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.

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.

• 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)

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.

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.

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