Autosomal recessive congenital ichthyosis (ARCI) is a nonsyndromic, genetically heterogeneous disorder of cornification. It is defined by biallelic pathogenic variants in genes controlling epidermal differentiation, cornified-envelope cross-linking, and lipid handling, producing abnormal skin scaling from birth or early infancy with variable erythroderma and barrier compromise.
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name: Autosomal Recessive Congenital Ichthyosis
creation_date: "2026-05-07T12:56:33Z"
updated_date: "2026-05-07T13:25:00Z"
category: Mendelian
description: >-
Autosomal recessive congenital ichthyosis (ARCI) is a nonsyndromic,
genetically heterogeneous disorder of cornification. It is defined by
biallelic pathogenic variants in genes controlling epidermal differentiation,
cornified-envelope cross-linking, and lipid handling, producing abnormal skin
scaling from birth or early infancy with variable erythroderma and barrier
compromise.
references:
- reference: DOI:10.1159/000536366
title: "Cross-Sectional Study on Autosomal Recessive Congenital Ichthyoses: Association of Genotype with Disease Severity, Phenotypic, and Ultrastructural Features in 74 Italian Patients."
found_in:
- Autosomal_Recessive_Congenital_Ichthyosis-deep-research-falcon.md
findings:
- statement: The 74-patient ARCI cohort links genotype to subtype distribution, severity, clinical signs, and ultrastructural features.
supporting_text: >-
The cohort included lamellar ichthyosis, congenital ichthyosiform
erythroderma, harlequin ichthyosis, and minor ARCI subtypes with variants
across TGM1, ALOX12B, CYP4F22, ABCA12, ALOXE3, NIPAL4, CERS3, PNPLA1,
and SDR9C7.
- reference: DOI:10.3390/genes14030717
title: Mutational Spectrum of the ABCA12 Gene and Genotype-Phenotype Correlation in a Cohort of 64 Patients with Autosomal Recessive Congenital Ichthyosis.
found_in:
- Autosomal_Recessive_Congenital_Ichthyosis-deep-research-falcon.md
findings:
- statement: ABCA12 genotype class correlates with harlequin ichthyosis versus CIE or lamellar ichthyosis.
supporting_text: >-
The ABCA12 cohort supports biallelic loss-of-function variants causing
harlequin ichthyosis and biallelic missense variants mainly causing CIE or
lamellar ichthyosis.
- reference: DOI:10.3389/fphar.2023.1274248
title: "Advances in the treatment of autosomal recessive congenital ichthyosis, a look towards the repositioning of drugs."
found_in:
- Autosomal_Recessive_Congenital_Ichthyosis-deep-research-falcon.md
findings:
- statement: ARCI treatment remains symptomatic, with topical therapy first-line and retinoids more efficacious but limited.
supporting_text: >-
The review describes variable desquamation with erythema, quality-of-life
burden, first-choice topical treatments, and retinoid efficacy with
limitations.
- reference: DOI:10.1002/mgg3.70000
title: Genetic testing and new variants in diagnosis of congenital ichthyoses.
found_in:
- Autosomal_Recessive_Congenital_Ichthyosis-deep-research-falcon.md
findings:
- statement: Next-generation sequencing has become a preferred diagnostic method for congenital ichthyoses.
supporting_text: >-
The register-based study reports genetic confirmation in 33 cases and
states that next-generation sequencing became the genetic testing method
of choice during the study period.
- reference: DOI:10.1007/s13555-024-01239-4
title: Highlights of Gene and Cell Therapy for Epidermolysis Bullosa and Ichthyosis.
found_in:
- Autosomal_Recessive_Congenital_Ichthyosis-deep-research-falcon.md
findings:
- statement: Gene and cell therapy development is underway for inherited ichthyosis and related congenital skin disorders.
supporting_text: >-
The review summarizes preclinical and clinical gene and cell therapy
development for epidermolysis bullosa and ichthyosis.
- reference: DOI:10.3390/biomedicines12051112
title: "Comprehensive Molecular Analysis of Disease-Related Genes as First-Tier Test for Early Diagnosis, Classification, and Management of Patients Affected by Nonsyndromic Ichthyosis."
found_in:
- Autosomal_Recessive_Congenital_Ichthyosis-deep-research-falcon.md
findings:
- statement: Broad molecular testing helps classify nonsyndromic ichthyosis and identifies ARCI-associated genes.
supporting_text: >-
The study used sequencing of more than 50 ichthyosis-related genes and
identified ARCI associated with ALOX12B, NIPAL4, and TGM1 mutations.
synonyms:
- ARCI
- autosomal recessive inherited ichthyosis
- ichthyosis, congenital, autosomal recessive
disease_term:
preferred_term: autosomal recessive congenital ichthyosis
term:
id: MONDO:0017265
label: autosomal recessive congenital ichthyosis
parents:
- inherited ichthyosis
- disorder of cornification
has_subtypes:
- name: Lamellar Ichthyosis
display_name: Lamellar Ichthyosis
subtype_term:
preferred_term: lamellar ichthyosis
term:
id: MONDO:0017778
label: lamellar ichthyosis
description: >-
Major ARCI phenotype with generalized large scales, typically less prominent
erythroderma, and variable ectropion or palmoplantar involvement.
subtype_frequency: 67.5% in a 74-patient Italian ARCI cohort
evidence:
- reference: PMID:38588653
reference_title: "Cross-Sectional Study on Autosomal Recessive Congenital Ichthyoses: Association of Genotype with Disease Severity, Phenotypic, and Ultrastructural Features in 74 Italian Patients."
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: "RESULTS: Seventy-four consecutive patients (mean age 11.0 years, range 0.1-48.8) affected with lamellar ichthyosis (50/74, 67.5%), congenital ichthyosiform erythroderma (18/74, 24.3%), harlequin ichthyosis (two/74, 2.7%), and other minor ARCI subtypes (four/74, 5.4%) were enrolled."
explanation: Supports lamellar ichthyosis as the largest major subtype in this genetically confirmed ARCI cohort.
- name: Congenital Ichthyosiform Erythroderma
display_name: Congenital Ichthyosiform Erythroderma
subtype_term:
preferred_term: congenital non-bullous ichthyosiform erythroderma
term:
id: MONDO:0019306
label: congenital non-bullous ichthyosiform erythroderma
description: >-
Major ARCI phenotype characterized by generalized scaling with more
conspicuous erythroderma than classic lamellar ichthyosis.
subtype_frequency: 24.3% in a 74-patient Italian ARCI cohort
evidence:
- reference: PMID:38588653
reference_title: "Cross-Sectional Study on Autosomal Recessive Congenital Ichthyoses: Association of Genotype with Disease Severity, Phenotypic, and Ultrastructural Features in 74 Italian Patients."
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: "RESULTS: Seventy-four consecutive patients (mean age 11.0 years, range 0.1-48.8) affected with lamellar ichthyosis (50/74, 67.5%), congenital ichthyosiform erythroderma (18/74, 24.3%), harlequin ichthyosis (two/74, 2.7%), and other minor ARCI subtypes (four/74, 5.4%) were enrolled."
explanation: Supports congenital ichthyosiform erythroderma as a major ARCI subtype in a genetically confirmed cohort.
- name: Harlequin Ichthyosis
display_name: Harlequin Ichthyosis
subtype_term:
preferred_term: harlequin ichthyosis
term:
id: MONDO:0009443
label: autosomal recessive congenital ichthyosis 4B
description: >-
Severe ARCI phenotype, most often linked to ABCA12 loss-of-function, with
profound neonatal hyperkeratosis and barrier compromise.
subtype_frequency: 2.7% in a 74-patient Italian ARCI cohort
evidence:
- reference: PMID:36980989
reference_title: "Mutational Spectrum of the ABCA12 Gene and Genotype-Phenotype Correlation in a Cohort of 64 Patients with Autosomal Recessive Congenital Ichthyosis."
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: "The most severe form of ARCI, harlequin ichthyosis, is caused by mutations in ABCA12."
explanation: Supports harlequin ichthyosis as the severe ABCA12-associated ARCI phenotype.
inheritance:
- name: Autosomal recessive
inheritance_term:
preferred_term: Autosomal recessive inheritance
term:
id: HP:0000007
label: Autosomal recessive inheritance
description: >-
ARCI is caused by biallelic pathogenic variants in multiple causative genes.
evidence:
- reference: PMID:36980989
reference_title: "Mutational Spectrum of the ABCA12 Gene and Genotype-Phenotype Correlation in a Cohort of 64 Patients with Autosomal Recessive Congenital Ichthyosis."
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: "ARCI is caused by biallelic mutations in ABCA12, ALOX12B, ALOXE3, CERS3, CYP4F22, NIPAL4, PNPLA1, SDR9C7, SULT2B1, and TGM1."
explanation: Directly supports autosomal recessive inheritance through biallelic pathogenic variants.
progression:
- phase: Congenital onset
age_range: Birth or early neonatal period
evidence:
- reference: PMID:36980989
reference_title: "Mutational Spectrum of the ABCA12 Gene and Genotype-Phenotype Correlation in a Cohort of 64 Patients with Autosomal Recessive Congenital Ichthyosis."
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: "Autosomal recessive congenital ichthyosis (ARCI) is a non-syndromic congenital disorder of cornification characterized by abnormal scaling of the skin."
explanation: Supports congenital onset and abnormal skin scaling as defining features.
- phase: Lifelong course
age_range: Lifelong
evidence:
- reference: PMID:38027029
reference_title: "Advances in the treatment of autosomal recessive congenital ichthyosis, a look towards the repositioning of drugs."
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: "Despite the treatment alternatives, ARCI will persist throughout life, disabling people."
explanation: Supports persistence of ARCI across the life course.
prevalence:
- population: Genetically confirmed Italian ARCI cohort
notes: >-
In the 74-patient Italian cohort, lamellar ichthyosis represented 67.5%,
congenital ichthyosiform erythroderma 24.3%, harlequin ichthyosis 2.7%, and
other minor ARCI subtypes 5.4%.
evidence:
- reference: PMID:38588653
reference_title: "Cross-Sectional Study on Autosomal Recessive Congenital Ichthyoses: Association of Genotype with Disease Severity, Phenotypic, and Ultrastructural Features in 74 Italian Patients."
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: "RESULTS: Seventy-four consecutive patients (mean age 11.0 years, range 0.1-48.8) affected with lamellar ichthyosis (50/74, 67.5%), congenital ichthyosiform erythroderma (18/74, 24.3%), harlequin ichthyosis (two/74, 2.7%), and other minor ARCI subtypes (four/74, 5.4%) were enrolled."
explanation: Provides subtype distribution in a genetically confirmed ARCI clinical cohort.
phenotypes:
- category: Dermatological
name: Abnormal skin scaling
frequency: Very frequent
description: >-
Generalized scaling is the core clinical phenotype across ARCI subtypes.
phenotype_term:
preferred_term: ichthyosis
term:
id: HP:0008064
label: Ichthyosis
evidence:
- reference: PMID:36980989
reference_title: "Mutational Spectrum of the ABCA12 Gene and Genotype-Phenotype Correlation in a Cohort of 64 Patients with Autosomal Recessive Congenital Ichthyosis."
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: "Autosomal recessive congenital ichthyosis (ARCI) is a non-syndromic congenital disorder of cornification characterized by abnormal scaling of the skin."
explanation: Directly supports abnormal skin scaling as a defining ARCI manifestation.
- category: Dermatological
name: Erythroderma
frequency: Variable
description: >-
Erythema accompanies scaling to a variable degree and is prominent in the
congenital ichthyosiform erythroderma phenotype.
phenotype_term:
preferred_term: erythroderma
term:
id: HP:0001019
label: Erythroderma
evidence:
- reference: PMID:38027029
reference_title: "Advances in the treatment of autosomal recessive congenital ichthyosis, a look towards the repositioning of drugs."
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: "Autosomal recessive congenital ichthyoses (ARCI) are a skin pathology due to genetic causes characterized by a variable degree of desquamation, accompanied by erythema."
explanation: Supports erythema as a variable clinical feature accompanying desquamation in ARCI.
- category: Dermatological
name: Hyperkeratosis
frequency: Variable
description: >-
Thickened scale and generalized hyperkeratosis are most severe in harlequin
ichthyosis and in higher-severity TGM1- or ABCA12-associated disease.
phenotype_term:
preferred_term: hyperkeratosis
term:
id: HP:0000962
label: Hyperkeratosis
evidence:
- reference: PMID:38588653
reference_title: "Cross-Sectional Study on Autosomal Recessive Congenital Ichthyoses: Association of Genotype with Disease Severity, Phenotypic, and Ultrastructural Features in 74 Italian Patients."
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: "Alopecia, ectropion, and eclabium were significantly associated with TGM1 and ABCA12 mutations, and large, thick, and brownish scales with TGM1 mutations."
explanation: Supports thick scaling, particularly in TGM1-associated ARCI.
- category: Dermatological
name: Ectropion
frequency: Genotype-associated
description: >-
Eyelid eversion is associated with more severe TGM1- and ABCA12-mutated
ARCI.
phenotype_term:
preferred_term: ectropion
term:
id: HP:0000656
label: Ectropion
evidence:
- reference: PMID:38588653
reference_title: "Cross-Sectional Study on Autosomal Recessive Congenital Ichthyoses: Association of Genotype with Disease Severity, Phenotypic, and Ultrastructural Features in 74 Italian Patients."
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: "Alopecia, ectropion, and eclabium were significantly associated with TGM1 and ABCA12 mutations, and large, thick, and brownish scales with TGM1 mutations."
explanation: Supports ectropion as a genotype-associated clinical sign in ARCI.
- category: Dermatological
name: Alopecia
frequency: Genotype-associated
description: >-
Alopecia is associated with TGM1- and ABCA12-mutated ARCI in cohort data.
phenotype_term:
preferred_term: alopecia
term:
id: HP:0001596
label: Alopecia
evidence:
- reference: PMID:38588653
reference_title: "Cross-Sectional Study on Autosomal Recessive Congenital Ichthyoses: Association of Genotype with Disease Severity, Phenotypic, and Ultrastructural Features in 74 Italian Patients."
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: "Alopecia, ectropion, and eclabium were significantly associated with TGM1 and ABCA12 mutations, and large, thick, and brownish scales with TGM1 mutations."
explanation: Supports alopecia as a genotype-associated ARCI feature.
- category: Craniofacial
name: Eclabium
frequency: Genotype-associated
description: >-
Eversion or outward turning of the lips is associated with TGM1- and
ABCA12-mutated ARCI in cohort data. No precise HPO term was confirmed
locally, so this is left as preferred-term-only rather than mapped to an
incorrect lip morphology term.
evidence:
- reference: PMID:38588653
reference_title: "Cross-Sectional Study on Autosomal Recessive Congenital Ichthyoses: Association of Genotype with Disease Severity, Phenotypic, and Ultrastructural Features in 74 Italian Patients."
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: "Alopecia, ectropion, and eclabium were significantly associated with TGM1 and ABCA12 mutations, and large, thick, and brownish scales with TGM1 mutations."
explanation: Supports eclabium as a genotype-associated ARCI feature.
- category: Dermatological
name: Pruritus and quality-of-life burden
frequency: Variable
description: >-
ARCI symptoms substantially affect patient quality of life; itch is commonly
considered in outcome measures and trials.
phenotype_term:
preferred_term: pruritus
term:
id: HP:0000989
label: Pruritus
evidence:
- reference: PMID:38027029
reference_title: "Advances in the treatment of autosomal recessive congenital ichthyosis, a look towards the repositioning of drugs."
supports: PARTIAL
evidence_source: HUMAN_CLINICAL
snippet: "The degree of symptoms is variable, different altered genes are involved, and the symptoms drastically affect patients' quality of life."
explanation: Supports clinically important symptom burden but does not quantify pruritus specifically.
pathophysiology:
- name: Biallelic ARCI Gene Defects
description: >-
ARCI begins with biallelic pathogenic variants in a heterogeneous set of
genes involved in epidermal cornification, lipid transport, and lipid
metabolism.
cell_types:
- preferred_term: keratinocyte
term:
id: CL:0000312
label: keratinocyte
biological_processes:
- preferred_term: keratinization
term:
id: GO:0031424
label: keratinization
modifier: ABNORMAL
- preferred_term: lipid metabolic process
term:
id: GO:0006629
label: lipid metabolic process
modifier: ABNORMAL
genes:
- preferred_term: TGM1
term:
id: hgnc:11777
label: TGM1
- preferred_term: ABCA12
term:
id: hgnc:14637
label: ABCA12
- preferred_term: ALOX12B
term:
id: hgnc:430
label: ALOX12B
- preferred_term: ALOXE3
term:
id: hgnc:13743
label: ALOXE3
- preferred_term: CYP4F22
term:
id: hgnc:26820
label: CYP4F22
- preferred_term: NIPAL4
term:
id: hgnc:28018
label: NIPAL4
- preferred_term: CERS3
term:
id: hgnc:23752
label: CERS3
- preferred_term: PNPLA1
term:
id: hgnc:21246
label: PNPLA1
- preferred_term: SDR9C7
term:
id: hgnc:29958
label: SDR9C7
- preferred_term: SULT2B1
term:
id: hgnc:11459
label: SULT2B1
locations:
- preferred_term: skin epidermis
term:
id: UBERON:0001003
label: skin epidermis
downstream:
- target: Cornified Envelope Cross-Linking Defect
- target: Epidermal Lipid Processing and Transport Defect
evidence:
- reference: PMID:36980989
reference_title: "Mutational Spectrum of the ABCA12 Gene and Genotype-Phenotype Correlation in a Cohort of 64 Patients with Autosomal Recessive Congenital Ichthyosis."
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: "ARCI is caused by biallelic mutations in ABCA12, ALOX12B, ALOXE3, CERS3, CYP4F22, NIPAL4, PNPLA1, SDR9C7, SULT2B1, and TGM1."
explanation: Directly supports the core biallelic ARCI gene spectrum.
- name: Cornified Envelope Cross-Linking Defect
description: >-
TGM1-associated ARCI disrupts transglutaminase-dependent cornified-envelope
formation in differentiating keratinocytes; this mechanism is associated
with higher severity and thick brownish scales in cohort data.
cell_types:
- preferred_term: keratinocyte
term:
id: CL:0000312
label: keratinocyte
biological_processes:
- preferred_term: epidermal cell differentiation
term:
id: GO:0009913
label: epidermal cell differentiation
modifier: ABNORMAL
genes:
- preferred_term: TGM1
term:
id: hgnc:11777
label: TGM1
locations:
- preferred_term: skin epidermis
term:
id: UBERON:0001003
label: skin epidermis
downstream:
- target: Abnormal Stratum Corneum and Barrier Phenotype
evidence:
- reference: PMID:38588653
reference_title: "Cross-Sectional Study on Autosomal Recessive Congenital Ichthyoses: Association of Genotype with Disease Severity, Phenotypic, and Ultrastructural Features in 74 Italian Patients."
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: "The mean ichthyosis severity score in TGM1- and ABCA12-mutated patients was significantly higher than in all other mutated genes, while the lowest score was observed in CYP4F22-mutated patients."
explanation: Supports TGM1 as a high-severity ARCI genotype.
- reference: PMID:38588653
reference_title: "Cross-Sectional Study on Autosomal Recessive Congenital Ichthyoses: Association of Genotype with Disease Severity, Phenotypic, and Ultrastructural Features in 74 Italian Patients."
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: "Ultrastructural data available for 56 patients showed a 100% specificity of cholesterol clefts for TGM1-mutated cases and revealed abnormal lamellar bodies in SDR9C7 and CERS3 patients."
explanation: Supports a genotype-informative ultrastructural abnormality in TGM1-associated ARCI.
- name: Epidermal Lipid Processing and Transport Defect
description: >-
Multiple ARCI genes affect epidermal lipid metabolism, lipid transport, or
acylceramide-related barrier biology. ABCA12-associated ARCI is especially
severe when both alleles cause loss of function.
cell_types:
- preferred_term: keratinocyte
term:
id: CL:0000312
label: keratinocyte
biological_processes:
- preferred_term: lipid transport
term:
id: GO:0006869
label: lipid transport
modifier: ABNORMAL
- preferred_term: ceramide biosynthetic process
term:
id: GO:0046513
label: ceramide biosynthetic process
modifier: ABNORMAL
- preferred_term: establishment of skin barrier
term:
id: GO:0061436
label: establishment of skin barrier
modifier: ABNORMAL
genes:
- preferred_term: ABCA12
term:
id: hgnc:14637
label: ABCA12
- preferred_term: ALOX12B
term:
id: hgnc:430
label: ALOX12B
- preferred_term: ALOXE3
term:
id: hgnc:13743
label: ALOXE3
- preferred_term: CYP4F22
term:
id: hgnc:26820
label: CYP4F22
- preferred_term: NIPAL4
term:
id: hgnc:28018
label: NIPAL4
- preferred_term: CERS3
term:
id: hgnc:23752
label: CERS3
- preferred_term: PNPLA1
term:
id: hgnc:21246
label: PNPLA1
- preferred_term: SDR9C7
term:
id: hgnc:29958
label: SDR9C7
- preferred_term: SULT2B1
term:
id: hgnc:11459
label: SULT2B1
locations:
- preferred_term: skin epidermis
term:
id: UBERON:0001003
label: skin epidermis
downstream:
- target: Abnormal Stratum Corneum and Barrier Phenotype
evidence:
- reference: PMID:36980989
reference_title: "Mutational Spectrum of the ABCA12 Gene and Genotype-Phenotype Correlation in a Cohort of 64 Patients with Autosomal Recessive Congenital Ichthyosis."
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: "Loss-of-function mutations on both alleles generally result in harlequin ichthyosis, whereas biallelic missense mutations mainly lead to CIE or LI."
explanation: Supports ABCA12 functional severity as a determinant of the ARCI phenotype.
- reference: PMID:38588653
reference_title: "Cross-Sectional Study on Autosomal Recessive Congenital Ichthyoses: Association of Genotype with Disease Severity, Phenotypic, and Ultrastructural Features in 74 Italian Patients."
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: "Ultrastructural data available for 56 patients showed a 100% specificity of cholesterol clefts for TGM1-mutated cases and revealed abnormal lamellar bodies in SDR9C7 and CERS3 patients."
explanation: Supports lamellar-body abnormalities in lipid-barrier ARCI genotypes.
- name: Abnormal Stratum Corneum and Barrier Phenotype
description: >-
Defective cornification and lipid-barrier biology converge on abnormal
stratum corneum structure, generalized scaling, variable erythema, and
chronic skin symptoms.
cell_types:
- preferred_term: keratinocyte
term:
id: CL:0000312
label: keratinocyte
biological_processes:
- preferred_term: keratinization
term:
id: GO:0031424
label: keratinization
modifier: ABNORMAL
- preferred_term: epidermis development
term:
id: GO:0008544
label: epidermis development
modifier: ABNORMAL
locations:
- preferred_term: skin epidermis
term:
id: UBERON:0001003
label: skin epidermis
evidence:
- reference: PMID:38027029
reference_title: "Advances in the treatment of autosomal recessive congenital ichthyosis, a look towards the repositioning of drugs."
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: "Autosomal recessive congenital ichthyoses (ARCI) are a skin pathology due to genetic causes characterized by a variable degree of desquamation, accompanied by erythema."
explanation: Supports the clinical consequence of abnormal scaling and erythema arising from genetic skin-barrier disease.
genetic:
- name: TGM1
gene_term:
preferred_term: TGM1
term:
id: hgnc:11777
label: TGM1
association: Causative
inheritance:
- name: Autosomal recessive
notes: >-
TGM1 was one of the two most common mutated genes in the Italian ARCI cohort
and was associated with higher severity, alopecia, ectropion, eclabium, and
large thick brownish scales.
evidence:
- reference: PMID:38588653
reference_title: "Cross-Sectional Study on Autosomal Recessive Congenital Ichthyoses: Association of Genotype with Disease Severity, Phenotypic, and Ultrastructural Features in 74 Italian Patients."
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: "Mutated genes were as follows: TGM1 in 18/74 (24.3%) patients, ALOX12B in 18/74 (24.3%), CYP4F22 in 12/74 (16.2%), ABCA12 in nine/74 (12.2%), ALOXE3 in seven/74 (9.5%), NIPAL4 in seven/74 (9.5%), and CERS3, PNPLA1, and SDR9C7 in 1 patient each (1.4%)."
explanation: Supports TGM1 as a common causative ARCI gene in the cohort.
- name: ALOX12B
gene_term:
preferred_term: ALOX12B
term:
id: hgnc:430
label: ALOX12B
association: Causative
inheritance:
- name: Autosomal recessive
evidence:
- reference: PMID:38588653
reference_title: "Cross-Sectional Study on Autosomal Recessive Congenital Ichthyoses: Association of Genotype with Disease Severity, Phenotypic, and Ultrastructural Features in 74 Italian Patients."
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: "Mutated genes were as follows: TGM1 in 18/74 (24.3%) patients, ALOX12B in 18/74 (24.3%), CYP4F22 in 12/74 (16.2%), ABCA12 in nine/74 (12.2%), ALOXE3 in seven/74 (9.5%), NIPAL4 in seven/74 (9.5%), and CERS3, PNPLA1, and SDR9C7 in 1 patient each (1.4%)."
explanation: Supports ALOX12B as a common causative ARCI gene in the cohort.
- name: CYP4F22
gene_term:
preferred_term: CYP4F22
term:
id: hgnc:26820
label: CYP4F22
association: Causative
inheritance:
- name: Autosomal recessive
notes: CYP4F22-mutated patients had the lowest mean severity score in the cohort.
evidence:
- reference: PMID:38588653
reference_title: "Cross-Sectional Study on Autosomal Recessive Congenital Ichthyoses: Association of Genotype with Disease Severity, Phenotypic, and Ultrastructural Features in 74 Italian Patients."
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: "The mean ichthyosis severity score in TGM1- and ABCA12-mutated patients was significantly higher than in all other mutated genes, while the lowest score was observed in CYP4F22-mutated patients."
explanation: Supports a lower-severity CYP4F22-associated ARCI pattern in this cohort.
- name: ABCA12
gene_term:
preferred_term: ABCA12
term:
id: hgnc:14637
label: ABCA12
association: Causative
inheritance:
- name: Autosomal recessive
variants:
- name: ABCA12 biallelic loss-of-function variants
description: Biallelic loss-of-function variants generally cause harlequin ichthyosis.
- name: ABCA12 biallelic missense variants
description: Biallelic missense variants mainly cause congenital ichthyosiform erythroderma or lamellar ichthyosis.
evidence:
- reference: PMID:36980989
reference_title: "Mutational Spectrum of the ABCA12 Gene and Genotype-Phenotype Correlation in a Cohort of 64 Patients with Autosomal Recessive Congenital Ichthyosis."
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: "The most severe form of ARCI, harlequin ichthyosis, is caused by mutations in ABCA12."
explanation: Supports ABCA12 as the gene classically associated with harlequin ichthyosis.
- reference: PMID:36980989
reference_title: "Mutational Spectrum of the ABCA12 Gene and Genotype-Phenotype Correlation in a Cohort of 64 Patients with Autosomal Recessive Congenital Ichthyosis."
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: "Loss-of-function mutations on both alleles generally result in harlequin ichthyosis, whereas biallelic missense mutations mainly lead to CIE or LI."
explanation: Supports variant-class correlation for ABCA12-associated ARCI phenotypes.
- name: ALOXE3
gene_term:
preferred_term: ALOXE3
term:
id: hgnc:13743
label: ALOXE3
association: Causative
inheritance:
- name: Autosomal recessive
evidence:
- reference: PMID:38588653
reference_title: "Cross-Sectional Study on Autosomal Recessive Congenital Ichthyoses: Association of Genotype with Disease Severity, Phenotypic, and Ultrastructural Features in 74 Italian Patients."
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: "Mutated genes were as follows: TGM1 in 18/74 (24.3%) patients, ALOX12B in 18/74 (24.3%), CYP4F22 in 12/74 (16.2%), ABCA12 in nine/74 (12.2%), ALOXE3 in seven/74 (9.5%), NIPAL4 in seven/74 (9.5%), and CERS3, PNPLA1, and SDR9C7 in 1 patient each (1.4%)."
explanation: Supports ALOXE3 as a causative ARCI gene in the cohort.
- name: NIPAL4
gene_term:
preferred_term: NIPAL4
term:
id: hgnc:28018
label: NIPAL4
association: Causative
inheritance:
- name: Autosomal recessive
notes: >-
NIPAL4-mutated ARCI showed psoriasis-like lesions, reticulate trunk scaling,
and striated keratoderma in the 2024 cohort.
evidence:
- reference: PMID:38588653
reference_title: "Cross-Sectional Study on Autosomal Recessive Congenital Ichthyoses: Association of Genotype with Disease Severity, Phenotypic, and Ultrastructural Features in 74 Italian Patients."
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: "Among specific phenotypic features, psoriasis-like lesions as well as a trunk reticulate scale pattern and striated keratoderma were present in NIPAL4-mutated patients."
explanation: Supports distinctive NIPAL4-associated features.
- name: Rare ARCI genes
association: Causative
inheritance:
- name: Autosomal recessive
notes: >-
CERS3, PNPLA1, SDR9C7, and SULT2B1 are established rarer ARCI genes; CERS3
and SDR9C7 had abnormal lamellar bodies in the Italian ultrastructural
review.
evidence:
- reference: PMID:36980989
reference_title: "Mutational Spectrum of the ABCA12 Gene and Genotype-Phenotype Correlation in a Cohort of 64 Patients with Autosomal Recessive Congenital Ichthyosis."
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: "ARCI is caused by biallelic mutations in ABCA12, ALOX12B, ALOXE3, CERS3, CYP4F22, NIPAL4, PNPLA1, SDR9C7, SULT2B1, and TGM1."
explanation: Supports CERS3, PNPLA1, SDR9C7, and SULT2B1 as part of the established ARCI gene spectrum.
diagnosis:
- name: Multigene molecular testing
diagnosis_term:
preferred_term: genetic testing
term:
id: MAXO:0000127
label: genetic testing
description: >-
Diagnosis is increasingly confirmed by next-generation sequencing panels or
broader sequencing with CNV-aware follow-up, because overlapping phenotypes
make molecular classification important.
results: Biallelic pathogenic variants in an ARCI gene confirm the molecular diagnosis.
evidence:
- reference: PMID:39189679
reference_title: Genetic testing and new variants in diagnosis of congenital ichthyoses.
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: "Diagnosis of ichthyosis was confirmed with genetic testing in 33 cases, and with conventional diagnostic methods, such as clinical findings, skin biopsy and family history of ichthyoses, in 55 cases."
explanation: Supports molecular testing as a diagnostic route for congenital ichthyoses.
- reference: PMID:39189679
reference_title: Genetic testing and new variants in diagnosis of congenital ichthyoses.
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: "During the study period next-generation sequencing became the genetic testing method of choice providing new opportunities in diagnostics."
explanation: Supports next-generation sequencing as the current preferred genetic testing method.
- name: Ultrastructural skin analysis
description: >-
Transmission electron microscopy can provide genotype-informative clues,
including cholesterol clefts in TGM1-mutated disease and abnormal lamellar
bodies in SDR9C7- or CERS3-associated disease.
results: Genotype-informative ultrastructural features can support ARCI classification.
evidence:
- reference: PMID:38588653
reference_title: "Cross-Sectional Study on Autosomal Recessive Congenital Ichthyoses: Association of Genotype with Disease Severity, Phenotypic, and Ultrastructural Features in 74 Italian Patients."
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: "Ultrastructural data available for 56 patients showed a 100% specificity of cholesterol clefts for TGM1-mutated cases and revealed abnormal lamellar bodies in SDR9C7 and CERS3 patients."
explanation: Supports ultrastructural skin analysis as a genotype-informative diagnostic adjunct.
treatments:
- name: Topical emollients and keratolytic/supportive topical therapy
description: >-
Topical treatments are first-line symptomatic management for scaling and
barrier dysfunction.
treatment_term:
preferred_term: supportive care
term:
id: MAXO:0000950
label: supportive care
target_phenotypes:
- preferred_term: ichthyosis
term:
id: HP:0008064
label: Ichthyosis
evidence:
- reference: PMID:38027029
reference_title: "Advances in the treatment of autosomal recessive congenital ichthyosis, a look towards the repositioning of drugs."
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: "Topical treatments are a first-choice strategy due to their ease of application and cost; however, enteral administration of retinoids offers greater efficacy, although with certain limitations."
explanation: Supports topical therapy as first-choice symptomatic treatment and retinoids as more efficacious but limited options.
- name: Retinoid pharmacotherapy
description: >-
Systemic or topical retinoid therapy is used to reduce scaling in severe
inherited ichthyosis, with efficacy balanced against tolerability and safety
limitations.
treatment_term:
preferred_term: Pharmacotherapy
term:
id: NCIT:C15986
label: Pharmacotherapy
therapeutic_agent:
- preferred_term: isotretinoin
term:
id: CHEBI:6067
label: isotretinoin
target_phenotypes:
- preferred_term: ichthyosis
term:
id: HP:0008064
label: Ichthyosis
evidence:
- reference: PMID:38027029
reference_title: "Advances in the treatment of autosomal recessive congenital ichthyosis, a look towards the repositioning of drugs."
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: "Topical treatments are a first-choice strategy due to their ease of application and cost; however, enteral administration of retinoids offers greater efficacy, although with certain limitations."
explanation: Supports retinoid pharmacotherapy as a more efficacious treatment class with limitations.
- reference: clinicaltrials:NCT04154293
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: "The purpose of this study is to investigate the efficacy and safety of two concentrations of topically applied ointment formulation of isotretinoin called TMB-001 (0.05% and 0.1% isotretinoin) in subjects 9 years of age and older for the treatment of congenital ichthyosis (CI), including recessive X-linked ichthyosis (RXLI) and autosomal recessive congenital ichthyosis-lamellar ichthyosis (ARCI-LI) subtypes."
explanation: Supports topical isotretinoin clinical development for congenital ichthyosis including ARCI-LI.
- name: Topical TGM1 gene therapy
description: >-
KB105 is a topical, non-integrating HSV-1 vector expressing TGM1 under
clinical investigation for TGM1-deficient ARCI.
treatment_term:
preferred_term: gene therapy
term:
id: MAXO:0001001
label: gene therapy
target_mechanisms:
- target: Cornified Envelope Cross-Linking Defect
treatment_effect: RESTORES
description: Topical TGM1 replacement is intended to restore deficient transglutaminase 1 expression in affected skin.
evidence:
- reference: clinicaltrials:NCT04047732
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: "This study is an intra-patient comparison of KB105 and placebo-administered Target Areas. The primary objectives of this study are to evaluate safety and Investigator Global Assessment (IGA) scale improvement of topically administered KB105."
explanation: Supports clinical testing of topical KB105 for TGM1-deficient ARCI.
- reference: clinicaltrials:NCT05735158
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: "KB105-02 is an intrasubject randomized, placebo-controlled, double-blind study to evaluate the safety and efficacy of KB105 in children and adults with autosomal recessive congenital ichthyosis (ARCI)."
explanation: Supports a randomized phase 2 study of KB105 in children and adults with ARCI.
- name: IL-17A-targeting biologic therapy
description: >-
Secukinumab has been studied as mechanism-based anti-inflammatory therapy in
ichthyoses, reflecting evidence of IL-17A pathway activation in ichthyosis
skin rather than a proven ARCI-specific standard of care.
treatment_term:
preferred_term: Pharmacotherapy
term:
id: NCIT:C15986
label: Pharmacotherapy
target_phenotypes:
- preferred_term: ichthyosis
term:
id: HP:0008064
label: Ichthyosis
evidence:
- reference: clinicaltrials:NCT03041038
supports: PARTIAL
evidence_source: HUMAN_CLINICAL
snippet: "The ichthyoses are a group of lifelong genetic disorders which share characteristics of generalized skin thickening, scaling and underlying cutaneous inflammation."
explanation: Supports inflammatory pathway targeting across ichthyoses, but this trial record is not ARCI-specific.
clinical_trials:
- name: NCT04154293
description: >-
Vehicle-controlled trial of topical TMB-001 isotretinoin ointment for
congenital ichthyosis including ARCI-lamellar ichthyosis.
target_phenotypes:
- preferred_term: ichthyosis
term:
id: HP:0008064
label: Ichthyosis
evidence:
- reference: clinicaltrials:NCT04154293
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: "The purpose of this study is to investigate the efficacy and safety of two concentrations of topically applied ointment formulation of isotretinoin called TMB-001 (0.05% and 0.1% isotretinoin) in subjects 9 years of age and older for the treatment of congenital ichthyosis (CI), including recessive X-linked ichthyosis (RXLI) and autosomal recessive congenital ichthyosis-lamellar ichthyosis (ARCI-LI) subtypes."
explanation: Supports this trial as directly relevant to ARCI-lamellar ichthyosis.
- name: NCT04047732
description: >-
Phase I/II topical KB105 intra-patient comparison trial for TGM1-deficient
ARCI.
evidence:
- reference: clinicaltrials:NCT04047732
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: "This study is an intra-patient comparison of KB105 and placebo-administered Target Areas. The primary objectives of this study are to evaluate safety and Investigator Global Assessment (IGA) scale improvement of topically administered KB105."
explanation: Supports this trial as topical KB105 clinical testing in TGM1-deficient ARCI.
- name: NCT05735158
description: >-
Randomized placebo-controlled topical KB105 study in children and adults
with ARCI.
evidence:
- reference: clinicaltrials:NCT05735158
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: "KB105-02 is an intrasubject randomized, placebo-controlled, double-blind study to evaluate the safety and efficacy of KB105 in children and adults with autosomal recessive congenital ichthyosis (ARCI)."
explanation: Supports this as a randomized ARCI KB105 trial record.
datasets:
Autosomal recessive congenital ichthyosis (ARCI) is a non-syndromic, congenital disorder of cornification characterized by generalized scaling with variable erythema and barrier dysfunction, typically presenting at birth (often as a collodion baby) and persisting lifelong. (hotz2023mutationalspectrumof pages 1-2, penacorona2023advancesinthe pages 1-2)
Direct abstract quote (treatment review): “Autosomal recessive congenital ichthyoses (ARCI) are a skin pathology due to genetic causes characterized by a variable degree of desquamation, accompanied by erythema.” (Frontiers in Pharmacology; 2023-11-09) (penacorona2023advancesinthe pages 1-2)
Evidence retrieved here did not include authoritative identifier pages (OMIM/Orphanet/MONDO/MeSH/ICD-10/ICD-11). Therefore, OMIM/Orphanet/MONDO/ICD/MeSH identifiers cannot be reliably asserted from this tool run.
ARCI is often used as an umbrella for major phenotypes/subtypes including: - Lamellar ichthyosis (LI) - Congenital ichthyosiform erythroderma (CIE) - Harlequin ichthyosis (HI) (most severe) - Minor/related clinical presentations: self-healing collodion baby, bathing suit ichthyosis, and related “collodion baby” neonatal presentations. (diociaiuti2024crosssectionalstudyon pages 2-3, hotz2023mutationalspectrumof pages 1-2, penacorona2023advancesinthe pages 1-2)
ARCI is a Mendelian (autosomal recessive) genetic disorder caused by biallelic pathogenic variants in multiple genes involved in cornified envelope formation and epidermal lipid processing/transport, leading to skin barrier failure. (hotz2023mutationalspectrumof pages 1-2, penacorona2023advancesinthe pages 1-2)
In a 2024 Italian ARCI cohort study (n=74), the genetic distribution was: TGM1 24.3%, ALOX12B 24.3%, CYP4F22 16.2%, ABCA12 12.2%, ALOXE3 9.5%, NIPAL4 9.5%, and CERS3/PNPLA1/SDR9C7 1.4% each. (Diociaiuti et al., Dermatology; 2024-04; https://doi.org/10.1159/000536366) (diociaiuti2024crosssectionalstudyon pages 1-2)
Evidence retrieved here did not include robust environmental, toxin, or lifestyle risk factors for ARCI as a genetic disorder.
No protective genetic or environmental factors were identified in the retrieved sources.
No explicit gene–environment interaction studies were identified in the retrieved sources.
In a 2024 cross-sectional Italian series (74 genetically confirmed ARCI patients): - Subtype distribution: LI 67.5% (50/74); CIE 24.3% (18/74); HI 2.7% (2/74); other minor ARCI subtypes 5.4% (4/74). (diociaiuti2024crosssectionalstudyon pages 1-2) - Symptom/feature frequencies (reported across cohort): - Pruritus: 86.3% (63/73); mean itch VAS 5.7 ± 2.0 - Pain: 15.1% (11/73); pain VAS 5.2 ± 2.7 - Palmoplantar keratoderma (PPK): 97.3% (72/74) - Fissures: 28.4% (21/74) - Ectropion: 25.7% (19/74) - Eclabium: 14.9% (11/74) These data support high burden of itch and frequent keratoderma with variable ocular/perioral involvement. (diociaiuti2024crosssectionalstudyon pages 2-3)
The Italian cohort operationalized severity using a SCORAD-based ichthyosis severity score incorporating body surface involvement, 10 clinical features, and VAS itch and pain. (diociaiuti2024crosssectionalstudyon pages 2-3)
ARCI is described as having symptoms that “drastically affect patients’ quality of life” in a 2023 treatment review. (penacorona2023advancesinthe pages 1-2) A diagnostic-practice study also states that ichthyosis has a negative effect on QoL, citing prior literature. (salo2024genetictestingand pages 1-2)
ARCI is genetically heterogeneous; recent sources list core causal genes including ABCA12, ALOX12B, ALOXE3, CERS3, CYP4F22, NIPAL4, PNPLA1, SDR9C7, SULT2B1, TGM1. (hotz2023mutationalspectrumof pages 1-2)
A large 2023 ABCA12 cohort paper states: “ARCI is caused by biallelic mutations in ABCA12, ALOX12B, ALOXE3, CERS3, CYP4F22, NIPAL4, PNPLA1, SDR9C7, SULT2B1, and TGM1.” (Genes; 2023-03; https://doi.org/10.3390/genes14030717) (hotz2023mutationalspectrumof pages 1-2)
| Gene | Protein/function (1 phrase) | ARCI subtype associations | Key genotype–phenotype notes/statistics | Key source (include DOI and year) |
|---|---|---|---|---|
| TGM1 | Transglutaminase-1; cornified envelope cross-linking | LI, CIE, bathing suit ichthyosis; severe ARCI | In the 74-patient Italian ARCI cohort, 18/74 (24.3%) had TGM1 variants; mean severity was among the highest across genes. Alopecia, ectropion, and eclabium were significantly associated with TGM1; large, thick, brownish scales were particularly linked to this genotype. On ultrastructure, cholesterol clefts were 100% specific for TGM1-mutated cases. TGM1 is also described as the most common cause of ARCI in review literature (diociaiuti2024crosssectionalstudyon pages 1-2, penacorona2023advancesinthe pages 1-2). | Diociaiuti 2024, DOI: 10.1159/000536366; Peña-Corona 2023, DOI: 10.3389/fphar.2023.1274248 (diociaiuti2024crosssectionalstudyon pages 1-2, penacorona2023advancesinthe pages 1-2) |
| ALOX12B | 12R-lipoxygenase; epidermal lipid processing | LI, CIE, collodion baby/self-improving phenotypes | In the Italian cohort, 18/74 (24.3%) had ALOX12B variants, tying TGM1 as the most frequent gene. Severity was lower than TGM1/ABCA12 overall. Reviews identify ALOX12B as a major ARCI gene involved in barrier lipid metabolism; phenotypes can range from collodion baby to later generalized ichthyosis (diociaiuti2024crosssectionalstudyon pages 1-2, penacorona2023advancesinthe pages 1-2). | Diociaiuti 2024, DOI: 10.1159/000536366; Peña-Corona 2023, DOI: 10.3389/fphar.2023.1274248 (diociaiuti2024crosssectionalstudyon pages 1-2, penacorona2023advancesinthe pages 1-2) |
| CYP4F22 | Cytochrome P450 ω-hydroxylase; acylceramide synthesis | LI/CIE spectrum, often milder ARCI | In the Italian cohort, 12/74 (16.2%) had CYP4F22 variants. This group had the lowest mean ichthyosis severity score among the common ARCI genes in that study. Founder effects are reported for some variants in prior population studies, supporting population-specific enrichment (diociaiuti2024crosssectionalstudyon pages 1-2). | Diociaiuti 2024, DOI: 10.1159/000536366 (diociaiuti2024crosssectionalstudyon pages 1-2) |
| ABCA12 | Lipid transporter for lamellar granule cargo/glucosylceramides | HI, also LI and CIE | In the Italian cohort, 9/74 (12.2%) had ABCA12 variants; severity was among the highest and alopecia, ectropion, eclabium were significantly associated. In the dedicated 64-patient ABCA12 cohort, 34 novel variants expanded the known spectrum to 217 mutations; putative hotspots included c.4541G>A p.(Arg1514His) and c.4139A>G p.(Asn1380Ser). Strong correlation: biallelic loss-of-function usually causes HI, whereas biallelic missense variants mainly cause CIE or LI (hotz2023mutationalspectrumof pages 1-2, diociaiuti2024crosssectionalstudyon pages 1-2). | Hotz 2023, DOI: 10.3390/genes14030717; Diociaiuti 2024, DOI: 10.1159/000536366 (hotz2023mutationalspectrumof pages 1-2, diociaiuti2024crosssectionalstudyon pages 1-2) |
| ALOXE3 | Epidermal lipoxygenase eLOX3; lipid barrier metabolism | LI/CIE spectrum | In the Italian cohort, 7/74 (9.5%) had ALOXE3 variants. Included among core ARCI genes in multiple recent reviews and diagnostic papers; phenotype overlaps with other lipid-metabolism ARCI genes, supporting need for molecular confirmation (diociaiuti2024crosssectionalstudyon pages 1-2, fioretti2024comprehensivemolecularanalysis pages 16-17). | Diociaiuti 2024, DOI: 10.1159/000536366; Fioretti 2024, DOI: 10.3390/biomedicines12051112 (diociaiuti2024crosssectionalstudyon pages 1-2, fioretti2024comprehensivemolecularanalysis pages 16-17) |
| NIPAL4 | Ichthyin; epidermal lipid homeostasis/acylceramide pathway | LI/CIE spectrum, distinctive patterned/psoriasiform ARCI | In the Italian cohort, 7/74 (9.5%) had NIPAL4 variants. Distinctive associations included psoriasis-like lesions, reticulate trunk scale pattern, and striated keratoderma; these were highlighted as a novel phenotypic feature with possible diagnostic/therapeutic implications. Prior referenced literature also links NIPAL4 to reduced stratum corneum acylceramides (diociaiuti2024crosssectionalstudyon pages 1-2, diociaiuti2024crosssectionalstudyon pages 17-17). | Diociaiuti 2024, DOI: 10.1159/000536366 (diociaiuti2024crosssectionalstudyon pages 1-2, diociaiuti2024crosssectionalstudyon pages 17-17) |
| CERS3 | Ceramide synthase 3; very-long-chain ceramide synthesis | Rare ARCI, LI/CIE-like phenotypes | Rare in the Italian cohort (1/74; 1.4%). Ultrastructural review showed abnormal lamellar bodies in the CERS3 case, consistent with a barrier-lipid trafficking/synthesis defect (diociaiuti2024crosssectionalstudyon pages 1-2). | Diociaiuti 2024, DOI: 10.1159/000536366 (diociaiuti2024crosssectionalstudyon pages 1-2) |
| PNPLA1 | Patatin-like phospholipase; acylceramide biosynthesis | Rare ARCI, typically LI/CIE-like | Rare in the Italian cohort (1/74; 1.4%). Included among established ARCI genes in recent reviews and sequencing studies; contributes to defective epidermal lipid barrier formation (diociaiuti2024crosssectionalstudyon pages 1-2, hotz2023mutationalspectrumof pages 1-2). | Diociaiuti 2024, DOI: 10.1159/000536366; Hotz 2023, DOI: 10.3390/genes14030717 (diociaiuti2024crosssectionalstudyon pages 1-2, hotz2023mutationalspectrumof pages 1-2) |
| SDR9C7 | Short-chain dehydrogenase/reductase; epidermal retinoid/vitamin A-related metabolism | Rare ARCI, LI/CIE-like | Rare in the Italian cohort (1/74; 1.4%). Ultrastructural analysis showed abnormal lamellar bodies in the SDR9C7 patient; referenced literature links SDR9C7 to impaired epidermal barrier function and vitamin A metabolism (diociaiuti2024crosssectionalstudyon pages 1-2, diociaiuti2024crosssectionalstudyon pages 17-17). | Diociaiuti 2024, DOI: 10.1159/000536366 (diociaiuti2024crosssectionalstudyon pages 1-2, diociaiuti2024crosssectionalstudyon pages 17-17) |
| SULT2B1 | Cholesterol sulfotransferase; epidermal sterol metabolism | Rare ARCI / nonsyndromic ichthyosis | Not represented among the 74 Italian patients, but listed as an established ARCI gene in recent ABCA12-focused and multi-gene diagnostic papers. Multi-gene NGS studies support inclusion of SULT2B1 on ichthyosis panels because phenotype overlaps with other ARCI forms (hotz2023mutationalspectrumof pages 1-2, fioretti2024comprehensivemolecularanalysis pages 16-17). | Hotz 2023, DOI: 10.3390/genes14030717; Fioretti 2024, DOI: 10.3390/biomedicines12051112 (hotz2023mutationalspectrumof pages 1-2, fioretti2024comprehensivemolecularanalysis pages 16-17) |
Table: This table summarizes major ARCI genes, their biological roles, subtype associations, and the most informative genotype–phenotype findings from the provided evidence. It emphasizes cohort-based frequencies from Diociaiuti 2024 and the ABCA12-specific correlations from Hotz 2023 for diagnostic and knowledge-base use.
No validated modifier genes were identified in the retrieved sources.
No ARCI-specific epigenetic mechanisms were identified in the retrieved sources.
Structural variants (CNVs) were reported in ARCI genes in the 2024 Italian cohort (microduplications/microdeletions), supporting CNV-aware diagnostic pipelines. (diociaiuti2024crosssectionalstudyon pages 1-2)
No consistent non-genetic environmental causes were identified in the retrieved sources, consistent with ARCI being primarily monogenic. Supportive care often includes environmental management (e.g., avoiding overheating due to hypohidrosis/heat intolerance), but specific external causal exposures were not established in these sources. (diociaiuti2024crosssectionalstudyon pages 2-3)
Upstream trigger: biallelic pathogenic variants in genes mediating cornified envelope formation (e.g., TGM1) and/or epidermal lipid transport/metabolism (e.g., ABCA12, lipoxygenases, acylceramide pathway genes). (hotz2023mutationalspectrumof pages 1-2, penacorona2023advancesinthe pages 1-2)
Intermediate biological effects: defective cornification and impaired lipid processing/transport produce an abnormal stratum corneum architecture and permeability barrier; ultrastructural signatures can be gene-informative (e.g., “cholesterol clefts” in TGM1). (diociaiuti2024crosssectionalstudyon pages 1-2)
Clinical manifestations: generalized hyperkeratosis/scaling with variable erythema, fissuring, ectropion/eclabium, pruritus and pain; severe ABCA12 loss-of-function produces harlequin ichthyosis with life-threatening neonatal complications. (diociaiuti2024crosssectionalstudyon pages 2-3, hotz2023mutationalspectrumof pages 1-2)
A 2023 treatment review frames ARCI as having an “inflammatory process” and motivates repurposing biologics based on overlapping immune signatures with psoriasis/atopic dermatitis. (penacorona2023advancesinthe pages 1-2) Clinical trial development targeting IL-17 (secukinumab) and IL-12/23 (ustekinumab) further reflects this mechanistic direction. (NCT03041038 chunk 1, penacorona2023advancesinthe pages 6-7)
Primary organ: skin (epidermis/stratum corneum). (hotz2023mutationalspectrumof pages 1-2, diociaiuti2024crosssectionalstudyon pages 1-2) Secondary/complication-relevant systems include eyes (ectropion), mouth/lips (eclabium), thermoregulation (hypohidrosis/heat intolerance), and infection susceptibility due to barrier compromise. (diociaiuti2024crosssectionalstudyon pages 2-3)
Key affected tissue: keratinizing stratified squamous epithelium of the epidermis; key cell type: keratinocytes undergoing abnormal terminal differentiation/cornification. (penacorona2023advancesinthe pages 1-2)
Cornified envelope structures and lipid-processing/transport organelles (e.g., lamellar body biology) are implicated; ultrastructural abnormalities were used diagnostically (including abnormal lamellar bodies in CERS3/SDR9C7 cases). (diociaiuti2024crosssectionalstudyon pages 1-2)
ARCI is typically congenital/early-onset; the “collodion baby” presentation is frequently described across ARCI. (hotz2023mutationalspectrumof pages 1-2, diociaiuti2024crosssectionalstudyon pages 2-3)
The 2024 cohort includes ages from infancy to adulthood (0.1–48.8 years), supporting the view that ARCI is generally chronic and lifelong, with variable severity across genotypes. (diociaiuti2024crosssectionalstudyon pages 1-2)
Autosomal recessive inheritance is explicit in the disease definition. (hotz2023mutationalspectrumof pages 1-2)
A 2023 ARCI treatment review cites: - TGM1-related prevalence “at 1:100,000 population” (citing Vahlquist et al., 2008), and - a French epidemiologic study reporting ARCI prevalence 7:1,000,000 (citing Dreyfus et al., 2014). (penacorona2023advancesinthe pages 1-2)
Because these are secondary citations within a review, they should be treated as contextual estimates rather than definitive contemporary global prevalence.
The 2024 Italian cohort reported 17.8% consanguinity (13/73 families). (diociaiuti2024crosssectionalstudyon pages 2-3)
Diagnosis generally starts from clinical phenotype (LI/CIE/HI spectrum, collodion baby) and is increasingly confirmed by genetic testing. (diociaiuti2024crosssectionalstudyon pages 1-2, salo2024genetictestingand pages 1-2)
The 2024 Italian ARCI study incorporated transmission electron microscopy and reported gene-informative ultrastructural patterns (e.g., “cholesterol clefts” specific for TGM1). (diociaiuti2024crosssectionalstudyon pages 1-2)
A 2024 register-based Finnish study (2000–2020; n=88) describes how diagnostic practice evolved: - “Diagnosis of ichthyosis was confirmed with genetic testing in 33 cases … and with conventional diagnostic methods … in 55 cases.” (Accepted 2024-08-06; https://doi.org/10.1002/mgg3.70000) (salo2024genetictestingand pages 1-2) - “When genetic testing became available, it was offered primarily to patients with severe forms of ichthyosis. During the study period next-generation sequencing became the genetic testing method of choice…” (salo2024genetictestingand pages 1-2)
The 2024 Italian cohort used targeted NGS panels and escalation to clinical exome/other methods, plus qPCR/array CGH for CNV detection and Sanger validation. (diociaiuti2024crosssectionalstudyon pages 2-3)
1) Phenotype-driven evaluation (LI/CIE/HI; collodion baby) with assessment of extracutaneous features to exclude syndromic ichthyoses. (salo2024genetictestingand pages 1-2) 2) NGS multigene panel covering core ARCI genes; consider CNV-aware methods (microarray/MLPA/NGS CNV calling) given reported microdeletions/duplications. (diociaiuti2024crosssectionalstudyon pages 1-2, salo2024genetictestingand pages 1-2) 3) If negative/uncertain: clinical exome or genome sequencing; segregation analysis where needed. (diociaiuti2024crosssectionalstudyon pages 2-3, salo2024genetictestingand pages 1-2)
The retrieved sources emphasize clinical heterogeneity and mention improved outcomes for severe forms with intensive neonatal care, but they do not provide cohort-level survival curves for ARCI/HI within 2023–2024 primary literature in this run. The Italian cohort supports long-term survivorship into adulthood across subtypes, while HI is highlighted as the most severe and high-burden neonatal condition. (hotz2023mutationalspectrumof pages 1-2, diociaiuti2024crosssectionalstudyon pages 1-2)
A 2023 review states: “Topical treatments are a first-choice strategy due to their ease of application and cost; however, enteral administration of retinoids offers greater efficacy, although with certain limitations.” (Published 2023-11-09; https://doi.org/10.3389/fphar.2023.1274248) (penacorona2023advancesinthe pages 1-2)
The retrieved evidence establishes systemic retinoids as commonly used in severe inherited ichthyosis management (review-level statement), but does not provide ARCI-specific response rates in 2023–2024 primary trials in this run. (penacorona2023advancesinthe pages 1-2)
Trial: NCT04154293 (Timber Pharmaceuticals; Phase 2; completed). (NCT04154293 chunk 1) - Population: age ≥9 years, genetically confirmed congenital ichthyosis including ARCI-LI and RXLI; 10–90% BSA involvement. (NCT04154293 chunk 1) - Design: randomized, double-blind, vehicle-controlled; 34 participants; 1:1:1 to 0.05% BID, 0.1% BID, or vehicle for 12 weeks. (Study start 2019-12-03; completion 2021-08-30) (NCT04154293 chunk 1) - Primary endpoint: VIIS-50 responder at Week 12 (≥50% reduction in VIIS scaling). (NCT04154293 chunk 1) - Patient-centered secondary endpoints included itch scale change and DLQI. (NCT04154293 chunk 1) URL: https://clinicaltrials.gov/study/NCT04154293 (registry-derived). (NCT04154293 chunk 1)
Gene/cell therapy review (2024) states: “Gene therapy for the most common type of ichthyosis, lamellar ichthyosis caused by biallelic pathogenic variants in TGM1, is currently being developed using an engineered herpes simplex virus type 1 vector.” (Published online 2024-08-07; https://doi.org/10.1007/s13555-024-01239-4) (koutsoukos2024highlightsofgene pages 1-3)
ClinicalTrials.gov trials: - NCT04047732 (KB105; Phase 1/2; single-group, intra-patient comparison; up to 6 adults; started 2019-08-27; primary completion estimated Oct 2022; completion estimated Mar 2025). Endpoints include safety (TEAEs) and improvement by Investigator’s Global Assessment (IGA), VIIS-L changes, and immunofluorescence measurement of TGM1 in treated skin. (NCT04047732 chunk 1) - NCT05735158 (KB105-02; Phase 2; randomized, placebo-controlled, double-blind intra-subject design; estimated 15; weekly dosing; primary endpoint Composite IGA responder at Week 9; includes systemic retinoid stability/washout rules). (Posted as 2023 trial record; sponsor Krystal Biotech) (NCT05735158 chunk 1) URLs: https://clinicaltrials.gov/study/NCT04047732 and https://clinicaltrials.gov/study/NCT05735158 (registry-derived). (NCT04047732 chunk 1, NCT05735158 chunk 1)
Trial: NCT03041038 (Northwestern University; Phase 2; completed; results posted 2021). (NCT03041038 chunk 1) - Enrollment: 20 adults. - Dosing: secukinumab 300 mg SC weekly ×5 then monthly vs placebo with crossover/open-label phases. (NCT03041038 chunk 1) - Primary efficacy endpoint: Week 16 reduction in Ichthyosis Area Severity Index (IASI). - Primary safety endpoint: bacterial/fungal mucocutaneous infections through Week 16. (NCT03041038 chunk 1) URL: https://clinicaltrials.gov/study/NCT03041038 (registry-derived). (NCT03041038 chunk 1)
A 2023 ARCI repositioning review notes a trial “with 13 participants receiving injections every 8 weeks for one year” aiming to reduce severity and assess infection safety endpoints (review-level summary). (penacorona2023advancesinthe pages 6-7)
Primary prevention is genetic (not environmental): carrier testing, prenatal diagnosis, and reproductive counseling are standard concepts for autosomal recessive disorders, but explicit ARCI-specific prevention guideline statements were not retrieved in this run. Genetic counseling is emphasized as enabled by molecular diagnosis in diagnostic-practice literature. (salo2024genetictestingand pages 1-2)
The retrieved sources in this run do not provide primary evidence for naturally occurring ARCI-equivalent disease across species. (No species-specific evidence retrieved.)
The retrieved sources in this run mention that gene and cell therapy development for ichthyosis is supported by preclinical work (review-level), but do not provide specific animal model identifiers or detailed phenotype recapitulation for ARCI subtypes in the captured excerpts. (koutsoukos2024highlightsofgene pages 1-3)
1) Genotype–phenotype resolution is improving with large cohorts: a 2024 single-center ARCI cohort (n=74) provides gene frequencies and statistically associated clinical features and ultrastructural signatures (including itch burden and high prevalence of PPK). (diociaiuti2024crosssectionalstudyon pages 2-3, diociaiuti2024crosssectionalstudyon pages 1-2) 2) ABCA12 genotype–phenotype correlation is reinforced: biallelic loss-of-function → HI; biallelic missense → LI/CIE; 34 novel variants in a 64-patient cohort (2023). (hotz2023mutationalspectrumof pages 1-2) 3) Diagnostics are shifting to NGS as first-tier with increasing use over time and improved classification/prognosis and counseling; conventional methods remain common where testing is unavailable (2024 register study). (salo2024genetictestingand pages 1-2) 4) Therapeutic innovation is moving toward targeted biologics and gene therapy: topical HSV-1–vector TGM1 gene therapy trials are ongoing/expanding; topical isotretinoin and IL-17 blockade have been tested in controlled trial frameworks. (koutsoukos2024highlightsofgene pages 1-3, NCT04047732 chunk 1, NCT05735158 chunk 1, NCT04154293 chunk 1, NCT03041038 chunk 1)
References
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(NCT04047732 chunk 1): Topical KB105 Gene Therapy for the Treatment of TGM1-deficient Autosomal Recessive Congenital Ichthyosis (ARCI). Krystal Biotech, Inc.. 2019. ClinicalTrials.gov Identifier: NCT04047732
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(NCT03041038 chunk 1): Amy Paller. The Efficacy and Safety of Secukinumab in Patients With Ichthyoses. Northwestern University. 2016. ClinicalTrials.gov Identifier: NCT03041038
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(NCT04154293 chunk 1): A Vehicle Controlled Study to Evaluate Safety and Efficacy of Topical TMB-001 for Treatment of Congenital Ichthyosis. Timber Pharmaceuticals Inc.. 2019. ClinicalTrials.gov Identifier: NCT04154293
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