Ichthyosis Prematurity Syndrome

Mendelian MONDO:0012089 Pathograph 33 Show in embeddings browser syndromic congenital ichthyosis inherited ichthyosis disorder of epidermal lipid metabolism

Ichthyosis prematurity syndrome (IPS) is an autosomal recessive syndromic congenital ichthyosis caused by biallelic germline variants in SLC27A4, which encodes fatty acid transport protein 4 (FATP4), an acyl-CoA synthetase that activates very-long-chain and omega-hydroxy fatty acids for synthesis of the epidermal barrier lipid omega-O-acylceramide. The fetal epidermis forms a defective barrier and sheds large amounts of corneocyte debris into the amniotic fluid. Pregnancies show polyhydramnios, echogenic amniotic fluid and separation of the chorionic and amniotic membranes from about 28 weeks, and the child is born prematurely, typically at 30 to 34 weeks, covered in a thick, greasy, clay- or vernix-like scale over erythrodermic, swollen skin. Aspiration of keratin-laden amniotic fluid causes neonatal respiratory distress or asphyxia, which is the main source of early morbidity and of the rare deaths. Peripheral eosinophilia is almost invariable and serum IgE is usually raised. The scale sheds within weeks to months; survivors have a favourable course but keep a mild, nonscaly ichthyosis or follicular hyperkeratosis, pruritus, and a lasting atopic diathesis with respiratory and food allergy.

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1
Inheritance
7
Pathophys.
17
Phenotypes
1
Hypotheses
3
Gaps
33
Pathograph
1
Genes
2
Variants
4
Medical Actions
3
Differentials
5
Models
1
Deep Research
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Inheritance

1
Autosomal recessive inheritance HP:0000007
Affected individuals carry biallelic SLC27A4 variants, homozygous (often the Scandinavian p.Cys168* founder allele, or in consanguineous families) or compound heterozygous.
Autosomal recessive inheritance
Show evidence (2 references)
PMID:19631310 SUPPORT Human Clinical
"Ichthyosis prematurity syndrome (IPS) is an autosomal-recessive disorder characterized by premature birth and neonatal asphyxia, followed by a lifelong nonscaly ichthyosis with atopic manifestations."
The gene-discovery study states the recessive mode of inheritance for the families in which it mapped the disease.
PMID:21450060 SUPPORT Human Clinical
"Four probands were compound heterozygous for four different mutations of which three are novel."
Compound heterozygosity in four of five unrelated probands supports biallelic, recessive causation.
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Mechanistic Hypotheses

1
Barrier-driven epicutaneous sensitization explains IPS atopy
ips_barrier_driven_atopy EMERGING
The atopic features of IPS arise from allergen sensitization through the defective epidermal barrier, as in filaggrin-related atopy, rather than from an intrinsic immune effect of FATP4 loss.
Pathograph links
Epidermal Permeability Barrier Failure -> Barrier-Associated Type 2 Sensitization INDIRECT UNKNOWN INTERMEDIATES The proposed route from the skin defect to eosinophilia, raised IgE and allergy is epicutaneous sensitization through the defective barrier. This is one of the explanations the literature offers, not a demonstrated one.
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Discussions and Knowledge Gaps

3
Why is complete FATP4 loss lethal in the mouse but compatible with survival and near-normal skin in humans?
HUMAN MODEL MISMATCH OPEN ips_mouse_human_severity
Attached to
pathophysiology#Epidermal Permeability Barrier Failure progression#Resolution of the birth scale
The mechanistic evidence for the acylceramide-to-barrier chain comes mainly from null mice, which die neonatally, whereas human patients with null alleles recover within weeks. If another acyl-CoA synthetase, such as FATP1, compensates in human skin after birth, the mouse overstates the lasting human barrier defect and the human postnatal course depends on a mechanism the model lacks. No study has measured FATP1 or acylceramide in patient epidermis over time.
Show evidence (2 references)
PMID:31519952 SUPPORT Model Organism
"FATP4 (SLC27A4) mutations cause ichthyosis prematurity syndrome, a nonlethal disorder. In contrast, Fatp4-/- mice die neonatally from a defective barrier."
States the mismatch.
PMID:25184958 SUPPORT Model Organism
"Here we tested the hypothesis that FATP1, the closest FATP4 homolog, can compensate for the lack of FATP4 in our mouse model of IPS, as it might do postnatally in IPS patients."
Proposes FATP1 compensation as the explanation, untested in patients.
What triggers preterm delivery in IPS pregnancies: uterine overdistension from polyhydramnios, the membrane separation, intra-amniotic inflammation from keratin debris, or something else?
KNOWLEDGE GAP OPEN ips_preterm_labour_mechanism
Attached to
phenotypes#Premature birth pathophysiology#Corneocyte Shedding into Amniotic Fluid
Preterm birth is near-universal and gives the syndrome its name, yet the only evidence linking it to the amniotic findings is their temporal order in small series. The edge from the amniotic node to premature birth is marked UNKNOWN for that reason.
Show evidence (1 reference)
PMID:21465607 SUPPORT Human Clinical
"All fetuses were delivered prematurely between 30 and 34 weeks."
Preterm delivery follows the amniotic changes in all five fetuses.
Is the eosinophilia, raised IgE and lifelong atopy of IPS a consequence of barrier-driven epicutaneous sensitization, or a direct effect of SLC27A4 loss on immune cells?
KNOWLEDGE GAP OPEN ips_atopy_mechanism
Attached to
pathophysiology#Barrier-Associated Type 2 Sensitization
Eosinophilia is present in the neonatal period, early for environmental sensitization, and atopy persists in many patients after the skin has largely normalised, which is hard to reconcile with a purely barrier-driven route. The review leaves both explanations open.
Show evidence (1 reference)
PMID:40000070 SUPPORT REVIEW SYNTHESIS Human Clinical
"Patients typically have a predisposition to atopic disease, possibly due to a defective skin barrier, epicutaneous sensitization, or as‐of‐yet effects of germline SLC27A4 variants on immune cell polarisation"
The review lists both candidate mechanisms without choosing.
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Pathophysiology

7
FATP4 Acyl-CoA Synthetase Deficiency
Biallelic loss-of-function variants in SLC27A4 (nonsense, splice-site, missense and exon deletions) leave the epidermis without functional FATP4. FATP4 is the principal very-long-chain fatty acyl-CoA synthetase of the skin, and patient fibroblasts show reduced very-long-chain fatty acid-CoA synthetase activity and reduced incorporation of very-long-chain fatty acids into cellular lipids. Missense alleles produce the same clinical picture as the nonsense founder allele, indicating that they too abolish function.
keratinocyte CL:0000312 Cell Ontology (CL) Relation: this pathophysiological event involves this cell type This pathophysiological event involves keratinocyte (CL:0000312). CL:0000312 is a cell type from the Cell Ontology.
SLC27A4 hgnc:10998 HUGO Gene Nomenclature Committee (hgnc) Relation: this pathophysiological event involves this gene This pathophysiological event involves SLC27A4 (hgnc:10998). hgnc:10998 is a gene from the HUGO Gene Nomenclature Committee.
Genetic context variant_origin: GERMLINE functional_impact_category: LOSS_OF_FUNCTION
very long-chain fatty acid metabolic process GO:0000038 ↓ DECREASED Gene Ontology (GO) Relation: this pathophysiological event involves this biological process This pathophysiological event involves decreased very long-chain fatty acid metabolic process (GO:0000038). GO:0000038 is a biological process from the Gene Ontology.
very long-chain fatty acid-CoA ligase activity GO:0031957 ↓ DECREASED Gene Ontology (GO) Relation: this pathophysiological event involves this molecular function This pathophysiological event involves decreased very long-chain fatty acid-CoA ligase activity (GO:0031957). GO:0031957 is a molecular function from the Gene Ontology.
Experimental models
IPS patient dermal fibroblasts PRIMARY CELL CULTURE Shows the reduced very-long-chain acyl-CoA synthetase activity directly.
Animal models
Great Dane ichthyosis Dog partially recapitulates Loss of intact SLC27A4 protein in affected skin with a severe skin phenotype.
Downstream
Reduced Epidermal omega-O-Acylceramide Synthesis FATP4 activates the omega-hydroxy ultra-long-chain fatty acid that is an intermediate of acylceramide synthesis; without it, acylceramide production falls.
Show evidence (4 references)
PMID:19631310 SUPPORT Human Clinical
"Here we show that the gene encoding the fatty acid transport protein 4 (FATP4) is mutated in individuals with IPS."
Gene-discovery result identifying SLC27A4/FATP4 as the disease gene.
PMID:19631310 SUPPORT In Vitro
"Fibroblasts derived from a patient with IPS show reduced activity of very long-chain fatty acids (VLCFA)-CoA synthetase and a specific reduction in the incorporation of VLCFA into cellular lipids."
Patient-derived cells show the enzymatic loss that defines this node. The assay was in cultured fibroblasts from one patient, not in epidermis.
PMID:17522045 SUPPORT INDIRECT In Vitro
"Compared with w.t. fibroblasts, cells lacking FATP4 had an 83% decrease in C24:0 activation."
Dermal fibroblast lines from FATP4-null mice show that FATP4 supplies most of the very-long-chain acyl-CoA synthetase activity, which is why its loss is not compensated in skin cells. Indirect because the cells are murine.
+ 1 more reference
Reduced Epidermal omega-O-Acylceramide Synthesis
Differentiating keratinocytes make far less omega-O-acylceramide and bound omega-hydroxyceramide, the lipids of the intercellular lamellae and the corneocyte lipid envelope, and the remaining ceramides have shortened chains. Lamellar bodies, the corneocyte lipid envelope and the cornified envelope are abnormal on electron microscopy in the knockout mouse. The lipid measurements come from Fatp4-null mice and FATP4-knockdown human keratinocytes; a comparable lipidomic study of patient epidermis has not been reported.
keratinocyte CL:0000312 Cell Ontology (CL) Relation: this pathophysiological event involves this cell type This pathophysiological event involves keratinocyte (CL:0000312). CL:0000312 is a cell type from the Cell Ontology. corneocyte CL:0002153 Cell Ontology (CL) Relation: this pathophysiological event involves this cell type This pathophysiological event involves corneocyte (CL:0002153). CL:0002153 is a cell type from the Cell Ontology.
epidermal acylceramide biosynthesis GO:0046513 ↓ DECREASED Gene Ontology (GO) Relation: this pathophysiological event involves this biological process This pathophysiological event involves decreased epidermal acylceramide biosynthesis, annotated with ceramide biosynthetic process (GO:0046513). GO:0046513 is a biological process from the Gene Ontology. cornified envelope assembly GO:1903575 ↓ DECREASED Gene Ontology (GO) Relation: this pathophysiological event involves this biological process This pathophysiological event involves decreased cornified envelope assembly (GO:1903575). GO:1903575 is a biological process from the Gene Ontology.
Experimental models
FATP4-knockdown human keratinocytes OTHER Reproduces the acylceramide deficit in human cells.
Animal models
Fatp4 targeted knockout mouse Mouse recapitulates Epidermal acylceramide falls to about a tenth of wild type. The readout is a lipid quantity, but it is measured by lipidomics of whole epidermis from the intact animal, so the model observes the tissue-level lipid content rather than the keratinocyte synthetic step itself.
Downstream
Epidermal Permeability Barrier Failure Acylceramide is the lipid that organises the stratum corneum lamellae; its loss leaves the barrier permeable.
Show evidence (4 references)
PMID:31974308 SUPPORT Model Organism
"Decreased levels and shortening of chain lengths were observed in the saturated, nonacylated ceramides."
Fatp4 knockout epidermis shows the ceramide deficit and chain shortening.
PMID:31974308 SUPPORT In Vitro
"A decrease in acylceramide levels was also observed in human keratinocytes with FATP4 knockdown."
The acylceramide deficit is reproduced in human keratinocytes, which is the only human-cell evidence for this node.
PMID:31519952 SUPPORT Model Organism
"Mutants showed lamellar body, corneocyte lipid envelope, and cornified envelope abnormalities."
Electron microscopy of Fatp4-null mouse epidermis shows the structural consequences in the lamellar lipid and cornified envelope compartments.
+ 1 more reference
Epidermal Permeability Barrier Failure
The fetal and neonatal stratum corneum fails as a permeability barrier. In the mouse this is lethal shortly after birth; in humans the barrier defect is most severe in fetal and neonatal skin and is partly compensated later. Restoring FATP4 with an intact acyl-CoA synthetase domain in suprabasal keratinocytes alone rescues the mouse skin phenotype, placing the defect in the epidermis rather than in a systemic or placental lipid disturbance.
Barrier-driven epicutaneous sensitization explains IPS atopy
corneocyte CL:0002153 Cell Ontology (CL) Relation: this pathophysiological event involves this cell type This pathophysiological event involves corneocyte (CL:0002153). CL:0002153 is a cell type from the Cell Ontology.
establishment of skin barrier GO:0061436 ↓ DECREASED Gene Ontology (GO) Relation: this pathophysiological event involves this biological process This pathophysiological event involves decreased establishment of skin barrier (GO:0061436). GO:0061436 is a biological process from the Gene Ontology.
stratum corneum UBERON:0002027 Uberon multi-species anatomy ontology (UBERON) Relation: this pathophysiological event occurs in this anatomical location This pathophysiological event occurs in stratum corneum, annotated with stratum corneum of epidermis (UBERON:0002027). UBERON:0002027 is an anatomical location from the Uberon multi-species anatomy ontology.
Animal models
Fatp4 targeted knockout mouse Mouse recapitulates Reproduces the epidermal barrier failure and hyperkeratosis.
Suprabasal FATP4 or FATP1 transgene rescue of Fatp4 mutant mice Mouse rescues Shows that the barrier defect is cell-autonomous to keratinocytes and depends on the acyl-CoA synthetase activity.
Downstream
Epidermal Hyperkeratosis with Lamellar Membrane Aggregates As in other disorders of cornification, the barrier defect is accompanied by a thickened, hyperproliferative epidermis and abnormal membrane material in the upper epidermis. The signal linking the lipid defect to hyperproliferation has not been defined in IPS.
Corneocyte Shedding into Amniotic Fluid The abnormal fetal epidermis sheds corneocytes into the amniotic fluid, producing echogenic sediment visible on ultrasound. Why the defective epidermis sheds so much material in utero has not been studied directly.
Barrier-Associated Type 2 Sensitization The proposed route from the skin defect to eosinophilia, raised IgE and allergy is epicutaneous sensitization through the defective barrier. This is one of the explanations the literature offers, not a demonstrated one. Barrier-driven epicutaneous sensitization explains IPS atopy
Erythroderma The newborn skin is red and swollen beneath the scale, which regresses as the scale sheds.
Ichthyosis After the neonatal period a mild, nonscaly ichthyosis persists, the residual expression of the barrier defect.
Show evidence (3 references)
PMID:31974308 SUPPORT Model Organism
"Fatp4 knockout (KO) mice exhibited severe skin barrier dysfunction and morphological abnormalities in the epidermis."
Direct demonstration of barrier failure in the knockout.
PMID:17401141 SUPPORT Model Organism
"We conclude that expression of FATP4 with an intact acyl-CoA synthetase domain in suprabasal keratinocytes is necessary for normal skin development and that FATP4 functions in establishing the cornified envelope."
Transgenic rescue localises the barrier defect to the acyl-CoA synthetase function of FATP4 in suprabasal keratinocytes.
PMID:19631310 SUPPORT INDIRECT Human Clinical
"The human phenotype is consistent with Fatp4 deficiency in mice that is characterized by a severe skin phenotype, a defective permeability barrier function, and perturbed VLCFA metabolism."
The discovery paper draws the mouse-to-human parallel; the human barrier defect is inferred from phenotype rather than measured.
Epidermal Hyperkeratosis with Lamellar Membrane Aggregates
Skin biopsy shows hyperkeratosis, acanthosis and dermal inflammation, and electron microscopy shows characteristic aggregates of curved, trilamellar membrane structures in the stratum granulosum and stratum corneum, which are regarded as diagnostic of IPS. Clinically this is the thick, caseous, vernix-like scale of the newborn.
keratinocyte CL:0000312 Cell Ontology (CL) Relation: this pathophysiological event involves this cell type This pathophysiological event involves keratinocyte (CL:0000312). CL:0000312 is a cell type from the Cell Ontology.
keratinization GO:0031424 ⚠ ABNORMAL Gene Ontology (GO) Relation: this pathophysiological event involves this biological process This pathophysiological event involves abnormal keratinization (GO:0031424). GO:0031424 is a biological process from the Gene Ontology.
skin epidermis UBERON:0001003 Uberon multi-species anatomy ontology (UBERON) Relation: this pathophysiological event occurs in this anatomical location This pathophysiological event occurs in skin epidermis (UBERON:0001003). UBERON:0001003 is an anatomical location from the Uberon multi-species anatomy ontology.
Downstream
Caseous vernix-like scale at birth The hyperkeratotic fetal epidermis is the thick, greasy, vernix-like scale seen at delivery.
Hyperkeratosis Hyperkeratosis is the histological readout of this node.
Follicular hyperkeratosis After the scale resolves, residual keratinization abnormality is often follicular.
Show evidence (2 references)
PMID:21856041 SUPPORT Human Clinical
"Histopathologic and ultrastructural examination of skin biopsy specimens showed hyperkeratosis, acanthosis, dermal inflammation, and characteristic aggregates of curved lamellar structures in the upper epidermis."
Biopsy findings in the Norwegian series define this node in human skin.
PMID:19119129 SUPPORT Human Clinical
"electron microscopy of a skin biopsy specimen showing pathognomonic trilamellar membrane aggregations in the stratum corneum and stratum granulosum"
Independent sibling report of the same ultrastructural lesion.
Corneocyte Shedding into Amniotic Fluid
Corneocytes and keratin debris from the fetal skin accumulate in the amniotic fluid from about 28 weeks, producing echogenic sediment in the amniotic cavity. The debris is thought to obstruct fetal swallowing and passage of fluid through the gut, which would explain the polyhydramnios and the empty fetal stomach seen on ultrasound, and it is the material later aspirated at birth.
amniotic fluid UBERON:0000173 Uberon multi-species anatomy ontology (UBERON) Relation: this pathophysiological event occurs in this anatomical location This pathophysiological event occurs in amniotic fluid (UBERON:0000173). UBERON:0000173 is an anatomical location from the Uberon multi-species anatomy ontology.
Downstream
Polyhydramnios Keratin debris is proposed to block fetal swallowing or gut transit of amniotic fluid. The mechanism is inferred, not demonstrated.
Spontaneous chorioamniotic separation Membrane separation accompanies the echogenic fluid in every fetus of the prenatal series. How the two are linked is not known; the review suggests a shared embryological origin of amnion and surface ectoderm.
Aspiration of Keratin Debris into the Airways At delivery the infant aspirates the corneocyte-containing amniotic fluid.
Premature birth Preterm delivery follows the polyhydramnios and membrane separation in nearly every affected pregnancy, but what triggers labour has not been established. Polyhydramnios-related uterine overdistension is one plausible route; it has not been tested in IPS.
Show evidence (1 reference)
PMID:21465607 SUPPORT Human Clinical
"Separation of chorionic and amniotic membranes with a peculiar appearance of echo-free fluid in the chorionic cavity and echogenic sediment in the amniotic cavity were observed between 28 + 5 and 32 + 3 weeks in all cases."
All five fetuses in the series showed echogenic amniotic sediment, the ultrasound sign of this node.
Aspiration of Keratin Debris into the Airways
Aspirated keratin debris fills the bronchial tree and alveoli, obstructing the airways at birth. Restricted chest expansion from tight skin, the main route in harlequin ichthyosis and collodion babies, is not thought to be the principal mechanism in IPS. Prematurity adds surfactant-deficiency risk, but the respiratory distress rate in IPS far exceeds the rate expected for gestational age.
bronchus UBERON:0002185 Uberon multi-species anatomy ontology (UBERON) Relation: this pathophysiological event occurs in this anatomical location This pathophysiological event occurs in bronchus (UBERON:0002185). UBERON:0002185 is an anatomical location from the Uberon multi-species anatomy ontology. alveolus of lung UBERON:0002299 Uberon multi-species anatomy ontology (UBERON) Relation: this pathophysiological event occurs in this anatomical location This pathophysiological event occurs in alveolus of lung (UBERON:0002299). UBERON:0002299 is an anatomical location from the Uberon multi-species anatomy ontology.
Downstream
Neonatal respiratory distress Airway obstruction by debris produces respiratory distress at birth.
Neonatal asphyxia In severe cases the obstruction causes life-threatening asphyxia.
Aspiration pneumonia Aspirated debris can be followed by aspiration pneumonia.
Show evidence (3 references)
PMID:21856041 SUPPORT Human Clinical
"postmortem examination of lung tissue in two patients revealed keratin debris filling the bronchial tree and alveoli"
Direct autopsy evidence of airway keratin debris, in two patients.
PMID:39865317 SUPPORT BACKGROUND Human Clinical
"While respiratory distress may also be seen in collodion and Harlequin presentations, in IPS it is thought to be primarily due to aspiration of keratin debris in amniotic fluid rather than restricted chest expansion"
Distinguishes the aspiration mechanism from the restrictive-skin mechanism of other severe neonatal ichthyoses; stated in the discussion of a case letter, citing earlier work.
PMID:40000070 SUPPORT Human Clinical
"with 79.7% reporting respiratory distress, significantly higher than the 5% approximate age‐matched incidence for the general population"
The excess over the gestational-age-matched rate argues that prematurity alone does not explain the respiratory distress.
Barrier-Associated Type 2 Sensitization
Peripheral eosinophilia is almost invariable in the neonate, serum IgE is raised in most patients, and respiratory or food allergy develops in most. Whether this follows from epicutaneous sensitization through the defective barrier, as in other barrier disorders, or from a direct effect of FATP4 loss on immune cells has not been resolved (see discussion ips_atopy_mechanism).
eosinophil CL:0000771 Cell Ontology (CL) Relation: this pathophysiological event involves this cell type This pathophysiological event involves eosinophil (CL:0000771). CL:0000771 is a cell type from the Cell Ontology.
Downstream
Increased total eosinophil count Eosinophilia is the blood readout of this node.
Increased circulating IgE concentration Raised total IgE reflects class switching in this node.
Allergy Sensitization leads to clinical respiratory and food allergy.
Pruritus Chronic pruritus accompanies the atopic diathesis and the residual ichthyosis; which contributes more is not established.
Show evidence (1 reference)
PMID:21856041 SUPPORT Human Clinical
"Peripheral blood eosinophilia was invariably present and most patients had increased serum immunoglobulin E levels."
The type 2 signature in the 23-patient Norwegian series.
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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 Ichthyosis Prematurity Syndrome 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

17
Blood 2
Increased total eosinophil count VERY_FREQUENT HP:0001880 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Peripheral blood eosinophilia, annotated with Increased total eosinophil count (HP:0001880). HP:0001880 is a phenotype from the Human Phenotype Ontology.
Show evidence (2 references)
PMID:40000070 SUPPORT Human Clinical
"Eosinophilia was identified in 37 out of 38 cases reporting blood eosinophil count, with values ranging from 1050 to 14,175 cells/μL and 9%–38% of white cell count."
Pooled frequency and range of eosinophilia.
PMID:21856041 SUPPORT Human Clinical
"Peripheral blood eosinophilia was invariably present"
Present in every patient of the Norwegian series.
Increased circulating IgE concentration VERY_FREQUENT HP:0003212 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Elevated serum IgE, annotated with Increased circulating IgE concentration (HP:0003212). HP:0003212 is a phenotype from the Human Phenotype Ontology.
Show evidence (2 references)
PMID:40000070 SUPPORT Human Clinical
"Raised IgE was identified in 17 out of 19 cases reporting IgE count."
Pooled frequency among cases tested.
PMID:21856041 SUPPORT Human Clinical
"most patients had increased serum immunoglobulin E levels"
Most patients of the Norwegian series had raised IgE.
Immune 3
Erythroderma HP:0001019 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Neonatal erythroderma, annotated with Erythroderma (HP:0001019), qualified as temporality transient. HP:0001019 is a phenotype from the Human Phenotype Ontology.
Temporal: TRANSIENT
Show evidence (1 reference)
PMID:21856041 SUPPORT Human Clinical
"The skin appeared erythrodermic, swollen, and covered by a greasy, thick vernix caseosa-like"
Erythroderma is part of the neonatal skin description.
Aspiration pneumonia HP:0011951 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Aspiration pneumonia (HP:0011951). HP:0011951 is a phenotype from the Human Phenotype Ontology.
Show evidence (1 reference)
PMID:21465607 SUPPORT Human Clinical
"All neonates had difficulties in breathing, two developed aspiration pneumonia"
Two of five neonates had aspiration pneumonia.
Allergy FREQUENT HP:0012393 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Respiratory and food allergy, annotated with Allergy (HP:0012393), qualified as temporality chronic. HP:0012393 is a phenotype from the Human Phenotype Ontology.
Temporal: CHRONIC
Show evidence (2 references)
PMID:21856041 SUPPORT Human Clinical
"Over 70% of the patients had a history of respiratory allergy and/or food allergy."
Frequency of clinical allergy in the series.
PMID:40000070 SUPPORT BACKGROUND Human Clinical
"Long‐term prognosis is good, and ichthyosis frequently resolves, leaving only an atopic diathesis as a persisting clinical feature"
The review's introduction describes atopy as the persisting feature.
Integument 7
Caseous vernix-like scale at birth VERY_FREQUENT Caseous vernix-like desquamation HP:0025724 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Thick caseous vernix-like desquamating scale, annotated with Caseous vernix-like desquamation (HP:0025724), qualified as temporality transient. HP:0025724 is a phenotype from the Human Phenotype Ontology.
Temporal: TRANSIENT
Show evidence (2 references)
PMID:40000070 SUPPORT Human Clinical
"All identified cases had classical cutaneous characteristics of IPS: congenital thick, clay‐like scale"
Present in all 59 published cases, though case selection depended on the phenotype.
PMID:21856041 SUPPORT Human Clinical
"The skin appeared erythrodermic, swollen, and covered by a greasy, thick vernix caseosa-like"
Clinical description of the scale in the Norwegian series.
Pruritus FREQUENT HP:0000989 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Chronic pruritus, annotated with Pruritus (HP:0000989), qualified as temporality chronic. HP:0000989 is a phenotype from the Human Phenotype Ontology.
Temporal: CHRONIC
Show evidence (1 reference)
PMID:21856041 SUPPORT Human Clinical
"Many patients subsequently had chronic, severe pruritus."
The series reports chronic severe pruritus in many patients, which maps to FREQUENT.
Ichthyosis HP:0008064 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Mild lifelong nonscaly ichthyosis, annotated with Ichthyosis (HP:0008064), qualified as temporality chronic. HP:0008064 is a phenotype from the Human Phenotype Ontology.
Temporal: CHRONIC
Show evidence (2 references)
PMID:19631310 SUPPORT Human Clinical
"followed by a lifelong nonscaly ichthyosis with atopic manifestations"
States the residual ichthyosis.
PMID:21856041 SUPPORT Human Clinical
"evolved rapidly to a mild chronic ichthyosis"
The neonatal scale evolves into mild chronic ichthyosis.
Follicular hyperkeratosis HP:0007502 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Follicular hyperkeratosis (HP:0007502), qualified as temporality chronic. HP:0007502 is a phenotype from the Human Phenotype Ontology.
Temporal: CHRONIC
Show evidence (1 reference)
PMID:40000070 SUPPORT Human Clinical
"Skin quality following resolution was characterized by persistent mild ichthyosis and/or follicular keratosis."
Residual follicular keratosis across published cases.
Hyperkeratosis HP:0000962 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Epidermal hyperkeratosis, annotated with Hyperkeratosis (HP:0000962). HP:0000962 is a phenotype from the Human Phenotype Ontology.
Show evidence (1 reference)
PMID:21856041 SUPPORT Human Clinical
"Histopathologic and ultrastructural examination of skin biopsy specimens showed hyperkeratosis, acanthosis, dermal inflammation"
Biopsy finding in the Norwegian series.
Alopecia HP:0001596 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Alopecia (HP:0001596). HP:0001596 is a phenotype from the Human Phenotype Ontology.
Show evidence (1 reference)
PMID:39865317 SUPPORT BACKGROUND Human Clinical
"patients may be left with persistent mild generalised ichthyosis, atopic manifestations or other skin abnormalities such as follicular hyperkeratosis, alopecia and hypohidrosis"
Names alopecia among the residual skin abnormalities; the review cites two earlier reports for it.
Hypohidrosis HP:0000966 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Hypohidrosis (HP:0000966). HP:0000966 is a phenotype from the Human Phenotype Ontology.
Show evidence (1 reference)
PMID:39865317 SUPPORT BACKGROUND Human Clinical
"patients may be left with persistent mild generalised ichthyosis, atopic manifestations or other skin abnormalities such as follicular hyperkeratosis, alopecia and hypohidrosis"
Names hypohidrosis among the residual skin abnormalities.
Prenatal and Birth 3
Polyhydramnios FREQUENT HP:0001561 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Polyhydramnios (HP:0001561). HP:0001561 is a phenotype from the Human Phenotype Ontology.
Show evidence (2 references)
PMID:40000070 SUPPORT Human Clinical
"Polyhydramnios remains the most frequently reported antenatal finding in IPS and was identified in 27 cases"
Pooled count across published cases.
PMID:21465607 SUPPORT Human Clinical
"All five developed polyhydramnios between 28 and 31 weeks."
Every fetus in the prenatal series developed polyhydramnios.
Spontaneous chorioamniotic separation HP:0025712 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Separation of chorionic and amniotic membranes, annotated with Spontaneous chorioamniotic separation (HP:0025712). HP:0025712 is a phenotype from the Human Phenotype Ontology.
Show evidence (2 references)
PMID:21465607 SUPPORT Human Clinical
"Prenatal sonographic signs of IPS are separation of the membranes, echogenic amniotic fluid and echo-free chorionic fluid occurring between 28 and 32 weeks' gestation."
Membrane separation is one of the defining prenatal signs.
PMID:22927265 SUPPORT Human Clinical
"At 31 weeks of gestation, separation of amniotic and chorionic membranes was identified as well as polyhydramnion."
An independent case with the same finding.
Premature birth VERY_FREQUENT HP:0001622 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Premature birth (HP:0001622). HP:0001622 is a phenotype from the Human Phenotype Ontology.
Show evidence (2 references)
PMID:21856041 SUPPORT Human Clinical
"All patients were born prematurely with sometimes life-threatening neonatal asphyxia"
Preterm birth in every patient of a 23-patient series.
PMID:19119129 SUPPORT Human Clinical
"Ichthyosis prematurity syndrome is a rare syndrome characterized by the clinical triad of premature birth, thick caseous desquamating epidermis, and neonatal asphyxia."
Names preterm birth as one of the three defining features.
Respiratory 2
Neonatal respiratory distress FREQUENT HP:0002643 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Neonatal respiratory distress (HP:0002643), qualified as temporality acute. HP:0002643 is a phenotype from the Human Phenotype Ontology.
Temporal: ACUTE
Show evidence (2 references)
PMID:40000070 SUPPORT Human Clinical
"the most common postnatal complication was respiratory distress syndrome (RDS)"
The commonest postnatal complication across published cases.
PMID:21465607 SUPPORT Human Clinical
"All neonates had difficulties in breathing"
Every neonate in the prenatal series had respiratory difficulty.
Neonatal asphyxia HP:0012768 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Neonatal asphyxia (HP:0012768), qualified as temporality acute. HP:0012768 is a phenotype from the Human Phenotype Ontology.
Temporal: ACUTE
Show evidence (1 reference)
PMID:19631310 SUPPORT Human Clinical
"characterized by premature birth and neonatal asphyxia"
Neonatal asphyxia is named as a defining feature.
🧬

Genetic Associations

1
SLC27A4
Gene: SLC27A4 hgnc:10998 gene page HUGO Gene Nomenclature Committee (hgnc) Relation: this disease-associated gene is this gene This disease-associated gene is SLC27A4 (hgnc:10998). hgnc:10998 is a gene from the HUGO Gene Nomenclature Committee. relationship_type: CAUSATIVE variant_origin: GERMLINE
Autosomal recessive inheritance
Show evidence (2 references)
PMID:19631310 SUPPORT Human Clinical
"Here we show that the gene encoding the fatty acid transport protein 4 (FATP4) is mutated in individuals with IPS."
The gene-disease discovery statement.
PMID:23271751 SUPPORT BACKGROUND Model Organism
"Mutations in human SLC27A4, which encodes FATP4, cause ichthyosis prematurity syndrome, characterized by a thick desquamating epidermis and premature birth."
Restates the established gene-disease relationship.
Variants (2)
c.504C>A (p.Cys168*)
Nonsense founder allele shared by the Scandinavian families, present homozygous or compound heterozygous in all Scandinavian patients screened in the cited study.
Show evidence (1 reference)
PMID:21450060 SUPPORT BACKGROUND Human Clinical
"The p.C168X nonsense variant is prevalent in the Scandinavian IPS population and all patients from this geographical region were found homozygous or compound heterozygous for this mutation."
Establishes p.C168X as the regional founder allele.
SLC27A4 exon 8-10 deletion Pathogenic
Gene-level deletion of exons 8 to 10, reported as pathogenic in trans with a missense variant of uncertain significance (c.986C>T, p.Thr329Met). It shows that deletion/duplication analysis is needed when sequencing finds only one allele.
Show evidence (1 reference)
PMID:39865317 SUPPORT Human Clinical
"The first was a pathogenic deletion of exons 8 to 10, previously implicated in IPS"
The case report classifies the exon deletion as pathogenic.
💊

Medical Actions

4
Neonatal respiratory support
Action: neonatal respiratory supportNCI Thesaurus (NCIT) Relation: this treatment is this clinical intervention This treatment is neonatal respiratory support, annotated with Mechanical Ventilation (NCIT:C70909). NCIT:C70909 is a clinical intervention from the NCI Thesaurus. Ontology label: Mechanical Ventilation NCIT:C70909
Platform: Device
A neonatal intensive care team should attend delivery because of the risk of asphyxia. Airway clearance and respiratory support, non-invasive (CPAP, nasal oxygen, high-frequency oscillation) or invasive ventilation, are the main treatment; 27 of 59 published cases needed support. Surfactant has been given but its benefit is uncertain because the cause is airway debris rather than surfactant deficiency.
Mechanism Target:
Aspiration of Keratin Debris into the Airways — Supports ventilation while the aspirated debris is cleared.
Target Phenotypes: Neonatal respiratory distress HP:0002643 Human Phenotype Ontology (HP) Relation: this treatment targets this phenotype This treatment targets Neonatal respiratory distress (HP:0002643). HP:0002643 is a phenotype from the Human Phenotype Ontology.
Show evidence (2 references)
PMID:40000070 SUPPORT Human Clinical
"Treatment primarily consisted of respiratory support to manage respiratory distress."
Respiratory support is the main treatment across published cases.
PMID:21465607 SUPPORT Human Clinical
"Delivery occurs at 30-34 weeks and, as there is a high risk of asphyxia, an experienced neonatal intensive care unit team should be present at delivery."
Recommends neonatal intensive care at delivery.
Emollient skin care
Action: emollient skin careNCI Thesaurus (NCIT) Relation: this treatment is this clinical intervention This treatment is emollient skin care, annotated with Supportive Care (NCIT:C15747). NCIT:C15747 is a clinical intervention from the NCI Thesaurus. Ontology label: Supportive Care NCIT:C15747
Platform: Other
Bland emollients such as white soft paraffin are used while the scale sheds spontaneously. There is no IPS-specific evidence that they speed resolution; they are used because they are safe and established in other ichthyoses and may support the defective barrier.
Mechanism Target:
Epidermal Permeability Barrier Failure — Topical occlusion supports the defective barrier.
Target Phenotypes: Caseous vernix-like desquamation HP:0025724 Human Phenotype Ontology (HP) Relation: this treatment targets this phenotype This treatment targets Caseous vernix-like desquamation (HP:0025724). HP:0025724 is a phenotype from the Human Phenotype Ontology.
Show evidence (3 references)
PMID:40000070 SUPPORT Human Clinical
"There is insufficient evidence that emollients confer any therapeutic advantage, as the scale‐like vernix sheds spontaneously"
Supports the description's statement that IPS-specific benefit is unproven.
PMID:40000070 SUPPORT REVIEW SYNTHESIS Human Clinical
"emollients are a simple and safe intervention that is well established in other forms of ichthyosis"
The rationale for use rests on safety and on experience in other ichthyoses, not on IPS data.
PMID:39865317 SUPPORT Human Clinical
"His skin was managed with white soft paraffin, with spontaneous shedding of scale."
A single case managed with white soft paraffin.
Low-dose dexamethasone for ventilator dependence
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: dexamethasone CHEBI:41879 Chemical Entities of Biological Interest (CHEBI) Relation: this treatment uses this therapeutic agent This treatment uses dexamethasone (CHEBI:41879). CHEBI:41879 is a therapeutic agent from Chemical Entities of Biological Interest.
Platform: Small molecule
Proposed from one family case report for ventilator-dependent infants with IPS. Case-report-level only; not an established treatment.
Target Phenotypes: Neonatal respiratory distress HP:0002643 Human Phenotype Ontology (HP) Relation: this treatment targets this phenotype This treatment targets Neonatal respiratory distress (HP:0002643). HP:0002643 is a phenotype from the Human Phenotype Ontology.
Show evidence (1 reference)
PMID:34417235 SUPPORT Human Clinical
"discuss a potential role for low-dose dexamethasone in the management of ventilator-dependent patients with IPS"
A single family case report proposing the use; it does not establish efficacy.
Genetic counselling
Action: Genetic counselingNCI Thesaurus (NCIT) Relation: this treatment is this clinical intervention This treatment is Genetic counseling (NCIT:C15240). NCIT:C15240 is a clinical intervention from the NCI Thesaurus. Ontology label: Genetic Counseling NCIT:C15240
Parents should be offered genetic counselling because the disease is germline and recessive.
Show evidence (1 reference)
PMID:39865317 SUPPORT Human Clinical
"Clinicians should consider genetic counselling for parents given the germline nature of the diagnosis."
Recommends counselling on the basis of germline inheritance.
🔬

Diagnosis

3
Prenatal ultrasound
From 28 weeks, polyhydramnios with separation of the chorionic and amniotic membranes, echo-free chorionic fluid and echogenic amniotic sediment suggests IPS and allows a neonatal team to be present at delivery. These signs are suggestive rather than diagnostic.
Results: Membrane separation, echogenic amniotic fluid and echo-free chorionic fluid between 28 and 32 weeks.
Show evidence (1 reference)
PMID:21465607 SUPPORT Human Clinical
"Prenatal sonographic signs of IPS are separation of the membranes, echogenic amniotic fluid and echo-free chorionic fluid occurring between 28 and 32 weeks' gestation."
The series proposes these as the prenatal signs.
Skin biopsy with electron microscopy
Electron microscopy shows trilamellar membrane aggregates in the stratum granulosum and stratum corneum, which support the diagnosis when genetic results are pending or inconclusive.
Results: Curved trilamellar membrane aggregates in the upper epidermis.
Show evidence (1 reference)
PMID:19119129 SUPPORT Human Clinical
"the diagnosis supported by electron microscopy of a skin biopsy specimen showing pathognomonic trilamellar membrane aggregations in the stratum corneum and stratum granulosum"
Electron microscopy supported the diagnosis in the index sibling pair.
SLC27A4 molecular testing
Sequencing of SLC27A4, alone or on a congenital ichthyosis panel, confirms the diagnosis. Because exon-level deletions occur, a single detected allele calls for deletion/duplication analysis.
genetic testing NCIT:C15709 NCI Thesaurus (NCIT)
Results: Biallelic pathogenic SLC27A4 variants.
Show evidence (1 reference)
PMID:39865317 SUPPORT Human Clinical
"Genetic testing confirmed the presence of germline, compound heterozygous variants of the SLC27A4 gene."
Molecular confirmation in a case where one allele was an exon deletion.
📈

Progression

4
Third-trimester prenatal phase
Age: from about 28 weeks of gestation to delivery
Polyhydramnios, separation of the chorionic and amniotic membranes, echogenic sediment in the amniotic cavity and echo-free chorionic fluid appear between 28 and 32 weeks. Delivery follows prematurely at 30 to 34 weeks.
Show evidence (2 references)
PMID:21465607 SUPPORT Human Clinical
"Prenatal sonographic signs of IPS are separation of the membranes, echogenic amniotic fluid and echo-free chorionic fluid occurring between 28 and 32 weeks' gestation."
A national fetal-medicine-centre series of five fetuses gives the timing of the prenatal phase.
PMID:21465607 SUPPORT Human Clinical
"All fetuses were delivered prematurely between 30 and 34 weeks."
Gives the end of the prenatal phase.
Neonatal phase
Age: birth to the first weeks of life
The newborn is covered in thick, greasy, vernix-like scale over erythrodermic, swollen skin and has respiratory distress or asphyxia, sometimes requiring ventilation. Eosinophilia is present. This is the period of risk: six of 59 published cases were fatal, giving an estimated six-month survival of 87.6%.
Show evidence (3 references)
PMID:21856041 SUPPORT Human Clinical
"All patients were born prematurely with sometimes life-threatening neonatal asphyxia"
The 23-patient Norwegian series describes the neonatal presentation.
PMID:40000070 SUPPORT Human Clinical
"Mortality in these cases was attributed to respiratory and/or cardiac sequelae or sepsis."
The fatal cases in the systematic review arise from the neonatal respiratory and infectious complications.
PMID:40000070 SUPPORT Human Clinical
"Long-term prognosis is generally good, although six (10.2%) fulminant cases were identified with an estimated 6-month survival rate of 87.6% (95% confidence interval: 78.8-97.4)."
Gives the case-fatality count and the Kaplan-Meier six-month survival across published cases with follow-up.
Resolution of the birth scale
Age: weeks to a few months after birth
The vernix-like scale sheds spontaneously; the median reported duration was 10 weeks, although an exact duration was available for only a minority of published cases.
Show evidence (2 references)
PMID:40000070 SUPPORT Human Clinical
"The median duration of the cutaneous scale was 10 weeks, though patients usually have persisting atopy."
Gives the duration of the scaling phase across published cases.
PMID:19119129 SUPPORT Human Clinical
"Marked regression of the edema and ichthyotic scaling was observed within a few weeks."
A sibling pair report documents the same rapid regression.
Lifelong mild phase
Age: infancy onward
After the birth scale resolves, the skin settles into a mild, nonscaly ichthyosis or follicular hyperkeratosis, often with chronic pruritus and atopic disease; long-term prognosis is otherwise good.
Show evidence (2 references)
PMID:21856041 SUPPORT Human Clinical
"evolved rapidly to a mild chronic ichthyosis. Many patients subsequently had chronic, severe pruritus."
Describes the course after the neonatal period in the Norwegian series.
PMID:40000070 SUPPORT Human Clinical
"The cutaneous manifestations of IPS resolve over a period of weeks, and patients generally have a favorable long-term prognosis."
Summarises the long-term course across published cases.
📊

Prevalence

3
Worldwide
Unknown 0.5 per 100,000 1–9 per 1,000,000
The 2025 systematic review repeats a worldwide estimate of 1 in 200,000 from earlier literature and says the true figure may be higher given recent cases from many ancestries. The measure (birth or point prevalence) is not stated by the source, so measure_type is UNKNOWN.
Show evidence (1 reference)
PMID:40000070 SUPPORT BACKGROUND Human Clinical
"Prevalence worldwide is estimated to be 1 in 200,000 cases, though recent cases from diverse ethnic backgrounds suggest that frequency may be underestimated"
States the worldwide estimate in the review's introduction, citing earlier work rather than deriving it, hence BACKGROUND.
Norway and Sweden
Carrier Frequency 2000.0 per 100,000 >1 in 1,000 (carriers)
Local carrier frequency of about 1 in 50, attributed to the p.Cys168* founder allele. Stated in the introduction of a mutation-screening paper, citing earlier work; not a population screening result of that paper.
Show evidence (1 reference)
PMID:21450060 SUPPORT BACKGROUND Human Clinical
"IPS is more prevalent in Norway and Sweden with an estimated local carrier frequency of one in 50 suggesting a founder mutation"
Gives the Scandinavian carrier frequency and links it to a founder allele.
Published IPS literature to September 2024
Cases In Literature
A PROSPERO-registered systematic review found 59 reported cases in 26 studies, from European, African, Middle Eastern, Asian and American patients, so the disease is not restricted to Scandinavia.
Show evidence (1 reference)
PMID:40000070 SUPPORT Human Clinical
"We identified 26 studies reporting 59 cases of IPS (PROSPERO database: CRD42024533988). While IPS was previously thought to predominantly affect Norwegian and Swedish patients, we identified cases from a broad range of ethnicities."
The cumulative case count and its ancestral breadth are stated directly.
🔀

Differential Diagnoses

3

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

Autosomal recessive congenital ichthyosis MONDO:0017265
Overlapping Features IPS shares recessive inheritance, congenital scaling and a lipid-barrier mechanism with non-syndromic ARCI, and SLC27A4 appears on ARCI gene panels. IPS is set apart as a syndromic congenital ichthyosis by its prematurity and prenatal amniotic findings, neonatal asphyxia, eosinophilia, characteristic epidermal ultrastructure, and the rapid improvement of the skin after birth, whereas ARCI scaling persists.
Distinguishing Features
  • Premature birth with polyhydramnios and chorioamniotic membrane separation
  • Neonatal asphyxia from aspirated keratin debris
  • Marked peripheral eosinophilia
  • Curved trilamellar membrane aggregates on electron microscopy
  • Scale sheds within weeks, leaving a mild nonscaly ichthyosis
Show evidence (2 references)
PMID:21856041 SUPPORT BACKGROUND Human Clinical
"Ichthyosis prematurity syndrome (IPS) is classified as a syndromic congenital ichthyosis based on the presence of skin changes at birth, ultrastructural abnormalities in the epidermis, and extracutaneous manifestations."
States the classification basis that separates IPS from the non-syndromic congenital ichthyoses.
PMID:19119129 SUPPORT Human Clinical
"Diagnosing this syndrome is important to reassure parents, obstetricians, and pediatricians about its benign course after complications in the perinatal period."
The benign course after the perinatal period is what distinguishes IPS prognostically from other severe congenital ichthyoses.
Harlequin ichthyosis Not Yet Curated MONDO:0009443
Overlapping Features Also presents with thick scale and respiratory distress at birth, but with thick constrictive plates; the respiratory compromise reflects restricted chest expansion rather than aspiration of amniotic keratin debris.
Distinguishing Features
  • Thick armour-like plates rather than clay-like vernix scale
  • Respiratory compromise from restricted chest expansion
Show evidence (2 references)
PMID:40000070 SUPPORT Human Clinical
"The clay‐like scale of IPS is pathognomonic, but depending on the phenotype, differential diagnoses may include the thick scale of harlequin ichthyosis or the feathery scale of Conradi‐Hünermann‐Happle syndrome"
Names harlequin ichthyosis as a differential by scale type.
PMID:39865317 SUPPORT BACKGROUND Human Clinical
"While respiratory distress may also be seen in collodion and Harlequin presentations, in IPS it is thought to be primarily due to aspiration of keratin debris in amniotic fluid rather than restricted chest expansion"
Distinguishes the respiratory mechanism.
Conradi-Hunermann-Happle syndrome MONDO:0020603
Overlapping Features X-linked dominant chondrodysplasia punctata with neonatal ichthyosiform erythroderma; its scale is feathery rather than clay-like.
Distinguishing Features
  • Feathery rather than clay-like scale
Show evidence (1 reference)
PMID:40000070 SUPPORT Human Clinical
"The clay‐like scale of IPS is pathognomonic, but depending on the phenotype, differential diagnoses may include the thick scale of harlequin ichthyosis or the feathery scale of Conradi‐Hünermann‐Happle syndrome"
Names Conradi-Hunermann-Happle syndrome as a differential by scale type.
🧫

Experimental Models

2
IPS patient dermal fibroblasts PRIMARY_CELL_CULTURE
Fibroblasts from a patient with IPS, used for acyl-CoA synthetase and lipid-incorporation assays.
Pathograph links
FATP4 Acyl-CoA Synthetase Deficiency recapitulates fidelity: moderate observes: cellular Shows the reduced very-long-chain acyl-CoA synthetase activity directly.
Limitations: Fibroblasts are not the epidermal cell type in which FATP4 builds the barrier, and the data come from a single patient.
Show evidence (1 reference)
PMID:19631310 SUPPORT In Vitro
"Fibroblasts derived from a patient with IPS show reduced activity of very long-chain fatty acids (VLCFA)-CoA synthetase and a specific reduction in the incorporation of VLCFA into cellular lipids."
The patient-cell assay result.
FATP4-knockdown human keratinocytes OTHER
Cultured human keratinocytes with FATP4 knocked down.
Pathograph links
Reduced Epidermal omega-O-Acylceramide Synthesis recapitulates fidelity: moderate observes: cellular Reproduces the acylceramide deficit in human cells.
Limitations: Knockdown rather than patient alleles, in culture without a stratified barrier, so the tissue consequence cannot be measured.
Show evidence (1 reference)
PMID:31974308 SUPPORT In Vitro
"A decrease in acylceramide levels was also observed in human keratinocytes with FATP4 knockdown."
The human-cell acylceramide result.
🐁

Animal Models

3
Fatp4 targeted knockout mouse
Neonatally lethal with tight, thick skin, hyperproliferative hyperkeratosis, a defective barrier and reduced ultra-long-chain ceramides. Much more severe than the human disease.
Species
Mouse
Genotype
Slc27a4 (Fatp4) targeted null
Publication
PMID:12821645
Pathograph links
Epidermal Permeability Barrier Failure recapitulates fidelity: moderate observes: tissue Reproduces the epidermal barrier failure and hyperkeratosis.
Limitations: Null mice die neonatally of dehydration and restricted movement, whereas human IPS is nonlethal and the skin improves after birth. Prenatal amniotic findings and aspiration have not been described in the mouse.
Show evidence (1 reference)
PMID:12821645 SUPPORT Model Organism
"Their skin was characterized by hyperproliferative hyperkeratosis with a disturbed epidermal barrier"
The barrier and hyperkeratosis phenotype.
Reduced Epidermal omega-O-Acylceramide Synthesis recapitulates fidelity: high observes: tissue Epidermal acylceramide falls to about a tenth of wild type. The readout is a lipid quantity, but it is measured by lipidomics of whole epidermis from the intact animal, so the model observes the tissue-level lipid content rather than the keratinocyte synthetic step itself.
Limitations: Acylceramide was measured across whole epidermis in a neonatally lethal null mouse, which is far more severe than human IPS. It does not resolve which keratinocyte layer or step is affected, and no comparable acylceramide measurement in patient epidermis has been reported, so the human deficit is inferred from the mouse and from knockdown keratinocytes.
Show evidence (1 reference)
PMID:31974308 SUPPORT Model Organism
"The total amount of acylceramide in Fatp4 KO mice was reduced to ∼10% of wild-type mice."
Quantifies the acylceramide deficit in knockout epidermis.
Show evidence (1 reference)
PMID:12821645 SUPPORT Model Organism
"Fatp4-null mice displayed features of a neonatally lethal restrictive dermopathy."
Describes the overall model phenotype.
Suprabasal FATP4 or FATP1 transgene rescue of Fatp4 mutant mice
Keratinocyte-restricted FATP4 rescues the lethal skin phenotype, while an FATP4 with a mutated acyl-CoA synthetase domain does not; FATP1 expressed in the same compartment also rescues.
Species
Mouse
Genotype
Fatp4-/- with a keratinocyte (suprabasal) FATP4 or FATP1 transgene
Publication
PMID:17401141
Pathograph links
Epidermal Permeability Barrier Failure rescues fidelity: moderate observes: organism Shows that the barrier defect is cell-autonomous to keratinocytes and depends on the acyl-CoA synthetase activity.
Limitations: Transgenic overexpression in mice; no equivalent intervention exists in humans.
Show evidence (2 references)
PMID:17401141 SUPPORT Model Organism
"Both modes of FATP4 expression led to rescue of the neonatally lethal skin defects, and the resulting mice were viable and fertile. Keratinocyte expression of an FATP4 variant with mutations in the acyl-CoA synthetase domain did not provide any degree of rescue."
Rescue and its dependence on the synthetase domain.
+ 1 more reference
Great Dane ichthyosis
Naturally occurring recessive ichthyosis in Great Danes with a variant that creates a new splice acceptor and loss of intact SLC27A4 protein in skin.
Species
Dog
Genotype
SLC27A4 g.8684G>A splice-acceptor variant, homozygous
Publication
PMID:26506231
Pathograph links
FATP4 Acyl-CoA Synthetase Deficiency partially recapitulates fidelity: moderate observes: molecular Loss of intact SLC27A4 protein in affected skin with a severe skin phenotype.
Limitations: Prematurity, amniotic findings and neonatal aspiration have not been described in the dogs, and the enzymatic activity was not measured.
Show evidence (1 reference)
PMID:26506231 SUPPORT Model Organism
"Our data provide evidence of a new splice acceptor site creating SNV that results in a reduction or loss of intact SLC27A4 protein and probably explains the severe skin phenotype in Great Danes."
The canine variant reduces or abolishes intact protein.
{ }

Source YAML

click to show 
name: Ichthyosis Prematurity Syndrome
creation_date: "2026-10-09T20:30:00Z"
description: >-
  Ichthyosis prematurity syndrome (IPS) is an autosomal recessive syndromic
  congenital ichthyosis caused by biallelic germline variants in SLC27A4, which
  encodes fatty acid transport protein 4 (FATP4), an acyl-CoA synthetase that
  activates very-long-chain and omega-hydroxy fatty acids for synthesis of the
  epidermal barrier lipid omega-O-acylceramide. The fetal epidermis forms a
  defective barrier and sheds large amounts of corneocyte debris into the
  amniotic fluid. Pregnancies show polyhydramnios, echogenic amniotic fluid and
  separation of the chorionic and amniotic membranes from about 28 weeks, and
  the child is born prematurely, typically at 30 to 34 weeks, covered in a thick,
  greasy, clay- or vernix-like scale over erythrodermic, swollen skin.
  Aspiration of keratin-laden amniotic fluid causes neonatal respiratory distress
  or asphyxia, which is the main source of early morbidity and of the rare
  deaths. Peripheral eosinophilia is almost invariable and serum IgE is usually
  raised. The scale sheds within weeks to months; survivors have a favourable
  course but keep a mild, nonscaly ichthyosis or follicular hyperkeratosis,
  pruritus, and a lasting atopic diathesis with respiratory and food allergy.
category: Mendelian
disease_term:
  preferred_term: ichthyosis prematurity syndrome
  term:
    id: MONDO:0012089
    label: ichthyosis prematurity syndrome
synonyms:
- IPS
- ichthyosis-prematurity syndrome
- ichthyosis congenita type IV
- congenital ichthyosis type 4
parents:
- syndromic congenital ichthyosis
- inherited ichthyosis
- disorder of epidermal lipid metabolism
inheritance:
- name: Autosomal recessive inheritance
  inheritance_term:
    preferred_term: Autosomal recessive inheritance
    term:
      id: HP:0000007
      label: Autosomal recessive inheritance
  description: >-
    Affected individuals carry biallelic SLC27A4 variants, homozygous (often the
    Scandinavian p.Cys168* founder allele, or in consanguineous families) or
    compound heterozygous.
  evidence:
  - reference: PMID:19631310
    reference_title: Mutations in the fatty acid transport protein 4 gene cause the ichthyosis prematurity syndrome.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Ichthyosis prematurity syndrome (IPS) is an autosomal-recessive disorder characterized by premature birth and neonatal asphyxia, followed by a lifelong nonscaly ichthyosis with atopic manifestations."
    explanation: >-
      The gene-discovery study states the recessive mode of inheritance for the
      families in which it mapped the disease.
  - reference: PMID:21450060
    reference_title: FATP4 missense and nonsense mutations cause similar features in Ichthyosis Prematurity Syndrome.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Four probands were compound heterozygous for four different mutations of which three are novel."
    explanation: >-
      Compound heterozygosity in four of five unrelated probands supports
      biallelic, recessive causation.
prevalence:
- population: Worldwide
  measure_type: UNKNOWN
  prevalence_class: BAND_1_9_PER_1000000
  rate_per_100000: 0.5
  notes: >-
    The 2025 systematic review repeats a worldwide estimate of 1 in 200,000 from
    earlier literature and says the true figure may be higher given recent cases
    from many ancestries. The measure (birth or point prevalence) is not stated
    by the source, so measure_type is UNKNOWN.
  evidence:
  - reference: PMID:40000070
    reference_title: "Ichthyosis Prematurity Syndrome: A Systematic Review of the Literature."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    quote_role: BACKGROUND
    snippet: "Prevalence worldwide is estimated to be 1 in 200,000 cases, though recent cases from diverse ethnic backgrounds suggest that frequency may be underestimated"
    explanation: >-
      States the worldwide estimate in the review's introduction, citing earlier
      work rather than deriving it, hence BACKGROUND.
- population: Norway and Sweden
  measure_type: CARRIER_FREQUENCY
  prevalence_class: ABOVE_1_IN_1000
  rate_per_100000: 2000.0
  notes: >-
    Local carrier frequency of about 1 in 50, attributed to the p.Cys168*
    founder allele. Stated in the introduction of a mutation-screening paper,
    citing earlier work; not a population screening result of that paper.
  evidence:
  - reference: PMID:21450060
    reference_title: FATP4 missense and nonsense mutations cause similar features in Ichthyosis Prematurity Syndrome.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    quote_role: BACKGROUND
    snippet: "IPS is more prevalent in Norway and Sweden with an estimated local carrier frequency of one in 50 suggesting a founder mutation"
    explanation: >-
      Gives the Scandinavian carrier frequency and links it to a founder allele.
- population: Published IPS literature to September 2024
  measure_type: CASES_IN_LITERATURE
  notes: >-
    A PROSPERO-registered systematic review found 59 reported cases in 26
    studies, from European, African, Middle Eastern, Asian and American
    patients, so the disease is not restricted to Scandinavia.
  evidence:
  - reference: PMID:40000070
    reference_title: "Ichthyosis Prematurity Syndrome: A Systematic Review of the Literature."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "We identified 26 studies reporting 59 cases of IPS (PROSPERO database: CRD42024533988). While IPS was previously thought to predominantly affect Norwegian and Swedish patients, we identified cases from a broad range of ethnicities."
    explanation: >-
      The cumulative case count and its ancestral breadth are stated directly.
progression:
- phase: Third-trimester prenatal phase
  age_range: from about 28 weeks of gestation to delivery
  notes: >-
    Polyhydramnios, separation of the chorionic and amniotic membranes, echogenic
    sediment in the amniotic cavity and echo-free chorionic fluid appear between
    28 and 32 weeks. Delivery follows prematurely at 30 to 34 weeks.
  evidence:
  - reference: PMID:21465607
    reference_title: Prenatal sonographic assessment and perinatal course of ichthyosis prematurity syndrome.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Prenatal sonographic signs of IPS are separation of the membranes, echogenic amniotic fluid and echo-free chorionic fluid occurring between 28 and 32 weeks' gestation."
    explanation: >-
      A national fetal-medicine-centre series of five fetuses gives the timing
      of the prenatal phase.
  - reference: PMID:21465607
    reference_title: Prenatal sonographic assessment and perinatal course of ichthyosis prematurity syndrome.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "All fetuses were delivered prematurely between 30 and 34 weeks."
    explanation: Gives the end of the prenatal phase.
- phase: Neonatal phase
  age_range: birth to the first weeks of life
  notes: >-
    The newborn is covered in thick, greasy, vernix-like scale over erythrodermic,
    swollen skin and has respiratory distress or asphyxia, sometimes requiring
    ventilation. Eosinophilia is present. This is the period of risk: six of
    59 published cases were fatal, giving an estimated six-month survival of
    87.6%.
  evidence:
  - reference: PMID:21856041
    reference_title: "Ichthyosis prematurity syndrome: clinical evaluation of 17 families with a rare disorder of lipid metabolism."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "All patients were born prematurely with sometimes life-threatening neonatal asphyxia"
    explanation: The 23-patient Norwegian series describes the neonatal presentation.
  - reference: PMID:40000070
    reference_title: "Ichthyosis Prematurity Syndrome: A Systematic Review of the Literature."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Mortality in these cases was attributed to respiratory and/or cardiac sequelae or sepsis."
    explanation: >-
      The fatal cases in the systematic review arise from the neonatal
      respiratory and infectious complications.
  - reference: PMID:40000070
    reference_title: "Ichthyosis Prematurity Syndrome: A Systematic Review of the Literature."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Long-term prognosis is generally good, although six (10.2%) fulminant cases were identified with an estimated 6-month survival rate of 87.6% (95% confidence interval: 78.8-97.4)."
    explanation: >-
      Gives the case-fatality count and the Kaplan-Meier six-month survival
      across published cases with follow-up.
- phase: Resolution of the birth scale
  age_range: weeks to a few months after birth
  notes: >-
    The vernix-like scale sheds spontaneously; the median reported duration was
    10 weeks, although an exact duration was available for only a minority of
    published cases.
  evidence:
  - reference: PMID:40000070
    reference_title: "Ichthyosis Prematurity Syndrome: A Systematic Review of the Literature."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "The median duration of the cutaneous scale was 10 weeks, though patients usually have persisting atopy."
    explanation: Gives the duration of the scaling phase across published cases.
  - reference: PMID:19119129
    reference_title: "Ichthyosis prematurity syndrome: a well-defined congenital ichthyosis subtype."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Marked regression of the edema and ichthyotic scaling was observed within a few weeks."
    explanation: A sibling pair report documents the same rapid regression.
- phase: Lifelong mild phase
  age_range: infancy onward
  notes: >-
    After the birth scale resolves, the skin settles into a mild, nonscaly
    ichthyosis or follicular hyperkeratosis, often with chronic pruritus and
    atopic disease; long-term prognosis is otherwise good.
  evidence:
  - reference: PMID:21856041
    reference_title: "Ichthyosis prematurity syndrome: clinical evaluation of 17 families with a rare disorder of lipid metabolism."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "evolved rapidly to a mild chronic ichthyosis. Many patients subsequently had chronic, severe pruritus."
    explanation: Describes the course after the neonatal period in the Norwegian series.
  - reference: PMID:40000070
    reference_title: "Ichthyosis Prematurity Syndrome: A Systematic Review of the Literature."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "The cutaneous manifestations of IPS resolve over a period of weeks, and patients generally have a favorable long-term prognosis."
    explanation: Summarises the long-term course across published cases.
pathophysiology:
- name: FATP4 Acyl-CoA Synthetase Deficiency
  conforms_to: "epidermal_cornification_failure#Cornification Program Component Deficiency"
  biological_scale: MOLECULAR
  description: >-
    Biallelic loss-of-function variants in SLC27A4 (nonsense, splice-site,
    missense and exon deletions) leave the epidermis without functional FATP4.
    FATP4 is the principal very-long-chain fatty acyl-CoA synthetase of the
    skin, and patient fibroblasts show reduced very-long-chain fatty acid-CoA
    synthetase activity and reduced incorporation of very-long-chain fatty acids
    into cellular lipids. Missense alleles produce the same clinical picture as
    the nonsense founder allele, indicating that they too abolish function.
  genes:
  - preferred_term: SLC27A4
    term:
      id: hgnc:10998
      label: SLC27A4
  genetic_context:
    variant_origin: GERMLINE
    functional_impact_category: LOSS_OF_FUNCTION
  cell_types:
  - preferred_term: keratinocyte
    term:
      id: CL:0000312
      label: keratinocyte
  molecular_functions:
  - preferred_term: very long-chain fatty acid-CoA ligase activity
    term:
      id: GO:0031957
      label: very long-chain fatty acid-CoA ligase activity
    modifier: DECREASED
  biological_processes:
  - preferred_term: very long-chain fatty acid metabolic process
    term:
      id: GO:0000038
      label: very long-chain fatty acid metabolic process
    modifier: DECREASED
  evidence:
  - reference: PMID:19631310
    reference_title: Mutations in the fatty acid transport protein 4 gene cause the ichthyosis prematurity syndrome.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Here we show that the gene encoding the fatty acid transport protein 4 (FATP4) is mutated in individuals with IPS."
    explanation: Gene-discovery result identifying SLC27A4/FATP4 as the disease gene.
  - reference: PMID:19631310
    reference_title: Mutations in the fatty acid transport protein 4 gene cause the ichthyosis prematurity syndrome.
    supports: SUPPORT
    evidence_source: IN_VITRO
    snippet: "Fibroblasts derived from a patient with IPS show reduced activity of very long-chain fatty acids (VLCFA)-CoA synthetase and a specific reduction in the incorporation of VLCFA into cellular lipids."
    explanation: >-
      Patient-derived cells show the enzymatic loss that defines this node. The
      assay was in cultured fibroblasts from one patient, not in epidermis.
  - reference: PMID:17522045
    reference_title: Fatty acid transport protein 4 is the principal very long chain fatty acyl-CoA synthetase in skin fibroblasts.
    supports: SUPPORT
    evidence_source: IN_VITRO
    directness: INDIRECT
    snippet: "Compared with w.t. fibroblasts, cells lacking FATP4 had an 83% decrease in C24:0 activation."
    explanation: >-
      Dermal fibroblast lines from FATP4-null mice show that FATP4 supplies most
      of the very-long-chain acyl-CoA synthetase activity, which is why its loss
      is not compensated in skin cells. Indirect because the cells are murine.
  - reference: PMID:21450060
    reference_title: FATP4 missense and nonsense mutations cause similar features in Ichthyosis Prematurity Syndrome.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Missense mutations and non-sense mutations in FATP4 are associated with similar clinical features suggesting that missense mutations have a severe impact on FATP4 function."
    explanation: >-
      Genotype-phenotype comparison across five families supports loss of
      function as the shared consequence of the different allele classes.
  downstream:
  - target: Reduced Epidermal omega-O-Acylceramide Synthesis
    causal_link_type: DIRECT
    description: >-
      FATP4 activates the omega-hydroxy ultra-long-chain fatty acid that is an
      intermediate of acylceramide synthesis; without it, acylceramide
      production falls.
    evidence:
    - reference: PMID:31974308
      reference_title: Skin permeability barrier formation by the ichthyosis-causative gene FATP4 through formation of the barrier lipid ω-O-acylceramide.
      supports: SUPPORT
      evidence_source: IN_VITRO
      snippet: "In vitro experiments revealed that FATP4 exhibits ACS activity toward an ω-hydroxy fatty acid (FA), an intermediate of the acylceramide synthetic pathway."
      explanation: >-
        Places FATP4's enzymatic activity on the acylceramide pathway
        intermediate, which is the link between the enzyme defect and the lipid
        deficit.
- name: Reduced Epidermal omega-O-Acylceramide Synthesis
  conforms_to: "epidermal_cornification_failure#Defective Cornified Envelope Assembly and Lamellar Lipid Delivery"
  biological_scale: CELLULAR
  description: >-
    Differentiating keratinocytes make far less omega-O-acylceramide and bound
    omega-hydroxyceramide, the lipids of the intercellular lamellae and the
    corneocyte lipid envelope, and the remaining ceramides have shortened
    chains. Lamellar bodies, the corneocyte lipid envelope and the cornified
    envelope are abnormal on electron microscopy in the knockout mouse. The
    lipid measurements come from Fatp4-null mice and FATP4-knockdown human
    keratinocytes; a comparable lipidomic study of patient epidermis has not
    been reported.
  cell_types:
  - preferred_term: keratinocyte
    term:
      id: CL:0000312
      label: keratinocyte
  - preferred_term: corneocyte
    term:
      id: CL:0002153
      label: corneocyte
  biological_processes:
  - preferred_term: epidermal acylceramide biosynthesis
    term:
      id: GO:0046513
      label: ceramide biosynthetic process
    modifier: DECREASED
  - preferred_term: cornified envelope assembly
    term:
      id: GO:1903575
      label: cornified envelope assembly
    modifier: DECREASED
  evidence:
  - reference: PMID:31974308
    reference_title: Skin permeability barrier formation by the ichthyosis-causative gene FATP4 through formation of the barrier lipid ω-O-acylceramide.
    supports: SUPPORT
    evidence_source: MODEL_ORGANISM
    snippet: "Decreased levels and shortening of chain lengths were observed in the saturated, nonacylated ceramides."
    explanation: Fatp4 knockout epidermis shows the ceramide deficit and chain shortening.
  - reference: PMID:31974308
    reference_title: Skin permeability barrier formation by the ichthyosis-causative gene FATP4 through formation of the barrier lipid ω-O-acylceramide.
    supports: SUPPORT
    evidence_source: IN_VITRO
    snippet: "A decrease in acylceramide levels was also observed in human keratinocytes with FATP4 knockdown."
    explanation: >-
      The acylceramide deficit is reproduced in human keratinocytes, which is
      the only human-cell evidence for this node.
  - reference: PMID:31519952
    reference_title: Fatty acid transport protein 4 is required for incorporation of saturated ultralong-chain fatty acids into epidermal ceramides and monoacylglycerols.
    supports: SUPPORT
    evidence_source: MODEL_ORGANISM
    snippet: "Mutants showed lamellar body, corneocyte lipid envelope, and cornified envelope abnormalities."
    explanation: >-
      Electron microscopy of Fatp4-null mouse epidermis shows the structural
      consequences in the lamellar lipid and cornified envelope compartments.
  - reference: PMID:12821645
    reference_title: Mice with targeted disruption of the fatty acid transport protein 4 (Fatp 4, Slc27a4) gene show features of lethal restrictive dermopathy.
    supports: SUPPORT
    evidence_source: MODEL_ORGANISM
    snippet: "Lipid analysis demonstrated a disturbed fatty acid composition of epidermal ceramides, in particular a decrease in the C26:0 and C26:0-OH fatty acid substitutes."
    explanation: >-
      An independent targeted knockout shows the loss of very-long-chain and
      omega-hydroxy acyl chains from epidermal ceramides.
  downstream:
  - target: Epidermal Permeability Barrier Failure
    causal_link_type: DIRECT
    description: >-
      Acylceramide is the lipid that organises the stratum corneum lamellae; its
      loss leaves the barrier permeable.
    evidence:
    - reference: PMID:31974308
      reference_title: Skin permeability barrier formation by the ichthyosis-causative gene FATP4 through formation of the barrier lipid ω-O-acylceramide.
      supports: SUPPORT
      evidence_source: MODEL_ORGANISM
      snippet: "From these results, we conclude that skin barrier dysfunction observed in IPS patients and Fatp4 KO mice is caused mainly by reduced acylceramide production."
      explanation: >-
        The authors' conclusion links the acylceramide deficit to barrier
        dysfunction. The data are from mice and cultured cells, so the human
        part of the claim is an inference.
- name: Epidermal Permeability Barrier Failure
  conforms_to: "epidermal_cornification_failure#Stratum Corneum Permeability Barrier Failure"
  biological_scale: TISSUE
  description: >-
    The fetal and neonatal stratum corneum fails as a permeability barrier. In
    the mouse this is lethal shortly after birth; in humans the barrier defect is
    most severe in fetal and neonatal skin and is partly compensated later.
    Restoring FATP4 with an intact acyl-CoA synthetase domain in suprabasal
    keratinocytes alone rescues the mouse skin phenotype, placing the defect in
    the epidermis rather than in a systemic or placental lipid disturbance.
  cell_types:
  - preferred_term: corneocyte
    term:
      id: CL:0002153
      label: corneocyte
  biological_processes:
  - preferred_term: establishment of skin barrier
    term:
      id: GO:0061436
      label: establishment of skin barrier
    modifier: DECREASED
  locations:
  - preferred_term: stratum corneum
    term:
      id: UBERON:0002027
      label: stratum corneum of epidermis
  evidence:
  - reference: PMID:31974308
    reference_title: Skin permeability barrier formation by the ichthyosis-causative gene FATP4 through formation of the barrier lipid ω-O-acylceramide.
    supports: SUPPORT
    evidence_source: MODEL_ORGANISM
    snippet: "Fatp4 knockout (KO) mice exhibited severe skin barrier dysfunction and morphological abnormalities in the epidermis."
    explanation: Direct demonstration of barrier failure in the knockout.
  - reference: PMID:17401141
    reference_title: Keratinocyte-specific expression of fatty acid transport protein 4 rescues the wrinkle-free phenotype in Slc27a4/Fatp4 mutant mice.
    supports: SUPPORT
    evidence_source: MODEL_ORGANISM
    snippet: "We conclude that expression of FATP4 with an intact acyl-CoA synthetase domain in suprabasal keratinocytes is necessary for normal skin development and that FATP4 functions in establishing the cornified envelope."
    explanation: >-
      Transgenic rescue localises the barrier defect to the acyl-CoA synthetase
      function of FATP4 in suprabasal keratinocytes.
  - reference: PMID:19631310
    reference_title: Mutations in the fatty acid transport protein 4 gene cause the ichthyosis prematurity syndrome.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    directness: INDIRECT
    snippet: "The human phenotype is consistent with Fatp4 deficiency in mice that is characterized by a severe skin phenotype, a defective permeability barrier function, and perturbed VLCFA metabolism."
    explanation: >-
      The discovery paper draws the mouse-to-human parallel; the human barrier
      defect is inferred from phenotype rather than measured.
  downstream:
  - target: Epidermal Hyperkeratosis with Lamellar Membrane Aggregates
    causal_link_type: INDIRECT_UNKNOWN_INTERMEDIATES
    description: >-
      As in other disorders of cornification, the barrier defect is accompanied
      by a thickened, hyperproliferative epidermis and abnormal membrane material
      in the upper epidermis. The signal linking the lipid defect to
      hyperproliferation has not been defined in IPS.
    evidence:
    - reference: PMID:12821645
      reference_title: Mice with targeted disruption of the fatty acid transport protein 4 (Fatp 4, Slc27a4) gene show features of lethal restrictive dermopathy.
      supports: SUPPORT
      evidence_source: MODEL_ORGANISM
      snippet: "Their skin was characterized by hyperproliferative hyperkeratosis with a disturbed epidermal barrier"
      explanation: The knockout shows barrier failure and hyperproliferative hyperkeratosis together.
  - target: Corneocyte Shedding into Amniotic Fluid
    causal_link_type: INDIRECT_UNKNOWN_INTERMEDIATES
    description: >-
      The abnormal fetal epidermis sheds corneocytes into the amniotic fluid,
      producing echogenic sediment visible on ultrasound. Why the defective
      epidermis sheds so much material in utero has not been studied directly.
    evidence:
    - reference: PMID:21856041
      reference_title: "Ichthyosis prematurity syndrome: clinical evaluation of 17 families with a rare disorder of lipid metabolism."
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: "IPS was characterized prenatally by ultrasound findings of polyhydramnios, separation of membranes, echogenic amniotic fluid, and clear chorionic fluid."
      explanation: >-
        Echogenic amniotic fluid is the in-utero sign of shed epidermal material.
  - target: Barrier-Associated Type 2 Sensitization
    causal_link_type: INDIRECT_UNKNOWN_INTERMEDIATES
    hypothesis_groups:
    - ips_barrier_driven_atopy
    description: >-
      The proposed route from the skin defect to eosinophilia, raised IgE and
      allergy is epicutaneous sensitization through the defective barrier. This
      is one of the explanations the literature offers, not a demonstrated one.
    evidence:
    - reference: PMID:40000070
      reference_title: "Ichthyosis Prematurity Syndrome: A Systematic Review of the Literature."
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      quote_role: REVIEW_SYNTHESIS
      snippet: "Patients typically have a predisposition to atopic disease, possibly due to a defective skin barrier, epicutaneous sensitization, or as‐of‐yet effects of germline SLC27A4 variants on immune cell polarisation"
      explanation: >-
        The review names barrier-driven sensitization as one candidate route
        and an intrinsic immune effect of the variants as another.
  - target: Erythroderma
    causal_link_type: INDIRECT_UNKNOWN_INTERMEDIATES
    description: >-
      The newborn skin is red and swollen beneath the scale, which regresses as
      the scale sheds.
    evidence:
    - reference: PMID:21856041
      reference_title: "Ichthyosis prematurity syndrome: clinical evaluation of 17 families with a rare disorder of lipid metabolism."
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: "The skin appeared erythrodermic, swollen, and covered by a greasy, thick vernix caseosa-like"
      explanation: Describes the erythroderma accompanying the neonatal skin defect.
  - target: Ichthyosis
    causal_link_type: INDIRECT_UNKNOWN_INTERMEDIATES
    description: >-
      After the neonatal period a mild, nonscaly ichthyosis persists, the
      residual expression of the barrier defect.
    evidence:
    - reference: PMID:19631310
      reference_title: Mutations in the fatty acid transport protein 4 gene cause the ichthyosis prematurity syndrome.
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: "followed by a lifelong nonscaly ichthyosis with atopic manifestations"
      explanation: States the lifelong residual ichthyosis.
- name: Epidermal Hyperkeratosis with Lamellar Membrane Aggregates
  conforms_to: "epidermal_cornification_failure#Compensatory Epidermal Hyperproliferation and Retention Hyperkeratosis"
  biological_scale: TISSUE
  description: >-
    Skin biopsy shows hyperkeratosis, acanthosis and dermal inflammation, and
    electron microscopy shows characteristic aggregates of curved, trilamellar
    membrane structures in the stratum granulosum and stratum corneum, which are
    regarded as diagnostic of IPS. Clinically this is the thick, caseous,
    vernix-like scale of the newborn.
  cell_types:
  - preferred_term: keratinocyte
    term:
      id: CL:0000312
      label: keratinocyte
  biological_processes:
  - preferred_term: keratinization
    term:
      id: GO:0031424
      label: keratinization
    modifier: ABNORMAL
  locations:
  - preferred_term: skin epidermis
    term:
      id: UBERON:0001003
      label: skin epidermis
  evidence:
  - reference: PMID:21856041
    reference_title: "Ichthyosis prematurity syndrome: clinical evaluation of 17 families with a rare disorder of lipid metabolism."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Histopathologic and ultrastructural examination of skin biopsy specimens showed hyperkeratosis, acanthosis, dermal inflammation, and characteristic aggregates of curved lamellar structures in the upper epidermis."
    explanation: Biopsy findings in the Norwegian series define this node in human skin.
  - reference: PMID:19119129
    reference_title: "Ichthyosis prematurity syndrome: a well-defined congenital ichthyosis subtype."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "electron microscopy of a skin biopsy specimen showing pathognomonic trilamellar membrane aggregations in the stratum corneum and stratum granulosum"
    explanation: Independent sibling report of the same ultrastructural lesion.
  downstream:
  - target: Caseous vernix-like scale at birth
    causal_link_type: DIRECT
    description: >-
      The hyperkeratotic fetal epidermis is the thick, greasy, vernix-like scale
      seen at delivery.
    evidence:
    - reference: PMID:19119129
      reference_title: "Ichthyosis prematurity syndrome: a well-defined congenital ichthyosis subtype."
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: "Remarkable skin changes were noticed with universal red, edematous and desquamating, spongy skin giving an impression of excessive vernix caseosa."
      explanation: Describes the clinical appearance of the hyperkeratotic newborn skin.
  - target: Hyperkeratosis
    causal_link_type: DIRECT
    description: Hyperkeratosis is the histological readout of this node.
    evidence:
    - reference: PMID:21856041
      reference_title: "Ichthyosis prematurity syndrome: clinical evaluation of 17 families with a rare disorder of lipid metabolism."
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: "Histopathologic and ultrastructural examination of skin biopsy specimens showed hyperkeratosis, acanthosis, dermal inflammation"
      explanation: Hyperkeratosis is reported directly on biopsy.
  - target: Follicular hyperkeratosis
    causal_link_type: INDIRECT_UNKNOWN_INTERMEDIATES
    description: >-
      After the scale resolves, residual keratinization abnormality is often
      follicular.
    evidence:
    - reference: PMID:40000070
      reference_title: "Ichthyosis Prematurity Syndrome: A Systematic Review of the Literature."
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: "Skin quality following resolution was characterized by persistent mild ichthyosis and/or follicular keratosis."
      explanation: Pooled description of residual skin findings after the neonatal period.
- name: Corneocyte Shedding into Amniotic Fluid
  biological_scale: TISSUE
  description: >-
    Corneocytes and keratin debris from the fetal skin accumulate in the
    amniotic fluid from about 28 weeks, producing echogenic sediment in the
    amniotic cavity. The debris is thought to obstruct fetal swallowing and
    passage of fluid through the gut, which would explain the polyhydramnios and
    the empty fetal stomach seen on ultrasound, and it is the material later
    aspirated at birth.
  locations:
  - preferred_term: amniotic fluid
    term:
      id: UBERON:0000173
      label: amniotic fluid
  evidence:
  - reference: PMID:21465607
    reference_title: Prenatal sonographic assessment and perinatal course of ichthyosis prematurity syndrome.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Separation of chorionic and amniotic membranes with a peculiar appearance of echo-free fluid in the chorionic cavity and echogenic sediment in the amniotic cavity were observed between 28 + 5 and 32 + 3 weeks in all cases."
    explanation: >-
      All five fetuses in the series showed echogenic amniotic sediment, the
      ultrasound sign of this node.
  downstream:
  - target: Polyhydramnios
    causal_link_type: INDIRECT_UNKNOWN_INTERMEDIATES
    description: >-
      Keratin debris is proposed to block fetal swallowing or gut transit of
      amniotic fluid. The mechanism is inferred, not demonstrated.
    evidence:
    - reference: PMID:40000070
      reference_title: "Ichthyosis Prematurity Syndrome: A Systematic Review of the Literature."
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      quote_role: REVIEW_SYNTHESIS
      snippet: "Keratin debris deposition likely contributes to polyhydramnios by obstructing the passage of amniotic fluid through the fetal gastrointestinal tract"
      explanation: The review states the proposed mechanism, with hedged wording.
    - reference: PMID:21465607
      reference_title: Prenatal sonographic assessment and perinatal course of ichthyosis prematurity syndrome.
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: "The fetal stomach appeared to be empty in four cases, and was not described in one case."
      explanation: >-
        An empty fetal stomach is consistent with impaired swallowing of the
        debris-laden fluid, the observation behind the proposed mechanism.
  - target: Spontaneous chorioamniotic separation
    causal_link_type: UNKNOWN
    description: >-
      Membrane separation accompanies the echogenic fluid in every fetus of the
      prenatal series. How the two are linked is not known; the review suggests
      a shared embryological origin of amnion and surface ectoderm.
    evidence:
    - reference: PMID:21465607
      reference_title: Prenatal sonographic assessment and perinatal course of ichthyosis prematurity syndrome.
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: "Separation of chorionic and amniotic membranes with a peculiar appearance of echo-free fluid in the chorionic cavity and echogenic sediment in the amniotic cavity were observed between 28 + 5 and 32 + 3 weeks in all cases."
      explanation: The two findings co-occur in all five fetuses.
  - target: Aspiration of Keratin Debris into the Airways
    causal_link_type: DIRECT
    description: >-
      At delivery the infant aspirates the corneocyte-containing amniotic fluid.
    evidence:
    - reference: PMID:21856041
      reference_title: "Ichthyosis prematurity syndrome: clinical evaluation of 17 families with a rare disorder of lipid metabolism."
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: "this was likely caused by aspiration of corneocyte-containing amniotic fluid as postmortem examination of lung tissue in two patients revealed keratin debris filling the bronchial tree and alveoli"
      explanation: Postmortem lung findings in two patients document the aspirated debris.
  - target: Premature birth
    causal_link_type: UNKNOWN
    description: >-
      Preterm delivery follows the polyhydramnios and membrane separation in
      nearly every affected pregnancy, but what triggers labour has not been
      established. Polyhydramnios-related uterine overdistension is one
      plausible route; it has not been tested in IPS.
    evidence:
    - reference: PMID:21465607
      reference_title: Prenatal sonographic assessment and perinatal course of ichthyosis prematurity syndrome.
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: "All five developed polyhydramnios between 28 and 31 weeks."
      explanation: >-
        Polyhydramnios precedes delivery at 30 to 34 weeks in all five fetuses,
        a temporal sequence rather than a demonstrated causal link.
- name: Aspiration of Keratin Debris into the Airways
  biological_scale: ORGANISM
  description: >-
    Aspirated keratin debris fills the bronchial tree and alveoli, obstructing
    the airways at birth. Restricted chest expansion from tight skin, the main
    route in harlequin ichthyosis and collodion babies, is not thought to be the
    principal mechanism in IPS. Prematurity adds surfactant-deficiency risk,
    but the respiratory distress rate in IPS far exceeds the rate expected for
    gestational age.
  locations:
  - preferred_term: bronchus
    term:
      id: UBERON:0002185
      label: bronchus
  - preferred_term: alveolus of lung
    term:
      id: UBERON:0002299
      label: alveolus of lung
  evidence:
  - reference: PMID:21856041
    reference_title: "Ichthyosis prematurity syndrome: clinical evaluation of 17 families with a rare disorder of lipid metabolism."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "postmortem examination of lung tissue in two patients revealed keratin debris filling the bronchial tree and alveoli"
    explanation: Direct autopsy evidence of airway keratin debris, in two patients.
  - reference: PMID:39865317
    reference_title: Ichthyosis Prematurity Syndrome.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    quote_role: BACKGROUND
    snippet: "While respiratory distress may also be seen in collodion and Harlequin presentations, in IPS it is thought to be primarily due to aspiration of keratin debris in amniotic fluid rather than restricted chest expansion"
    explanation: >-
      Distinguishes the aspiration mechanism from the restrictive-skin mechanism
      of other severe neonatal ichthyoses; stated in the discussion of a case
      letter, citing earlier work.
  - reference: PMID:40000070
    reference_title: "Ichthyosis Prematurity Syndrome: A Systematic Review of the Literature."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "with 79.7% reporting respiratory distress, significantly higher than the 5% approximate age‐matched incidence for the general population"
    explanation: >-
      The excess over the gestational-age-matched rate argues that prematurity
      alone does not explain the respiratory distress.
  downstream:
  - target: Neonatal respiratory distress
    causal_link_type: DIRECT
    description: Airway obstruction by debris produces respiratory distress at birth.
    evidence:
    - reference: PMID:40000070
      reference_title: "Ichthyosis Prematurity Syndrome: A Systematic Review of the Literature."
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      quote_role: REVIEW_SYNTHESIS
      snippet: "Pathogenesis is likely due to keratin debris in the amniotic fluid that accumulates in the airways and is aspirated at birth"
      explanation: The review attributes the respiratory distress to aspirated debris.
  - target: Neonatal asphyxia
    causal_link_type: DIRECT
    description: In severe cases the obstruction causes life-threatening asphyxia.
    evidence:
    - reference: PMID:22927265
      reference_title: Ichthyosis prematurity syndrome with separation of fetal membranes and neonatal asphyxia.
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: "Children are born prematurely with thick skin and have been found to develop neonatal asphyxia due to occlusions in the bronchial tree from debris in the amniotic fluid."
      explanation: Links asphyxia to bronchial occlusion by amniotic debris.
  - target: Aspiration pneumonia
    causal_link_type: DIRECT
    description: Aspirated debris can be followed by aspiration pneumonia.
    evidence:
    - reference: PMID:21465607
      reference_title: Prenatal sonographic assessment and perinatal course of ichthyosis prematurity syndrome.
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: "All neonates had difficulties in breathing, two developed aspiration pneumonia"
      explanation: Two of five neonates in the series developed aspiration pneumonia.
- name: Barrier-Associated Type 2 Sensitization
  conforms_to: "epithelial_barrier_dysfunction#Type 2 Sensitization and IgE Class Switch"
  biological_scale: ORGANISM
  description: >-
    Peripheral eosinophilia is almost invariable in the neonate, serum IgE is
    raised in most patients, and respiratory or food allergy develops in most.
    Whether this follows from epicutaneous sensitization through the defective
    barrier, as in other barrier disorders, or from a direct effect of FATP4
    loss on immune cells has not been resolved (see discussion
    ips_atopy_mechanism).
  cell_types:
  - preferred_term: eosinophil
    term:
      id: CL:0000771
      label: eosinophil
  evidence:
  - reference: PMID:21856041
    reference_title: "Ichthyosis prematurity syndrome: clinical evaluation of 17 families with a rare disorder of lipid metabolism."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Peripheral blood eosinophilia was invariably present and most patients had increased serum immunoglobulin E levels."
    explanation: The type 2 signature in the 23-patient Norwegian series.
  downstream:
  - target: Increased total eosinophil count
    causal_link_type: DIRECT
    description: Eosinophilia is the blood readout of this node.
    evidence:
    - reference: PMID:40000070
      reference_title: "Ichthyosis Prematurity Syndrome: A Systematic Review of the Literature."
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: "Eosinophilia was identified in 37 out of 38 cases reporting blood eosinophil count"
      explanation: Pooled frequency of eosinophilia among cases with a count.
  - target: Increased circulating IgE concentration
    causal_link_type: DIRECT
    description: Raised total IgE reflects class switching in this node.
    evidence:
    - reference: PMID:40000070
      reference_title: "Ichthyosis Prematurity Syndrome: A Systematic Review of the Literature."
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: "Raised IgE was identified in 17 out of 19 cases reporting IgE count."
      explanation: Pooled frequency of raised IgE among cases tested.
  - target: Allergy
    causal_link_type: INDIRECT_UNKNOWN_INTERMEDIATES
    description: Sensitization leads to clinical respiratory and food allergy.
    evidence:
    - reference: PMID:21856041
      reference_title: "Ichthyosis prematurity syndrome: clinical evaluation of 17 families with a rare disorder of lipid metabolism."
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: "Over 70% of the patients had a history of respiratory allergy and/or food allergy."
      explanation: Clinical allergy rate in the Norwegian series.
  - target: Pruritus
    causal_link_type: INDIRECT_UNKNOWN_INTERMEDIATES
    description: >-
      Chronic pruritus accompanies the atopic diathesis and the residual
      ichthyosis; which contributes more is not established.
    evidence:
    - reference: PMID:22927265
      reference_title: Ichthyosis prematurity syndrome with separation of fetal membranes and neonatal asphyxia.
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: "At 2 years of age, the patient has developed an atopic skin condition with severe itching, recurrent skin infections, food intolerance and periods of wheezing."
      explanation: A single case in which severe itching arises with the atopic skin condition.
genetic:
- name: SLC27A4
  gene_term:
    preferred_term: SLC27A4
    term:
      id: hgnc:10998
      label: SLC27A4
  presence: PRESENT
  relationship_type: CAUSATIVE
  variant_origin: GERMLINE
  inheritance:
  - name: Autosomal recessive inheritance
    inheritance_term:
      preferred_term: Autosomal recessive inheritance
      term:
        id: HP:0000007
        label: Autosomal recessive inheritance
  notes: >-
    No ClinGen Gene-Disease Validity assertion for SLC27A4 was found in the
    repository's ClinGen-derived gene ingest, so gene_disease_validity is left
    absent. The gene encodes FATP4 (also ACSVL4).
  variants:
  - name: c.504C>A (p.Cys168*)
    description: >-
      Nonsense founder allele shared by the Scandinavian families, present
      homozygous or compound heterozygous in all Scandinavian patients screened
      in the cited study.
    evidence:
    - reference: PMID:21450060
      reference_title: FATP4 missense and nonsense mutations cause similar features in Ichthyosis Prematurity Syndrome.
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      quote_role: BACKGROUND
      snippet: "The p.C168X nonsense variant is prevalent in the Scandinavian IPS population and all patients from this geographical region were found homozygous or compound heterozygous for this mutation."
      explanation: Establishes p.C168X as the regional founder allele.
  - name: SLC27A4 exon 8-10 deletion
    description: >-
      Gene-level deletion of exons 8 to 10, reported as pathogenic in trans with
      a missense variant of uncertain significance (c.986C>T, p.Thr329Met). It
      shows that deletion/duplication analysis is needed when sequencing finds
      only one allele.
    clinical_significance: PATHOGENIC
    evidence:
    - reference: PMID:39865317
      reference_title: Ichthyosis Prematurity Syndrome.
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: "The first was a pathogenic deletion of exons 8 to 10, previously implicated in IPS"
      explanation: The case report classifies the exon deletion as pathogenic.
  evidence:
  - reference: PMID:19631310
    reference_title: Mutations in the fatty acid transport protein 4 gene cause the ichthyosis prematurity syndrome.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Here we show that the gene encoding the fatty acid transport protein 4 (FATP4) is mutated in individuals with IPS."
    explanation: The gene-disease discovery statement.
  - reference: PMID:23271751
    reference_title: Requirement of fatty acid transport protein 4 for development, maturation, and function of sebaceous glands in a mouse model of ichthyosis prematurity syndrome.
    supports: SUPPORT
    evidence_source: MODEL_ORGANISM
    quote_role: BACKGROUND
    snippet: "Mutations in human SLC27A4, which encodes FATP4, cause ichthyosis prematurity syndrome, characterized by a thick desquamating epidermis and premature birth."
    explanation: Restates the established gene-disease relationship.
phenotypes:
- category: Prenatal
  name: Polyhydramnios
  frequency: FREQUENT
  description: >-
    Reported in 27 of 59 published cases (45.8%), with only 2 recorded as absent
    and 30 not reported, so the true frequency among assessed pregnancies is
    higher. All five fetuses in the Norwegian ultrasound series developed it
    between 28 and 31 weeks.
  phenotype_term:
    preferred_term: Polyhydramnios
    term:
      id: HP:0001561
      label: Polyhydramnios
  evidence:
  - reference: PMID:40000070
    reference_title: "Ichthyosis Prematurity Syndrome: A Systematic Review of the Literature."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Polyhydramnios remains the most frequently reported antenatal finding in IPS and was identified in 27 cases"
    explanation: Pooled count across published cases.
  - reference: PMID:21465607
    reference_title: Prenatal sonographic assessment and perinatal course of ichthyosis prematurity syndrome.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "All five developed polyhydramnios between 28 and 31 weeks."
    explanation: Every fetus in the prenatal series developed polyhydramnios.
- category: Prenatal
  name: Spontaneous chorioamniotic separation
  diagnostic: true
  description: >-
    Separation of the chorionic and amniotic membranes, with echo-free chorionic
    fluid and echogenic amniotic fluid, from 28 to 32 weeks; together these are
    the proposed prenatal sonographic signs of IPS.
  phenotype_term:
    preferred_term: Separation of chorionic and amniotic membranes
    term:
      id: HP:0025712
      label: Spontaneous chorioamniotic separation
  evidence:
  - reference: PMID:21465607
    reference_title: Prenatal sonographic assessment and perinatal course of ichthyosis prematurity syndrome.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Prenatal sonographic signs of IPS are separation of the membranes, echogenic amniotic fluid and echo-free chorionic fluid occurring between 28 and 32 weeks' gestation."
    explanation: Membrane separation is one of the defining prenatal signs.
  - reference: PMID:22927265
    reference_title: Ichthyosis prematurity syndrome with separation of fetal membranes and neonatal asphyxia.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "At 31 weeks of gestation, separation of amniotic and chorionic membranes was identified as well as polyhydramnion."
    explanation: An independent case with the same finding.
- category: Prenatal
  name: Premature birth
  frequency: VERY_FREQUENT
  diagnostic: true
  description: >-
    Preterm birth is part of the defining triad. All 23 patients of the
    Norwegian series were born prematurely; mean gestational age across
    published cases was 32.3 weeks.
  phenotype_term:
    preferred_term: Premature birth
    term:
      id: HP:0001622
      label: Premature birth
  evidence:
  - reference: PMID:21856041
    reference_title: "Ichthyosis prematurity syndrome: clinical evaluation of 17 families with a rare disorder of lipid metabolism."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "All patients were born prematurely with sometimes life-threatening neonatal asphyxia"
    explanation: Preterm birth in every patient of a 23-patient series.
  - reference: PMID:19119129
    reference_title: "Ichthyosis prematurity syndrome: a well-defined congenital ichthyosis subtype."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Ichthyosis prematurity syndrome is a rare syndrome characterized by the clinical triad of premature birth, thick caseous desquamating epidermis, and neonatal asphyxia."
    explanation: Names preterm birth as one of the three defining features.
- category: Skin
  name: Caseous vernix-like scale at birth
  frequency: VERY_FREQUENT
  diagnostic: true
  description: >-
    A thick, greasy, clay- or vernix caseosa-like scale covers the newborn,
    most often on the scalp; it was present in every published case and is
    regarded as pathognomonic. It sheds spontaneously over weeks.
  phenotype_term:
    preferred_term: Thick caseous vernix-like desquamating scale
    term:
      id: HP:0025724
      label: Caseous vernix-like desquamation
    temporality: TRANSIENT
  evidence:
  - reference: PMID:40000070
    reference_title: "Ichthyosis Prematurity Syndrome: A Systematic Review of the Literature."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "All identified cases had classical cutaneous characteristics of IPS: congenital thick, clay‐like scale"
    explanation: >-
      Present in all 59 published cases, though case selection depended on the
      phenotype.
  - reference: PMID:21856041
    reference_title: "Ichthyosis prematurity syndrome: clinical evaluation of 17 families with a rare disorder of lipid metabolism."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "The skin appeared erythrodermic, swollen, and covered by a greasy, thick vernix caseosa-like"
    explanation: Clinical description of the scale in the Norwegian series.
- category: Skin
  name: Erythroderma
  description: Red, swollen neonatal skin beneath the scale, regressing within weeks.
  phenotype_term:
    preferred_term: Neonatal erythroderma
    term:
      id: HP:0001019
      label: Erythroderma
    temporality: TRANSIENT
  evidence:
  - reference: PMID:21856041
    reference_title: "Ichthyosis prematurity syndrome: clinical evaluation of 17 families with a rare disorder of lipid metabolism."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "The skin appeared erythrodermic, swollen, and covered by a greasy, thick vernix caseosa-like"
    explanation: Erythroderma is part of the neonatal skin description.
- category: Respiratory
  name: Neonatal respiratory distress
  frequency: FREQUENT
  description: >-
    Respiratory distress was reported in 47 of 59 published cases (79.7%) and
    respiratory support was needed in 27.
  phenotype_term:
    preferred_term: Neonatal respiratory distress
    term:
      id: HP:0002643
      label: Neonatal respiratory distress
    temporality: ACUTE
  evidence:
  - reference: PMID:40000070
    reference_title: "Ichthyosis Prematurity Syndrome: A Systematic Review of the Literature."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "the most common postnatal complication was respiratory distress syndrome (RDS)"
    explanation: The commonest postnatal complication across published cases.
  - reference: PMID:21465607
    reference_title: Prenatal sonographic assessment and perinatal course of ichthyosis prematurity syndrome.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "All neonates had difficulties in breathing"
    explanation: Every neonate in the prenatal series had respiratory difficulty.
- category: Respiratory
  name: Neonatal asphyxia
  diagnostic: true
  description: >-
    Sometimes life-threatening asphyxia at birth; part of the defining clinical
    triad.
  phenotype_term:
    preferred_term: Neonatal asphyxia
    term:
      id: HP:0012768
      label: Neonatal asphyxia
    temporality: ACUTE
  evidence:
  - reference: PMID:19631310
    reference_title: Mutations in the fatty acid transport protein 4 gene cause the ichthyosis prematurity syndrome.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "characterized by premature birth and neonatal asphyxia"
    explanation: Neonatal asphyxia is named as a defining feature.
- category: Respiratory
  name: Aspiration pneumonia
  description: Reported in two of five neonates of the prenatal series.
  phenotype_term:
    preferred_term: Aspiration pneumonia
    term:
      id: HP:0011951
      label: Aspiration pneumonia
  evidence:
  - reference: PMID:21465607
    reference_title: Prenatal sonographic assessment and perinatal course of ichthyosis prematurity syndrome.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "All neonates had difficulties in breathing, two developed aspiration pneumonia"
    explanation: Two of five neonates had aspiration pneumonia.
- category: Hematologic
  name: Increased total eosinophil count
  frequency: VERY_FREQUENT
  diagnostic: true
  description: >-
    Eosinophilia, often marked (1,050 to 14,175 cells per microlitre in the
    pooled cases), in 37 of 38 cases with a reported count; usually transient.
  phenotype_term:
    preferred_term: Peripheral blood eosinophilia
    term:
      id: HP:0001880
      label: Increased total eosinophil count
  evidence:
  - reference: PMID:40000070
    reference_title: "Ichthyosis Prematurity Syndrome: A Systematic Review of the Literature."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Eosinophilia was identified in 37 out of 38 cases reporting blood eosinophil count, with values ranging from 1050 to 14,175 cells/μL and 9%–38% of white cell count."
    explanation: Pooled frequency and range of eosinophilia.
  - reference: PMID:21856041
    reference_title: "Ichthyosis prematurity syndrome: clinical evaluation of 17 families with a rare disorder of lipid metabolism."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Peripheral blood eosinophilia was invariably present"
    explanation: Present in every patient of the Norwegian series.
- category: Immunologic
  name: Increased circulating IgE concentration
  frequency: VERY_FREQUENT
  description: Raised total IgE in 17 of 19 published cases in which IgE was measured.
  phenotype_term:
    preferred_term: Elevated serum IgE
    term:
      id: HP:0003212
      label: Increased circulating IgE concentration
  evidence:
  - reference: PMID:40000070
    reference_title: "Ichthyosis Prematurity Syndrome: A Systematic Review of the Literature."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Raised IgE was identified in 17 out of 19 cases reporting IgE count."
    explanation: Pooled frequency among cases tested.
  - reference: PMID:21856041
    reference_title: "Ichthyosis prematurity syndrome: clinical evaluation of 17 families with a rare disorder of lipid metabolism."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "most patients had increased serum immunoglobulin E levels"
    explanation: Most patients of the Norwegian series had raised IgE.
- category: Immunologic
  name: Allergy
  frequency: FREQUENT
  description: >-
    Respiratory and/or food allergy in over 70% of the Norwegian series; the
    atopic diathesis is the main persisting feature after the skin improves.
  phenotype_term:
    preferred_term: Respiratory and food allergy
    term:
      id: HP:0012393
      label: Allergy
    temporality: CHRONIC
  evidence:
  - reference: PMID:21856041
    reference_title: "Ichthyosis prematurity syndrome: clinical evaluation of 17 families with a rare disorder of lipid metabolism."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Over 70% of the patients had a history of respiratory allergy and/or food allergy."
    explanation: Frequency of clinical allergy in the series.
  - reference: PMID:40000070
    reference_title: "Ichthyosis Prematurity Syndrome: A Systematic Review of the Literature."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    quote_role: BACKGROUND
    snippet: "Long‐term prognosis is good, and ichthyosis frequently resolves, leaving only an atopic diathesis as a persisting clinical feature"
    explanation: The review's introduction describes atopy as the persisting feature.
- category: Skin
  name: Pruritus
  frequency: FREQUENT
  description: Chronic, sometimes severe pruritus after the neonatal period.
  phenotype_term:
    preferred_term: Chronic pruritus
    term:
      id: HP:0000989
      label: Pruritus
    temporality: CHRONIC
  evidence:
  - reference: PMID:21856041
    reference_title: "Ichthyosis prematurity syndrome: clinical evaluation of 17 families with a rare disorder of lipid metabolism."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Many patients subsequently had chronic, severe pruritus."
    explanation: The series reports chronic severe pruritus in many patients, which maps to FREQUENT.
- category: Skin
  name: Ichthyosis
  description: >-
    A mild, nonscaly ichthyosis that persists for life after the birth scale
    has shed; in some patients the skin becomes essentially normal.
  phenotype_term:
    preferred_term: Mild lifelong nonscaly ichthyosis
    term:
      id: HP:0008064
      label: Ichthyosis
    temporality: CHRONIC
  evidence:
  - reference: PMID:19631310
    reference_title: Mutations in the fatty acid transport protein 4 gene cause the ichthyosis prematurity syndrome.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "followed by a lifelong nonscaly ichthyosis with atopic manifestations"
    explanation: States the residual ichthyosis.
  - reference: PMID:21856041
    reference_title: "Ichthyosis prematurity syndrome: clinical evaluation of 17 families with a rare disorder of lipid metabolism."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "evolved rapidly to a mild chronic ichthyosis"
    explanation: The neonatal scale evolves into mild chronic ichthyosis.
- category: Skin
  name: Follicular hyperkeratosis
  description: Persistent follicular keratosis after the scale resolves.
  phenotype_term:
    preferred_term: Follicular hyperkeratosis
    term:
      id: HP:0007502
      label: Follicular hyperkeratosis
    temporality: CHRONIC
  evidence:
  - reference: PMID:40000070
    reference_title: "Ichthyosis Prematurity Syndrome: A Systematic Review of the Literature."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Skin quality following resolution was characterized by persistent mild ichthyosis and/or follicular keratosis."
    explanation: Residual follicular keratosis across published cases.
- category: Histopathology
  name: Hyperkeratosis
  description: >-
    Hyperkeratosis and acanthosis on light microscopy, with characteristic
    curved lamellar membrane aggregates on electron microscopy.
  phenotype_term:
    preferred_term: Epidermal hyperkeratosis
    term:
      id: HP:0000962
      label: Hyperkeratosis
  evidence:
  - reference: PMID:21856041
    reference_title: "Ichthyosis prematurity syndrome: clinical evaluation of 17 families with a rare disorder of lipid metabolism."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Histopathologic and ultrastructural examination of skin biopsy specimens showed hyperkeratosis, acanthosis, dermal inflammation"
    explanation: Biopsy finding in the Norwegian series.
- category: Skin
  name: Alopecia
  description: >-
    Reported in a small number of cases as a long-term finding; not a core
    feature.
  phenotype_term:
    preferred_term: Alopecia
    term:
      id: HP:0001596
      label: Alopecia
  evidence:
  - reference: PMID:39865317
    reference_title: Ichthyosis Prematurity Syndrome.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    quote_role: BACKGROUND
    snippet: "patients may be left with persistent mild generalised ichthyosis, atopic manifestations or other skin abnormalities such as follicular hyperkeratosis, alopecia and hypohidrosis"
    explanation: Names alopecia among the residual skin abnormalities; the review cites two earlier reports for it.
- category: Skin
  name: Hypohidrosis
  description: Reported in a single case as a long-term finding.
  phenotype_term:
    preferred_term: Hypohidrosis
    term:
      id: HP:0000966
      label: Hypohidrosis
  evidence:
  - reference: PMID:39865317
    reference_title: Ichthyosis Prematurity Syndrome.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    quote_role: BACKGROUND
    snippet: "patients may be left with persistent mild generalised ichthyosis, atopic manifestations or other skin abnormalities such as follicular hyperkeratosis, alopecia and hypohidrosis"
    explanation: Names hypohidrosis among the residual skin abnormalities.
diagnosis:
- name: Prenatal ultrasound
  description: >-
    From 28 weeks, polyhydramnios with separation of the chorionic and amniotic
    membranes, echo-free chorionic fluid and echogenic amniotic sediment suggests
    IPS and allows a neonatal team to be present at delivery. These signs are
    suggestive rather than diagnostic.
  results: Membrane separation, echogenic amniotic fluid and echo-free chorionic fluid between 28 and 32 weeks.
  evidence:
  - reference: PMID:21465607
    reference_title: Prenatal sonographic assessment and perinatal course of ichthyosis prematurity syndrome.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Prenatal sonographic signs of IPS are separation of the membranes, echogenic amniotic fluid and echo-free chorionic fluid occurring between 28 and 32 weeks' gestation."
    explanation: The series proposes these as the prenatal signs.
- name: Skin biopsy with electron microscopy
  description: >-
    Electron microscopy shows trilamellar membrane aggregates in the stratum
    granulosum and stratum corneum, which support the diagnosis when genetic
    results are pending or inconclusive.
  results: Curved trilamellar membrane aggregates in the upper epidermis.
  evidence:
  - reference: PMID:19119129
    reference_title: "Ichthyosis prematurity syndrome: a well-defined congenital ichthyosis subtype."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "the diagnosis supported by electron microscopy of a skin biopsy specimen showing pathognomonic trilamellar membrane aggregations in the stratum corneum and stratum granulosum"
    explanation: Electron microscopy supported the diagnosis in the index sibling pair.
- name: SLC27A4 molecular testing
  diagnosis_term:
    preferred_term: genetic testing
    term:
      id: NCIT:C15709
      label: Genetic Testing
  description: >-
    Sequencing of SLC27A4, alone or on a congenital ichthyosis panel, confirms
    the diagnosis. Because exon-level deletions occur, a single detected allele
    calls for deletion/duplication analysis.
  results: Biallelic pathogenic SLC27A4 variants.
  evidence:
  - reference: PMID:39865317
    reference_title: Ichthyosis Prematurity Syndrome.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Genetic testing confirmed the presence of germline, compound heterozygous variants of the SLC27A4 gene."
    explanation: Molecular confirmation in a case where one allele was an exon deletion.
differential_diagnoses:
- name: Autosomal recessive congenital ichthyosis
  disease_term:
    preferred_term: autosomal recessive congenital ichthyosis
    term:
      id: MONDO:0017265
      label: autosomal recessive congenital ichthyosis
  description: >-
    IPS shares recessive inheritance, congenital scaling and a lipid-barrier
    mechanism with non-syndromic ARCI, and SLC27A4 appears on ARCI gene panels.
    IPS is set apart as a syndromic congenital ichthyosis by its prematurity and
    prenatal amniotic findings, neonatal asphyxia, eosinophilia, characteristic
    epidermal ultrastructure, and the rapid improvement of the skin after birth,
    whereas ARCI scaling persists.
  distinguishing_features:
  - Premature birth with polyhydramnios and chorioamniotic membrane separation
  - Neonatal asphyxia from aspirated keratin debris
  - Marked peripheral eosinophilia
  - Curved trilamellar membrane aggregates on electron microscopy
  - Scale sheds within weeks, leaving a mild nonscaly ichthyosis
  evidence:
  - reference: PMID:21856041
    reference_title: "Ichthyosis prematurity syndrome: clinical evaluation of 17 families with a rare disorder of lipid metabolism."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    quote_role: BACKGROUND
    snippet: "Ichthyosis prematurity syndrome (IPS) is classified as a syndromic congenital ichthyosis based on the presence of skin changes at birth, ultrastructural abnormalities in the epidermis, and extracutaneous manifestations."
    explanation: >-
      States the classification basis that separates IPS from the non-syndromic
      congenital ichthyoses.
  - reference: PMID:19119129
    reference_title: "Ichthyosis prematurity syndrome: a well-defined congenital ichthyosis subtype."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Diagnosing this syndrome is important to reassure parents, obstetricians, and pediatricians about its benign course after complications in the perinatal period."
    explanation: >-
      The benign course after the perinatal period is what distinguishes IPS
      prognostically from other severe congenital ichthyoses.
- name: Harlequin ichthyosis
  disease_term:
    preferred_term: harlequin ichthyosis
    term:
      id: MONDO:0009443
      label: autosomal recessive congenital ichthyosis 4B
  description: >-
    Also presents with thick scale and respiratory distress at birth, but with
    thick constrictive plates; the respiratory compromise reflects restricted
    chest expansion rather than aspiration of amniotic keratin debris.
  distinguishing_features:
  - Thick armour-like plates rather than clay-like vernix scale
  - Respiratory compromise from restricted chest expansion
  evidence:
  - reference: PMID:40000070
    reference_title: "Ichthyosis Prematurity Syndrome: A Systematic Review of the Literature."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "The clay‐like scale of IPS is pathognomonic, but depending on the phenotype, differential diagnoses may include the thick scale of harlequin ichthyosis or the feathery scale of Conradi‐Hünermann‐Happle syndrome"
    explanation: Names harlequin ichthyosis as a differential by scale type.
  - reference: PMID:39865317
    reference_title: Ichthyosis Prematurity Syndrome.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    quote_role: BACKGROUND
    snippet: "While respiratory distress may also be seen in collodion and Harlequin presentations, in IPS it is thought to be primarily due to aspiration of keratin debris in amniotic fluid rather than restricted chest expansion"
    explanation: Distinguishes the respiratory mechanism.
- name: Conradi-Hunermann-Happle syndrome
  disease_term:
    preferred_term: Conradi-Hunermann-Happle syndrome
    term:
      id: MONDO:0020603
      label: X-linked chondrodysplasia punctata 2
  description: >-
    X-linked dominant chondrodysplasia punctata with neonatal ichthyosiform
    erythroderma; its scale is feathery rather than clay-like.
  distinguishing_features:
  - Feathery rather than clay-like scale
  evidence:
  - reference: PMID:40000070
    reference_title: "Ichthyosis Prematurity Syndrome: A Systematic Review of the Literature."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "The clay‐like scale of IPS is pathognomonic, but depending on the phenotype, differential diagnoses may include the thick scale of harlequin ichthyosis or the feathery scale of Conradi‐Hünermann‐Happle syndrome"
    explanation: Names Conradi-Hunermann-Happle syndrome as a differential by scale type.
treatments:
- name: Neonatal respiratory support
  description: >-
    A neonatal intensive care team should attend delivery because of the risk
    of asphyxia. Airway clearance and respiratory support, non-invasive (CPAP,
    nasal oxygen, high-frequency oscillation) or invasive ventilation, are the
    main treatment; 27 of 59 published cases needed support. Surfactant has been
    given but its benefit is uncertain because the cause is airway debris rather
    than surfactant deficiency.
  treatment_term:
    preferred_term: neonatal respiratory support
    term:
      id: NCIT:C70909
      label: Mechanical Ventilation
  therapeutic_modality: DEVICE
  target_phenotypes:
  - preferred_term: Neonatal respiratory distress
    term:
      id: HP:0002643
      label: Neonatal respiratory distress
  target_mechanisms:
  - target: Aspiration of Keratin Debris into the Airways
    description: Supports ventilation while the aspirated debris is cleared.
  evidence:
  - reference: PMID:40000070
    reference_title: "Ichthyosis Prematurity Syndrome: A Systematic Review of the Literature."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Treatment primarily consisted of respiratory support to manage respiratory distress."
    explanation: Respiratory support is the main treatment across published cases.
  - reference: PMID:21465607
    reference_title: Prenatal sonographic assessment and perinatal course of ichthyosis prematurity syndrome.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Delivery occurs at 30-34 weeks and, as there is a high risk of asphyxia, an experienced neonatal intensive care unit team should be present at delivery."
    explanation: Recommends neonatal intensive care at delivery.
- name: Emollient skin care
  description: >-
    Bland emollients such as white soft paraffin are used while the scale sheds
    spontaneously. There is no IPS-specific evidence that they speed resolution;
    they are used because they are safe and established in other ichthyoses and
    may support the defective barrier.
  treatment_term:
    preferred_term: emollient skin care
    term:
      id: NCIT:C15747
      label: Supportive Care
  therapeutic_modality: OTHER
  target_phenotypes:
  - preferred_term: Caseous vernix-like desquamation
    term:
      id: HP:0025724
      label: Caseous vernix-like desquamation
  target_mechanisms:
  - target: Epidermal Permeability Barrier Failure
    description: Topical occlusion supports the defective barrier.
  evidence:
  - reference: PMID:40000070
    reference_title: "Ichthyosis Prematurity Syndrome: A Systematic Review of the Literature."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "There is insufficient evidence that emollients confer any therapeutic advantage, as the scale‐like vernix sheds spontaneously"
    explanation: >-
      Supports the description's statement that IPS-specific benefit is
      unproven.
  - reference: PMID:40000070
    reference_title: "Ichthyosis Prematurity Syndrome: A Systematic Review of the Literature."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    quote_role: REVIEW_SYNTHESIS
    snippet: "emollients are a simple and safe intervention that is well established in other forms of ichthyosis"
    explanation: >-
      The rationale for use rests on safety and on experience in other
      ichthyoses, not on IPS data.
  - reference: PMID:39865317
    reference_title: Ichthyosis Prematurity Syndrome.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "His skin was managed with white soft paraffin, with spontaneous shedding of scale."
    explanation: A single case managed with white soft paraffin.
- name: Low-dose dexamethasone for ventilator dependence
  description: >-
    Proposed from one family case report for ventilator-dependent infants with
    IPS. Case-report-level only; not an established treatment.
  treatment_term:
    preferred_term: Pharmacotherapy
    term:
      id: NCIT:C15986
      label: Pharmacotherapy
    therapeutic_agent:
    - preferred_term: dexamethasone
      term:
        id: CHEBI:41879
        label: dexamethasone
  therapeutic_modality: SMALL_MOLECULE
  target_phenotypes:
  - preferred_term: Neonatal respiratory distress
    term:
      id: HP:0002643
      label: Neonatal respiratory distress
  evidence:
  - reference: PMID:34417235
    reference_title: Experience of low-dose dexamethasone use in the respiratory management of ichthyosis prematurity syndrome.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "discuss a potential role for low-dose dexamethasone in the management of ventilator-dependent patients with IPS"
    explanation: >-
      A single family case report proposing the use; it does not establish
      efficacy.
- name: Genetic counselling
  description: >-
    Parents should be offered genetic counselling because the disease is
    germline and recessive.
  treatment_term:
    preferred_term: Genetic counseling
    term:
      id: NCIT:C15240
      label: Genetic Counseling
  evidence:
  - reference: PMID:39865317
    reference_title: Ichthyosis Prematurity Syndrome.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Clinicians should consider genetic counselling for parents given the germline nature of the diagnosis."
    explanation: Recommends counselling on the basis of germline inheritance.
experimental_models:
- name: IPS patient dermal fibroblasts
  experimental_model_type: PRIMARY_CELL_CULTURE
  description: >-
    Fibroblasts from a patient with IPS, used for acyl-CoA synthetase and
    lipid-incorporation assays.
  modeled_mechanisms:
  - target: FATP4 Acyl-CoA Synthetase Deficiency
    relationship: RECAPITULATES
    fidelity: MODERATE
    model_scale: CELLULAR
    description: Shows the reduced very-long-chain acyl-CoA synthetase activity directly.
    limitations: >-
      Fibroblasts are not the epidermal cell type in which FATP4 builds the
      barrier, and the data come from a single patient.
    evidence:
    - reference: PMID:19631310
      reference_title: Mutations in the fatty acid transport protein 4 gene cause the ichthyosis prematurity syndrome.
      supports: SUPPORT
      evidence_source: IN_VITRO
      snippet: "Fibroblasts derived from a patient with IPS show reduced activity of very long-chain fatty acids (VLCFA)-CoA synthetase and a specific reduction in the incorporation of VLCFA into cellular lipids."
      explanation: The patient-cell assay result.
- name: FATP4-knockdown human keratinocytes
  experimental_model_type: OTHER
  description: Cultured human keratinocytes with FATP4 knocked down.
  modeled_mechanisms:
  - target: Reduced Epidermal omega-O-Acylceramide Synthesis
    relationship: RECAPITULATES
    fidelity: MODERATE
    model_scale: CELLULAR
    description: Reproduces the acylceramide deficit in human cells.
    limitations: >-
      Knockdown rather than patient alleles, in culture without a stratified
      barrier, so the tissue consequence cannot be measured.
    evidence:
    - reference: PMID:31974308
      reference_title: Skin permeability barrier formation by the ichthyosis-causative gene FATP4 through formation of the barrier lipid ω-O-acylceramide.
      supports: SUPPORT
      evidence_source: IN_VITRO
      snippet: "A decrease in acylceramide levels was also observed in human keratinocytes with FATP4 knockdown."
      explanation: The human-cell acylceramide result.
animal_models:
- name: Fatp4 targeted knockout mouse
  species: Mouse
  genotype: Slc27a4 (Fatp4) targeted null
  publication: PMID:12821645
  description: >-
    Neonatally lethal with tight, thick skin, hyperproliferative hyperkeratosis,
    a defective barrier and reduced ultra-long-chain ceramides. Much more
    severe than the human disease.
  modeled_mechanisms:
  - target: Epidermal Permeability Barrier Failure
    relationship: RECAPITULATES
    fidelity: MODERATE
    model_scale: TISSUE
    description: Reproduces the epidermal barrier failure and hyperkeratosis.
    limitations: >-
      Null mice die neonatally of dehydration and restricted movement, whereas
      human IPS is nonlethal and the skin improves after birth. Prenatal
      amniotic findings and aspiration have not been described in the mouse.
    evidence:
    - reference: PMID:12821645
      reference_title: Mice with targeted disruption of the fatty acid transport protein 4 (Fatp 4, Slc27a4) gene show features of lethal restrictive dermopathy.
      supports: SUPPORT
      evidence_source: MODEL_ORGANISM
      snippet: "Their skin was characterized by hyperproliferative hyperkeratosis with a disturbed epidermal barrier"
      explanation: The barrier and hyperkeratosis phenotype.
  - target: Reduced Epidermal omega-O-Acylceramide Synthesis
    relationship: RECAPITULATES
    fidelity: HIGH
    model_scale: TISSUE
    description: >-
      Epidermal acylceramide falls to about a tenth of wild type. The readout is
      a lipid quantity, but it is measured by lipidomics of whole epidermis from
      the intact animal, so the model observes the tissue-level lipid content
      rather than the keratinocyte synthetic step itself.
    limitations: >-
      Acylceramide was measured across whole epidermis in a neonatally lethal
      null mouse, which is far more severe than human IPS. It does not resolve
      which keratinocyte layer or step is affected, and no comparable
      acylceramide measurement in patient epidermis has been reported, so the
      human deficit is inferred from the mouse and from knockdown keratinocytes.
    evidence:
    - reference: PMID:31974308
      reference_title: Skin permeability barrier formation by the ichthyosis-causative gene FATP4 through formation of the barrier lipid ω-O-acylceramide.
      supports: SUPPORT
      evidence_source: MODEL_ORGANISM
      snippet: "The total amount of acylceramide in Fatp4 KO mice was reduced to ∼10% of wild-type mice."
      explanation: Quantifies the acylceramide deficit in knockout epidermis.
  - target: Caseous vernix-like scale at birth
    relationship: FAILS_TO_RECAPITULATE
    fidelity: LOW
    description: >-
      The mouse shows a tight restrictive-dermopathy-like skin and dies, rather
      than the transient, shedding vernix-like scale of human IPS.
    limitations: >-
      Species and severity differ; compensation by other FATPs postnatally in
      humans is one proposed explanation.
    evidence:
    - reference: PMID:31519952
      reference_title: Fatty acid transport protein 4 is required for incorporation of saturated ultralong-chain fatty acids into epidermal ceramides and monoacylglycerols.
      supports: SUPPORT
      evidence_source: MODEL_ORGANISM
      snippet: "FATP4 (SLC27A4) mutations cause ichthyosis prematurity syndrome, a nonlethal disorder. In contrast, Fatp4-/- mice die neonatally from a defective barrier."
      explanation: States the severity mismatch between the human disease and the null mouse.
  evidence:
  - reference: PMID:12821645
    reference_title: Mice with targeted disruption of the fatty acid transport protein 4 (Fatp 4, Slc27a4) gene show features of lethal restrictive dermopathy.
    supports: SUPPORT
    evidence_source: MODEL_ORGANISM
    snippet: "Fatp4-null mice displayed features of a neonatally lethal restrictive dermopathy."
    explanation: Describes the overall model phenotype.
- name: Suprabasal FATP4 or FATP1 transgene rescue of Fatp4 mutant mice
  species: Mouse
  genotype: Fatp4-/- with a keratinocyte (suprabasal) FATP4 or FATP1 transgene
  publication: PMID:17401141
  description: >-
    Keratinocyte-restricted FATP4 rescues the lethal skin phenotype, while an
    FATP4 with a mutated acyl-CoA synthetase domain does not; FATP1 expressed in
    the same compartment also rescues.
  modeled_mechanisms:
  - target: Epidermal Permeability Barrier Failure
    relationship: RESCUES
    fidelity: MODERATE
    model_scale: ORGANISM
    description: >-
      Shows that the barrier defect is cell-autonomous to keratinocytes and
      depends on the acyl-CoA synthetase activity.
    limitations: >-
      Transgenic overexpression in mice; no equivalent intervention exists in
      humans.
    evidence:
    - reference: PMID:17401141
      reference_title: Keratinocyte-specific expression of fatty acid transport protein 4 rescues the wrinkle-free phenotype in Slc27a4/Fatp4 mutant mice.
      supports: SUPPORT
      evidence_source: MODEL_ORGANISM
      snippet: "Both modes of FATP4 expression led to rescue of the neonatally lethal skin defects, and the resulting mice were viable and fertile. Keratinocyte expression of an FATP4 variant with mutations in the acyl-CoA synthetase domain did not provide any degree of rescue."
      explanation: Rescue and its dependence on the synthetase domain.
    - reference: PMID:25184958
      reference_title: Fatty acid transport protein 1 can compensate for fatty acid transport protein 4 in the developing mouse epidermis.
      supports: SUPPORT
      evidence_source: MODEL_ORGANISM
      snippet: "Transgenic expression of FATP1 in suprabasal keratinocytes rescued the phenotype of Fatp4 mutants, and FATP1 sorted to the same intracellular organelles as endogenous FATP4."
      explanation: The closest homolog can substitute for FATP4 in the same cells.
- name: Great Dane ichthyosis
  species: Dog
  genotype: SLC27A4 g.8684G>A splice-acceptor variant, homozygous
  publication: PMID:26506231
  description: >-
    Naturally occurring recessive ichthyosis in Great Danes with a variant that
    creates a new splice acceptor and loss of intact SLC27A4 protein in skin.
  modeled_mechanisms:
  - target: FATP4 Acyl-CoA Synthetase Deficiency
    relationship: PARTIALLY_RECAPITULATES
    fidelity: MODERATE
    model_scale: MOLECULAR
    description: Loss of intact SLC27A4 protein in affected skin with a severe skin phenotype.
    limitations: >-
      Prematurity, amniotic findings and neonatal aspiration have not been
      described in the dogs, and the enzymatic activity was not measured.
    evidence:
    - reference: PMID:26506231
      reference_title: A Novel SLC27A4 Splice Acceptor Site Mutation in Great Danes with Ichthyosis.
      supports: SUPPORT
      evidence_source: MODEL_ORGANISM
      snippet: "Our data provide evidence of a new splice acceptor site creating SNV that results in a reduction or loss of intact SLC27A4 protein and probably explains the severe skin phenotype in Great Danes."
      explanation: The canine variant reduces or abolishes intact protein.
discussions:
- discussion_id: ips_mouse_human_severity
  kind: HUMAN_MODEL_MISMATCH
  prompt: >-
    Why is complete FATP4 loss lethal in the mouse but compatible with survival
    and near-normal skin in humans?
  attaches_to:
  - pathophysiology#Epidermal Permeability Barrier Failure
  - progression#Resolution of the birth scale
  rationale: >-
    The mechanistic evidence for the acylceramide-to-barrier chain comes mainly
    from null mice, which die neonatally, whereas human patients with null
    alleles recover within weeks. If another acyl-CoA synthetase, such as FATP1,
    compensates in human skin after birth, the mouse overstates the lasting
    human barrier defect and the human postnatal course depends on a mechanism
    the model lacks. No study has measured FATP1 or acylceramide in patient
    epidermis over time.
  status: OPEN
  evidence:
  - reference: PMID:31519952
    reference_title: Fatty acid transport protein 4 is required for incorporation of saturated ultralong-chain fatty acids into epidermal ceramides and monoacylglycerols.
    supports: SUPPORT
    evidence_source: MODEL_ORGANISM
    snippet: "FATP4 (SLC27A4) mutations cause ichthyosis prematurity syndrome, a nonlethal disorder. In contrast, Fatp4-/- mice die neonatally from a defective barrier."
    explanation: States the mismatch.
  - reference: PMID:25184958
    reference_title: Fatty acid transport protein 1 can compensate for fatty acid transport protein 4 in the developing mouse epidermis.
    supports: SUPPORT
    evidence_source: MODEL_ORGANISM
    snippet: "Here we tested the hypothesis that FATP1, the closest FATP4 homolog, can compensate for the lack of FATP4 in our mouse model of IPS, as it might do postnatally in IPS patients."
    explanation: Proposes FATP1 compensation as the explanation, untested in patients.
- discussion_id: ips_preterm_labour_mechanism
  kind: KNOWLEDGE_GAP
  prompt: >-
    What triggers preterm delivery in IPS pregnancies: uterine overdistension
    from polyhydramnios, the membrane separation, intra-amniotic inflammation
    from keratin debris, or something else?
  attaches_to:
  - phenotypes#Premature birth
  - pathophysiology#Corneocyte Shedding into Amniotic Fluid
  rationale: >-
    Preterm birth is near-universal and gives the syndrome its name, yet the
    only evidence linking it to the amniotic findings is their temporal order in
    small series. The edge from the amniotic node to premature birth is marked
    UNKNOWN for that reason.
  status: OPEN
  evidence:
  - reference: PMID:21465607
    reference_title: Prenatal sonographic assessment and perinatal course of ichthyosis prematurity syndrome.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "All fetuses were delivered prematurely between 30 and 34 weeks."
    explanation: Preterm delivery follows the amniotic changes in all five fetuses.
- discussion_id: ips_atopy_mechanism
  kind: KNOWLEDGE_GAP
  prompt: >-
    Is the eosinophilia, raised IgE and lifelong atopy of IPS a consequence of
    barrier-driven epicutaneous sensitization, or a direct effect of SLC27A4
    loss on immune cells?
  attaches_to:
  - pathophysiology#Barrier-Associated Type 2 Sensitization
  rationale: >-
    Eosinophilia is present in the neonatal period, early for environmental
    sensitization, and atopy persists in many patients after the skin has
    largely normalised, which is hard to reconcile with a purely barrier-driven
    route. The review leaves both explanations open.
  status: OPEN
  evidence:
  - reference: PMID:40000070
    reference_title: "Ichthyosis Prematurity Syndrome: A Systematic Review of the Literature."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    quote_role: REVIEW_SYNTHESIS
    snippet: "Patients typically have a predisposition to atopic disease, possibly due to a defective skin barrier, epicutaneous sensitization, or as‐of‐yet effects of germline SLC27A4 variants on immune cell polarisation"
    explanation: The review lists both candidate mechanisms without choosing.
mechanistic_hypotheses:
- hypothesis_group_id: ips_barrier_driven_atopy
  hypothesis_label: Barrier-driven epicutaneous sensitization explains IPS atopy
  status: EMERGING
  description: >-
    The atopic features of IPS arise from allergen sensitization through the
    defective epidermal barrier, as in filaggrin-related atopy, rather than from
    an intrinsic immune effect of FATP4 loss.
notes: >-
  No disease-specific GeneReviews chapter exists for ichthyosis prematurity
  syndrome: a PubMed search for "ichthyosis prematurity[TI] AND genereviews[book]"
  returned no records. The only GeneReviews chapter with ichthyosis in its title
  covers autosomal recessive congenital ichthyosis, a neighbouring entity rather
  than this disease, and is not used as the phenotype baseline here.

  Phenotype frequencies come mainly from a 2025 systematic review of 59
  published cases and from a 23-patient Norwegian clinical series. Published
  cases are selected for the full phenotype, and many reports do not mention a
  given feature, so the percentages describe the literature rather than
  penetrance.
📚

References & Deep Research

Deep Research

1

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Evaluations and curation notes (1)

Create: Ichthyosis_Prematurity_Syndrome · 2026-10-09T21:23:00Z · View source

New entry for ichthyosis prematurity syndrome (MONDO:0012089; SLC27A4/FATP4, hgnc:10998), curated from a Perplexity deep-research report (research/Ichthyosis_Prematurity_Syndrome-deep-research-perplexity.md) plus primary papers found through PubMed. The report's 25 references all resolved; its one off-topic reference (PMC:PMC8613581, a renal agenesis GO-enrichment study) was not used. The report's pointer to a GeneReviews recommendation for SLC27A4 testing was not used, because PubMed returns no GeneReviews chapter for this disease and the only ichthyosis chapter is the ARCI one. PMID:39189679 (Finnish congenital ichthyosis testing study) was read and dropped because its abstract does not mention IPS. Case reports without a PubMed abstract (PMID:26341232 KID-like presentation, PMID:40664333 and PMID:42598826 hyper-IgE-like presentation, PMID:27224495, PMID:41805040) could not be quoted and were not cited, so those two differentials are not recorded. ORPHA:88621 could not be fetched by the reference fetcher, so the Orphanet prevalence class was not recorded. The pathograph runs FATP4 acyl-CoA synthetase deficiency -> reduced omega-O-acylceramide -> epidermal barrier failure, branching to hyperkeratosis (scale), corneocyte shedding into amniotic fluid (polyhydramnios, membrane separation, aspiration -> respiratory distress/asphyxia, and an UNKNOWN edge to premature birth) and to type 2 sensitization (eosinophilia, IgE, allergy, pruritus), conforming to epidermal_cornification_failure and epithelial_barrier_dysfunction. preflight-dr exited 2 for lack of a local mondo.db; the report was checked by hand and is about SLC27A4 throughout. Validation: just validate clean, validate-terms clean, 112/112 snippets verified, entity refs, causal targets, duplicate keys, qualifier terms and coarse phenotypes clean; check-genereviews NO_CHAPTER; 15/17 phenotypes causally connected (alopecia and hypohidrosis left unconnected, mechanism unknown). just validate-disorders passed (schema, terms, 112 snippets, 0 issues); whole-KB snippet-length, title-snippet, snippet-grading, folded-hyphen, retired-prose and reference-title ratchets reported nothing new.

Perplexity ▸
Ichthyosis Prematurity Syndrome: disease-characteristics report
sonar-deep-research 58 citations 2026-10-09T20:59:06.000756

Ichthyosis Prematurity Syndrome: disease-characteristics report

Ichthyosis prematurity syndrome (IPS; MONDO:0012089) is a rare, autosomal-recessive disorder caused by biallelic germline pathogenic variants in SLC27A4. It typically presents with premature birth, thick vernix-like desquamating skin, and potentially life-threatening neonatal respiratory distress. The conspicuous birth scale usually sheds over weeks; mild ichthyosis, follicular hyperkeratosis, pruritus, or atopic disease can persist. The strongest mechanistic evidence implicates defective epidermal acylceramide synthesis and skin-barrier formation. [1][45][75]

Evidence conventions. “Human” below denotes clinical observations or patient-derived material; “mouse,” “dog,” and “in vitro” identify other evidence types. Phenotype percentages come from a 2025 systematic review of 59 published patients, searched through September 3, 2024—not a population-based registry. A percentage calculated across all 59 must not be interpreted as penetrance when many reports did not assess or mention the feature. [30][90][web:31974308][web:12285567]

1. Disease information

Identifier or name Value Interpretation
MONDO MONDO:0012089 Target disease concept. [6]
OMIM phenotype 608649 Ichthyosis prematurity syndrome. [1]
OMIM gene 604194 SLC27A4. [1]
Orphanet ORPHA:88621 Ichthyosis-prematurity syndrome. [3]
ICD-10 Q80.8 Broader “other congenital ichthyosis” code, not IPS-specific. [107]
ICD-11 LD27.2 Listed by Orphanet for IPS. [107]
MeSH C536271 Supplementary concept; the broader ichthyosis descriptor is D007057. [122][70]
Other names IPS; ichthyosis-prematurity syndrome; ichthyosis congenita type IV; congenital ichthyosis type 4 Naming varies by resource. [62][73]

This is an aggregated disease-level synthesis, not an analysis of identifiable patients or EHR records. Its numerical observations derive chiefly from published cases and a 23-patient clinical series; neither is an unselected epidemiological sample. [45][web:12285567]

2. Etiology, risk, protection, and gene–environment interaction

The established initiating cause is biallelic loss or impairment of SLC27A4 function. SLC27A4 encodes fatty acid transport protein 4 (FATP4), also called ACSVL4. Disease has been observed with homozygous and compound-heterozygous alleles, including nonsense, missense, splice-site, and exon-deletion variants. Patient-derived cells lacking full-length FATP4 have reduced very-long-chain-fatty-acid CoA-synthetase activity. PMID: 19631310; https://pubmed.ncbi.nlm.nih.gov/19631310/. [84][145]

Factor Disease-specific assessment
Genetic and family-history risk Having two carrier parents creates the conventional 25% affected / 50% carrier / 25% neither familial variant risk for each pregnancy, assuming both parental alleles are pathogenic and independently transmitted. Consanguinity can increase the chance that both parents carry the same rare allele; it is not required. The 59-case review recorded consanguinity in 10/59, but it was unreported in 33/59. [105][web:12285567]
Founder effect Scandinavian families shared the nonsense allele NM_005094.4:c.504C>A, p.(Cys168*); the original study reported a shared approximately 786-kb haplotype. This is a population-specific allele observation, not evidence that IPS is restricted to Scandinavia. PMID: 19631310. [84]
Environmental or lifestyle causes No toxin, diet, occupation, smoking exposure, or infectious agent is established as a cause of IPS. Polyhydramnios and prematurity are manifestations/consequences of an affected pregnancy, rather than independently established causes of the Mendelian condition. [45][47]
Protective factors No verified protective allele, diet, supplement, vaccine, or exposure prevents disease in someone with a causative biallelic genotype. Carrier identification and reproductive options can prevent recurrence of an affected pregnancy; neonatal planning can reduce complications, not reverse the genotype. [105][106]
Gene–environment interaction The best-supported interaction is developmental: impaired fetal epidermis sheds corneocytes into amniotic fluid, creating a physical aspiration hazard around delivery. Prematurity also contributes to respiratory vulnerability. This is not evidence of a specific chemical-exposure-by-genotype interaction. PMIDs: 21856041, 21465607. [45][47]

3. Phenotypes

Frequency key: the numerator/59 is the number positively reported in the 2025 published-case review, not the proportion among patients actually assessed. Where useful, the assessed denominator is supplied. The review reports a mean gestational age of 32.30 weeks (range 28.00–35.86). Its 23-patient Norwegian source series found peripheral eosinophilia in every patient it examined and a history of respiratory and/or food allergy in more than 70%; neither estimate establishes population-wide penetrance. PMID: 21856041. [web:12285567][45]

Phenotype and type Suggested HPO term Onset, severity, course, and reported frequency Function or quality-of-life impact
Premature birth; birth outcome Premature birth HP:0001622 Prenatal; characteristic in clinically recognized IPS. Mean 32.30 weeks in the 59-case review; all 23 patients in the Norwegian series were born prematurely. [71][45][web:12285567] NICU admission and complications of prematurity; IPS-specific quality-of-life score unavailable.
Polyhydramnios, sometimes echogenic amniotic fluid or membrane separation; prenatal sign Polyhydramnios HP:0001561 Usually detectable in the third trimester; 27/59 reported positive, 30/59 unreported. All five pregnancies in one ultrasound series developed polyhydramnios between 28 and 31 weeks. PMID: 21465607. [47][web:12285567] Prompts fetal assessment and delivery planning; no separate IPS quality-of-life measurement.
Thick caseous/vernix-like scale and desquamation; physical sign Ichthyosis HP:0008064; desquamation shortly after birth HP:0007549 Severe or extensive at birth in all 59 reviewed cases by case selection; subsequently improves. Median reported scale duration 10 weeks among only 14 cases with an exact duration. [71][web:12285567] Skin-care burden; occasionally constriction or ear-canal blockage.
Respiratory distress/asphyxia; clinical sign Neonatal respiratory distress HP:0002643 Acute at birth; potentially critical. 47/59 reported positive, 10/59 unreported. The Norwegian series documents variable, sometimes life-threatening asphyxia. PMID: 21856041. [45][71][web:12285567] May require suction, oxygen, ventilation, and prolonged NICU care.
Erythroderma/swollen skin; physical sign Erythroderma HP:0001019 Neonatal; 41/59 reported positive, 18/59 unreported; improves as scale sheds. [71][web:12285567] Skin discomfort and intensive neonatal monitoring.
Peripheral eosinophilia; laboratory abnormality Increased total eosinophil count HP:0001880 Neonatal, often transient; 37/59 reported positive, but 37/38 among cases reporting a count; reported values 1,050–14,175 cells/µL. [71][web:12285567] A diagnostic clue, not by itself a measure of disability.
Elevated serum IgE and allergic disease; laboratory finding/clinical manifestation Use the corresponding current HPO elevated-IgE and allergy terms after ontology validation Raised IgE in 17/59 reported positive, 17/19 assessed. Respiratory or food allergy occurred in >70% of the 23-patient clinical series; atopy can persist after neonatal improvement. PMID: 21856041. [45][web:12285567] Allergy symptoms, treatment burden, and possible effects on sleep and daily functioning; IPS-specific EQ-5D/SF-36 data unavailable.
Mild chronic ichthyosis and follicular hyperkeratosis; physical signs Follicular hyperkeratosis HP:0007502; ichthyosis HP:0008064 Childhood through adulthood; generally milder than neonatal scale. No defensible pooled frequency; a 2024 adult report documents extensive follicular hyperkeratosis at age 25. [45][48][71] Persistent dryness, visible skin change, and ongoing skin care.
Pruritus; symptom Pruritus HP:0000989 Variable, sometimes chronic and severe; present in the clinical series, without a dependable pooled percentage. PMID: 21856041. [45][71] Can impair comfort and sleep; no IPS-specific validated score located.
Alopecia, hypotrichosis, or hypohidrosis; physical signs/symptoms Select the precise HPO term for the observed hair-loss or reduced-sweating phenotype Not core neonatal criteria or quantified population features. The 2024 report describes adult scalp alopecia, sparse body hair, reduced sweating, and overheating. [48] Cosmetic burden or heat intolerance, depending on the individual.
Epidermal acanthosis, hyperkeratosis, and curved lamellar aggregates; biopsy findings Epidermal acanthosis HP:0025092; add a histology/ultrastructure term only after exact ontology matching Characteristic biopsy findings, not universal clinical tests. Hyperkeratosis was reported in 11/15 biopsied cases and curved multilamellar aggregates in 9 cases in the review. PMIDs: 21856041, 19119129. [45][50][web:12285567] Diagnostic relevance; no independent demonstrated quality-of-life effect.

Scalp scale was reported in 55/59 (93.2%), upper limbs 51/59 (86.4%), trunk 49/59 (83.1%), lower limbs 47/59 (79.7%), palms/soles 46/59 (78.0%), and face 37/59 (62.7%). These are distributions within selected published cases, not separate disease prevalences. [web:12285567]

4. Genetic and molecular information

SLC27A4 is the established causal gene, located at 9q34.11: HGNC:10998; NCBI Gene:10999; OMIM:604194; UniProt:Q6P1M0. The associated phenotype is OMIM:608649. The relevant variants are germline, not somatic cancer drivers. There is no established recurrent aneuploidy or chromosomal rearrangement defining IPS; a gene-level exon deletion is reported. [1][60][61][145]

SLC27A4 variant or class Evidence and classification Population frequency and functional interpretation
NM_005094.4:c.504C>A; p.(Cys168*) Pathogenic homozygous nonsense variant in one 2024 Finnish genetically tested patient; originally established as a Scandinavian founder allele. PMIDs: 39189679, 19631310. [135][199][84] A ClinVar frequency display lists gnomAD 0.00009, with other source-specific figures also shown; version, ancestry, and dataset must accompany reuse. Patient cells had no detectable full-length protein and reduced very-long-chain acyl-CoA synthetase activity. [182][84]
c.716-1G>A Homozygous canonical splice-acceptor variant reported in a North African family; predicted truncation. PMID: 19631310. [84] A reliable current population frequency was not established from the consulted sources.
c.556+2T>G, in trans with c.899A>G; p.(Gln300Arg) A 2024 conference case describes the splice variant as pathogenic and the missense variant as likely pathogenic; the adult patient had IPS-compatible lifelong findings. These are the case authors’ classifications, not independently established consensus classifications. [48] Population frequencies not established here.
c.1430T>A; p.(Val477Asp) ClinVar likely pathogenic, one submitter/one star, evaluated May 8, 2024; missense, germline. This is not expert-panel adjudication. [32] Population allele frequency not verified from the accessed condition record.
c.1628-1G>A ClinVar likely pathogenic splice-acceptor variant, reported in a premature infant with congenital ichthyosis in compound-heterozygous state. [180] ClinVar submitter reports 1/248,182 gnomAD chromosomes—approximately 4.0 × 10⁻⁶ for that stated dataset. [180]
Deletion of exons 8–10, in trans with c.986C>T; p.(Thr329Met) A 2025 human case describes the exon deletion as pathogenic and the missense allele as a variant of uncertain significance; the latter should not be promoted to pathogenic solely because it occurred in an affected patient. [145] Frequencies not established here; the deletion shows why a negative sequencing-only result may warrant deletion/duplication analysis.

Modifiers and epigenetics: No clinically validated modifier gene, protective allele, IPS-specific DNA-methylation signature, histone signature, or diagnostic epigenetic assay was established in the consulted evidence. Reduced epidermal Elovl1 expression in knockout mice is an observed downstream molecular change, not proof that ELOVL1 is a human IPS modifier. PMID: 31974308. [web:31974308]

5. Environmental information

No pathogen, occupational exposure, pollution exposure, radiation exposure, diet, alcohol use, or smoking pattern has been shown to initiate IPS. The clinically important non-genetic setting is the affected pregnancy and birth: corneocytes accumulate in amniotic fluid and can enter neonatal airways. This is a downstream fetal–maternal/physical interaction, not infection or person-to-person transmission. PMIDs: 21856041, 22927265. [45][57]

6. Mechanism and pathophysiology

Ordered causal chain—upstream lesion to manifestations

  1. Biallelic pathogenic SLC27A4 variants lead to absent or impaired FATP4 fatty-acid–activating function. This is supported by human genetics and patient-cell assays. PMID: 19631310. [84]
  2. Reduced FATP4 acyl-CoA-synthetase activity leads to impaired activation of very-long-chain and ω-hydroxy fatty acids needed for epidermal lipid synthesis. The ω-hydroxy substrate activity is demonstrated in vitro; its disease contribution is supported by mouse and human-keratinocyte experiments. PMIDs: 19631310, 31974308. [84][web:31974308]
  3. Impaired fatty-acid activation leads to reduced epidermal ω-O-acylceramide production and altered ceramide composition. Fatp4-knockout mouse epidermis had approximately 10% of wild-type total acylceramide; FATP4 knockdown also reduced acylceramide in cultured human keratinocytes. PMID: 31974308. [web:31974308]
  4. Altered barrier lipids lead to a defective epidermal permeability barrier and abnormal keratinization, producing thick fetal/neonatal scale. The barrier defect is demonstrated in mice; the complete lipid-to-clinical-scale sequence in human fetal skin is a strong mechanistic inference, not a controlled human experiment. PMIDs: 12821645, 31974308. [197][web:31974308]
  5. The abnormal fetal epidermis leads to excessive corneocyte shedding into amniotic fluid; one branch leads to echogenic fluid, polyhydramnios, and association with preterm delivery. The findings are documented clinically; exactly how debris produces polyhydramnios or triggers labor remains inferred. PMIDs: 21856041, 21465607. [45][47]
  6. A second branch—corneocyte-containing amniotic fluid entering the airway—leads to bronchial/alveolar obstruction and neonatal respiratory failure. Keratin debris was found in the lungs of two deceased patients in the clinical series, directly supporting this route; prematurity can contribute independently. PMID: 21856041. [45]
  7. Barrier dysfunction and downstream inflammation may lead to eosinophilia, raised IgE, pruritus, and later atopy. The clinical association is strong, but a particular immune-signaling cascade causally connecting FATP4 loss to each finding has not been demonstrated in affected humans. PMID: 21856041. [45]

Cellular, biochemical, and profiling evidence. In patient fibroblasts homozygous for p.(Cys168), activity using a C22:1 substrate fell 55%, whereas measured activity using C16:0 was unchanged; incorporation of C22:1 into cholesterol esters, triglycerides, and phospholipids fell 69%, 60%, and 37%, respectively. These are in-vitro patient-cell measurements, not circulating diagnostic cutoffs. Patient epidermis also showed altered lipid-droplet staining. PMID: 19631310.* [84]

The pathway to annotate is fatty-acyl-CoA formation → epidermal sphingolipid/acylceramide synthesis → cornified-layer barrier assembly, rather than an established IPS-specific Wnt, MAPK, mTOR, or PI3K–AKT signaling lesion. Suggested GO biological-process terms are GO:0006629 lipid metabolic process, GO:0006665 sphingolipid metabolic process, GO:0008544 epidermis development, GO:0030216 keratinocyte differentiation, and GO:0031424 keratinization; these are annotation suggestions, not claims that every term has been individually demonstrated in IPS. Principal CL cell types are CL:0000312 keratinocyte and, for the downstream blood finding, CL:0000771 eosinophil. [153][156][150][151][web:31974308]

Targeted lipid measurements and cell knockdown provide the principal molecular-profiling evidence. No IPS-specific clinically validated whole-transcriptome, proteomic, metabolomic, epigenomic, single-cell, spatial-transcriptomic, multi-omics, or CRISPR-screen signature was established from the consulted literature. [84][web:31974308]

Exact primary-abstract excerpts: “Fibroblasts derived from a patient with IPS show reduced activity of very long-chain fatty acids (VLCFA)-CoA synthetase”; and “The total amount of acylceramide in Fatp4 KO mice was reduced to ∼10% of wild-type mice.” PMIDs: 19631310, 31974308, respectively. [84][web:31974308]

7. Anatomical structures affected

Level or site Disease relationship and suggested ontology term
Skin and epidermis—primary Generalized cutaneous disease, particularly fetal/neonatal epidermis and cornified layer. Suggested UBERON:0002097 skin of body; UBERON:0001003 skin epidermis; UBERON:0002027 stratum corneum of epidermis. Scale is often prominent on the scalp but is not characteristically unilateral. [45][web:12285567][158][161]
Hair follicles and skin appendages Later follicular hyperkeratosis; alopecia or reduced sweating in some reported adults. Mouse experiments additionally demonstrate altered sebaceous-gland biology, which should not be recorded as a universal human phenotype. [48][web:12285567]
Amniotic compartment—pregnancy manifestation Echogenic, corneocyte-containing amniotic fluid and sometimes polyhydramnios or membrane separation; annotate a precise amniotic-fluid or membrane UBERON term only after terminology validation. PMIDs: 21465607, 21856041. [47][45]
Airways and lungs—secondary injury Aspiration/obstruction of bronchial tree and alveoli; suggested UBERON:0002048 lung, with specific airway terms selected to match the documented site. PMID: 21856041. [45][158]
Cells and subcellular sites CL:0000312 keratinocyte, including differentiated corneocytes; CL:0000771 eosinophil for the laboratory phenotype. Suggested compartments: GO:0005783 endoplasmic reticulum; GO:0005789 endoplasmic-reticulum membrane; GO:0005886 plasma membrane. Compartment annotations require care because FATP4 has fatty-acid-transport and intracellular activation functions; they are not evidence of mitochondrial disease. [84][150][151][169]

8. Temporal development

IPS is prenatal in origin and evident at birth, not an early-childhood-onset ichthyosis despite occasional later molecular diagnosis. In a five-pregnancy ultrasound study, polyhydramnios appeared at 28–31 weeks; neonatal respiratory compromise is acute. The birth scale typically sheds over weeks—median 10 weeks among 14 cases with timing—while residual skin or atopic manifestations can be lifelong. The 2024 account of a woman diagnosed at 25 years illustrates persistence of follicular hyperkeratosis, alopecia, and hypohidrosis, not adult onset. IPS has no validated stage classification, predictable remission timetable, or documented anticipation pattern. PMIDs: 21465607, 21856041. [47][45][48][web:12285567]

The critical intervention window is delivery through neonatal stabilization, when airway obstruction and consequences of prematurity are most concerning. A later, different opportunity is evaluation and management of persistent skin or allergic symptoms. [45][106]

9. Inheritance and population

IPS is autosomal recessive. Penetrance for particular biallelic variant combinations has not been reliably estimated, and expression varies, particularly for respiratory severity and longer-term manifestations. There is no established anticipation or quantified germline-mosaicism risk. Disease has been reported across multiple geographic and ancestral backgrounds; a Scandinavian founder allele is not an ancestry restriction. [1][84][web:12285567]

Orphanet lists prevalence as <1 per 1,000,000, whereas the 2025 review repeats an estimate of 1 per 200,000. These estimates conflict and lack a comparably defined population denominator; do not convert either into a measured incidence. Incidence per 100,000/year and overall carrier frequency are not established. In the review’s selected 59 reports, 29 were male and 30 female—not proof of a population sex ratio. [3][web:12285567]

10. Diagnostics

Suspect IPS immediately when a preterm neonate has thick, greasy or clay-like vernix-like scale and respiratory distress, especially after a pregnancy with polyhydramnios or echogenic amniotic fluid. Stabilization must not await genetic confirmation. PMIDs: 21856041, 21465607. [45][47]

Assessment Practical interpretation
Prenatal ultrasound Look for polyhydramnios, echogenic amniotic fluid, and separation of amniotic/chorionic membranes; findings can support planning but are not diagnostic alone. PMID: 21465607. [47]
Neonatal examination and respiratory assessment Document gestational age, distribution and appearance of scale, oxygenation, and need for airway support. Chest radiography may evaluate respiratory complications, not diagnose the genotype. [45][web:12285567]
Blood tests CBC with differential can detect eosinophilia; total IgE may be elevated. Neither is specific or sufficient for molecular confirmation. PMID: 21856041. [45]
Skin biopsy Light microscopy may show hyperkeratosis, acanthosis, and inflammation; electron microscopy can reveal characteristic curved lamellar/membrane aggregates. Useful when the phenotype or genotype remains uncertain, but invasive sampling is not mandatory when molecular findings are decisive. PMIDs: 21856041, 19119129. [45][50]
First-line molecular testing Sequence SLC27A4 when the IPS pattern is convincing. Alternatively use a congenital-ichthyosis multigene panel containing SLC27A4; establish that the two qualifying alleles are in trans, preferably through parental testing. GeneReviews specifically recommends starting IPS testing with SLC27A4. [105]
If initial sequencing is unresolved Assess gene-level deletion/duplication, then consider exome or genome sequencing and clinical/genetic re-evaluation. WES or WGS can help with atypical cases or alternative diagnoses; CMA, karyotype, FISH, mitochondrial testing, and repeat-expansion testing are not routine IPS tests. A reported exons 8–10 deletion supports considering copy-number assessment. [105][145]
Specialized omics RNA studies can investigate a difficult splice allele, but routine transcriptomics, proteomics, metabolomics, epigenomics, and liquid biopsy have no established IPS diagnostic role. [105][web:31974308]

A 2024 Finnish retrospective study found one patient with homozygous pathogenic SLC27A4 p.(Cys168) through Sanger sequencing. Its overall congenital-ichthyosis testing results—33 molecular diagnoses among 41 tested patients—must not be presented as an IPS-specific test sensitivity. PMID: 39189679*; https://pubmed.ncbi.nlm.nih.gov/39189679/. [135][199]

The differential includes harlequin ichthyosis (ABCA12; characteristic severe constrictive plates), other congenital ichthyoses including TGM1-related disease, and syndromic disorders with neonatal skin changes. Respiratory disease can occur in other severe ichthyoses, so the combination of prematurity, vernix-like scale, eosinophilia, and amniotic-fluid findings is more informative than one feature. There is no IPS-specific population newborn biochemical screen or validated standalone clinical scoring criterion. [52][105][web:12285567]

11. Outcome and prognosis

The 2025 review identified six reported deaths among 59 patients (10.2%), occurring by six months; its estimated six-month survival was 87.6% (95% CI 78.8%–97.4%) among cases with usable follow-up. These figures describe published cases, with ascertainment, missing-data, and short-follow-up limitations; they are not a general-population mortality rate or an estimate of untreated risk. Severe early respiratory/cardiac complications and sepsis were reported among fatal cases. Most surviving patients improve markedly after the neonatal period, though atopy, pruritus, and milder skin findings may continue. No reliable IPS-specific five- or ten-year survival, life expectancy, disability rate, EQ-5D/SF-36 result, or validated prognostic biomarker is established. PMID: 40000070; https://pubmed.ncbi.nlm.nih.gov/40000070/. [web:12285567]

12. Treatment

There is no established treatment that corrects the inherited FATP4 defect. Management is principally neonatal airway support and supportive skin care, followed by individualized care for persistent skin or allergic symptoms. The congenital-ichthyosis guideline titled the “2024 update” was published April 7, 2025; its IPS-specific recommendation—immediate oropharyngeal suction, with ventilation/intubation as needed, and NICU care—is expert/low-level evidence (level 4, grade D). [106]

Intervention IPS application, evidence, and cautions Suggested NCIT annotation
Immediate oropharyngeal suction; NICU assessment IPS-specific guideline recommendation at delivery, reflecting the aspiration hazard. [106] Map to the current NCIT oropharyngeal suctioning and neonatal intensive care concepts after code verification.
Oxygen, CPAP, or invasive ventilation when indicated Treat respiratory compromise according to neonatal findings; 16/59 published cases reported noninvasive ventilation and 14/59 invasive ventilation, with substantial missing treatment reporting and some overlap. These are use counts, not response rates. [web:12285567] NCIT oxygen therapy, noninvasive ventilation, mechanical ventilation concepts; verify current codes.
Temperature/humidity, fluids, electrolytes, and nutrition Individualize neonatal supportive care. Humidified incubators, monitoring, and nutritional support are described in broader severe congenital-ichthyosis guidance; do not assume every IPS infant requires an incubator. [106][web:12285567] NCIT supportive care and nutritional support concepts; verify current codes.
Gentle cleansing and bland emollients Reduce dryness and support skin care, commonly with petrolatum/paraffin preparations. Because birth scale often sheds spontaneously, IPS-specific comparative benefit is unproven. Avoid contamination and monitor skin condition. [web:12285567][106] NCIT skin care/emollient therapy concept; verify current code.
Treatment of clinically diagnosed atopic dermatitis, allergy, infection, or pruritus Treat the identified condition using age-appropriate usual care; no IPS-specific drug-response or pharmacogenomic rule is validated. Antibiotics are for suspected/confirmed infection, not routine prophylaxis. [45][web:12285567] NCIT symptom management or the intervention-specific drug concept, once an actual therapy is recorded.
Keratolytics or retinoids in selected later cases Specialist judgment is required; evidence from other ichthyosis types must not be represented as IPS trial evidence. Broader neonatal congenital-ichthyosis guidance contraindicates salicylic acid because of systemic toxicity risk and cautions against potentially absorbed active topical agents. [16][106] Drug-specific NCIT concept only if actually used; not a standard IPS intervention.
Surgery or rehabilitation for an exceptional complication One reported constrictive-scale compartment syndrome required escharotomy/fasciotomy and later motor rehabilitation. It is not routine disease treatment. [web:12285567] NCIT fasciotomy or rehabilitation concepts if applicable; verify codes.

No IPS-specific approved gene, cell, RNA, immunologic, or molecularly targeted replacement therapy—and no established IPS-specific treatment-response rate—was identified in the consulted sources. Experimental mouse keratinocyte rescue demonstrates a biological principle, not a clinically available human gene therapy. [201][web:12285567]

13. Prevention

Primary prevention of the genotype is not available through lifestyle modification or vaccination. For families with a known causative genotype, carrier/parental testing, genetic counseling, prenatal testing, and preimplantation genetic testing can inform reproductive decisions. Secondary prevention of severe complications means recognizing a high-risk pregnancy, planning delivery where neonatal airway care is available, and promptly recognizing affected newborns. Tertiary prevention addresses respiratory complications, skin-barrier problems, nutrition, and later atopy. There is no IPS-specific population newborn-screening program, prophylactic medication, or relevant vaccine. [105][47][106]

14. Other species and naturally occurring disease

Species or breed Gene and natural disease Relevance and limitation
Homo sapiens; NCBI Taxon 9606 Biallelic SLC27A4 causes IPS. [84] Reference human disease.
Domestic dog, Canis lupus familiaris; NCBI Taxon 9615; Great Dane, VBO:0200623 Naturally occurring SLC27A4-related ichthyosis, OMIA:001973-9615. A 2015 study found an associated g.8684G>A allele predicted to create a splice acceptor, with markedly reduced skin FATP4 protein in affected dogs. PMID: 26506231; https://pubmed.ncbi.nlm.nih.gov/26506231/. [165][167][90] Supports conservation of the epidermal function and offers veterinary carrier-testing relevance. Canine ichthyosis is not shown to reproduce human prematurity, amniotic-fluid changes, or neonatal aspiration. [90][45]

The disorder is inherited rather than infectious: no zoonotic transmission applies. [84][90]

15. Model organisms and experimental systems

Model Recapitulated finding and research application Important limitation
Mouse, Slc27a4/Fatp4 targeted knockout Hyperproliferative hyperkeratosis, abnormal ceramides, defective skin barrier, restrictive skin, impaired breathing/suckling, and neonatal lethality. Establishes an upstream requirement for FATP4 in epidermal integrity. PMID: 12821645; https://pubmed.ncbi.nlm.nih.gov/12821645/. [197][198] More severe and often lethal than the course of many human survivors; it does not reproduce the full obstetric IPS phenotype.
Mouse, Fatp4 knockout lipid analysis Approximately 90% lower acylceramide than wild type, altered other ceramides, and severe barrier dysfunction; tests the ω-hydroxy-fatty-acid/acylceramide mechanism. PMID: 31974308; https://pubmed.ncbi.nlm.nih.gov/31974308/. [web:31974308] Mouse epidermal biochemistry strengthens, but does not replace, direct measurement across a representative human IPS cohort.
Mouse, keratinocyte-specific FATP4 re-expression on a mutant background Rescued neonatally lethal skin defects and produced viable, fertile mice; tests whether restoring cutaneous enzyme function can address the model phenotype. Moulson and colleagues, 2007. [201][202] A genetic rescue experiment, not an available human treatment.
Mouse, spontaneous Slc27a4 splice-site mutant Inherited skin phenotype resembling congenital ichthyosis; useful for genotype–barrier studies. PMID: 23226340; https://pubmed.ncbi.nlm.nih.gov/23226340/. [30] Human pregnancy and airway manifestations are not established by its skin resemblance.
Human patient fibroblasts/keratinocytes and FATP4-knockdown keratinocytes Assay altered fatty-acid activation, lipid incorporation, protein expression, and acylceramide production. PMIDs: 19631310, 31974308. [84][web:31974308] Cultures cannot reproduce a fetus, pregnancy, or neonatal airway aspiration.
Naturally affected Great Danes Validate conserved SLC27A4 skin biology outside engineered models. PMID: 26506231. [90] A related canine ichthyosis, not proven to be the entire human IPS syndrome.

Knowledge-base priorities: record SLC27A4 biallelic germline disease causation as established; record ω-O-acylceramide deficiency as strongly supported mechanistically by in-vitro and mouse evidence; retain prenatal fluid accumulation and aspiration as clinically supported downstream mechanisms with the indicated inferential links. Keep case-report frequencies, individual variant classifications, and animal phenotypes explicitly separate from population penetrance and validated human-treatment effects. [84][web:31974308][45][web:12285567]

Reference Validation

Checked with linkml-reference-validator 0.3.0.

Outcome Count
References checked 25
Resolved 25
Unresolved (possible confabulation) 0
Unverifiable 0
References weighed for topical relevance 25
On topic 9
Off topic 1

References that may not be about this subject

These identifiers resolve, so they are not fabrications, but the records they resolve to share almost none of this report's vocabulary. That is a clue and not a verdict - a paper can be relevant in ways its title and abstract do not spell out - so read them before deciding:

  • PMC:PMC8613581 (1 mention) - Gene Ontology Enrichment Analysis of Renal Agenesis: Improving Prenatal Molecular Diagnosis.
  • shared terms: neonatal

Weighed against this report's own most characteristic terms: web, ips, neonatal, disease, skin, respiratory, ichthyosis, established, patient, ips-specific, slc27a4, fluid, affected, airway, prematurity, human, validated, phenotype, scale, fatp4.

All extracted references resolved successfully. Resolving is not the same as being relevant, though - see the references listed above as possibly off topic.

Term Validation

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

Outcome Count
Terms checked 31
Resolved 25
Unresolved (possible confabulation) 0
Obsolete 0
Unverifiable 6
Terms whose name was checked 1
Terms named correctly 0
Terms named as a different term 1

Terms the report names something else

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

  • MONDO:0012089 (2 mentions) - the report calls it "MONDO"; MONDO calls it ichthyosis prematurity syndrome

Prefixes with no resolver

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