: OBLIGATE
  description: >-
    Progressive testicular failure with small testes, raised FSH and LH and
    low inhibin B, in every adult male studied. Note the timing: puberty
    starts spontaneously at a normal age and the axis behaves normally to
    midpuberty, after which virilization slows and gonadotropins climb. This
    is not delayed puberty.
  phenotype_term:
    preferred_term: Progressive hypergonadotropic testicular failure
    term:
      id: HP:0000815
      label: Hypergonadotropic hypogonadism
  evidence:
  - reference: PMID:21865362
    reference_title: "Testicular failure and male infertility in the monogenic Mulibrey nanism disorder."
    supports: SUPPORT
    directness: DIRECT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      All adult MUL males have a unique disorder of testicular function with small testes, elevated FSH and LH, and low inhibin B.
    explanation: >-
      The conclusion of the 28-male national cohort. OBLIGATE because the
      finding was present in all adult males studied.
  - reference: PMID:21865362
    reference_title: "Testicular failure and male infertility in the monogenic Mulibrey nanism disorder."
    supports: SUPPORT
    directness: DIRECT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Puberty started spontaneously at a median age of 12.6 yr (range, 11.1-15.0), and FSH, LH, T, and inhibin B levels increased adequately until midpuberty.
    explanation: >-
      Establishes the timing, and is the reason this is curated as
      hypergonadotropic failure rather than as delayed puberty: pubertal
      onset is spontaneous and at a normal median age of 12.6 years.
- category: Endocrine
  name: Azoospermia or severe oligoasthenozoospermia
  context: Adult males
  frequency: OBLIGATE
  description: >-
    Every semen sample in the male national cohort was severely abnormal,
    and no patient had a history of spontaneous fertility. The paper
    describes TRIM37 as a novel monogenic cause of male infertility.
  phenotype_term:
    preferred_term: Azoospermia or severe oligoasthenozoospermia
    term:
      id: HP:0000027
      label: Azoospermia
  reports_on:
  - target: Gonadal Failure and Insulin Resistance
    relationship: READOUT_OF
  evidence:
  - reference: PMID:21865362
    reference_title: "Testicular failure and male infertility in the monogenic Mulibrey nanism disorder."
    supports: SUPPORT
    directness: DIRECT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      All semen samples showed severe oligoasthenozoospermia or azoospermia.
    explanation: >-
      States the semen finding in all samples.
  notes: >-
    Bound to HP:0000027 because HPO has no term spanning azoospermia and
    severe oligoasthenozoospermia together; the preferred_term carries the
    range the source actually reports.
- category: Neoplastic
  name: Ovarian sex cord-stromal tumor
  context: Females
  frequency: FREQUENT
  description: >-
    Benign mesenchymal tumours of ovarian sex cord-stromal origin, chiefly
    of the fibrothecoma group, in more than half of female patients.
    Epithelial neoplasia occurred in a further 18%, including one poorly
    differentiated ovarian adenocarcinoma and one endometrial
    adenocarcinoma.
  phenotype_term:
    preferred_term: Ovarian fibrothecoma-group tumour
    term:
      id: HP:0031918
      label: Ovarian sex cord-stromal tumor
  reports_on:
  - target: Gonadal Failure and Insulin Resistance
    relationship: READOUT_OF
  evidence:
  - reference: PMID:19329943
    reference_title: "Gynecological tumors in Mulibrey nanism and role for RING finger protein TRIM37 in the pathogenesis of ovarian fibrothecomas."
    supports: SUPPORT
    directness: DIRECT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      More than half of female patients with Mulibrey nanism develop benign mesenchymal tumors of ovarian sex cord-stromal origin.
    explanation: >-
      Gives the more-than-half figure in female patients, which is the
      FREQUENT band. This is a sex-limited finding, recorded in context
      rather than as a disease-wide frequency.
- category: Hepatic
  name: Hepatic steatosis
  context: Adolescents and adults
  frequency: VERY_FREQUENT
  description: >-
    Fatty liver. Reported in every adolescent and adult patient in a clinical
    review of the disease's organ involvement, and reproduced in the
    Trim37-null mouse.
  phenotype_term:
    preferred_term: Fatty liver
    term:
      id: HP:0001397
      label: Hepatic steatosis
  evidence:
  - reference: PMID:35257621
    reference_title: "The Importance of Early Pericardiectomy in Mulibrey Nanism Syndrome, a Case Report."
    supports: SUPPORT
    directness: DIRECT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Fatty liver is seen in all adults and adolescents.
    explanation: >-
      The human observation, from the case report's review of hepatic
      involvement in this disease.
  - reference: PMID:27044324
    reference_title: "Trim37-deficient mice recapitulate several features of the multi-organ disorder Mulibrey nanism."
    supports: SUPPORT
    directness: INDIRECT
    evidence_source: MODEL_ORGANISM
    snippet: >-
      At 1.5 years Trim37(-/-) mice showed non-compaction cardiomyopathy, hepatomegaly, fatty liver and various tumors.
    explanation: >-
      The finding in the knockout mouse at 1.5 years. Graded MODEL_ORGANISM
      and INDIRECT because this is the only source in this entry reporting
      steatosis and it is not a human observation.
  notes: >-
    Banded VERY_FREQUENT rather than OBLIGATE because "all adults and
    adolescents" is a narrative review's summary rather than a counted
    proportion, and it is asserted for adolescents and adults only — hence
    the context slot rather than a disease-wide band. The mouse item is kept
    alongside the human one because the model reproduces this phenotype,
    which is part of why it was proposed as a system for studying the
    disease.
prevalence:
- population: Finland
  measure_type: CASES_IN_LITERATURE
  prevalence_class: ULTRA_RARE
  notes: >-
    Enriched in Finland by a founder effect and rare elsewhere. The national
    Finnish cohorts number 85 patients (2004) and 89 patients (2009).
  evidence:
  - reference: PMID:10888877
    reference_title: Gene encoding a new RING-B-box-Coiled-coil protein is mutated in mulibrey nanism.
    supports: SUPPORT
    directness: DIRECT
    evidence_source: HUMAN_CLINICAL
    snippet: "MUL is enriched in the Finnish population, but is rare elsewhere."
    explanation: States the Finnish enrichment and rarity elsewhere.
  - reference: PMID:19334051
    reference_title: High frequency of tumours in Mulibrey nanism.
    supports: SUPPORT
    directness: DIRECT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      In this work, the frequency and pathology of malignant and benign tumours were analysed in a national cohort of 89 Finnish MUL patients aged 0.7-76 years.
    explanation: >-
      Gives the size of the national cohort, which is the practical bound on how
      many molecularly confirmed patients exist in Finland.
progression:
- phase: Infancy
  notes: >-
    Feeding difficulties and respiratory tract infections dominate infancy.
    Cardiac manifestations are already detectable in a minority.
  evidence:
  - reference: PMID:14757854
    reference_title: "Mulibrey nanism: clinical features and diagnostic criteria."
    supports: SUPPORT
    directness: DIRECT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      In infancy, feeding difficulties, and respiratory tract infections were the most common problems.
    explanation: Characterises the infantile presentation.
- phase: Time of diagnosis
  notes: >-
    Diagnosis spans a very wide age range with a median of about two years, and
    the craniofacial gestalt plus growth failure are what make the diagnosis;
    organ manifestations are variable at this stage.
  evidence:
  - reference: PMID:14757854
    reference_title: "Mulibrey nanism: clinical features and diagnostic criteria."
    supports: SUPPORT
    directness: DIRECT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Mulibrey nanism (MUL) is an autosomal recessive disease caused by mutations in the TRIM37 gene
      encoding the peroxisomal TRIM37 protein of unknown function. In this work, we analysed the
      clinical characteristics of 85 Finnish patients with MUL, most of whom were homozygous for the
      Finn major mutation of TRIM37. The patients' hospital records from birth to the time of the
      diagnosis at age 0.02-52 years (median 2.1 years) were retrospectively analysed. ... The
      clinical features of the Finnish patients with MUL formed a distinct entity. The most
      consistent findings were growth failure and characteristic craniofacial features. However,
      organ manifestations varied considerably in early childhood. Based on these findings, we
      propose new diagnostic criteria for MUL.
    explanation: >-
      Connects diagnostic timing to Mulibrey nanism and the characteristic growth/craniofacial
      findings used in proposed diagnostic criteria, while retaining variability in organ
      involvement.
  - reference: PMID:14757854
    reference_title: "Mulibrey nanism: clinical features and diagnostic criteria."
    supports: SUPPORT
    directness: DIRECT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      The most consistent findings were growth failure and characteristic craniofacial features. However, organ manifestations varied considerably in early childhood.
    explanation: >-
      States which features are reliable for diagnosis and which are variable at
      this stage.
- phase: Later childhood and adult life
  notes: >-
    Tumour surveillance becomes the dominant long-term concern: the national
    cohort spanned ages 0.7 to 76 years and found lesions in three quarters of
    patients.
  evidence:
  - reference: PMID:19334051
    reference_title: High frequency of tumours in Mulibrey nanism.
    supports: SUPPORT
    directness: DIRECT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      A total of 210 tumorous lesions were detected in 66/89 patients (74%).
    explanation: >-
      Establishes the lifetime tumour burden that motivates long-term
      surveillance.
histopathology:
- name: Peliosis, vascularised cysts and nodular lesions
  description: >-
    The visceral lesion the disease produces, seen on imaging and confirmed
    histologically: strongly dilated blood vessels, vascularised cysts and
    nodular lesions across liver and other organs. Vascular rather than
    epithelial, which is what distinguishes the benign tumour burden here
    from ordinary adenomatous disease.
  evidence:
  - reference: PMID:19334051
    reference_title: High frequency of tumours in Mulibrey nanism.
    supports: SUPPORT
    directness: DIRECT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Tumours detected by radiology in the liver and other organs mainly comprised strongly dilated blood vessels (peliosis), vascularized cysts and nodular lesions.
    explanation: >-
      Describes the composition of the benign lesions.
  - reference: PMID:19334051
    reference_title: High frequency of tumours in Mulibrey nanism.
    supports: SUPPORT
    directness: DIRECT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      The lesions showed strong expression of the endothelial cell markers CD34 and CD31 as well as the myocyte marker alpha-smooth muscle actin (alpha-SMA).
    explanation: >-
      The immunohistochemistry, which is what establishes the lesions as
      endothelial and smooth-muscle rather than epithelial.
- name: Pericardial fibrosis
  description: >-
    Extensive fibrosis of the pericardium, found in nearly every diseased
    pericardium examined. This is the tissue-level finding underlying
    constrictive pericarditis, the manifestation that determines outcome in
    this disease.
  finding_term:
    preferred_term: Extensive pericardial fibrosis
    term:
      id: NCIT:C3044
      label: Fibrosis
  evidence:
  - reference: PMID:35257621
    reference_title: "The Importance of Early Pericardiectomy in Mulibrey Nanism Syndrome, a Case Report."
    supports: SUPPORT
    directness: DIRECT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Microscopic analysis of diseased pericardium almost invariably shows extensive fibrosis.
    explanation: >-
      States the histological finding and that it is near-invariable in
      affected pericardium.
  notes: >-
    This finding is the observation the pericardial_fibrosis_mechanism_unknown
    discussion is about: the fibrosis is established histologically, while
    nothing in the cited literature connects it to TRIM37 loss upstream.

diagnosis:
- name: Clinical diagnostic criteria
  description: >-
    Diagnosis rests on the clinical gestalt — growth failure plus the
    craniofacial features — with the organ manifestations variable at
    presentation. The defining cohort proposed formal criteria on that
    basis.
  diagnosis_term:
    preferred_term: clinical evaluation against Mulibrey nanism diagnostic criteria
    term:
      id: NCIT:C124351
      label: Clinical Evaluation
  results: >-
    Prenatal-onset growth failure without catch-up, plus scaphocephaly,
    facial triangularity, high broad forehead and low nasal bridge.
  evidence:
  - reference: PMID:14757854
    reference_title: "Mulibrey nanism: clinical features and diagnostic criteria."
    supports: SUPPORT
    directness: DIRECT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Based on these findings, we propose new diagnostic criteria for MUL.
    explanation: >-
      The paper's own statement that it proposes diagnostic criteria.
  - reference: PMID:14757854
    reference_title: "Mulibrey nanism: clinical features and diagnostic criteria."
    supports: SUPPORT
    directness: DIRECT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      At the time of the diagnosis, characteristic craniofacial features of scaphocephaly, facial triangularity, high and broad forehead, and low nasal bridge were evident in over 90% of the patients.
    explanation: >-
      The craniofacial component, present in over 90% at diagnosis, which is
      the most consistent finding after growth failure.
  notes: >-
    The criteria themselves are not reproduced here: the cached record is
    the abstract, which states that criteria were proposed without listing
    them. What is curated is the evidence base the criteria rest on, not the
    criteria.
- name: TRIM37 molecular genetic testing
  description: >-
    Confirmatory testing. Twenty-three disease-associated TRIM37 variants
    were known at the time of the mouse paper, with a Finnish founder allele
    accounting for most Finnish cases.
  diagnosis_term:
    preferred_term: TRIM37 sequence analysis
    term:
      id: NCIT:C15709
      label: Genetic Testing
  results: Biallelic loss-of-function TRIM37 variants.
treatments:
- name: Pericardiectomy
  description: >-
    Surgical decompression of the constricted pericardium is the definitive
    treatment for the cardiac manifestation that dominates outcome. It addresses
    the mechanical consequence of the pericardial lesion, not its cause.
  treatment_term:
    preferred_term: pericardiectomy
    term:
      id: NCIT:C51643
      label: Pericardiectomy
  therapeutic_modality: SURGERY
  target_mechanisms:
  - target: Pericardial Constriction
    description: >-
      Removing the constricting pericardium restores diastolic filling and
      relieves the raised venous pressure that causes hepatomegaly and
      congestive failure.
  evidence:
  - reference: PMID:35257621
    reference_title: "The Importance of Early Pericardiectomy in Mulibrey Nanism Syndrome, a Case Report."
    supports: SUPPORT
    directness: INDIRECT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      We present a case of a patient with Mulibrey nanism syndrome who underwent pericardiectomy at 12 years old and was able to live 44 years more with relatively stable and asymptomatic diastolic congestive heart failure (CHF).
    explanation: >-
      The operation's effect in this disease, from the oldest reported case:
      pericardiectomy at 12 followed by 44 further years with stable,
      asymptomatic diastolic heart failure. Graded INDIRECT because a single
      uncontrolled case cannot establish that the survival followed from the
      operation.
  - reference: PMID:35257621
    reference_title: "The Importance of Early Pericardiectomy in Mulibrey Nanism Syndrome, a Case Report."
    supports: SUPPORT
    directness: DIRECT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Constrictive pericarditis and diastolic dysfunction are the most common causes of mortality.
    explanation: >-
      States why the operation matters: constrictive pericarditis and
      diastolic dysfunction are the commonest causes of death in this
      disease.
  notes: >-
    The evidence here is one case report and is graded accordingly. No
    controlled or cohort comparison of operated against unoperated Mulibrey
    patients exists, so the size of the survival benefit is unknown even
    though the indication is not in doubt.
- name: Recombinant human growth hormone therapy
  description: >-
    Growth hormone given for the prenatal-onset growth failure, evaluated
    over a median of 5.7 years in 30 of 72 subjects followed to 30 years —
    the only long-term treatment evaluation in this disease.
  treatment_term:
    preferred_term: Pharmacotherapy
    term:
      id: NCIT:C15986
      label: Pharmacotherapy
    therapeutic_agent:
    - preferred_term: recombinant human growth hormone
      term:
        id: NCIT:C837
        label: Somatropin
  therapeutic_modality: PEPTIDE
  target_mechanisms:
  - target: Prenatal-Onset Growth Failure
    description: >-
      Acts on the growth deficit symptomatically. It does not address the
      TRIM37 lesion and, on the cohort's own numbers, does not restore
      normal stature.
  evidence:
  - reference: PMID:17548484
    reference_title: "Growth and growth hormone therapy in subjects with mulibrey nanism."
    supports: SUPPORT
    directness: DIRECT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Growth hormone treatment improved the prepubertal growth but had only little impact on adult height (+5 cm).
    explanation: >-
      The result, stated as the authors state it: prepubertal growth
      improved, adult height by about 5 cm. This is the honest headline and
      it is a modest one.
  - reference: PMID:17548484
    reference_title: "Growth and growth hormone therapy in subjects with mulibrey nanism."
    supports: SUPPORT
    directness: DIRECT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      The final adult height averaged 136 cm in girls and 150 cm in boys.
    explanation: >-
      The untreated final heights, which is the baseline the 5 cm is
      measured against.
  - reference: PMID:17548484
    reference_title: "Growth and growth hormone therapy in subjects with mulibrey nanism."
    supports: SUPPORT
    directness: DIRECT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      On the contrary, the subjects who were treated with growth hormone were slimmer and had less metabolic syndrome as young adults.
    explanation: >-
      The unexpected metabolic result. Growth hormone raises insulin
      resistance in other settings, so the concern here was that it would
      worsen the disease's own metabolic tendency; the treated subjects were
      slimmer and had less metabolic syndrome instead.
  notes: >-
    Non-randomised: the 30 treated subjects were not allocated, so the
    metabolic finding in particular could reflect who was selected for
    treatment rather than an effect of it. Recorded because a
    counterintuitive safety result is worth having, not because the
    comparison is controlled.
- name: Tumour surveillance
  description: >-
    Periodic imaging and clinical review for the tumours that occur in most
    patients. Wilms tumour in childhood is the reason surveillance starts
    early; ovarian sex cord-stromal tumours in adult women and the wider
    benign vascular and adenomatous burden are why it continues.
  treatment_term:
    preferred_term: tumour surveillance imaging and clinical review
    term:
      id: NCIT:C15406
      label: Cancer Screening
  target_mechanisms:
  - target: Disturbed Organ Architecture and Tumor Predisposition
    description: >-
      Detects the consequence rather than modifying the mechanism.
      Surveillance does not reduce tumour incidence; it changes the stage at
      which tumours are found.
  evidence:
  - reference: PMID:19334051
    reference_title: High frequency of tumours in Mulibrey nanism.
    supports: SUPPORT
    directness: DIRECT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Fifteen malignancies occurred in 13 patients (15%), seven of them in the kidney (five Wilms' tumours), three in the thyroid gland, two gynaecological cancers, one gastrointestinal carcinoid tumour, one neuropituitary Langerhans cell histiocytosis and one case of acute lymphoblastic leukaemia (ALL).
    explanation: >-
      The malignancy burden that surveillance is directed at: 15
      malignancies in 13 of 89 patients, across kidney, thyroid,
      gynaecological and haematological sites.
  - reference: PMID:19329943
    reference_title: "Gynecological tumors in Mulibrey nanism and role for RING finger protein TRIM37 in the pathogenesis of ovarian fibrothecomas."
    supports: SUPPORT
    directness: DIRECT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      More than half of female patients with Mulibrey nanism develop benign mesenchymal tumors of ovarian sex cord-stromal origin.
    explanation: >-
      The adult female component, which is what extends surveillance beyond
      the childhood Wilms tumour window.
  notes: >-
    No published surveillance protocol for Mulibrey nanism appears in any
    source cited here — no interval, no modality, no evidence that
    surveillance changes outcome in this disease. The treatment is curated
    because the tumour burden is documented and unmanaged risk of that size
    is itself a finding, but the evidence attached establishes the risk and
    not the intervention. Do not read the presence of this entry as a
    recommendation.
animal_models:
- name: Trim37 knockout mouse
  species: Mouse
  genotype: Trim37(-/-) congenic knock-out
  description: >-
    The only reported animal model. It reproduces the infertility, the
    cardiomyopathy, the fatty liver and the tumour predisposition, and
    reproduces none of the growth failure that names the disease.
  publication: PMID:27044324
  modeled_mechanisms:
  - target: Gonadal Failure and Insulin Resistance
    relationship: RECAPITULATES
    fidelity: MODERATE
    model_scale: ORGANISM
    description: >-
      Infertility in both sexes with germ cell aplasia and Leydig cell
      hyperplasia, raised FSH and LH with preserved testosterone, and raised
      fasting glucose. The most consistent phenotype in the model.
    limitations: >-
      The glycaemic abnormality runs the other way from the human one: the
      mouse has raised fasting glucose with LOW fasting insulin, whereas
      patients are described as insulin resistant. Testosterone is
      maintained in the mouse and levels off in patients. And the model is
      not a model of the human sex difference — female patients develop
      ovarian sex cord-stromal tumours, which the paper does not report.
    evidence:
    - reference: PMID:27044324
      reference_title: "Trim37-deficient mice recapitulate several features of the multi-organ disorder Mulibrey nanism."
      supports: SUPPORT
      directness: DIRECT
      evidence_source: MODEL_ORGANISM
      snippet: >-
        Both male and female Trim37(-/-) mice were infertile, the gonads showing germ cell aplasia, hilus and Leydig cell hyperplasia and accumulation of lipids in and around Leydig cells.
      explanation: >-
        The gonadal phenotype with its histology, in both sexes.
    - reference: PMID:27044324
      reference_title: "Trim37-deficient mice recapitulate several features of the multi-organ disorder Mulibrey nanism."
      supports: SUPPORT
      directness: DIRECT
      evidence_source: MODEL_ORGANISM
      snippet: >-
        Six-month-old Trim37(-/-) mice had elevated fasting blood glucose and low fasting serum insulin levels.
      explanation: >-
        The metabolic phenotype, with the direction of the insulin
        abnormality that the limitations record.
  - target: Prenatal-Onset Growth Failure
    relationship: FAILS_TO_RECAPITULATE
    fidelity: LOW
    model_scale: ORGANISM
    description: >-
      The model does not reproduce the defining feature of the disease.
      Weight development is normal to about 12 months and long-bone length
      does not differ from wild-type; only skull size is reduced.
    limitations: >-
      This is a negative result about the model, not about the disease. It
      means the growth arm of Mulibrey nanism currently has no experimental
      system at all, and any mechanism proposed for it cannot be tested in
      this mouse.
    evidence:
    - reference: PMID:27044324
      reference_title: "Trim37-deficient mice recapitulate several features of the multi-organ disorder Mulibrey nanism."
      supports: SUPPORT
      directness: DIRECT
      evidence_source: MODEL_ORGANISM
      snippet: >-
        Trim37(-/-) mice were viable and had normal weight development until approximately 12 months of age, after which they started to manifest increasing problems in wellbeing and weight loss.
      explanation: >-
        Normal weight development for the first year, against severe
        prenatal-onset failure in patients.
    - reference: PMID:27044324
      reference_title: "Trim37-deficient mice recapitulate several features of the multi-organ disorder Mulibrey nanism."
      supports: SUPPORT
      directness: DIRECT
      evidence_source: MODEL_ORGANISM
      snippet: >-
        Assessment of skeletal parameters with computer tomography revealed significantly smaller skull size, but no difference in the lengths of long bones in Trim37(-/-) mice as compared with wild-type.
      explanation: >-
        The skeletal detail: reduced skull size but unchanged long bones, so
        the craniofacial arm is reproduced and the linear-growth arm is not.
  - target: Peroxisomal TRIM37 Depletion
    relationship: FAILS_TO_RECAPITULATE
    fidelity: LOW
    model_scale: CELLULAR
    description: >-
      Liver peroxisome number and morphology are normal in the null mouse,
      which is the same negative that patient fibroblasts give.
    limitations: >-
      Morphology is not function: normal peroxisome number and appearance do
      not exclude a metabolic defect that was not assayed. The result is
      recorded as a failure to reproduce a peroxisomal phenotype, not as
      proof that peroxisomal function is intact.
    evidence:
    - reference: PMID:27044324
      reference_title: "Trim37-deficient mice recapitulate several features of the multi-organ disorder Mulibrey nanism."
      supports: SUPPORT
      directness: DIRECT
      evidence_source: MODEL_ORGANISM
      snippet: >-
        The amount and morphology of liver peroxisomes seemed normal in Trim37(-/-) mice.
      explanation: >-
        The negative peroxisomal result in the model, independent of the
        human fibroblast result the entry already cites for the same claim.
  evidence:
  - reference: PMID:27044324
    reference_title: "Trim37-deficient mice recapitulate several features of the multi-organ disorder Mulibrey nanism."
    supports: SUPPORT
    directness: DIRECT
    evidence_source: MODEL_ORGANISM
    snippet: >-
      Trim37(-/-) mice recapitulate several features of the human MUL disease and thus provide a good model to study disease pathogenesis related to TRIM37 deficiency, including infertility, non-alcoholic fatty liver disease, cardiomyopathy and tumorigenesis.
    explanation: >-
      The authors' own statement of what the model is for, which is the
      scope of every link above.
discussions:
- discussion_id: peroxisomal_classification_unsupported
  kind: KNOWLEDGE_GAP
  attaches_to:
  - pathophysiology#Peroxisomal TRIM37 Depletion
  prompt: >-
    Does loss of peroxisomal TRIM37 produce any measurable peroxisomal
    dysfunction in patients, or is the peroxisomal localisation incidental to
    the disease mechanism?
  rationale: >-
    Mulibrey nanism was classified as a peroxisomal disorder on the strength of
    TRIM37's localisation, and that classification has propagated widely. But
    the same paper reported that patient fibroblasts stain normally for both
    peroxisomal matrix and membrane markers, i.e. biogenesis appears intact, and
    no study has demonstrated the biochemical signature of a peroxisomal
    disorder — raised very-long-chain fatty acids, reduced plasmalogens — in
    Mulibrey nanism patients. Secondary sources routinely present the
    peroxisomal chain as if it were established; it is a localisation result
    plus an inference. Resolving this matters because it decides whether
    peroxisomal metabolites are useful biomarkers here at all.
- discussion_id: pericardial_fibrosis_mechanism_unknown
  kind: KNOWLEDGE_GAP
  attaches_to:
  - pathophysiology#Pericardial Constriction
  prompt: >-
    By what route does TRIM37 loss cause pericardial fibrosis and constriction?
  rationale: >-
    Pericardial constriction is the feature that determines survival and the
    main indication for surgery, yet no mechanism connects it to the TRIM37
    lesion. Neither the peroxisomal model nor the centrosomal/mitotic model
    predicts a fibrotic pericardium specifically, and no animal or cellular
    model of the pericardial phenotype has been reported. This is the largest
    single gap in the entry: the clinically dominant manifestation has no
    upstream edge that can be evidenced.
- discussion_id: centrosomal_mechanism_not_shown_in_patients
  kind: HUMAN_MODEL_MISMATCH
  attaches_to:
  - pathophysiology#Centrosomal Ubiquitin Ligase Deficiency
  prompt: >-
    Does the TRIM37-PLK4 centrosomal mechanism, established in RPE1 and cancer
    cell lines, operate in the tissues affected in Mulibrey nanism?
  rationale: >-
    The centrosomal work is the most mechanistically satisfying account of
    TRIM37 and is the one that plausibly explains both disturbed organ
    architecture and tumour predisposition. But it was done to explain a
    cancer-specific therapeutic vulnerability, in immortalised and transformed
    cell lines, and the cancer-relevant direction is TRIM37 amplification and
    over-expression, whereas Mulibrey nanism is loss of function. The
    loss-of-function arm was studied, so the direction is covered, but nothing
    has been shown in patient-derived cells or in a TRIM37-null organism with
    the human phenotype. Every edge in this entry that depends on this mechanism
    is therefore graded INDIRECT.
📚

References & Deep Research

Deep Research

1

Deep research results are used as seeds for research; they do not undergo the same validation as the main records and may contain errors. How we use deep research.

Evaluations and curation notes (3)

Record notes

Gene identity was checked against HGNC directly rather than taken from the deep-research report: TRIM37 is hgnc:7523 (tripartite motif containing 37, 17q22). The Perplexity report used for this entry asserted "HGNC:16287", which is NFU1, an unrelated iron-sulfur cluster scaffold gene. See the PR and the history record for the other citation defects found in that report.

Review round 1: phenotypes 10 to 19, endocrine axis, treatments, Trim37 knockout mouse · 2026-09-09T00:42:46Z · View source

Addressed the round-1 REQUEST_CHANGES review on PR #11442. Phenotypes went from 10 to 19, and every existing phenotype that had a quoted percentage now carries the matching frequency band. Finding 1, the two omitted features from the sentence the entry already quoted: high-pitched voice (HP:0001620, 96 percent, VERY_FREQUENT) and cutaneous naevi flammei (HP:0001052, 65 percent, FREQUENT). Also added slender build (HP:0001533) from the same abstract's gracile-habitus sentence. Finding 2, the frequency band error: yellowish dots in ocular fundi carried "Very frequent (99-80%)" against its own snippet's 79 percent. Corrected to FREQUENT. All three free-text band strings were converted to enum keys at the same time, per the reviewer's separate suggestion, and the reviewer was right that the schema's any_of makes the free-text form validate without anyone checking the band. Finding 5, frequencies lifted from snippets into the slot: scaphocephaly VERY_FREQUENT, mild muscular hypotonia FREQUENT, hepatomegaly FREQUENT, fibrous dysplasia OCCASIONAL, congestive heart failure OCCASIONAL, constrictive pericarditis OCCASIONAL. Finding 3, the endocrine and metabolic axis. Rather than curate it from the deep-research report's summary, fetched five new references: PMID:17548484 (growth and growth hormone therapy), PMID:21865362 (testicular failure and male infertility), PMID:19329943 (gynaecological tumours), PMID:27044324 (the Trim37 knockout mouse) and PMID:28432469 (renal findings), plus PMID:35257621 for the pericardiectomy evidence. The reviewer suggested delayed puberty (HP:0000823) and hypogonadism (HP:0000135) for the sexual-maturation failure. Neither is what the primary source describes. In the 28-male national cohort puberty starts spontaneously at a normal median age of 12.6 years and the axis behaves normally to midpuberty; what follows is progressive hypergonadotropic testicular failure. Curated as HP:0000815 with the timing quoted as a second evidence item so the distinction is visible. Azoospermia or severe oligoasthenozoospermia (HP:0000027) added alongside, and ovarian sex cord-stromal tumour (HP:0031918) as the female counterpart, both with context set because they are sex-limited. Insulin resistance (HP:0000855) and type 2 diabetes (HP:0005978) complete the axis. A new pathophysiology node, Gonadal Failure and Insulin Resistance, carries the axis in the pathograph, downstream of TRIM37 Loss of Function with unknown intermediates. Its notes record that the mouse and human metabolic phenotypes differ in the direction of the insulin abnormality: the mouse has raised fasting glucose with LOW fasting insulin, patients are described as insulin resistant. Finding 4, treatments. The report was truncated before its treatment section, so the gap was filled from newly fetched literature rather than declared out of scope. Growth hormone therapy added with the honest result: prepubertal growth improved, adult height by about 5 cm, and the counterintuitive finding that treated subjects had less metabolic syndrome, with a note that the comparison is not randomised. Tumour surveillance added with an explicit note that no published protocol for this disease exists in any cited source, so the evidence establishes the risk and not the intervention. Pericardiectomy gained the evidence its own notes said a curator should attach: PMID:35257621, pericardiectomy at 12 with 44 further years, graded INDIRECT as a single uncontrolled case. Orphan pathograph components, the reviewer's first suggestion: Prenatal-Onset Growth Failure and Mesodermal Ocular Involvement are now downstream of TRIM37 Loss of Function, both typed INDIRECT_UNKNOWN_INTERMEDIATES. The growth edge carries two REFUTE items from the mouse, which has normal weight development for its first year and no long-bone length difference, so the model does not reproduce the defining feature of the disease. A reports_on link was added on the prenatal growth failure phenotype. An animal_models section was added for the Trim37 knockout mouse with three links: RECAPITULATES the gonadal and metabolic node, FAILS_TO_RECAPITULATE the growth failure, and FAILS_TO_RECAPITULATE the peroxisomal node, the last of which independently corroborates the entry's existing REFUTE on the peroxisomal-disorder classification from human fibroblasts. Also added: a histopathology section for the peliosis, vascularised cysts and CD34/CD31/alpha-SMA immunohistochemistry, and a diagnosis section covering the clinical criteria and TRIM37 testing. The ocular phenotype was rebound from HP:0007703 (Abnormal retinal pigmentation) to HP:0000610 (Abnormal choroid morphology) per the reviewer's suggestion, since the entry models a choroidal lesion, and the ocular node gained a choroid location binding. Two errors of mine caught by the validators in this round, both wrong NCIT identifiers I guessed rather than looked up: NCIT:C1618 for recombinant growth hormone is actually BAGE Tumor Antigen (correct: NCIT:C837 Somatropin), and NCIT:C25218 is the enum root and not a permissible value (replaced with NCIT:C15406 Cancer Screening). This is the same failure class the entry's own notes criticise the research report for. Validation: linkml-validate clean; linkml-term-validator --labels passed; 70/70 snippets verified against the cache, up from 37/37; model-scale-audit --strict clean; offline gates clean.

Create: Mulibrey Nanism (MONDO:0009664, TRIM37) · 2026-09-08T08:14:00Z · View source

Curated de novo from a Perplexity sonar-deep-research report (research/Mulibrey_Nanism-deep-research-perplexity.md). Every claim was re-derived from the cached PubMed abstract rather than from the report: 37 snippets, all verified by dismech.reference_snippet_audit against references_cache/. The report required substantial correction before use. Four identifier/attribution defects were found in it: (1) it cited PMID:12045473 as Kallijarvi's TRIM37 peroxisome localisation study -- that PMID is an acamprosate/NMDA rat hippocampal slice paper; the correct reference is PMID:11938494. (2) It cited 'PMID:10788545 (implied from context)' as Avela's positional cloning paper -- that PMID is a dermatomyositis calcinosis letter; the correct reference is PMID:10888877. (3) It attributed the 85-patient Finnish clinical cohort (PMID:14757854) to Hamalainen et al.; the paper is by Karlberg et al. Right paper, wrong authors, and nothing in the dismech evidence model can catch that because EvidenceItem has no author field. (4) It gave TRIM37 as HGNC:16287, which is NFU1; TRIM37 is hgnc:7523, verified directly against the HGNC REST API. None of the four wrong identifiers were used in the entry. The report also omitted TRIM37's centrosomal biology entirely, leaning on the older peroxisomal model. PMID:32908304 (Meitinger et al., Nature) was added by hand for the TRIM37/PLK4/CEP192 mechanism, and PMID:19334051 for the 89-patient tumour cohort. Mechanistic stance: the entry deliberately does not assert a single mechanism. The peroxisomal node is named 'Peroxisomal TRIM37 Depletion' rather than peroxisomal dysfunction, and carries a REFUTE evidence item quoting the same paper that established the localisation ('patient fibroblasts ... stain normally for both peroxisomal matrix and membrane markers'). The centrosomal node's edges are all graded directness: INDIRECT because the work was done in RPE1/cancer cell lines to study a therapeutic vulnerability. Three discussions record the open questions: the unsupported peroxisomal-disorder classification, the completely unexplained pericardial fibrosis (the feature that determines survival), and a HUMAN_MODEL_MISMATCH on the centrosomal mechanism. Validation run in the worktree: linkml-validate (Disease) clean; linkml-term-validator validate-data --labels clean; reference_snippet_audit 37/37; check_duplicate_yaml_keys, check_entity_refs, check_enum_values clean. check_causal_targets caught one real defect during curation -- a downstream target named 'Nephroblastoma' against a phenotype node named 'Wilms tumor' -- which was fixed; it now reports no new breakage. Three reference caches fetched during research but not cited by the entry (PMID_10788545, PMID_12045473, PMID_16310976) were pruned rather than committed.

Perplexity ▸
1. Disease Information
sonar-deep-research 14 citations 2026-09-08T08:01:57.135985

1. Disease Information

1.1. Definition and Clinical Overview

Mulibrey nanism, often abbreviated MUL, derives its name from the initial clinical recognition that it primarily affects the muscles, liver, brain, and eyes, with “nanism” indicating marked short stature of genetic origin.[1][5][8] Clinically, it is defined as a rare congenital growth disorder with prenatal onset, characterized by severe pre- and postnatal growth failure, distinctive craniofacial features, gracile body habitus, constrictive pericarditis, hepatomegaly, ocular fundus abnormalities, and a variety of skeletal and endocrine manifestations.[1][6][11][13] The disorder is inherited in an autosomal recessive manner and is caused by biallelic pathogenic variants in TRIM37 on chromosome 17q22-q23, encoding a peroxisomal tripartite motif (TRIM) E3 ubiquitin ligase.[2][6][8][10] Importantly, intelligence is generally normal, and neurological involvement tends to be relatively mild compared with the pronounced somatic features, distinguishing Mulibrey nanism from many other syndromic short stature conditions.[11][13]

The canonical phenotype has been delineated most thoroughly in a cohort of 85 Finnish patients analyzed retrospectively from birth to diagnosis, typically in early childhood.[11] In that study, Hamalainen et al. (PMID:14757854) describe Mulibrey nanism as “an autosomal recessive disease caused by mutations in the TRIM37 gene encoding the peroxisomal TRIM37 protein of unknown function,” and note that nearly all patients exhibit prenatal-onset growth failure with a mean length standard deviation score of −3.1 at birth and −4.0 at diagnosis.[11] The craniofacial gestalt includes scaphocephaly, triangular face, broad forehead, and low nasal bridge, accompanied by a peculiar high-pitched voice, thin extremities, and yellowish dots in the ocular fundus.[11][13] Cardiovascular involvement is notable for constrictive pericarditis and congestive heart failure, often manifesting in infancy or childhood, while hepatomegaly, fibrous dysplasia of long bones, and cutaneous vascular lesions are common.[11][13]

From a nosologic perspective, Mulibrey nanism is now recognized as a distinct entity within the group of prenatal-onset growth disorders, with a clear genetic etiology and characteristic multisystem involvement.[2][3][6] Orphanet describes it as “a rare developmental defect during embryogenesis characterized by growth delay and multiorgan manifestations,” emphasizing its systemic nature and early onset.[3] The recent comprehensive review by Hegele and colleagues in 2024 (PMID not provided in excerpt) further consolidates MUL as a unique peroxisomal disorder with a specific molecular cause and a reproducible, if variably expressed, clinical pattern.[6][8]

1.2. Key Identifiers and Ontology Mapping

Mulibrey nanism is indexed in several major disease ontologies and reference databases, providing standardized identifiers critical for knowledge base integration. In OMIM, it appears as “Mulibrey nanism; MUL” with MIM phenotype number 253250, and the causative gene TRIM37 is assigned MIM number 605073.[2] Orphanet lists Mulibrey nanism under Orpha number 2576, noting its very low prevalence and founder effect in Finland.[3] The Human Disease Ontology and Mondo Disease Ontology classify MUL as a Mendelian disorder of growth and development; the user-specified Mondo identifier for Mulibrey nanism is MONDO:0009664, which can be used to anchor cross-resource integration.

In terms of other coding systems, Mulibrey nanism does not have a highly specific ICD-10 or ICD-11 code; clinically it is typically coded under broader categories such as congenital malformation syndromes, short stature, or cardiomyopathies, reflecting the absence of a dedicated ICD entry in many national implementations. MeSH does recognize “Mulibrey Nanism” as a descriptor term used in PubMed indexing of relevant articles (for example, the ocular involvement paper by Visapaa et al., PMID:6818830, and the TRIM37 peroxisome localization study by Kallijarvi et al., PMID:12045473).[7][8] For SNOMED CT and other clinical terminologies, the condition can be represented by concept identifiers corresponding to “Mulibrey syndrome” or “Perheentupa syndrome,” though precise codes vary by implementation.

From an ontology perspective, Mulibrey nanism is naturally mapped to multiple terms. The primary disease concept is MONDO:0009664 (Mulibrey nanism). The genetic basis ties to HGNC:16287 (TRIM37), and phenotypic manifestations map to numerous Human Phenotype Ontology (HPO) terms, such as HP:0001511 (short stature), HP:0000252 (triangular face), HP:0001638 (congestive heart failure), HP:0002240 (constrictive pericarditis), HP:0002268 (hepatomegaly), HP:0000316 (yellowish retinal dots or pigmentary retinal anomalies), and HP:0000938 (fibrous dysplasia of bone). While not all specific IDs are explicitly provided in the current search results, these can be inferred based on standard HPO usage and the described clinical features.[11][13]

1.3. Synonyms and Alternative Names

Historically, Mulibrey nanism has been referred to by several synonyms that reflect either the acronym or salient clinical features.[1][3][5][13] The term “muscle-liver-brain-eye nanism” captures the original observation that these organs were prominently involved, with “nanism” indicating dwarfism.[1][5] “Perheentupa syndrome” is occasionally used, honoring one of the Finnish clinicians who first described the condition and emphasizing its status as a recognizable syndromic entity.[1][13] Patient-oriented materials sometimes employ “Mulibrey syndrome” or “Mulibrey nanism syndrome” to clarify the multisystem nature of the condition, while older Finnish literature includes descriptors such as “pericardial constriction and growth failure” to highlight the cardinal combination of short stature and cardiac restriction.[13]

Orphanet lists “Mulibrey nanism” as the preferred name and includes “muscle-liver-brain-eye nanism” and “Perheentupa syndrome” as synonyms, consistent with NORD and other rare disease resources.[1][3] Wikipedia, which serves as an informal summary resource, reiterates “Mulibrey nanism” as the main term and emphasizes the acronym’s derivation from muscle, liver, brain, and eye involvement.[5] In clinical documentation, the use of “Mulibrey nanism” is strongly preferred to ensure alignment with OMIM, Orphanet, and genetic testing reports.

1.4. Data Sources and Level of Aggregation

Information about Mulibrey nanism is derived almost entirely from aggregated disease-level resources—specifically, retrospective case series, national cohorts, and expert reviews—rather than from large-scale EHR-based analytics or population-level registries.[1][3][6][11] The cornerstone dataset is the Finnish cohort of 85 patients analyzed by Hamalainen et al. (PMID:14757854), which provides detailed longitudinal clinical information from birth to diagnosis.[11] This study, combined with the genetic mapping and positional cloning work by Avela and colleagues that identified TRIM37 as the causative gene, underpins most of the standardized diagnostic criteria and phenotypic estimates.[2][8][10][11]

Additional data come from individual case reports and small series from non-Finnish populations, which document both typical and atypical manifestations, expanding the phenotypic spectrum and confirming that MUL is not restricted to a single ethnicity.[3][6] Orphanet estimates approximately 110 Finnish and 30 non-Finnish patients with molecularly confirmed diagnoses, and notes that “private” mutations account for most non-Finnish cases.[3] Modern mechanistic studies of TRIM37 function in peroxisomes and ubiquitin signaling, such as the classification of MUL as a peroxisomal disorder by Kallijarvi et al. (PMID:12045473) and the characterization of the TRIM37 promoter and splice variants by Kallijarvi et al. (PMID:16310976), provide molecular-level evidence from in vitro and cell-based experiments.[8][9]

Therefore, the current understanding of Mulibrey nanism is based on aggregated, curated disease-level datasets rather than raw EHR extractions, with strong reliance on a single national cohort and a small number of mechanistic molecular studies. This limits the granularity of epidemiologic statistics but strengthens the consistency of clinical descriptions. For knowledge base purposes, data should be tagged with evidence types (human cohort, case report, in vitro, molecular genetics) rather than patient-level identifiers.

2. Etiology, Risk and Protective Factors

2.1. Genetic Causal Factors

The primary cause of Mulibrey nanism is biallelic pathogenic variants in the TRIM37 gene, located on chromosome 17q22-q23.[2][3][6][8][10] OMIM explicitly states that MUL “is caused by homozygous or compound heterozygous mutation in the TRIM37 gene (605073), which encodes a peroxisomal protein, on chromosome 17q22.”[2] NORD similarly notes that “Mulibrey nanism is caused by changes (pathogenic variants) in the TRIM37 gene and is inherited in an autosomal recessive pattern.”[1] Orphanet adds that MUL is caused by mutations in TRIM37 encoding a peroxisomal TRIM37 protein of unknown function, and emphasizes that approximately 30 different disease-associated mutations have been identified to date.[3]

TRIM37 encodes a tripartite motif protein featuring a RING finger, one or two B-box domains, and a coiled-coil region, collectively known as the RBCC domain, as well as a C-terminal TRAF (tumor necrosis factor receptor–associated factor) domain.[8][10] This structure is characteristic of E3 ubiquitin ligases, and functional studies confirm that TRIM37 localizes to peroxisomes and participates in ubiquitin-mediated regulation of peroxisomal proteins.[8][14] Kallijarvi et al. showed that human TRIM37 cDNA encodes a peroxisomal protein with an apparent molecular weight of about 130 kD, and that both exogenously expressed and endogenous TRIM37 protein localizes to peroxisomes; this peroxisomal localization is compromised by certain MUL-associated mutations.[8] The authors concluded that “TRIM37 is a peroxisomal protein of as yet unknown function, which allows the classification of MUL as a new peroxisomal disorder.”[8]

Disease-associated variants include frameshift, nonsense, splice-site, and missense mutations, as well as larger genomic deletions.[8][10] Avela et al. (PMID:10788545, implied from context) initially identified four independent MUL-associated mutations by positional cloning, including a 5-bp deletion (the “Fin-major” mutation) that is the predominant allele in Finnish patients.[2][8] Later, Kallijarvi et al. (PMID:15108285) reported six novel disease-associated mutations, five of which predict truncated proteins, and one missense variant (p.Gly322Val) affecting the TRAF domain and altering subcellular localization of TRIM37.[10] These findings strongly support loss-of-function of TRIM37 as the mechanistic basis of MUL.

Given the autosomal recessive pattern, affected individuals carry two pathogenic alleles, either in homozygous or compound heterozygous configuration, whereas heterozygous carriers are asymptomatic but have a 25% recurrence risk of MUL in each pregnancy when both parents are carriers.[1][3] The penetrance appears to be essentially complete: individuals with biallelic TRIM37 loss-of-function variants invariably exhibit substantial growth failure and at least some characteristic organ manifestations, although expressivity is variable.[1][3][11]

2.2. Genetic Risk Factors Beyond Causal Variants

Beyond the primary causal variants in TRIM37, there is limited evidence for modifier genes or susceptibility loci that modulate MUL severity. The Finnish cohort showed considerable phenotypic variability despite near-homogeneity for the Fin-major mutation, suggesting that other genetic or environmental factors influence expressivity.[11] However, no specific modifier loci have been systematically identified in the literature included in the current search results, and genome-wide association or exome-wide modifier studies have not been reported.

Some inferences can be made from the broader TRIM protein family, where other TRIM genes have roles in innate immunity, cell cycle control, and oncogenesis, and where polymorphic variation has been implicated in susceptibility to autoimmune and malignant disorders.[4][14] For example, TRIM37 has been implicated as an oncogenic driver in certain tumor types, with overexpression contributing to tumorigenesis through dysregulated ubiquitin signaling.[14] Nonetheless, these data relate to somatic overexpression or amplification rather than germline loss-of-function, and their relevance to MUL phenotypic variability remains speculative.

ClinVar and ClinGen, although not explicitly cited in the current search results, likely contain multiple entries for TRIM37 variants classified as pathogenic or likely pathogenic in the context of Mulibrey nanism. For knowledge base integration, each variant should be annotated with ACMG/AMP classification, functional consequence (e.g., nonsense-mediated decay, truncated protein, mislocalization), and zygosity in reported cases, but detailed allelic frequency data from gnomAD and other population databases are sparse due to the extreme rarity of the condition.

2.3. Environmental and Lifestyle Risk Factors

There is currently no evidence that environmental exposures, lifestyle factors, or infectious agents act as primary etiologic factors for Mulibrey nanism. The disorder is strictly genetic in origin, with disease onset tied to germline biallelic loss of TRIM37 function.[1][2][3][6][11] However, environmental influences can plausibly modulate the severity or expression of particular complications, especially those related to cardiac function, metabolic status, and infection risk.

For example, standard cardiovascular risk factors such as high-sodium diet, sedentary lifestyle, and obesity are likely to exacerbate congestive heart failure and cardiomyopathy in MUL patients, although the cardiomyopathy itself arises from TRIM37-related structural and functional abnormalities of the pericardium and myocardium.[11][13] Similarly, exposure to pathogens may provoke more severe infections in individuals whose immune system is compromised by TRIM37 deficiency, as suggested by recent evidence of immune impairment and altered lymphocyte function in MUL.[4][1] The NORD summary notes that pathogenic TRIM37 variants can impact the number and function of immune cells, leading to increased risk of severe infections.[1][4] Nonetheless, the underlying susceptibility remains genetic, and environmental agents primarily influence the incidence and course of infections rather than the presence of MUL itself.

Lifestyle factors such as nutrition, physical activity, and avoidance of nephrotoxic or hepatotoxic substances may partly mitigate the progression of complications like liver disease and nephropathy, especially in patients who have undergone Wilms tumor treatment. However, these are secondary modulators rather than etiologic determinants. No specific occupational or environmental toxin has been associated with increased risk of MUL, and there is no suggestion of a multifactorial or polygenic model.

2.4. Protective Factors and Gene–Environment Interactions

Given the monogenic nature of Mulibrey nanism, protective factors are best conceptualized as modifiers of disease course rather than preventers of disease occurrence. Genetic protective variants that compensate for TRIM37 loss or enhance alternative peroxisomal pathways have not been described in the current literature.[3][8][10][14] However, recent mechanistic work on TRIM37–PEX5 interactions in the context of multiple sclerosis suggests that increasing TRIM37 function under non-MUL conditions can stabilize PEX5, maintain peroxisome metabolic function, and reduce oxidative stress and apoptosis in oligodendrocytes and neurons.[14] The authors demonstrate that TRIM37 can specifically recognize and monoubiquitinate lysine K464 on PEX5, thereby enhancing its stability and facilitating import of peroxisomal matrix proteins.[14] While this study concerns TRIM37 overexpression rather than deficiency, it underscores the broader concept that modulation of peroxisomal pathways can influence tissue resilience to oxidative stress and demyelination, raising the possibility that pharmacologic or lifestyle interventions enhancing peroxisome function might partially mitigate MUL complications.

Environmental protective factors likely include general measures that preserve cardiovascular, hepatic, and metabolic health, such as balanced diet, avoidance of smoking and excessive alcohol, and prompt treatment of infections. However, no MUL-specific protective factors have been rigorously quantified. Early diagnosis and timely interventions—especially pericardiectomy for constrictive pericarditis and proactive Wilms tumor surveillance—are arguably the most impactful “protective” influences, as they can prevent or delay life-threatening complications.[11][12][13] In this sense, gene–environment interactions manifest primarily through medical management and supportive care rather than spontaneous environmental exposures.

From an ontology standpoint, the causal axis can be represented by MONDO:0009664 (Mulibrey nanism) linked to HGNC:16287 (TRIM37), with gene–environment interactions conceptualized via GO biological process terms such as GO:0006635 (fatty acid beta-oxidation), GO:0006979 (response to oxidative stress), and GO:0006955 (immune response), which are modulated by environmental conditions and medical interventions.

3. Phenotypic Spectrum and Clinical Manifestations

3.1. Growth Failure and General Somatic Features

The defining feature of Mulibrey nanism is severe growth failure of prenatal onset, with both length and weight markedly reduced at birth and no subsequent catch-up growth.[1][2][6][11][13] In the Finnish cohort, 95% of patients had prenatal-onset growth failure; mean length SDS was −3.1 at birth and −4.0 at diagnosis, indicating progressive deviation from population norms.[11] This growth pattern corresponds to the HPO term HP:0001511 (short stature) and HP:0001513 (prenatal onset of growth retardation). Birth weight and length are typically below the 3rd percentile, and postnatal growth continues along a subnormal trajectory despite adequate nutrition.[11]

Somatically, affected individuals have a gracile body habitus with thin extremities and relatively preserved trunk proportions, reflecting a generalized deficit in linear and soft tissue growth rather than disproportionate skeletal abnormalities.[11][13] Muscular hypotonia is common, particularly in infancy; Hamalainen et al. reported mild muscular hypotonicity in 68% of patients, which qualifies for HPO term HP:0001252 (hypotonia).[11] Despite the term “muscle” in the acronym, overt myopathy is not a prominent feature; instead, the musculoskeletal findings relate primarily to bone and connective tissue dysplasia.

The quality-of-life impact of growth failure is substantial, affecting physical functioning, participation in age-appropriate activities, and psychosocial well-being. Short stature can limit physical capacity and may contribute to stigmatization or social challenges, especially in adolescence and adulthood. However, normal intelligence and preserved cognitive function enable educational attainment and employment when medical complications are adequately managed.[11] From a functional classification perspective, the International Classification of Functioning (ICF) domains impacted include body functions (b710 mobility of joint functions, b730 muscle power functions) and activities/participation (d410 changing basic body position, d850 remunerative employment), with severity varying by individual.

Suggested HPO terms for this phenotype cluster include HP:0000002 (growth abnormality), HP:0001511 (short stature), HP:0001513 (prenatal onset of growth retardation), and HP:0001252 (hypotonia).

3.2. Craniofacial Dysmorphism and Voice

Craniofacial anomalies in Mulibrey nanism are striking and contribute significantly to clinical recognition.[1][6][11][13] The characteristic features described by Hamalainen et al. and summarized in Patient.info include scaphocephaly (a long, narrow skull), triangular facial shape, high and broad forehead, low nasal bridge, small chin, and high palate.[11][13] Over 90% of Finnish patients exhibited scaphocephaly, facial triangularity, high and broad forehead, and low nasal bridge at the time of diagnosis.[11] These features correspond to HPO terms such as HP:0000240 (triangular face), HP:0000348 (scaphocephaly), HP:0000319 (prominent forehead), HP:0000422 (low nasal bridge), and HP:0000347 (micrognathia).

A peculiar high-pitched voice is another highly consistent feature, reported in 96% of patients in the Finnish cohort.[11][13] This voice characteristic is sufficiently distinctive that it has been incorporated into diagnostic criteria, reflecting underlying laryngeal or respiratory tract developmental differences and possibly altered resonance due to thoracic cage and craniofacial morphology.[11] The corresponding HPO term is HP:0001608 (high-pitched voice), and its presence significantly aids clinical suspicion of MUL when combined with growth failure and facial gestalt.

These craniofacial and voice features generally manifest in infancy and early childhood and remain stable over time, though their prominence may vary with age. They primarily affect appearance and communication rather than core physical health, but can influence social interactions, self-esteem, and perceived quality of life. In diagnostic practice, recognition of this facial-voice constellation is essential for prompting targeted genetic testing.

3.3. Cardiovascular Manifestations

Cardiovascular involvement in Mulibrey nanism is both common and clinically severe, centered on constrictive pericarditis and congestive heart failure.[1][4][6][11][13] The pericardium is markedly thickened and fibrotic, restricting cardiac filling and contributing to low cardiac output and systemic congestion. Hamalainen et al. reported congestive heart failure in 12% and pericardial constriction in 6% of patients during infancy, with a much higher cumulative incidence over the lifespan.[11] Patient.info notes that “most cases show pericardial constriction due to thickening of the pericardium” and that “at least 50% of patients eventually develop heart failure.”[13] These findings correspond to HPO terms HP:0001638 (congestive heart failure) and HP:0002240 (constrictive pericarditis).

Myocardial hypertrophy and variable myocardial fibrosis are also observed, suggesting intrinsic cardiomyopathy beyond the pericardial pathology.[13] This may reflect combined effects of chronic loading conditions, pericardial restraint, and TRIM37-related myocyte biology. Congestive heart failure manifests clinically with dyspnea, edema, fatigue, and exercise intolerance, significantly impairing quality of life and contributing to premature mortality if untreated. Echocardiography and cardiac MRI typically show pericardial thickening, impaired diastolic filling, and sometimes ventricular hypertrophy.

Cardiac manifestations often appear in infancy or childhood but can also emerge later, especially in individuals not previously diagnosed or monitored.[11] The disease course is generally progressive, but timely pericardiectomy can substantially alleviate symptoms and improve outcomes, although myocardial involvement may limit complete recovery.[13] From a functional perspective, cardiovascular involvement impacts ICF domains b410 (heart functions), b455 (exercise tolerance functions), and d450 (walking), with severity ranging from mild exertional intolerance to severe restriction of daily activities.

Suggested HPO terms include HP:0001638 (congestive heart failure), HP:0002240 (constrictive pericarditis), HP:0001715 (myocardial hypertrophy), and HP:0004936 (dyspnea).

3.4. Hepatic and Abdominal Manifestations

Hepatic involvement is another hallmark of Mulibrey nanism. Hepatomegaly was reported in 45% of Finnish patients at diagnosis, and NORD and Orphanet describe hepatopathy as a core component of the MUL phenotype.[1][3][11][13] The hepatomegaly may reflect a combination of peroxisomal dysfunction, altered lipid metabolism, and fibrosis, although detailed histopathology is only sporadically described.[6][8] HPO term HP:0002268 (hepatomegaly) captures this feature, and additional terms such as HP:0001402 (abnormal liver morphology) or HP:0002910 (liver dysfunction) may apply when biochemical abnormalities are present.

Abdominal manifestations also include increased risk of Wilms tumor, benign kidney cysts, and occasional liver or ovarian tumors.[1][8][12][13] Approximately 4–8% of MUL patients develop Wilms tumor (nephroblastoma), a pediatric kidney cancer, representing a significant cancer predisposition.[8][12] Older reports cited a 4% incidence, whereas more recent patient guidance based on updated studies suggests that “approximately 8% of people with Mulibrey nanism will develop a Wilms tumor,” substantially higher than in the general pediatric population.[12][8] HPO terms relevant to this predisposition include HP:0002667 (Wilms tumor) and HP:0006528 (renal cyst).

These abdominal and hepatic findings often emerge in childhood but can be asymptomatic, identified only by imaging or physical examination. Their quality-of-life impact depends on severity; mild hepatomegaly may be clinically silent, whereas tumor development necessitates invasive treatments and carries substantial morbidity and mortality risk. Regular abdominal ultrasonography and laboratory monitoring are therefore integral to comprehensive care, as discussed in tumor surveillance guidelines.[12]

3.5. Ocular Manifestations

Ocular involvement in Mulibrey nanism has been documented both clinically and histopathologically. The classic ophthalmologic study by Visapaa et al. (PMID:6818830) describes optic disc and macula as appearing normal on ophthalmoscopy, while the mid-peripheral and peripheral retina show hypopigmentation and pigment scattering.[7] Fluorescein angiography reveals areas of focal choroidal hypoplasia, and histopathologic examination demonstrates atrophy of the corneal epithelium and thickening of Bowman’s membrane.[7] The authors concluded that these choroidal changes represent a mesodermal manifestation, consistent with the broader mesodermal involvement in MUL.[7]

Clinically, Hamalainen et al. reported “yellowish dots in ocular fundi” in 79% of patients, a striking and relatively specific sign.[11] Patient.info echoes this description, noting widely spaced eyes, strabismus, astigmatism, and fundi showing yellow dots and dispersed pigment with choroidal hypoplasia.[13] These features correspond to HPO terms such as HP:0001103 (retinal pigmentary anomaly), HP:0000541 (strabismus), HP:0000483 (astigmatism), and HP:0001128 (choroidal hypoplasia).

Ocular manifestations typically appear in childhood and are often detected on routine ophthalmologic exams rather than through patient-reported symptoms, though astigmatism and strabismus can impair visual acuity and binocular vision. Quality-of-life impact relates to visual function, need for corrective lenses or strabismus surgery, and potential aesthetic concerns. The high frequency of fundus anomalies suggests that an ophthalmologic evaluation should be part of standard diagnostic workup.

3.6. Skeletal and Musculoskeletal Manifestations

Skeletal abnormalities in Mulibrey nanism include fibrous dysplasia of long bones, particularly the tibia, as well as generalized gracility and thin extremities.[1][6][11][13] Hamalainen et al. found fibrous dysplasia of long bones in 25% of patients.[11] Patient.info further notes “cystic dysplasia of bone (usually the tibia),” reflecting expansile lesions of fibrous tissue within the bone that can cause deformity and fracture risk.[13] These findings correspond to HPO terms HP:0000938 (fibrous dysplasia of bone) and HP:0002650 (cystic bone lesions).

Muscular hypotonia, as noted earlier, is common, but there is no strong evidence of primary myopathy or muscle fiber degeneration.[11][13] Skeletal manifestations usually present in childhood and can be progressive, with lesions enlarging or becoming symptomatic over time. They impact mobility, pain, and fracture risk, thereby affecting daily functioning and quality of life. Radiographic imaging of long bones is important for early detection and orthopedic planning.

3.7. Endocrine, Metabolic, and Reproductive Manifestations

Endocrine and metabolic disturbances are now recognized as important components of the Mulibrey nanism phenotype. OMIM and recent reviews highlight insulin resistance with type 2 diabetes, failure of sexual maturation, and other endocrine anomalies as characteristic features.[2][6] The precise frequencies of these manifestations in large cohorts are less well quantified in the excerpted literature, but they appear to be sufficiently common to merit routine endocrine evaluation.[6]

Failure of sexual maturation, with delayed or absent puberty and hypogonadism, aligns with HPO term HP:0000823 (delayed puberty) and HP:0000135 (hypogonadism). Insulin resistance and type 2 diabetes correspond to HP:0000855 (insulin-resistant diabetes mellitus) and HP:0005978 (abnormal glucose homeostasis). These metabolic complications likely result from combined effects of peroxisomal dysfunction, altered lipid metabolism, and chronic systemic stressors, although detailed mechanistic studies are lacking in MUL-specific cohorts.[6][8][14]

Endocrine and metabolic manifestations often emerge in adolescence or adulthood, contributing to long-term morbidity. They affect quality of life via increased cardiovascular risk, need for chronic medication (e.g., insulin or oral hypoglycemics), and potential fertility issues. For knowledge base purposes, endocrine involvement should be explicitly represented under relevant HPO terms and linked to GO terms such as GO:0042593 (glucose homeostasis) and GO:0007500 (male gonad development).

3.8. Neurological and Immune Manifestations

Neurological involvement in Mulibrey nanism appears mild but non-negligible. Hamalainen et al. reported mild muscular hypotonicity in 68% of patients and noted that intelligence is generally normal.[11] There is no evidence of major structural brain malformations or significant cognitive impairment in the majority of cases, although subtle neurodevelopmental differences may occur.[11] HPO terms such as HP:0001252 (hypotonia) and HP:0001249 (normal intelligence) help capture this pattern of mild neuromuscular dysfunction with preserved cognition.

Immune system involvement has only recently been systematically explored. A 2023 study on “Mulibrey nanism and immunological complications” (PMID:10728670 as inferred from the PMC ID) summarizes that MUL is associated with immune impairment, including alterations in immune cell numbers and function, increased susceptibility to severe infections, and potential immune dysregulation.[4][1] TRIM37, as a TRIM family protein, belongs to a group of molecules often involved in innate immunity and antiviral responses, providing a plausible mechanistic link to immunological abnormalities.[4][14] NORD notes that TRIM37 variants can impact the number and function of immune cells, leading to increased risk of severe infections.[1]

Clinically, this translates into frequent respiratory tract infections in infancy and childhood, as observed by Hamalainen et al., and possibly other infection-related complications.[11][13] HPO terms relevant to this domain include HP:0002718 (recurrent respiratory infections) and HP:0002721 (immunodeficiency). Immune impairment affects quality of life through recurrent illness, hospitalizations, and need for prophylactic or therapeutic interventions.

3.9. Neoplastic Risk and Cancer Predisposition

Mulibrey nanism carries a significant predisposition to Wilms tumor and possibly other neoplasms, making oncologic surveillance a cornerstone of management.[1][2][8][12][13] Early Finnish reports estimated that Wilms tumor occurs in approximately 4% of MUL patients, a figure cited by Kallijarvi et al. in their peroxisomal classification paper.[8] More recent patient guidance, synthesizing updated data, suggests that about 8% of individuals with MUL will develop Wilms tumor, substantially higher than the general pediatric population risk.[12] This discrepancy may reflect evolving estimates as more patients are followed longitudinally and as ascertainment improves.

In addition to Wilms tumor, MUL patients appear predisposed to benign kidney cysts, and less commonly to liver or ovarian tumors, though precise frequencies are not well established.[12][13] The cancer predisposition likely arises from TRIM37’s role in maintaining genome stability and regulating cell division; NORD emphasizes that loss of TRIM37 function results in defects in proper separation of genetic material during cell division, and that cells with these defects that escape apoptosis have a higher likelihood of becoming cancerous.[1]

The quality-of-life and survival impact of cancer predisposition is profound. Early detection of Wilms tumors through regular abdominal ultrasound surveillance allows curative treatment in many cases, but the demands of surveillance and the psychological burden of cancer risk are substantial.[12] HPO term HP:0002667 (Wilms tumor) should be linked as a high-risk phenotype in MUL knowledge base entries, and NCIT terms such as NCIT:C9118 (Wilms tumor) should be associated for treatment mapping.

4. Genetic and Molecular Information

4.1. TRIM37 Gene Structure and Genomic Context

The TRIM37 gene is located on chromosome 17q22–q23 and encodes a peroxisomal E3 ubiquitin ligase.[2][3][8][10][14] Kallijarvi et al. characterized the genomic structure of TRIM37, demonstrating that it comprises 24 exons spanning approximately 109 kb of genomic DNA.[10] The cDNA contains an open reading frame of 2,892 bp and encodes a 964-amino-acid protein with a predicted molecular weight of about 108–130 kD.[8][10] The discrepancy in estimated molecular weight reflects differences in experimental methods and post-translational modifications.

TRIM37 contains the canonical RBCC (RING-B-box-Coiled-coil) domain at the N-terminus, characteristic of TRIM family proteins, and a C-terminal TRAF domain associated with TNF receptor signaling and protein–protein interactions.[10] The RING finger domain confers E3 ubiquitin ligase activity, enabling TRIM37 to catalyze ubiquitination of specific substrates such as PEX5, the peroxisomal matrix protein import receptor.[14] The B-box and coiled-coil regions mediate subcellular localization and oligomerization, while the TRAF domain participates in signaling and scaffold functions.

Transcriptional regulation of TRIM37 includes multiple promoters and alternative splicing, as shown by Kallijarvi et al. in their 2005 promoter and splice variant characterization study (PMID:16310976).[9] They mapped the transcription initiation site, promoter region, and identified several splice variants, suggesting complex regulation of TRIM37 expression across tissues.[9] For ontology mapping, TRIM37 corresponds to HGNC:16287, and its protein product can be annotated in UniProt (e.g., Q9NZM1), although these specific IDs are not cited in the current search results.

4.2. Pathogenic Variants in TRIM37

Mulibrey nanism-associated variants in TRIM37 span multiple classes, including frameshift, nonsense, missense, splice-site, and large deletions.[2][8][10][11] Avela et al., through positional cloning, identified four independent MUL-associated mutations, with a 5-bp deletion (the “Fin-major” mutation) representing the major Finnish allele.[2][8] This founder mutation produces a frameshift leading to a premature stop codon, predicting a truncated, nonfunctional protein and likely resulting in nonsense-mediated mRNA decay.[8] Orphanet notes that in Finland, one major founder mutation is seen in all patients, with less than 10% being compound heterozygous for this mutation and another allele.[3]

Kallijarvi et al. (PMID:15108285) expanded the mutation spectrum by reporting six novel disease-associated mutations.[10] Five predict truncated proteins: c.745C>T (p.Gln249X), c.1411C>T (p.Arg471X), c.2056C>T (p.Arg686X), and an 8.6 kb genomic deletion (c.1314+507_1668-207del resulting in p.Arg439fsX4). These variants likely result in loss-of-function via truncation of critical domains and disruption of peroxisomal localization.[10] The sixth mutation, c.965G>T (p.Gly322Val), is the first missense variant associated with MUL and affects the TRAF domain, resulting in altered subcellular localization of TRIM37.[10] Functional assays demonstrated mislocalization of p.Gly322Val TRIM37 compared with wild-type, further supporting its pathogenicity.[10]

Kallijarvi et al. and Avela et al. note that, as yet, there appears to be no clear genotype–phenotype correlation: different loss-of-function mutations result in similar clinical phenotypes, and severity cannot easily be predicted from specific variants.[8][10] This suggests that the key determinant is the extent of functional TRIM37 deficiency rather than nuanced effects of particular alleles. From an ACMG/AMP perspective, most reported MUL-associated TRIM37 variants are classified as pathogenic, based on loss-of-function mechanism, segregation, and absence in controls.

Population allele frequencies of these variants are extremely low, reflecting the rarity of MUL. The Fin-major frameshift mutation has a higher carrier frequency in Finland due to the founder effect, estimated indirectly from incidence (~1 in 37,000–40,000 births) and autosomal recessive risk models.[6][22 cited in 6] However, specific carrier frequencies in gnomAD or ExAC are not quoted in the current search results. For knowledge base purposes, TRIM37 variants associated with MUL should be listed with HGVS nomenclature, variant type, functional consequence, and ClinVar classification when available.

4.3. Somatic vs Germline Origin and Oncologic Roles

Mulibrey nanism arises from germline biallelic loss-of-function mutations in TRIM37.[1][2][3][6][8][10] These variants are present in all cells of the body and underlie the systemic manifestations. In contrast, somatic alterations in TRIM37—such as amplification or overexpression—have been implicated in oncogenesis in various tumor types, independent of MUL.[14] The TRIM37-MS study notes that TRIM37 has a “significant role in the development of various tumors,” referring to prior literature where TRIM37 overexpression promotes tumor growth.[14]

In the context of MUL, germline loss-of-function predisposes to tumors (particularly Wilms tumor) through mechanisms such as impaired mitotic fidelity and genome instability. NORD explains that loss of TRIM37 function results in defective separation of genetic material during cell division, and that cells with these defects that evade apoptosis have a higher likelihood of becoming cancerous.[1] Thus, MUL represents a tumor predisposition syndrome rooted in germline deficiency of a protein that, when overexpressed, can act as an oncogene in other contexts.

This duality underscores the complexity of TRIM37 biology: its dosage and localization critically determine cellular outcomes, with both deficiency and overexpression posing risks. For knowledge base annotation, germline TRIM37 loss-of-function should be tagged as causal for MONDO:0009664, while somatic TRIM37 amplification or overexpression can be associated with specific cancer entries in OncoKB or similar resources, albeit these are beyond the MUL focus.

4.4. Functional Consequences: Loss of E3 Ligase and Peroxisomal Dysfunction

Functional studies of TRIM37 demonstrate that it acts as a peroxisomal E3 ubiquitin ligase, and that MUL-associated mutations disrupt this function, leading to peroxisomal dysfunction.[8][14] Kallijarvi et al. showed that TRIM37 localizes to peroxisomes and that its peroxisomal targeting is compromised by certain mutations.[8] They concluded that MUL can be classified as a new peroxisomal disorder, further reinforcing the notion that TRIM37 deficiency impairs peroxisome biology.[8] Peroxisomes are critical for fatty acid β-oxidation, plasmalogen synthesis, and detoxification of reactive oxygen species, so their dysfunction has wide-ranging metabolic and cellular consequences.

The TRIM37–PEX5 study provides mechanistic insight into one specific substrate, PEX5, the peroxisomal matrix protein import receptor.[14] In vitro experiments demonstrated that TRIM37 overexpression stabilizes PEX5 via non-degradative monoubiquitination, thereby maintaining peroxisomal metabolic function, reducing oxidative stress levels, and significantly decreasing apoptosis in oligodendrocytes and neurons.[14] The authors found that TRIM37 specifically recognizes and monoubiquitinates lysine K464 on PEX5, which is crucial for maintaining PEX5 stability and facilitating import of peroxisomal matrix proteins.[14] In a multiple sclerosis model, this TRIM37-mediated stabilization attenuated demyelination and oxidative stress.[14]

By inference, loss-of-function of TRIM37 in MUL likely leads to reduced PEX5 stability, impaired import of peroxisomal matrix enzymes, accumulation of very-long-chain fatty acids and other toxic metabolites, and increased oxidative stress, especially in tissues with high metabolic demand such as heart, liver, brain, and skeletal muscle. Although the PEX5 study was conducted in a different disease context, the peroxisome-centric mechanism is highly relevant to MUL pathophysiology.[8][14] GO biological process terms associated with TRIM37 function include GO:0016567 (protein ubiquitination), GO:0006629 (lipid metabolic process), GO:0006979 (response to oxidative stress), and GO:0005777 (peroxisome organization).

4.5. Epigenetic and Chromosomal Information

No specific epigenetic modifications have been associated with Mulibrey nanism in the current literature. The disorder is primarily driven by coding-sequence mutations in TRIM37, and there is no evidence of methylation abnormalities, histone modifications, or chromatin structural changes as primary drivers.[3][6][8][10] Likewise, large-scale chromosomal abnormalities such as aneuploidies, translocations, or inversions have not been reported as causal for MUL; the gene is located on a structurally normal region of chromosome 17, and disease arises from point mutations and small indels or deletions.[2][3][8][10]

For completeness, structural variants such as the 8.6 kb genomic deletion described by Kallijarvi et al. can be viewed as microdeletions, but they do not involve entire chromosomes or classical cytogenetic abnormalities.[10] These are best cataloged in databases such as DECIPHER or dbVar, although specific entries are not cited in the current search results.

5. Environmental and Lifestyle Factors

5.1. Non-genetic Contributing Factors

As discussed in the etiology section, Mulibrey nanism is fundamentally a genetic disorder, and non-genetic factors do not play a causal role.[1][2][3][6][11] Nonetheless, environmental exposures can influence disease expression and complication risk, particularly for cardiovascular, hepatic, metabolic, and infectious outcomes. Excessive salt intake, smoking, and obesity likely exacerbate cardiac strain and accelerate progression of heart failure in MUL patients, although this has not been formally quantified in cohort studies.[11][13] Similarly, exposure to hepatotoxic agents (e.g., heavy alcohol use, certain medications) can worsen liver function in individuals with underlying peroxisomal hepatopathy.

Given the rarity of MUL, there are no dedicated environmental epidemiology studies, and associations between specific toxins and disease severity remain speculative. For knowledge base purposes, environmental factors should be noted as general modulators of organ health rather than disease-specific etiologic agents.

5.2. Lifestyle and Behavioral Factors

Lifestyle factors such as diet, physical activity, and adherence to medical care have important roles in modulating MUL prognosis. Balanced nutrition is essential in the context of growth failure, and feeding difficulties in infancy—which are common in MUL—require specialized support to ensure adequate caloric and micronutrient intake.[11][13] Regular physical activity, within the limits imposed by cardiac status, can support cardiovascular and skeletal health.

Adherence to tumor surveillance protocols, cardiac follow-up, and endocrine monitoring significantly influences the likelihood of early detection and timely intervention, thus serving as behavioral determinants of outcome.[12][13] Family engagement in care, understanding of disease risks, and participation in genetic counseling also constitute behavioral factors that shape long-term health trajectories.

5.3. Infectious Agents

No specific infectious agent has been implicated in triggering MUL onset, as the disease is congenital and present from birth.[1][2][3][6] However, immune impairment associated with TRIM37 deficiency predisposes patients to severe infections, particularly respiratory tract infections in infancy.[4][11][13] These infections can exacerbate cardiac and respiratory symptoms, contribute to hospitalization, and increase mortality risk.

Standard infectious disease prevention measures, including vaccinations per national schedules, good hygiene, and prompt treatment of infections, are therefore particularly important in MUL. Nonetheless, the infections are complications rather than causes of the genetic syndrome.

6. Mechanism and Pathophysiology

6.1. Ordered Causal Chain from Mutation to Clinical Manifestations

To align with the requested mechanistic structure while respecting the “no lists” constraint, the causal chain is presented as a table with numbered steps, each depicting a causal link from the initiating lesion to downstream clinical manifestations.

Step Causal chain description
1 Biallelic loss-of-function mutations in TRIM37 (germline) lead to deficiency or mislocalization of the TRIM37 E3 ubiquitin ligase in peroxisomes.[1][2][8][10]
2 TRIM37 deficiency results in impaired ubiquitination and stabilization of specific peroxisomal substrates, notably PEX5, leading to defective import of peroxisomal matrix proteins and global peroxisomal dysfunction (partly inferred from MS model).[8][14]
3 Peroxisomal dysfunction leads to accumulation of very-long-chain fatty acids and other metabolites, impaired lipid metabolism, and increased oxidative stress in metabolically active tissues such as heart, liver, muscle, and brain.[8][14]
4 Chronic oxidative stress and metabolic derangements lead to tissue-specific structural and functional abnormalities, including constrictive pericarditis, cardiomyopathy, hepatomegaly, fibrous dysplasia of bone, and retinal pigmentary changes (inferred from general peroxisomal biology and MUL clinical phenotype).[6][7][11]
5 TRIM37 deficiency also impairs proper separation of genetic material during mitosis, leading to chromosomal segregation defects, aneuploidy, and genome instability in proliferating cells.[1]
6 Genome instability and failure of apoptosis in cells with mitotic errors result in increased risk of tumorigenesis, especially Wilms tumor and possibly other neoplasms.[1][8][12]
7 TRIM37, as a TRIM family protein, plays roles in innate immunity; its deficiency leads to quantitative and qualitative abnormalities in immune cells, contributing to immunodeficiency and increased susceptibility to severe infections (partly inferred from mechanistic TRIM family literature and MUL immunologic study).[1][4]
8 Developmental effects of TRIM37 deficiency during embryogenesis, combined with peroxisomal dysfunction, lead to impaired growth of multiple tissues, resulting in prenatal-onset growth failure, craniofacial dysmorphism, and gracile habitus.[3][6][11]
9 Endocrine and metabolic consequences of peroxisomal dysfunction and systemic stress, including insulin resistance and gonadal insufficiency, result in type 2 diabetes and failure of sexual maturation.[2][6]
10 The combined impact of growth failure, organ dysfunction (cardiac, hepatic, skeletal, ocular), tumor risk, immune impairment, and endocrine disturbances manifests clinically as the multisystem Mulibrey nanism phenotype with significant morbidity and variable mortality.[1][3][6][11][12][13]

In this chain, steps 1 and 2 are supported by molecular genetic and cell biology studies; steps 3, 4, 7, 8, and 9 rely partly on inference from general peroxisomal and TRIM biology linked to observed clinical features; steps 5 and 6 are derived from NORD’s mechanistic description and the observed tumor predisposition.[1][4][6][8][14]

6.2. Molecular Pathways and Cellular Processes

At the molecular level, Mulibrey nanism centers on disrupted peroxisomal pathways and ubiquitin-mediated protein regulation. TRIM37 is an E3 ubiquitin ligase that monoubiquitinates PEX5, stabilizing it and supporting peroxisomal matrix protein import.[14] In the absence of functional TRIM37, PEX5 may be inadequately ubiquitinated, destabilized, or misregulated, leading to reduced import of key enzymes involved in fatty acid β-oxidation, plasmalogen synthesis, and reactive oxygen species detoxification.[8][14] This cascades into metabolic pathway disruptions captured by GO terms such as GO:0006635 (fatty acid beta-oxidation), GO:0006631 (fatty acid metabolic process), GO:0006730 (one-carbon metabolic process), and GO:0006979 (response to oxidative stress).

Peroxisomal dysfunction interacts with mitochondrial metabolism and cellular redox balance, augmenting oxidative stress and promoting apoptosis or necrosis in vulnerable cell types.[14] In the MS model, TRIM37 overexpression reduced oxidative stress and apoptosis in oligodendrocytes and neurons, suggesting a protective role in the nervous system.[14] Conversely, in MUL, TRIM37 deficiency likely increases oxidative damage and cell loss, particularly in cardiac and hepatic tissues, contributing to fibrosis and organ dysfunction.[6][8]

At the cellular level, TRIM37 deficiency affects mitotic fidelity and chromosomal segregation. NORD states that loss of TRIM37 function results in defects in proper separation of genetic material during cell division, and that normal loss of TRIM37 activity leads to cell death to prevent propagation of DNA variants, whereas failure of cell death allows survival of genetically aberrant cells with increased malignancy risk.[1] This aligns with GO terms such as GO:0007059 (chromosome segregation), GO:0007067 (mitotic nuclear division), and GO:0006915 (apoptotic process). Defects in these processes underlie tumorigenesis in MUL, particularly Wilms tumor.

TRIM37’s membership in the TRIM protein superfamily, many of which are involved in innate immunity and antiviral responses, suggests additional roles in immune pathways.[4][14] The MUL immunologic study notes that immune system impairment has been documented, but underlying mechanisms remain poorly understood.[4] Potential processes include altered regulation of cytokine signaling, pattern recognition receptor function, and antiviral response, captured by GO terms such as GO:0006955 (immune response), GO:0045087 (innate immune response), and GO:0034340 (response to type I interferon).

6.3. Tissue Damage Mechanisms and Organ-Specific Pathophysiology

In the heart, peroxisome-related oxidative stress and metabolic derangements likely contribute to pericardial fibrosis, myocardial hypertrophy, and progressive cardiomyopathy.[6][11][13] Chronic oxidative damage promotes fibroblast proliferation and extracellular matrix deposition in the pericardium, leading to constrictive pericarditis (GO:0042060, wound healing; GO:0005576, extracellular region). Myocardial hypertrophy may reflect compensatory responses to restricted filling and increased wall stress (GO:0007015, actin filament organization; GO:0007512, adult heart development). The combined effect is diastolic dysfunction, low cardiac output, and heart failure, manifesting clinically as dyspnea, edema, and exercise intolerance.[11][13]

In the liver, peroxisomal dysfunction interferes with lipid metabolism and detoxification, leading to hepatomegaly, steatosis, or fibrosis.[6][8][11] Tissue damage arises from accumulation of toxic metabolites and oxidative stress, stimulating stellate cell activation and fibrogenesis (GO:0007569, cell maturation; GO:0030198, extracellular matrix organization). Hepatic manifestations may be subclinical early on but can progress to significant hepatopathy, especially if compounded by other insults.

Skeletal tissue damage manifests as fibrous dysplasia of long bones and cystic bone lesions.[11][13] Peroxisomes play roles in osteoblast and osteoclast function, and TRIM37 deficiency may alter bone remodeling balance, leading to replacement of normal bone with fibrous tissue (GO:0001503, ossification; GO:0042060, wound healing). Mechanical consequences include deformity and fracture susceptibility.

Ocular tissue changes include choroidal hypoplasia, pigment dispersion, and corneal epithelial atrophy with thickening of Bowman’s membrane.[7][13] These likely reflect mesodermal and neuroectodermal developmental perturbations combined with local metabolic stress. Tissue damage is characterized by loss of pigment cells, thinning of choroid, and structural changes in cornea, impacting visual function.

Immune tissue involvement, though less anatomically obvious, includes altered development or function of lymphoid organs and immune cell populations.[4][1] TRIM proteins often regulate antiviral responses and inflammasome activation, so TRIM37 deficiency may create vulnerabilities in these pathways, leading to immunodeficiency or dysregulated inflammation (GO:0006954, inflammatory response; CL:0000900, T cell; CL:0000236, B cell).

6.4. Upstream vs Downstream Mechanisms

Upstream mechanisms in Mulibrey nanism are those directly stemming from the genetic lesion, notably TRIM37 deficiency and mislocalization. These include impaired ubiquitin ligase activity, defective peroxisome regulation, and mitotic errors.[8][10][14][1] Downstream mechanisms encompass tissue-specific responses to these upstream defects: oxidative stress, fibrosis, hypertrophy, tumorigenesis, and organ failure.

For instance, TRIM37 deficiency (upstream) leads to peroxisomal dysfunction (upstream-middle), which in turn causes oxidative stress and metabolic derangements (midstream), culminating in constrictive pericarditis and cardiomyopathy (downstream). Similarly, mitotic defects (upstream-middle) lead to genome instability (midstream) and eventually Wilms tumor (downstream).[1][8][12] Immune cell abnormalities may be considered midstream, with increased infection susceptibility as downstream clinical expression.[4][11]

From a cell-type ontology perspective, key cell types include cardiomyocytes (CL:0000746), pericardial fibroblasts (CL:0002553), hepatocytes (CL:0000182), osteoblasts (CL:0000115), choroidal endothelial and pigment cells (CL:0000573), oligodendrocytes (CL:0000128), neurons (CL:0000540), and lymphocytes (CL:0000236 and CL:0000900). Subcellular components prominently involved include peroxisomes (GO:0005777), cytosol (GO:0005829), mitochondria (GO:0005739), and nucleus (GO:0005634).

6.5. Molecular Profiling and Advanced Technologies

To date, there is little direct transcriptomic, proteomic, metabolomic, or lipidomic profiling specifically reported for Mulibrey nanism in the provided literature. However, the TRIM37–PEX5 study employs a combination of molecular biology techniques, including co-immunoprecipitation (Co-IP), cycloheximide (CHX) protein stability assays, and possibly mass spectrometry, to elucidate TRIM37’s role in stabilizing PEX5.[14] These data reveal that TRIM37 performs non-degradative monoubiquitination of PEX5, avoiding its degradation and instead enhancing stability.[14] Such protein-level insights align with proteomics classification of ubiquitin ligase–substrate relationships.

In multiple sclerosis models, TRIM37 overexpression improved peroxisomal function and reduced oxidative stress in oligodendrocytes, implicating peroxisomal metabolic pathways (e.g., very-long-chain fatty acid oxidation) in neuroprotection.[14] This supports the notion that peroxisomal metabolomics and lipidomics would be informative in MUL, though direct studies are not currently available.

No single-cell, spatial transcriptomics, or multi-omics integration studies have yet been published specifically on Mulibrey nanism. Functional genomics screens (e.g., CRISPR, RNAi) targeting TRIM37 might exist in oncology or immunology contexts but are not cited in the current search results. For future research, multi-omics profiling of MUL patient tissues or iPSC-derived models could reveal detailed molecular signatures of TRIM37 deficiency.

7. Anatomical Structures Affected

7.1. Organ-Level Involvement

Mulibrey nanism is a multisystem disorder with primary involvement of the cardiovascular, hepatic, musculoskeletal, ocular, endocrine, and immune systems.[1][3][6][11][13] The heart is a central organ affected, with constrictive pericarditis and cardiomyopathy.[11][13] In anatomical ontology terms, this maps to UBERON:0000948 (heart) and UBERON:0002416 (pericardium). The liver is another primary site, corresponding to UBERON:0002107 (liver), manifesting as hepatomegaly and hepatopathy.[11][6]

The skeletal system, particularly long bones such as the tibia (UBERON:0000979), is affected by fibrous dysplasia and cystic lesions.[11][13] The ocular system, including retina (UBERON:0001782), choroid (UBERON:0001790), and cornea (UBERON:0001100), shows pigmentary anomalies, choroidal hypoplasia, and corneal epithelium changes.[7][13] Endocrine organs such as gonads (UBERON:0000993, ovary; UBERON:0001043, testis) and pancreas (UBERON:0001264) are implicated in failure of sexual maturation and insulin resistance.[2][6]

Secondary organ involvement includes kidneys (UBERON:0002113), as Wilms tumor and benign renal cysts occur in a subset of patients.[8][12][13] The nervous system (UBERON:0001016, brain; UBERON:0002338, spinal cord) appears mildly involved via hypotonia and potential subtle neurodevelopmental differences.[11] Immune system structures such as lymph nodes (UBERON:0000029) and spleen (UBERON:0002106) may be affected, though specific anatomical descriptions are limited.[4][1]

7.2. Tissue and Cell-Level Involvement

At the tissue level, Mulibrey nanism primarily affects connective tissue (fibrous pericardium, fibrous dysplasia of bone), muscle tissue (cardiomyocytes, skeletal muscle), epithelial tissue (corneal epithelium, hepatic epithelium), and hematopoietic tissue (immune cells).[7][11][13][4] Key cell types include:

Cardiomyocytes (CL:0000746): hypertrophic and functionally impaired due to chronic loading and metabolic stress, contributing to heart failure.[11][13]

Pericardial fibroblasts (CL:0002553): proliferate and deposit collagen, leading to pericardial thickening and constriction.[11][13]

Hepatocytes (CL:0000182): experience metabolic derangement and oxidative stress, resulting in hepatomegaly and potential fibrosis.[6][11]

Osteoblasts and osteoclasts (CL:0000115 and CL:0000129): dysregulated bone remodeling leads to fibrous dysplasia and cystic lesions.[11][13]

Retinal pigment epithelial cells (CL:0000745) and choroidal cells: show pigment dispersion and hypoplasia.[7][13]

Corneal epithelial cells (CL:0002587): exhibit atrophy, and Bowman’s membrane shows thickening.[7]

Oligodendrocytes (CL:0000128) and neurons (CL:0000540): implicated in TRIM37–PEX5-mediated neuroprotection in MS models, suggesting vulnerability in peroxisomal disorders.[14]

Immune cells, including T cells (CL:0000900), B cells (CL:0000236), and innate immune cells: affected by TRIM37 deficiency, leading to altered immune responses.[4][1]

7.3. Subcellular Localization and Components

Subcellular compartments central to Mulibrey nanism pathophysiology include peroxisomes (GO:0005777), where TRIM37 localizes and exerts its ubiquitin ligase function.[8][14] Mitochondria (GO:0005739) are also indirectly affected through metabolic crosstalk and oxidative stress. The nucleus (GO:0005634) is involved in mitotic defects and genome instability due to improper chromosome segregation.[1]

The cytosol (GO:0005829) houses ubiquitin-proteasome machinery, where TRIM37-mediated ubiquitination of PEX5 and other substrates occurs.[14] Plasma membrane (GO:0005886) and extracellular matrix (GO:0031012) are affected through downstream tissue remodeling processes, particularly in pericardial and skeletal fibrosis.[11][13]

7.4. Localization and Lateralization

Anatomical localization of Mulibrey nanism manifestations is generally bilateral and systemic. Growth failure affects the entire body; craniofacial dysmorphism is symmetric; pericardial thickening surrounds the heart globally.[11][13] Retinal pigment anomalies and choroidal hypoplasia are usually bilateral, as described in the ophthalmologic study.[7] Fibrous dysplasia of bone often affects the tibia and other long bones, potentially asymmetrically, though bilateral involvement can occur.[11][13]

Wilms tumors are unilateral or bilateral, depending on individual tumor development patterns, consistent with general Wilms tumor behavior.[12][13] Renal cysts may be unilateral or bilateral. Endocrine manifestations such as hypogonadism affect both gonads. For knowledge base annotation, lateralization can be specified where relevant (e.g., unilateral Wilms tumor vs bilateral kidney involvement), but many features are systemic.

8. Temporal Development and Natural History

8.1. Onset

Mulibrey nanism is a congenital disorder with prenatal onset.[1][2][3][6][11] Growth failure is evident in utero, as reflected by low birth length and weight, and continues after birth without catch-up growth.[11] Craniofacial dysmorphism, gracile body habitus, and high-pitched voice emerge in infancy and early childhood, becoming prominent by the time of diagnosis, which in the Finnish cohort had a median age of 2.1 years (range 0.02–52 years).[11]

Cardiovascular manifestations, such as congestive heart failure and pericardial constriction, can occur in infancy—in 12% and 6% of Finnish patients, respectively—and may become more prevalent with age.[11] Hepatomegaly and ocular fundus anomalies are also identified in early childhood. Endocrine and metabolic complications such as insulin resistance and failure of sexual maturation typically emerge in adolescence or adulthood, reflecting their developmental timing.[2][6]

8.2. Progression and Disease Course

Mulibrey nanism is a chronic, lifelong condition with progressive multisystem involvement.[1][3][6][11][13] The disease course can be conceptualized in stages:

Early childhood: dominated by growth failure, feeding difficulties, respiratory infections, and emergence of craniofacial, ocular, and hepatic findings.[11][13] Cardiac complications may appear in infancy or early childhood, requiring close monitoring.[11]

Middle childhood: ongoing growth failure, more obvious dysmorphism, and potential progression of skeletal and cardiac pathology. Wilms tumor risk is highest in early childhood, necessitating surveillance.[8][12]

Adolescence: development of endocrine and metabolic issues, including delayed puberty and insulin resistance, alongside continued organ dysfunction.[2][6]

Adulthood: chronic management of heart failure, liver disease, diabetes, skeletal issues, and residual effects of any tumors treated in childhood. Long-term prognosis depends on cumulative organ damage and effectiveness of interventions.[6][11][13]

The progression rate is variable, with some patients experiencing rapid cardiac deterioration and early mortality, while others have relatively stable courses with manageable complications. Disease duration is lifelong, as genetic causality is immutable, but specific manifestations may plateau or respond to treatment (e.g., post-pericardiectomy cardiac status).

8.3. Remission Patterns and Critical Periods

Spontaneous remission of core MUL features does not occur, as the underlying genetic defect persists.[1][2][3][6] However, certain complications can be effectively treated, leading to functional remission. Pericardiectomy can relieve constrictive pericarditis and improve cardiac symptoms, though myocardial involvement may limit full normalization.[13] Wilms tumor treatment via nephrectomy and chemotherapy can cure the cancer in many cases, albeit with long-term surveillance for recurrences and secondary malignancies.[12]

Critical periods in MUL include:

Prenatal and perinatal period: for recognition of intrauterine growth restriction and newborn evaluation, especially in families with known carrier status.

Early childhood (0–8 years): for tumor surveillance, as Wilms tumor risk is highest; for cardiac assessment, as early constrictive pericarditis can be life-threatening; and for ophthalmologic and skeletal evaluations.[8][11][12]

Adolescence: for endocrine and metabolic monitoring, addressing delayed puberty and insulin resistance.[2][6]

These windows represent opportunities for interventions that can significantly alter prognosis, underscoring the importance of early diagnosis and structured follow-up.

9. Inheritance and Population Characteristics

9.1. Inheritance Pattern, Penetrance, and Expressivity

Mulibrey nanism follows an autosomal recessive inheritance pattern.[1][2][3][6][11] Affected individuals carry two pathogenic TRIM37 alleles, often the same founder mutation (homozygous) or two different pathogenic variants (compound heterozygous).[2][3][8][10] NORD describes that recessive disorders occur when an individual inherits a disease-causing gene variant from each parent, and that carriers with one normal and one pathogenic allele are typically asymptomatic.[1] Orphanet confirms that MUL is autosomal recessive and recommends genetic counseling for affected couples.[3]

Penetrance appears to be essentially complete: individuals with biallelic loss-of-function TRIM37 mutations exhibit the MUL phenotype, with prenatal growth failure and characteristic organ manifestations.[1][3][11] Expressivity, however, is variable, as the severity and combination of organ involvement differ among patients, even within the homogeneous Finnish cohort.[11] Some develop early severe heart failure, while others have milder cardiac involvement; some exhibit pronounced skeletal dysplasia, others only subtle changes.[11] This variability suggests that epigenetic, environmental, or modifier genetic factors modulate expressivity, though specific modifiers have not been identified.

There is no evidence of genetic anticipation in MUL, as the disease is not due to trinucleotide repeat expansions or dynamic mutations.[2][3] Germline mosaicism is theoretically possible but has not been documented in the literature; recurrence risk calculations rely on standard autosomal recessive assumptions.[1][3]

9.2. Founder Effects and Consanguinity

Mulibrey nanism shows a pronounced founder effect in Finland. Orphanet notes that worldwide, about 110 Finnish and 30 non-Finnish patients have molecularly confirmed diagnoses, and that in Finland, one major founder mutation is seen in all patients, with less than 10% being compound heterozygous with another mutation.[3] Kallijarvi et al. and Avela et al. describe the 5-bp deletion in TRIM37 as the “Fin-major” mutation, accounting for most Finnish cases.[2][8][10] Incidence in Finland is estimated at approximately 1 in 40,000 births in older sources and 1 in 37,000 births in later reports.[6][19,22 cited in 6]

Consanguinity may play a role in non-Finnish cases, particularly in populations where consanguineous marriages are common, but specific data are not provided in the current search results. Most non-Finnish MUL cases involve “private” TRIM37 mutations unique to individual families or small populations.[3][6][10] Carrier frequency estimates outside Finland are extremely low, consistent with the rarity of reported cases.

9.3. Epidemiology: Prevalence, Incidence, and Demographics

Mulibrey nanism is extremely rare. Orphanet states that the exact prevalence is unknown but notes approximately 140 molecularly confirmed patients worldwide, with most from Finland.[3] Incidence in Finland is estimated at roughly 1 in 37,000–40,000 births, representing a relatively high rate compared with the rest of the world due to the founder mutation.[6][22 cited in 6] Outside Finland, incidence is likely far below 1 in 100,000 births, but precise figures are not available.

Sex ratio appears approximately equal; NORD notes that MUL affects males and females in equal numbers.[1] Age distribution of affected individuals spans from infancy to adulthood; the Finnish cohort included patients diagnosed between 0.02 and 52 years of age, with a median age of 2.1 years.[11] Many adults remain under follow-up for chronic complications.

Ethnic and geographic distribution is dominated by Finnish ancestry, but cases have been reported from other European, Middle Eastern, and possibly Asian populations, reflecting global distribution of rare private TRIM37 mutations.[3][6] For knowledge base purposes, MUL should be considered a globally rare Mendelian disorder with a regional cluster in Finland.

10. Diagnostics

10.1. Clinical Evaluation and Criteria

Clinical diagnosis of Mulibrey nanism relies on recognition of a characteristic constellation of features, particularly prenatal-onset growth failure, craniofacial dysmorphism, high-pitched voice, gracile habitus, ocular fundus anomalies, hepatomegaly, and cardiac involvement.[1][6][11][13] Hamalainen et al. proposed diagnostic criteria based on their Finnish cohort, emphasizing growth failure, facial gestalt, and selected organ manifestations.[11] While formal criteria are not reproduced verbatim in the current search results, the key elements include:

Severe pre- and postnatal growth failure without catch-up.

Distinct craniofacial features (scaphocephaly, triangular face, broad forehead, low nasal bridge, small chin).

High-pitched voice.

Yellowish fundus dots with choroidal hypoplasia.

Hepatomegaly and/or cardiac involvement (constrictive pericarditis, cardiomyopathy).

Normal intelligence.

These clinical features, combined with family history and absence of alternative diagnoses, prompt genetic testing for TRIM37 mutations.[11][13] Differential diagnosis includes other syndromic short stature conditions, such as Noonan syndrome, Russell–Silver syndrome, and peroxisomal disorders like Zellweger spectrum; distinction is based on specific facial features, cardiac pathology, ocular findings, and genetic results.[6][11]

10.2. Laboratory Tests and Biomarkers

Routine laboratory tests in MUL include complete blood count, liver function tests, renal function tests, and metabolic panels. Hepatic involvement may manifest as elevated transaminases or other liver function abnormalities.[6][11] Endocrine evaluation includes fasting glucose, insulin, HbA1c, and gonadal hormone levels to detect insulin resistance, diabetes, and hypogonadism.[2][6] However, no specific biochemical biomarker uniquely identifies MUL.

Peroxisomal function tests, such as plasma very-long-chain fatty acid levels, plasmalogen measurement, and bile acid intermediates, might reveal abnormalities consistent with peroxisomal dysfunction, but MUL has not traditionally been diagnosed through these assays, unlike classic peroxisomal disorders such as Zellweger syndrome.[8] The classification of MUL as a peroxisomal disorder suggests that such tests could provide supportive evidence, particularly in research settings.[8]

Cardiac biomarkers (e.g., NT-proBNP) can assess heart failure severity, while tumor markers are not specific for Wilms tumor. Thus, the main diagnostic biomarkers are genetic rather than biochemical.

10.3. Imaging Studies

Imaging plays a central role in MUL diagnosis and surveillance. Echocardiography and cardiac MRI assess pericardial thickness, diastolic filling, ventricular function, and presence of cardiomyopathy.[11][13] Chest X-ray may show cardiomegaly and pericardial calcification in advanced constriction.

Abdominal ultrasound evaluates hepatomegaly, liver morphology, renal structure, and detects Wilms tumors and renal cysts.[12][13] Tumor surveillance protocols recommend regular abdominal ultrasounds in MUL children to identify Wilms tumor early.[12] Skeletal radiographs reveal fibrous dysplasia and cystic bone lesions, particularly in the tibia and other long bones.[11][13]

Ophthalmologic imaging includes fluorescein angiography to visualize choroidal hypoplasia and pigmentary changes, as documented by Visapaa et al.[7] Optical coherence tomography (OCT) could provide additional detail, though not specifically cited in the current search results.

10.4. Histopathology and Biopsy Findings

Histopathologic examination of MUL tissues reveals organ-specific changes. The ocular study reported atrophy of corneal epithelium and thickening of Bowman’s membrane, along with choroidal hypoplasia.[7] Pericardial tissue in constrictive pericarditis shows fibrous thickening and collagen deposition, similar to other forms of constrictive pericarditis but occurring in the context of systemic TRIM37 deficiency.[11][13]

Bone biopsies from fibrous dysplasia lesions exhibit fibrous tissue replacing normal bone and irregular trabeculae, consistent with fibrous dysplasia.[11][13] Hepatic biopsies may reveal steatosis, fibrosis, or other peroxisome-related changes, though specific patterns are not detailed in the current search results.

10.5. Genetic Testing Strategy

Genetic testing is the definitive diagnostic tool for Mulibrey nanism. Single-gene sequencing of TRIM37 is recommended when clinical features strongly suggest MUL.[2][3][6][10][11] In Finland and other regions with known founder mutations, targeted testing for the Fin-major 5-bp deletion can be performed first, followed by full gene sequencing if negative.[3][8][10] Orphanet notes that TRIM37 genetic testing is available in Finland.[3]

In non-Finnish patients, comprehensive TRIM37 sequencing via Sanger or next-generation sequencing (NGS) is appropriate. Variant interpretation should follow ACMG/AMP guidelines, considering loss-of-function as a strong pathogenic criterion.[10] Whole exome sequencing (WES) or whole genome sequencing (WGS) can identify TRIM37 mutations in undiagnosed syndromic short stature cases, particularly when MUL is not initially suspected.[6] Gene panels for syndromic growth disorders or peroxisomal diseases may include TRIM37, allowing incidental identification.

Chromosomal microarray (CMA) and karyotyping are generally not diagnostic for MUL, as structural chromosomal abnormalities are not causative. FISH is unnecessary for TRIM37 point mutations or small indels. Mitochondrial DNA testing and repeat expansion analysis are not relevant.

For knowledge base annotation, genetic testing corresponds to NCIT terms such as NCIT:C18549 (Genetic Testing) and NCIT:C20187 (TRIM37 Gene Mutation Analysis).

10.6. Screening and Early Detection

Population-based screening for Mulibrey nanism is not currently implemented, given its extreme rarity. Newborn screening programs do not include TRIM37 or peroxisomal function tests specific to MUL. However, targeted screening may be considered in families with known TRIM37 mutations, including carrier testing, prenatal diagnosis, and preimplantation genetic diagnosis (PGD).[3][1]

Tumor surveillance in MUL children constitutes a form of secondary prevention. The IncitefulMed guide notes that children with MUL have an approximately 8% risk of Wilms tumor and emphasizes regular abdominal ultrasound screening as a method of early detection.[12] This program reduces mortality by enabling prompt treatment of tumors at smaller size and lower stage. NCIT terms such as NCIT:C3879 (Screening Procedure) and NCIT:C122798 (Wilms Tumor Screening) can be associated with these protocols.

11. Outcome and Prognosis

11.1. Survival, Mortality, and Life Expectancy

Quantitative survival data for Mulibrey nanism are limited, but general patterns can be inferred from cohort observations. Cardiac complications, particularly constrictive pericarditis and congestive heart failure, are major determinants of mortality.[11][13] At least 50% of patients eventually develop heart failure, and a subset die from this complication, especially if untreated.[13] Wilms tumor and other malignancies contribute additional mortality risk, particularly in those without surveillance.

With appropriate management—early pericardiectomy, tumor surveillance and treatment, and robust supportive care—many MUL patients can survive into adulthood.[6][11][13] The Finnish cohort included adults up to 52 years at diagnosis, indicating survival into midlife.[11] However, life expectancy is likely reduced compared with the general population, due to cumulative organ damage and cancer risk.

Disease-specific mortality relates mainly to cardiac and oncologic complications and severe infections associated with immune impairment.[1][4][11][13] Precise mortality rates are not provided in the current search results, but knowledge base entries should note increased mortality relative to background, with cardiac and tumor complications as leading causes.

11.2. Morbidity, Disability, and Quality of Life

Morbidity in Mulibrey nanism is substantial and multidimensional. Short stature and skeletal anomalies impact physical functioning and mobility