👪

Inheritance

1

Autosomal dominant inheritance HP:0000006

Autosomal dominant. The causal variant segregated with disease across a large multigenerational family, and a sporadic case consistent with a de novo event has been reported. Adermatoglyphia appears fully penetrant in reported families; expressivity of the extracutaneous features varies.

Autosomal dominant inheritance

Show evidence (2 references)

PMID:34909722 SUPPORT Human Clinical

"Basan syndrome is an autosomal dominant genodermatosis characterized by congenital adermatoglyphia, transient congenital facial milia, neonatal acral bullae, and absent or reduced sweating."

States autosomal dominant inheritance and the cardinal feature set.

PMID:21820097 SUPPORT Human Clinical

"This mutation segregated with the disease phenotype throughout the entire family."

Co-segregation of the SMARCAD1 variant with disease in a large family, consistent with dominant inheritance.

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Pathophysiology

5

SMARCAD1 Skin-Specific Isoform Splice-Donor Variant

A heterozygous variant affecting the skin-specific short isoform of SMARCAD1, which begins with an alternative, otherwise-noncoding first exon. In almost all reported families the variant is a point mutation in the donor splice site of that alternative exon 1; one family instead carries a large structural variant (a deletion with nontandem inverted duplication) that removes the first nine exons including the skin-isoform exon 1. SMARCAD1 is a SNF2-family chromatin remodeller.

SMARCAD1 hgnc:18398

ATP-dependent chromatin remodeler activity GO:0140658 ↓ DECREASED

Downstream

Reduced Skin-Specific SMARCAD1 Expression The splice-donor variant disrupts splicing of the skin-specific transcript.

Show evidence (3 references)

PMID:21820097 SUPPORT Human Clinical

"Sequencing of all SMARCAD1 coding and noncoding exons revealed a heterozygous transversion predicted to disrupt a conserved donor splice site adjacent to the 3' end of a noncoding exon uniquely present in the skin-specific short isoform of the gene."

Identifies the founding variant as a donor-splice-site change in the noncoding exon unique to the skin-specific isoform.

PMID:21820097 SUPPORT Human Clinical

"One of the genes located in this interval is SMARCAD1, a member of the SNF subfamily of the helicase protein superfamily."

Grounds SMARCAD1 as a SNF2-family helicase / chromatin remodeller.

PMID:34909722 SUPPORT Human Clinical

"All reported variants, except for one large deletion, are point mutations within the donor splice site of the alternative exon 1."

Summarises the allelic spectrum as donor-splice-site point mutations plus one large deletion.

Reduced Skin-Specific SMARCAD1 Expression

A minigene assay of the founding variant showed aberrant splicing with reduced stability of the short RNA isoform, demonstrated by RT-PCR; the structural deletion family shows that one copy of full-length SMARCAD1 suffices, so it is the loss of the skin-specific isoform that is pathogenic. Reduced protein level is inferred from the RNA-level data.

Downstream

Impaired Epidermal Chromatin Remodeling Reduced skin-specific SMARCAD1, a chromatin remodeller, is presumed to impair chromatin remodelling in developing epidermis (inferred; the mechanism is described as unclear in the primary sources).

Show evidence (2 references)

PMID:21820097 SUPPORT In Vitro

"Using a minigene system, we found that this mutation causes aberrant splicing, resulting in decreased stability of the short RNA isoform as predicted by computational analysis and shown by RT-PCR."

Minigene and RT-PCR evidence that the variant destabilises the short, skin-specific transcript.

PMID:34909722 SUPPORT Human Clinical

"Although this variant results in the removal of the first nine exons of SMARCAD1 and exon 1 of the skin-specific isoform, it manifested in the typical Basan phenotype. This suggests that unlike the skin-specific isoform, a single copy of full-length SMARCAD1 is sufficient for its respective function."

The structural-deletion family localises pathogenicity to loss of the skin-specific isoform rather than of full-length SMARCAD1.

Impaired Epidermal Chromatin Remodeling

Loss of the skin-specific SMARCAD1 isoform is presumed to impair ATP-dependent chromatin remodelling in developing epidermal keratinocytes. This step is inferred: the reviewed sources state that the mechanism linking SMARCAD1 to dermatoglyph and ectodermal development is not established.

epidermal keratinocyte CL:4052061

chromatin remodeling GO:0006338 ↓ DECREASED

skin epidermis UBERON:0001003

Downstream

Failure of Dermatoglyph Development

Abnormal Epidermal and Adnexal Development

Show evidence (1 reference)

PMID:21820097 SUPPORT Human Clinical

"Taken together, the present findings implicate a skin-specific isoform of SMARCAD1 in the regulation of dermatoglyph development."

Implicates the skin-specific SMARCAD1 isoform in dermatoglyph development; the intervening chromatin-remodelling step is inferred.

Failure of Dermatoglyph Development

Failure of epidermal ridge (dermatoglyph) patterning on the fingers, palms, toes, and soles, producing congenital adermatoglyphia.

skin epidermis UBERON:0001003

Downstream

Adermatoglyphia

Show evidence (1 reference)

PMID:21820097 SUPPORT Human Clinical

"Taken together, the present findings implicate a skin-specific isoform of SMARCAD1 in the regulation of dermatoglyph development."

Links the skin-specific isoform to regulation of dermatoglyph development, whose failure produces adermatoglyphia.

Abnormal Epidermal and Adnexal Development

Beyond the ridge defect, deficiency of the skin-specific isoform produces an ectodermal-dysplasia phenotype affecting the epidermis and its appendages: transient congenital facial milia, rapidly healing neonatal acral bullae, reduced eccrine sweating, and nail dystrophy. The specific developmental mechanism tying these appendage defects to SMARCAD1 loss is not established and is inferred here from the shared causal variant.

Downstream

Congenital facial milia

Neonatal acral blistering

Hypohidrosis

Nail dystrophy

Show evidence (1 reference)

PMID:30289605 SUPPORT Human Clinical

"Basan syndrome is an autosomal dominant ectodermal dysplasia (ED) with congenital adermatoglyphia, transient neonatal acral bullae, and congenital facial milia."

Classifies Basan syndrome as an ectodermal dysplasia encompassing the appendage features.

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Pathograph

Use the checkboxes to hide or show graph categories. Hover nodes for evidence and cross-linked metadata.

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Phenotypes

7

Adermatoglyphia Dermatologic HP:0007455

Show evidence (1 reference)

PMID:34909722 SUPPORT Human Clinical

"Basan syndrome is an autosomal dominant genodermatosis characterized by congenital adermatoglyphia, transient congenital facial milia, neonatal acral bullae, and absent or reduced sweating."

Lists congenital adermatoglyphia as a defining feature.

Congenital facial milia Dermatologic HP:0001056

Show evidence (2 references)

PMID:34909722 SUPPORT Human Clinical

"Basan syndrome is an autosomal dominant genodermatosis characterized by congenital adermatoglyphia, transient congenital facial milia, neonatal acral bullae, and absent or reduced sweating."

Lists transient congenital facial milia as a cardinal feature.

PMID:33486784 SUPPORT Human Clinical

"Basan syndrome is a rare autosomal dominant genodermatosis, characterized by rapidly healing congenital acral bullae, congenital milia and adermatoglyphia (lack of finger and toeprints)."

Independent report confirming congenital milia as a cardinal feature.

Neonatal acral blistering Dermatologic HP:0031045

Show evidence (2 references)

PMID:26932190 SUPPORT Human Clinical

"Basan syndrome is a rare autosomal dominant genodermatosis, characterized by rapidly healing congenital acral bullae, congenital milia and lack of fingerprints."

Lists rapidly healing congenital acral bullae as a cardinal feature.

PMID:34909722 SUPPORT Human Clinical

"Basan syndrome is an autosomal dominant genodermatosis characterized by congenital adermatoglyphia, transient congenital facial milia, neonatal acral bullae, and absent or reduced sweating."

Confirms neonatal acral bullae as a cardinal feature.

Hypohidrosis Dermatologic HP:0000966

Show evidence (2 references)

PMID:34909722 SUPPORT Human Clinical

"Basan syndrome is an autosomal dominant genodermatosis characterized by congenital adermatoglyphia, transient congenital facial milia, neonatal acral bullae, and absent or reduced sweating."

Lists absent or reduced sweating as a cardinal feature.

PMID:30289605 SUPPORT Human Clinical

"Autosomal dominant adermatoglyphia (ADG) is characterized as adermatoglyphia with hypohidrosis."

Records hypohidrosis in the allelic adermatoglyphia phenotype.

Nail dystrophy Dermatologic HP:0008404

Show evidence (1 reference)

PMID:30289605 SUPPORT Human Clinical

"We offer a new acronym: SMARCAD syndrome (SMARCAD1-associated congenital facial Milia, Adermatoglyphia, Reduced sweating, Contractures, Acral Bullae, and Dystrophy of nails)."

Lists dystrophy of nails among the features of the SMARCAD syndrome spectrum.

Knuckle pads Dermatologic HP:0032541

Show evidence (1 reference)

PMID:26932190 SUPPORT Human Clinical

"Here, we present a large Chinese family with Basan syndrome; some patients presented with hyperpigmentation and knuckle pads in addition to previously reported clinical manifestations."

Reports knuckle pads as an additional feature in a Chinese family.

Hyperpigmentation of the skin Dermatologic HP:0000953

Show evidence (1 reference)

PMID:26932190 SUPPORT Human Clinical

"Here, we present a large Chinese family with Basan syndrome; some patients presented with hyperpigmentation and knuckle pads in addition to previously reported clinical manifestations."

Reports hyperpigmentation as an additional feature in a Chinese family.

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Genetic Associations

1

SMARCAD1 (Causative)

Gene: SMARCAD1 hgnc:18398 relationship_type: CAUSATIVE variant_origin: GERMLINE

Show evidence (3 references)

PMID:21820097 SUPPORT Human Clinical

"We demonstrated the existence of a short isoform of SMARCAD1 exclusively expressed in the skin."

Establishes the skin-specific SMARCAD1 isoform that disease variants disrupt.

PMID:26932190 SUPPORT Human Clinical

"WGS in one patient identified a splice variant (c.378+1G>T) in the SMARCAD1 gene (NG_031945.1) that was confirmed by Sanger sequencing."

The recurrent donor-splice-site variant identified by WGS and confirmed by segregation in a large Chinese family.

PMID:30289605 SUPPORT Human Clinical

"This variant and the other five previously reported variants in Basan syndrome and ADG are all within the same donor splice site."

All known Basan/ADG variants cluster in the single skin-isoform donor splice site.

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Diagnosis

1

Molecular genetic testing of SMARCAD1

Sequencing of SMARCAD1 including the non-canonical first exon of the skin-specific isoform, since the disease variants lie in that donor splice site. Whole-genome sequencing and whole-genome optical mapping have been needed to detect the structural variant, which standard exome panels can miss.

molecular genetic testing NCIT:C15709

Show evidence (2 references)

PMID:34909722 SUPPORT Human Clinical

"In one family, we have identified a complex structural variant (a deletion and a nontandem inverted duplication) using whole-genome optical mapping and whole-genome sequencing."

Whole-genome optical mapping and WGS were required to detect the structural variant underlying one family's disease.

PMID:26932190 SUPPORT Human Clinical

"We used genome-wide linkage analysis and whole-genome sequencing (WGS) to identify the pathogenic gene in this unique pedigree."

WGS with linkage analysis identified the SMARCAD1 variant in the Chinese family.

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Prevalence

1

Worldwide

Cases In Literature Ultra Rare

Source phrasing: reported in only 10 kindreds worldwide. No prevalence or incidence estimate has been published.

Show evidence (1 reference)

PMID:34909722 SUPPORT Human Clinical

"Basan syndrome is rare and has been reported in only 10 kindreds worldwide."

The only occurrence statement available: about ten kindreds reported.

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Differential Diagnoses

2

Conditions with similar clinical presentations that must be differentiated from absence of fingerprints-congenital milia syndrome:

Isolated autosomal dominant adermatoglyphia

Overlapping Features Isolated autosomal dominant adermatoglyphia ("immigration delay disease"; adermatoglyphia with hypohidrosis, OMIM 136000) presents with absence of fingerprints as an essentially isolated feature, without the congenital milia and neonatal acral bullae of Basan syndrome. It maps to the same skin-specific SMARCAD1 donor splice site - the recurrent c.378+1G>T variant was found in both - and has been proposed to be the same disorder on a phenotypic spectrum ("SMARCAD syndrome"). Whether Basan syndrome and isolated adermatoglyphia are one entity or distinct is unsettled; see notes.

Show evidence (2 references)

PMID:20619487 SUPPORT Human Clinical

"Absent fingerprints, or adermatoglyphia, were inherited over 4 generations of her family in an autosomal dominant fashion."

Describes isolated autosomal dominant adermatoglyphia without the extracutaneous features of Basan syndrome.

PMID:26932190 SUPPORT Human Clinical

"This indicates that ADG and Basan syndrome may be the phenotypic variants of the same disease."

The shared recurrent variant argues that isolated ADG and Basan syndrome may be the same disease.

Huriez syndrome

Overlapping Features Huriez syndrome (OMIM 181600) is an allelic SMARCAD1 skin-isoform disorder with scleroatrophy of the hands and feet, hypoplastic nails, palmoplantar keratoderma, and predisposition to cutaneous squamous cell carcinoma - features that are not part of Basan syndrome. Huriez patients also show adermatoglyphia and hypohidrosis, and the same skin-isoform donor splice site is involved, so Huriez has been proposed as part of the SMARCAD syndrome spectrum.

Show evidence (2 references)

PMID:35212137 SUPPORT Human Clinical

"Huriez syndrome (HRZ, OMIM181600) is a rare genodermatosis characterized by scleroatrophic hands and feet, hypoplastic nails, palmoplantar keratoderma, and predisposition to cutaneous squamous cell carcinoma (cSCC)."

Distinguishing features of Huriez syndrome absent from Basan syndrome.

PMID:35212137 SUPPORT Human Clinical

"On the basis of phenotypic and genotypic convergence with Adermatoglyphia (OMIM136000) and Basan syndrome (OMIM129200), our results lend credence to the notion that these three Mendelian disorders are allelic."

Places Huriez syndrome in the allelic SMARCAD1 skin-isoform spectrum.

{ }

Source YAML

click to show

name: absence of fingerprints-congenital milia syndrome
category: Mendelian
creation_date: "2026-10-12T15:45:00Z"
description: >-
  Absence of fingerprints-congenital milia syndrome (Basan syndrome) is a rare
  autosomal dominant ectodermal dysplasia. Its cardinal feature is congenital
  adermatoglyphia (absence of finger- and toeprints), accompanied by transient
  congenital facial milia, rapidly healing neonatal acral bullae, and absent or
  reduced sweating. Additional features reported in individual pedigrees include
  nail dystrophy, contractures, and (in one large Chinese family) hyperpigmentation
  and knuckle pads. It has been described in only about ten kindreds worldwide.
  The disorder is caused by heterozygous variants that disrupt a skin-specific
  short isoform of SMARCAD1, a SNF2-family chromatin-remodelling ATPase/helicase.
  The skin isoform starts with an alternative, otherwise-noncoding first exon; all
  reported variants except one large structural deletion are point mutations in the
  donor splice site of that exon, and a minigene assay shows the variant causes
  aberrant splicing and reduced stability of the short transcript. The implication
  is that the skin-specific isoform is required for normal dermatoglyph development;
  the downstream developmental steps linking its deficiency to the ectodermal
  features are not yet established. Basan syndrome, isolated autosomal dominant
  adermatoglyphia, and Huriez syndrome all map to the same skin-isoform donor splice
  site and have been proposed to be allelic ("SMARCAD syndrome").
synonyms:
- Basan syndrome
- SMARCAD syndrome
disease_term:
  preferred_term: Basan syndrome
  term:
    id: MONDO:0007507
    label: absence of fingerprints-congenital milia syndrome
parents:
- ectodermal dysplasia
- genodermatosis
inheritance:
- name: Autosomal dominant inheritance
  inheritance_term:
    preferred_term: Autosomal dominant inheritance
    term:
      id: HP:0000006
      label: Autosomal dominant inheritance
  description: >-
    Autosomal dominant. The causal variant segregated with disease across a large
    multigenerational family, and a sporadic case consistent with a de novo event
    has been reported. Adermatoglyphia appears fully penetrant in reported families;
    expressivity of the extracutaneous features varies.
  evidence:
  - reference: PMID:34909722
    reference_title: Two SMARCAD1 Variants Causing Basan Syndrome in a Canadian and a Dutch Family.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Basan syndrome is an autosomal dominant genodermatosis characterized by congenital adermatoglyphia, transient congenital facial milia, neonatal acral bullae, and absent or reduced sweating."
    explanation: >-
      States autosomal dominant inheritance and the cardinal feature set.
  - reference: PMID:21820097
    reference_title: A mutation in a skin-specific isoform of SMARCAD1 causes autosomal-dominant adermatoglyphia.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "This mutation segregated with the disease phenotype throughout the entire family."
    explanation: >-
      Co-segregation of the SMARCAD1 variant with disease in a large family,
      consistent with dominant inheritance.
pathophysiology:
- name: SMARCAD1 Skin-Specific Isoform Splice-Donor Variant
  biological_scale: MOLECULAR
  description: >-
    A heterozygous variant affecting the skin-specific short isoform of SMARCAD1,
    which begins with an alternative, otherwise-noncoding first exon. In almost all
    reported families the variant is a point mutation in the donor splice site of
    that alternative exon 1; one family instead carries a large structural variant
    (a deletion with nontandem inverted duplication) that removes the first nine
    exons including the skin-isoform exon 1. SMARCAD1 is a SNF2-family chromatin
    remodeller.
  genes:
  - preferred_term: SMARCAD1
    term:
      id: hgnc:18398
      label: SMARCAD1
  molecular_functions:
  - preferred_term: ATP-dependent chromatin remodeler activity
    term:
      id: GO:0140658
      label: ATP-dependent chromatin remodeler activity
    modifier: DECREASED
  evidence:
  - reference: PMID:21820097
    reference_title: A mutation in a skin-specific isoform of SMARCAD1 causes autosomal-dominant adermatoglyphia.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Sequencing of all SMARCAD1 coding and noncoding exons revealed a heterozygous transversion predicted to disrupt a conserved donor splice site adjacent to the 3' end of a noncoding exon uniquely present in the skin-specific short isoform of the gene."
    explanation: >-
      Identifies the founding variant as a donor-splice-site change in the
      noncoding exon unique to the skin-specific isoform.
  - reference: PMID:21820097
    reference_title: A mutation in a skin-specific isoform of SMARCAD1 causes autosomal-dominant adermatoglyphia.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "One of the genes located in this interval is SMARCAD1, a member of the SNF subfamily of the helicase protein superfamily."
    explanation: >-
      Grounds SMARCAD1 as a SNF2-family helicase / chromatin remodeller.
  - reference: PMID:34909722
    reference_title: Two SMARCAD1 Variants Causing Basan Syndrome in a Canadian and a Dutch Family.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "All reported variants, except for one large deletion, are point mutations within the donor splice site of the alternative exon 1."
    explanation: >-
      Summarises the allelic spectrum as donor-splice-site point mutations plus
      one large deletion.
  downstream:
  - target: Reduced Skin-Specific SMARCAD1 Expression
    causal_link_type: DIRECT
    description: >-
      The splice-donor variant disrupts splicing of the skin-specific transcript.
- name: Reduced Skin-Specific SMARCAD1 Expression
  biological_scale: MOLECULAR
  description: >-
    A minigene assay of the founding variant showed aberrant splicing with reduced
    stability of the short RNA isoform, demonstrated by RT-PCR; the structural
    deletion family shows that one copy of full-length SMARCAD1 suffices, so it is
    the loss of the skin-specific isoform that is pathogenic. Reduced protein level
    is inferred from the RNA-level data.
  evidence:
  - reference: PMID:21820097
    reference_title: A mutation in a skin-specific isoform of SMARCAD1 causes autosomal-dominant adermatoglyphia.
    supports: SUPPORT
    evidence_source: IN_VITRO
    snippet: "Using a minigene system, we found that this mutation causes aberrant splicing, resulting in decreased stability of the short RNA isoform as predicted by computational analysis and shown by RT-PCR."
    explanation: >-
      Minigene and RT-PCR evidence that the variant destabilises the short,
      skin-specific transcript.
  - reference: PMID:34909722
    reference_title: Two SMARCAD1 Variants Causing Basan Syndrome in a Canadian and a Dutch Family.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Although this variant results in the removal of the first nine exons of SMARCAD1 and exon 1 of the skin-specific isoform, it manifested in the typical Basan phenotype. This suggests that unlike the skin-specific isoform, a single copy of full-length SMARCAD1 is sufficient for its respective function."
    explanation: >-
      The structural-deletion family localises pathogenicity to loss of the
      skin-specific isoform rather than of full-length SMARCAD1.
  downstream:
  - target: Impaired Epidermal Chromatin Remodeling
    causal_link_type: INDIRECT_UNKNOWN_INTERMEDIATES
    description: >-
      Reduced skin-specific SMARCAD1, a chromatin remodeller, is presumed to impair
      chromatin remodelling in developing epidermis (inferred; the mechanism is
      described as unclear in the primary sources).
- name: Impaired Epidermal Chromatin Remodeling
  biological_scale: CELLULAR
  description: >-
    Loss of the skin-specific SMARCAD1 isoform is presumed to impair ATP-dependent
    chromatin remodelling in developing epidermal keratinocytes. This step is
    inferred: the reviewed sources state that the mechanism linking SMARCAD1 to
    dermatoglyph and ectodermal development is not established.
  cell_types:
  - preferred_term: epidermal keratinocyte
    term:
      id: CL:4052061
      label: epidermal keratinocyte
  biological_processes:
  - preferred_term: chromatin remodeling
    term:
      id: GO:0006338
      label: chromatin remodeling
    modifier: DECREASED
  locations:
  - preferred_term: skin epidermis
    term:
      id: UBERON:0001003
      label: skin epidermis
  evidence:
  - reference: PMID:21820097
    reference_title: A mutation in a skin-specific isoform of SMARCAD1 causes autosomal-dominant adermatoglyphia.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Taken together, the present findings implicate a skin-specific isoform of SMARCAD1 in the regulation of dermatoglyph development."
    explanation: >-
      Implicates the skin-specific SMARCAD1 isoform in dermatoglyph development;
      the intervening chromatin-remodelling step is inferred.
  downstream:
  - target: Failure of Dermatoglyph Development
    causal_link_type: INDIRECT_UNKNOWN_INTERMEDIATES
  - target: Abnormal Epidermal and Adnexal Development
    causal_link_type: INDIRECT_UNKNOWN_INTERMEDIATES
- name: Failure of Dermatoglyph Development
  biological_scale: TISSUE
  description: >-
    Failure of epidermal ridge (dermatoglyph) patterning on the fingers, palms,
    toes, and soles, producing congenital adermatoglyphia.
  locations:
  - preferred_term: skin epidermis
    term:
      id: UBERON:0001003
      label: skin epidermis
  evidence:
  - reference: PMID:21820097
    reference_title: A mutation in a skin-specific isoform of SMARCAD1 causes autosomal-dominant adermatoglyphia.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Taken together, the present findings implicate a skin-specific isoform of SMARCAD1 in the regulation of dermatoglyph development."
    explanation: >-
      Links the skin-specific isoform to regulation of dermatoglyph development,
      whose failure produces adermatoglyphia.
  downstream:
  - target: Adermatoglyphia
    causal_link_type: DIRECT
- name: Abnormal Epidermal and Adnexal Development
  biological_scale: TISSUE
  description: >-
    Beyond the ridge defect, deficiency of the skin-specific isoform produces an
    ectodermal-dysplasia phenotype affecting the epidermis and its appendages:
    transient congenital facial milia, rapidly healing neonatal acral bullae,
    reduced eccrine sweating, and nail dystrophy. The specific developmental
    mechanism tying these appendage defects to SMARCAD1 loss is not established and
    is inferred here from the shared causal variant.
  evidence:
  - reference: PMID:30289605
    reference_title: "Basan gets a new fingerprint: Mutations in the skin-specific isoform of SMARCAD1 cause ectodermal dysplasia syndromes with adermatoglyphia."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Basan syndrome is an autosomal dominant ectodermal dysplasia (ED) with congenital adermatoglyphia, transient neonatal acral bullae, and congenital facial milia."
    explanation: >-
      Classifies Basan syndrome as an ectodermal dysplasia encompassing the
      appendage features.
  downstream:
  - target: Congenital facial milia
    causal_link_type: INDIRECT_UNKNOWN_INTERMEDIATES
  - target: Neonatal acral blistering
    causal_link_type: INDIRECT_UNKNOWN_INTERMEDIATES
  - target: Hypohidrosis
    causal_link_type: INDIRECT_UNKNOWN_INTERMEDIATES
  - target: Nail dystrophy
    causal_link_type: INDIRECT_UNKNOWN_INTERMEDIATES
phenotypes:
- name: Adermatoglyphia
  category: Dermatologic
  description: >-
    Congenital absence of the epidermal ridges (dermatoglyphs) on the fingers,
    palms, toes, and soles, so that fingerprints are absent. This is the defining
    feature and gives the syndrome its "immigration delay disease" alias through
    failed fingerprint-based identification.
  phenotype_term:
    preferred_term: Adermatoglyphia
    term:
      id: HP:0007455
      label: Adermatoglyphia
  evidence:
  - reference: PMID:34909722
    reference_title: Two SMARCAD1 Variants Causing Basan Syndrome in a Canadian and a Dutch Family.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Basan syndrome is an autosomal dominant genodermatosis characterized by congenital adermatoglyphia, transient congenital facial milia, neonatal acral bullae, and absent or reduced sweating."
    explanation: >-
      Lists congenital adermatoglyphia as a defining feature.
- name: Congenital facial milia
  category: Dermatologic
  description: >-
    Transient congenital milia, typically on the face, present in the neonatal
    period and resolving over time.
  phenotype_term:
    preferred_term: Congenital facial milia
    term:
      id: HP:0001056
      label: Milia
  evidence:
  - reference: PMID:34909722
    reference_title: Two SMARCAD1 Variants Causing Basan Syndrome in a Canadian and a Dutch Family.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Basan syndrome is an autosomal dominant genodermatosis characterized by congenital adermatoglyphia, transient congenital facial milia, neonatal acral bullae, and absent or reduced sweating."
    explanation: >-
      Lists transient congenital facial milia as a cardinal feature.
  - reference: PMID:33486784
    reference_title: "Ectodermal dysplasia with congenital adermatoglyphia (Basan syndrome): Report of two cases presenting with extensive congenital milia."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Basan syndrome is a rare autosomal dominant genodermatosis, characterized by rapidly healing congenital acral bullae, congenital milia and adermatoglyphia (lack of finger and toeprints)."
    explanation: >-
      Independent report confirming congenital milia as a cardinal feature.
- name: Neonatal acral blistering
  category: Dermatologic
  description: >-
    Rapidly healing congenital acral bullae (blistering of the hands and feet) in
    the neonatal period.
  phenotype_term:
    preferred_term: Neonatal acral bullae
    term:
      id: HP:0031045
      label: Acral blistering
  evidence:
  - reference: PMID:26932190
    reference_title: Genome-wide linkage analysis and whole-genome sequencing identify a recurrent SMARCAD1 variant in a unique Chinese family with Basan syndrome.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Basan syndrome is a rare autosomal dominant genodermatosis, characterized by rapidly healing congenital acral bullae, congenital milia and lack of fingerprints."
    explanation: >-
      Lists rapidly healing congenital acral bullae as a cardinal feature.
  - reference: PMID:34909722
    reference_title: Two SMARCAD1 Variants Causing Basan Syndrome in a Canadian and a Dutch Family.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Basan syndrome is an autosomal dominant genodermatosis characterized by congenital adermatoglyphia, transient congenital facial milia, neonatal acral bullae, and absent or reduced sweating."
    explanation: >-
      Confirms neonatal acral bullae as a cardinal feature.
- name: Hypohidrosis
  category: Dermatologic
  description: >-
    Absent or reduced sweating, reported in Basan syndrome and in the allelic
    adermatoglyphia phenotype.
  phenotype_term:
    preferred_term: Reduced sweating
    term:
      id: HP:0000966
      label: Hypohidrosis
  evidence:
  - reference: PMID:34909722
    reference_title: Two SMARCAD1 Variants Causing Basan Syndrome in a Canadian and a Dutch Family.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Basan syndrome is an autosomal dominant genodermatosis characterized by congenital adermatoglyphia, transient congenital facial milia, neonatal acral bullae, and absent or reduced sweating."
    explanation: >-
      Lists absent or reduced sweating as a cardinal feature.
  - reference: PMID:30289605
    reference_title: "Basan gets a new fingerprint: Mutations in the skin-specific isoform of SMARCAD1 cause ectodermal dysplasia syndromes with adermatoglyphia."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Autosomal dominant adermatoglyphia (ADG) is characterized as adermatoglyphia with hypohidrosis."
    explanation: >-
      Records hypohidrosis in the allelic adermatoglyphia phenotype.
- name: Nail dystrophy
  category: Dermatologic
  description: >-
    Dystrophy of the nails, included as a feature of the unified SMARCAD syndrome
    spectrum (the "D" of the proposed acronym).
  phenotype_term:
    preferred_term: Nail dystrophy
    term:
      id: HP:0008404
      label: Nail dystrophy
  evidence:
  - reference: PMID:30289605
    reference_title: "Basan gets a new fingerprint: Mutations in the skin-specific isoform of SMARCAD1 cause ectodermal dysplasia syndromes with adermatoglyphia."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "We offer a new acronym: SMARCAD syndrome (SMARCAD1-associated congenital facial Milia, Adermatoglyphia, Reduced sweating, Contractures, Acral Bullae, and Dystrophy of nails)."
    explanation: >-
      Lists dystrophy of nails among the features of the SMARCAD syndrome spectrum.
- name: Knuckle pads
  category: Dermatologic
  description: >-
    Knuckle pads, reported together with hyperpigmentation as additional features
    in one large Chinese pedigree, extending the phenotypic spectrum.
  phenotype_term:
    preferred_term: Knuckle pads
    term:
      id: HP:0032541
      label: Knuckle pad
  evidence:
  - reference: PMID:26932190
    reference_title: Genome-wide linkage analysis and whole-genome sequencing identify a recurrent SMARCAD1 variant in a unique Chinese family with Basan syndrome.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Here, we present a large Chinese family with Basan syndrome; some patients presented with hyperpigmentation and knuckle pads in addition to previously reported clinical manifestations."
    explanation: >-
      Reports knuckle pads as an additional feature in a Chinese family.
- name: Hyperpigmentation of the skin
  category: Dermatologic
  description: >-
    Cutaneous hyperpigmentation, reported with knuckle pads as an additional
    feature in one large Chinese pedigree.
  phenotype_term:
    preferred_term: Hyperpigmentation
    term:
      id: HP:0000953
      label: Hyperpigmentation of the skin
  evidence:
  - reference: PMID:26932190
    reference_title: Genome-wide linkage analysis and whole-genome sequencing identify a recurrent SMARCAD1 variant in a unique Chinese family with Basan syndrome.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Here, we present a large Chinese family with Basan syndrome; some patients presented with hyperpigmentation and knuckle pads in addition to previously reported clinical manifestations."
    explanation: >-
      Reports hyperpigmentation as an additional feature in a Chinese family.
genetic:
- name: SMARCAD1
  gene_term:
    preferred_term: SMARCAD1
    term:
      id: hgnc:18398
      label: SMARCAD1
  association: Causative
  relationship_type: CAUSATIVE
  variant_origin: GERMLINE
  notes: >-
    Heterozygous loss-of-function variants disrupting the skin-specific short isoform
    of SMARCAD1, which starts with an alternative first exon. Reported disease alleles
    are point mutations in the donor splice site of that exon (for example
    NM_001254949.1:c.-10+2T>G and the recurrent c.378+1G>T) or, in one family, a large
    complex structural variant (deletion plus nontandem inverted duplication) removing
    the first nine exons. A 12-bp deletion spanning the exon-intron junction of the
    alternative exon 1 was found in a further family. The structural-deletion family
    indicates that loss of the skin-specific isoform, not of full-length SMARCAD1, is
    pathogenic. No ClinGen gene-disease validity record for SMARCAD1 and Basan syndrome
    was found in the local reference cache, so no gene_disease_validity assertion is
    recorded.
  evidence:
  - reference: PMID:21820097
    reference_title: A mutation in a skin-specific isoform of SMARCAD1 causes autosomal-dominant adermatoglyphia.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "We demonstrated the existence of a short isoform of SMARCAD1 exclusively expressed in the skin."
    explanation: >-
      Establishes the skin-specific SMARCAD1 isoform that disease variants disrupt.
  - reference: PMID:26932190
    reference_title: Genome-wide linkage analysis and whole-genome sequencing identify a recurrent SMARCAD1 variant in a unique Chinese family with Basan syndrome.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "WGS in one patient identified a splice variant (c.378+1G>T) in the SMARCAD1 gene (NG_031945.1) that was confirmed by Sanger sequencing."
    explanation: >-
      The recurrent donor-splice-site variant identified by WGS and confirmed by
      segregation in a large Chinese family.
  - reference: PMID:30289605
    reference_title: "Basan gets a new fingerprint: Mutations in the skin-specific isoform of SMARCAD1 cause ectodermal dysplasia syndromes with adermatoglyphia."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "This variant and the other five previously reported variants in Basan syndrome and ADG are all within the same donor splice site."
    explanation: >-
      All known Basan/ADG variants cluster in the single skin-isoform donor splice
      site.
prevalence:
- population: Worldwide
  measure_type: CASES_IN_LITERATURE
  prevalence_class: ULTRA_RARE
  notes: >-
    Source phrasing: reported in only 10 kindreds worldwide. No prevalence or
    incidence estimate has been published.
  evidence:
  - reference: PMID:34909722
    reference_title: Two SMARCAD1 Variants Causing Basan Syndrome in a Canadian and a Dutch Family.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Basan syndrome is rare and has been reported in only 10 kindreds worldwide."
    explanation: >-
      The only occurrence statement available: about ten kindreds reported.
diagnosis:
- name: Molecular genetic testing of SMARCAD1
  description: >-
    Sequencing of SMARCAD1 including the non-canonical first exon of the
    skin-specific isoform, since the disease variants lie in that donor splice site.
    Whole-genome sequencing and whole-genome optical mapping have been needed to
    detect the structural variant, which standard exome panels can miss.
  diagnosis_term:
    preferred_term: molecular genetic testing
    term:
      id: NCIT:C15709
      label: Genetic Testing
  evidence:
  - reference: PMID:34909722
    reference_title: Two SMARCAD1 Variants Causing Basan Syndrome in a Canadian and a Dutch Family.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "In one family, we have identified a complex structural variant (a deletion and a nontandem inverted duplication) using whole-genome optical mapping and whole-genome sequencing."
    explanation: >-
      Whole-genome optical mapping and WGS were required to detect the structural
      variant underlying one family's disease.
  - reference: PMID:26932190
    reference_title: Genome-wide linkage analysis and whole-genome sequencing identify a recurrent SMARCAD1 variant in a unique Chinese family with Basan syndrome.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "We used genome-wide linkage analysis and whole-genome sequencing (WGS) to identify the pathogenic gene in this unique pedigree."
    explanation: >-
      WGS with linkage analysis identified the SMARCAD1 variant in the Chinese
      family.
differential_diagnoses:
- name: Isolated autosomal dominant adermatoglyphia
  description: >-
    Isolated autosomal dominant adermatoglyphia ("immigration delay disease";
    adermatoglyphia with hypohidrosis, OMIM 136000) presents with absence of
    fingerprints as an essentially isolated feature, without the congenital milia
    and neonatal acral bullae of Basan syndrome. It maps to the same skin-specific
    SMARCAD1 donor splice site - the recurrent c.378+1G>T variant was found in both -
    and has been proposed to be the same disorder on a phenotypic spectrum
    ("SMARCAD syndrome"). Whether Basan syndrome and isolated adermatoglyphia are one
    entity or distinct is unsettled; see notes.
  evidence:
  - reference: PMID:20619487
    reference_title: "The immigration delay disease: adermatoglyphia-inherited absence of epidermal ridges."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Absent fingerprints, or adermatoglyphia, were inherited over 4 generations of her family in an autosomal dominant fashion."
    explanation: >-
      Describes isolated autosomal dominant adermatoglyphia without the
      extracutaneous features of Basan syndrome.
  - reference: PMID:26932190
    reference_title: Genome-wide linkage analysis and whole-genome sequencing identify a recurrent SMARCAD1 variant in a unique Chinese family with Basan syndrome.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "This indicates that ADG and Basan syndrome may be the phenotypic variants of the same disease."
    explanation: >-
      The shared recurrent variant argues that isolated ADG and Basan syndrome may
      be the same disease.
- name: Huriez syndrome
  description: >-
    Huriez syndrome (OMIM 181600) is an allelic SMARCAD1 skin-isoform disorder with
    scleroatrophy of the hands and feet, hypoplastic nails, palmoplantar keratoderma,
    and predisposition to cutaneous squamous cell carcinoma - features that are not
    part of Basan syndrome. Huriez patients also show adermatoglyphia and
    hypohidrosis, and the same skin-isoform donor splice site is involved, so Huriez
    has been proposed as part of the SMARCAD syndrome spectrum.
  evidence:
  - reference: PMID:35212137
    reference_title: "Huriez syndrome: Additional pathogenic variants supporting allelism to SMARCAD syndrome."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Huriez syndrome (HRZ, OMIM181600) is a rare genodermatosis characterized by scleroatrophic hands and feet, hypoplastic nails, palmoplantar keratoderma, and predisposition to cutaneous squamous cell carcinoma (cSCC)."
    explanation: >-
      Distinguishing features of Huriez syndrome absent from Basan syndrome.
  - reference: PMID:35212137
    reference_title: "Huriez syndrome: Additional pathogenic variants supporting allelism to SMARCAD syndrome."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "On the basis of phenotypic and genotypic convergence with Adermatoglyphia (OMIM136000) and Basan syndrome (OMIM129200), our results lend credence to the notion that these three Mendelian disorders are allelic."
    explanation: >-
      Places Huriez syndrome in the allelic SMARCAD1 skin-isoform spectrum.
notes: >-
  Lump/split: curated as a single-gene leaf DISEASE for Basan syndrome
  (MONDO:0007507). The entity is defined by congenital adermatoglyphia plus the
  extracutaneous ectodermal-dysplasia features (facial milia, neonatal acral bullae,
  reduced sweating). Isolated autosomal dominant adermatoglyphia (OMIM 136000) and
  Huriez syndrome (OMIM 181600) are allelic, map to the same skin-specific SMARCAD1
  donor splice site, and have been proposed to form one "SMARCAD syndrome" spectrum
  (PMID:30289605, PMID:35212137); the recurrent c.378+1G>T variant was found in both
  a Basan family and an isolated-adermatoglyphia family (PMID:26932190). They are kept
  as differential diagnoses here rather than merged or split into subtypes, because
  MONDO retains distinct concepts and the primary sources describe the unification as
  a proposal rather than settled nosology; a reviewer may wish to consider a Grouping
  for the SMARCAD1 skin-isoform spectrum. A 2022 report of cutaneous squamous cell
  carcinoma in a Basan family (PMID:35592705) was retracted (PMID:37387737) and is not
  cited; cSCC risk is a feature of the allelic Huriez syndrome, not of Basan syndrome.

📚

References & Deep Research

Deep Research

1

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

Evaluations and curation notes (1)

Create: Absence_Of_Fingerprints-congenital_Milia_Syndrome · 2026-10-12T16:19:52Z · View source

De novo curation of Basan syndrome (absence of fingerprints-congenital milia syndrome, MONDO:0007507, SMARCAD1 skin-specific isoform). Claim issue #13949. Deep-research report (research/Absence_Of_Fingerprints-congenital_Milia_Syndrome-deep-research-claude_code.md) used as leads only; all primary sources (PMID:21820097 Nousbeck 2011 AJHG, PMID:34909722, PMID:26932190, PMID:30289605, PMID:33486784, PMID:35212137, PMID:20619487) re-fetched and every snippet verified exact against references_cache. Pathograph: 5-node SMARCAD1 skin-isoform chain (splice-donor variant -> reduced skin-specific transcript -> inferred impaired epidermal chromatin remodeling -> failure of dermatoglyph development; branch to abnormal epidermal/adnexal development) wiring 5 of 7 phenotypes. Gene node grounded with GO:0140658 ATP-dependent chromatin remodeler activity. No ClinGen CGGV record for SMARCAD1 in cache, so gene_disease_validity omitted and noted. Lump/split: single-gene leaf DISEASE; isolated AD adermatoglyphia and Huriez syndrome kept as allelic differentials (proposed 'SMARCAD syndrome' spectrum unsettled). Retracted cSCC report PMID:35592705 excluded. Validation: validate-disorders clean, 30/30 snippets verified, check-gene-activity-grounding/snippet-length/snippet-grading/entity-refs/causal-targets/coarse-phenotypes all OK.

Claude Code ▸

Research report: absence of fingerprints–congenital milia syndrome (Basan syndrome)

claude-haiku-5-5, claude-sonnet-5-5 6 citations 2026-10-12T15:59:24.188398

I'll load the search tools first, then run the literature searches.

Bash is gated; I'll use WebFetch against Europe PMC instead.

Research report: absence of fingerprints–congenital milia syndrome (Basan syndrome)

Scope and verification limits. I ran a limited set of searches. Europe PMC returned titles and abstracts. PubMed and PMC full text were blocked from this environment (bot checks). Four consequences follow: - Items marked [verified] come from an abstract or record I actually saw. - Items marked [unverified] come from an aggregator or my own recall. Resolve them with just fetch-reference and OAK before binding. - I have not provided exact abstract quotes. Take snippets from the cached references after just fetch-reference PMID:<id>. - Per the CURIE rule in CLAUDE.md, every ontology ID below is a lead until it has been looked up.

1. Disease information

Overview. Basan syndrome is a rare autosomal dominant ectodermal dysplasia-like genodermatosis. It features congenital absence of dermatoglyphs (adermatoglyphia), transient facial milia, and neonatal acral blistering. Reduced or absent sweating is also described. It is caused by variants that disrupt the skin-specific isoform of SMARCAD1. A 2021 paper describes it as having "congenital adermatoglyphia (absent fingerprints), transient facial milia, neonatal acral bullae, and absent or reduced sweating", with only about 10 kindreds reported worldwide (PMID:34909722) [verified, paraphrased].

Identifiers.

System	Value	Status
OMIM (Basan syndrome)	129200	secondary aggregator [unverified]
Orphanet	1658	aggregator [unverified]
MONDO	MONDO:0007507	aggregator [unverified]
MedGen	140808	aggregator [unverified]
OMIM (isolated adermatoglyphia, AD)	136000	my recall [unverified]

Synonyms. These come from the OMIM text quoted by GeneBe [verified]: - Basan syndrome - Baird syndrome - Adermatoglyphia with congenital facial milia and acral blisters, digital contractures, and nail abnormalities - Absence of fingerprints-congenital milia syndrome

Related terms are "SMARCAD syndrome" and "immigration delay disease" (the isolated form, PMID:20619487).

Nosology (important for lump/split). A 2018 report proposes that Basan syndrome and isolated autosomal dominant adermatoglyphia (ADG, which includes hypohidrosis) are one spectrum, which it calls "SMARCAD syndrome" (PMID:30289605) [verified]. A 2022 paper adds Huriez syndrome as allelic (PMID:35212137) [verified]. - The 2016 Chinese-family study found the same splice variant (c.378+1G>T) in Basan syndrome and in a previously reported isolated-ADG family (PMID:26932190) [verified]. - Recommendation: enter this as a DISEASE with has_subtypes or mondo_mappings for ADG. Consider a Grouping for the SMARCAD1 skin-isoform spectrum (Basan, ADG, Huriez), and read the lump/split rules before deciding.

Data source. All sources are aggregated literature on families. There is no EHR-derived data.

2. Etiology

Cause. Germline heterozygous variants in SMARCAD1 affecting the skin-specific isoform. Apart from one large deletion, all reported variants are point mutations in the donor splice site of the alternative exon 1 that defines that isoform (PMID:34909722) [verified].
Genetic risk and modifiers. No modifier genes or protective alleles are reported in what I found.
Environmental risk, protective factors and gene-environment interactions. None are reported. Heat exposure matters only as a complication of reduced sweating (see §11).

3. Phenotypes

Frequencies are not quantified in the abstracts I saw. Entries are qualitative. HPO IDs are leads, not verified.

Phenotype	Notes	HPO lead
Adermatoglyphia	Present from birth, defining feature; stable	HP:0010293
Facial milia, congenital	Transient; extensive in some neonates (PMID:33486784)	HP:0001056
Neonatal acral blistering	Hands and feet; recurrent in infancy	HP:0007410 (check)
Hypohidrosis / reduced sweating	Described in Basan and ADG (PMID:30289605, PMID:34909722)	HP:0000966
Digital contractures	Part of the OMIM-described syndrome	HP:0001188 (check)
Nail dystrophy / nail abnormalities	Part of the OMIM-described syndrome	HP:0001597 (check)
Hyperpigmentation, knuckle pads	Seen in some members of a Chinese pedigree (PMID:26932190)	HP:0000953, HP:0001806 (check)

Onset. Congenital or neonatal. Milia regress in early life [inferred].
Quality of life. Mainly practical. Fingerprint-based identification fails (PMID:31011502, PMID:36578701). Heat intolerance is possible. No QoL instrument data found.
Cancer. A report of cutaneous SCC in a Basan family (PMID:35592705) was retracted (PMID:37387737). Do not cite it. SCC risk is a feature of the allelic Huriez syndrome (PMID:40806836).

4. Genetic/molecular information

Gene. SMARCAD1 (4q22-q23; the linkage region in the Nousbeck family was 4q22). HGNC hgnc:18398 and NCBI Gene 56916 are my recall [unverified]. Look the CURIE up before binding.
Variants [verified unless noted]:
ADG family: a heterozygous donor-splice-site mutation in a skin-specific exon of the short isoform. Minigene assays show aberrant splicing that destabilises the short RNA isoform (PMID:21820097).
Chinese family: c.378+1G>T (NG_031945.1), segregating with disease, LOD 3.01 (PMID:26932190).
Sporadic case: NM_001254949.1:c.-10+2T>G in the skin-isoform exon 1 donor site. The six reported splice variants all affect this donor (PMID:30289605).
Canadian family: a complex structural variant (deletion plus nontandem inverted duplication) removing the first nine exons, including the skin-isoform exon 1. The authors infer that one copy of full-length SMARCAD1 suffices, but not of the skin isoform (PMID:34909722).
Dutch family: a 12-bp deletion spanning the exon-intron junction of the skin-specific exon 1 (PMID:34909722).
South Indian family: a novel variant (PMID:37966719; details not retrieved).
Consequence. Loss of the skin-specific isoform. This is a loss-of-function / isoform-specific haploinsufficiency model (functional_impact_category likely LOSS_OF_FUNCTION, but the sources frame it as isoform loss).
Epigenetic and chromosomal. SMARCAD1 encodes a chromatin remodeller; no methylation signature has been reported. Other than the structural variant above, no chromosomal abnormalities are reported.

5. Environmental information

No environmental, lifestyle or infectious factors are reported.

6. Mechanism / pathophysiology

Causal chain. 1. A heterozygous germline splice-donor (or exon-1-deleting) variant in the skin-specific SMARCAD1 exon 1 alters splicing of the skin isoform (demonstrated by minigene assay, PMID:21820097). 2. This destabilises the short, skin-specific transcript, so there is less skin-specific SMARCAD1 protein (demonstrated at RNA level; protein level inferred). 3. Reduced SMARCAD1, a SNF2-family helicase and chromatin remodeller, is presumed to impair chromatin remodelling in developing epidermis (inferred; the reviewed sources describe the mechanism as unclear). 4. The authors "conclude that the skin-specific isoform plays a role in dermatoglyph development" (PMID:21820097, paraphrased). This leads to failure of epidermal ridge patterning (adermatoglyphia). 5. Branch, inferred: altered epidermal and appendage development leads to the features seen in Basan syndrome. These are milia (probably retention of keratinising structures), acral blistering and impaired sweat gland function (hypohidrosis). 6. Some of the milder, ridge-only presentations correspond to the isolated ADG end of the spectrum. The determinants of this variability are unknown.

Steps 3 to 5 are not experimentally demonstrated in the sources I saw.

Cell types and structures. Epidermal keratinocytes (CL:0000312, lead), eccrine sweat gland, and the dermal-epidermal junction.
GO leads. Chromatin remodeling (GO:0006338), nucleosome remodeling, epidermis development (GO:0008544). Verify each by lookup.
Molecular profiling. No omics data found.
Other mechanisms. SMARCAD1 interacts with TFIIIC and architectural proteins (PMID:37761933), and zebrafish smarcad1a loss accelerates nerve sheath tumorigenesis (PMID:34296799). These are context for the gene, not shown to be disease mechanisms here.

7. Anatomical structures affected

Primary. Skin of the fingertips, palms and soles (UBERON:0002097 skin; fingertip and palm are leads), face (milia), acral skin (blisters), and nails.
Secondary. Eccrine sweat glands; joints and digits (contractures).
Laterality. Bilateral, symmetric [inferred].

8. Temporal development

Onset. Congenital. Blistering is neonatal.
Course. Milia are transient. Absent dermatoglyphs are permanent. No progression has been described.

9. Inheritance and population

Inheritance. Autosomal dominant (HP:0000006, lead). Penetrance for adermatoglyphia is apparently complete in the reported families; expressivity of the extracutaneous features varies. This is partly my reading and not quantified in the sources.
Epidemiology. Only about 10 kindreds have been reported worldwide (PMID:34909722). No prevalence or incidence estimate was found; consider prevalence_class of NOT_YET_DOCUMENTED or an ultra-rare class, supported by the "~10 kindreds" statement, with measure_type: CASES_IN_LITERATURE.
Population. Families are reported from Switzerland and the Middle East (ADG), China, Canada, the Netherlands and India. No founder effect is established.
De novo cases. The sporadic case in PMID:30289605 suggests de novo occurrence is possible.

10. Diagnostics

Clinical. Examination shows absent ridge patterns, neonatal milia and acral blisters, and a family history.
Genetic. Sequence SMARCAD1, including the non-canonical exon 1 of the skin isoform. Standard exome panels may miss it, and a structural variant may need optical mapping or WGS (PMID:34909722; PMID:26932190 used WGS).
Differential. Huriez syndrome (palmoplantar keratoderma, sclerodactyly, SCC risk, allelic), other ectodermal dysplasias, and epidermolysis bullosa for the neonatal blistering. Features to distinguish them are not fully sourced here.
Screening. None applicable. No biochemical or imaging markers are known.

11. Outcome/prognosis

Survival. No life-shortening is reported in the sources found. No survival data.
Complications. Heat intolerance from hypohidrosis; practical identification problems (PMID:31011502); contractures and nail dystrophy.
Cancer. Not established for Basan syndrome (retracted report, above).

12. Treatment

No disease-specific therapy exists. Management is supportive: wound care for blisters, avoiding overheating, hand therapy for contractures, and genetic counselling. NCIT leads such as NCIT:C15747 (Supportive Care) and NCIT:C15240 (Genetic Counseling) are those listed in CLAUDE.md. I found no clinical trials; a ClinicalTrials.gov search should be run before recording that none exist. No pharmacogenomics or gene therapy has been reported.

13. Prevention

Genetic counselling for autosomal dominant transmission, prenatal or preimplantation diagnosis if the family variant is known, and counselling about heat avoidance. No primary or secondary prevention is established.

14. Other species / natural disease

I did not search OMIA, so I cannot say whether a naturally occurring analogue exists. Smarcad1 orthologues exist in mouse and zebrafish. A zebrafish smarcad1a loss study exists, but it concerns tumour suppression (PMID:34296799).

15. Model organisms

I found no animal model that recapitulates adermatoglyphia. Mice lack human-type fingerprint ridges, which makes a model of ridge patterning inherently limited. Check MGI/IMPC for Smarcad1 alleles before recording this as a KNOWLEDGE_GAP or HUMAN_MODEL_MISMATCH.

Key references (PMIDs verified through Europe PMC listings)

PMID	Year	Topic
21820097	2011	Nousbeck et al., Am J Hum Genet. Skin-specific SMARCAD1 isoform mutation causes AD adermatoglyphia
20619487	2010/2011	Burger et al., J Am Acad Dermatol. Immigration delay disease
26932190	2016	Chinese Basan family, c.378+1G>T, Eur J Hum Genet
30289605	2018	"Basan gets a new fingerprint", unifying SMARCAD syndrome, Am J Med Genet A
33400266	2021	Large deletion removing the skin isoform causes Huriez syndrome, Br J Dermatol
33486784	2021	Two cases with extensive congenital milia, Pediatr Dermatol
34909722	2021	Canadian and Dutch families, JID Innovations
35212137	2022	Huriez syndrome allelism, Am J Med Genet A
37966719	2024	South Indian family, Clin Exp Dermatol
31011502	2019	Biometric identification barriers, Cureus
36578701	2022	Adermatoglyphia and biometrics, Indian J Dermatol
35592705 / 37387737	2022 / 2023	SCC report and its retraction; do not cite as evidence

Gaps to close before curation. Confirm the OMIM, Orphanet and MONDO IDs and the HGNC ID. Verify the HPO and GO leads. Obtain the phenotype frequencies from full text (especially PMID:21820097, PMID:34909722 and PMID:33486784). Check OMIA, MGI and ClinicalTrials.gov. Fetch the references and take exact snippets from the cache.

Sources: - Nousbeck et al. 2011, PMC3155166 - Basan syndrome, Wikipedia - Chinese Basan family, PMID 26932190 - Basan syndrome, KEGG - Two SMARCAD1 variants, JID Innovations - Huriez allelism, PMID 35212137 - Europe PMC REST search results (PMIDs and abstracts)

Reference Validation

Checked with linkml-reference-validator 0.3.0.

Outcome	Count
References checked	16
Resolved	16
Unresolved (possible confabulation)	0
Unverifiable	0
Quoted claims checked	2
Quoted claims found in source	1
Quoted claims not found in source	1
References weighed for topical relevance	16
On topic	8
Off topic	1

Quotes not found in the cited source

Searched the abstract, any retrieved full text, and the title. A quote drawn from a part of the paper that was not retrieved will appear here too, so check before treating one as invented:

Every one of these was searched against an abstract alone, with no full text retrieved - marked abstract only below. Where full text can be fetched, re-running with it will settle them; where the source publishes only a summary to PubMed, as GeneReviews chapters do, it will not, and the quote has to be checked by hand against the chapter itself.

PMID:21820097 (abstract only): "conclude that the skin-specific isoform plays a role in dermatoglyph development"
closest text in source: "Taken together, the present findings implicate a skin-specific isoform of SMARCAD1 in the regulation of dermatoglyph development."

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:

PMID:31011502 (2 mentions) - Adermatoglyphia: Barriers to Biometric Identification and the Need for a Standardized Alternative.
shared terms: adermatoglyphia

Weighed against this report's own most characteristic terms: smarcad1, milia, syndrome, found, variant, lead, basan, family, isoform, adermatoglyphia, verified, skin-specific, congenital, acral, adg, skin, disease, feature, genetic, blistering.

Term Validation

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

Outcome	Count
Terms checked	16
Resolved	16
Unresolved (possible confabulation)	0
Obsolete	0
Unverifiable	0
Terms whose name was checked	5
Terms named correctly	0
Terms named as a different term	5

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:0007507 (1 mention) - the report calls it "MONDO"; MONDO calls it absence of fingerprints-congenital milia syndrome
HP:0010293 (1 mention) - the report calls it "Present from birth, defining feature; stable"; HP calls it Aplasia/Hypoplasia of the uvula
HP:0007410 (1 mention) - the report calls it "check"; HP calls it Palmoplantar hyperhidrosis
HP:0001188 (1 mention) - the report calls it "check"; HP calls it Hand clenching
HP:0001597 (1 mention) - the report calls it "check"; HP calls it Abnormal nail morphology

absence of fingerprints-congenital milia syndrome

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Inheritance

Pathophysiology

Pathograph

Phenotypes

Genetic Associations

Diagnosis

Prevalence

Differential Diagnoses

Source YAML

References & Deep Research

Deep Research

Research report: absence of fingerprints–congenital milia syndrome (Basan syndrome)

1. Disease information

2. Etiology

3. Phenotypes

4. Genetic/molecular information

5. Environmental information

6. Mechanism / pathophysiology

7. Anatomical structures affected

8. Temporal development

9. Inheritance and population

10. Diagnostics

11. Outcome/prognosis

12. Treatment

13. Prevention

14. Other species / natural disease

15. Model organisms

Key references (PMIDs verified through Europe PMC listings)

Reference Validation

Quotes not found in the cited source

References that may not be about this subject

Term Validation

Terms the report names something else