SERPINA12 Splice Site Variant in Tunisian Familial Psoriasis Vulgaris: Segregation to Inheritance
Ennouri, M., Marrakchi, S., Frikha, F., Bahloul, E. B., Ltaief, A. B. H., Ammar, R., Turki, H., Elleuch, N. B.
dermatology
Quick verdict
Claims SERPINA12 splice variant underlies familial psoriasis via vaspin-KLK7 loss; intriguing but lacks linkage stats, functional assays, and the pedigree.
Summary
This preprint reports whole-exome sequencing of three affected and one unaffected member of consanguineous Tunisian nuclear families with psoriasis vulgaris, identifying a heterozygous canonical splice-donor variant, c.905+1G>T, in SERPINA12 (encoding vaspin). Sanger segregation analysis across 19 relatives (8 affected, 11 unaffected) plus 51 controls yields 7/12 carriers affected (~58% penetrance), one affected non-carrier, five unaffected heterozygous carriers, and one homozygous carrier with earlier onset; the authors interpret this as autosomal dominant inheritance with incomplete penetrance. Fruitfly splice prediction and 100-ns molecular dynamics on a homology-truncated model (residues 37-302 vs 37-414) suggest a frameshift and premature stop that destabilizes the C-terminal serpin region, which the authors extrapolate to loss of KLK7 inhibition and a mechanism linking psoriasis to type 2 diabetes. Strengths include the rare predicted-loss-of-function variant, long clinical follow-up, and convergent literature on vaspin/KLK7 in skin. Major limitations: no linkage (LOD) analysis or statistical test is reported — the paper's own 7/12 vs 1/7 numbers fall short of nominal significance (Fisher exact one-sided p≈0.08); the pedigree figure is 'available upon request'; the KLK7-inhibition defect is never assayed; 'affected' status includes one scrotal-tongue case; and the finding is not reconciled with biallelic SERPINA12 loss of function causing recessive palmoplantar keratoderma. Findings are hypothesis-generating pending replication.
Review complete
Assessment at a glance
6
risk flags identified
● high 2
● medium 3
● low 1
4 strengths · 5 weaknesses · 5 author questions
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Key claims under review
- A heterozygous canonical splice-donor variant c.905+1G>T in SERPINA12 co-segregates with psoriasis vulgaris in Tunisian nuclear families consistent with autosomal dominant inheritance with ~58% penetrance.
- The variant causes retention of five intronic nucleotides, a frameshift and a premature stop truncating vaspin near residue 302.
- Molecular dynamics indicates the truncation destabilizes vaspin's C-terminal serpin region, implying impaired serine-protease (KLK7) inhibition.
- Loss of the vaspin-KLK7 axis offers a shared mechanism linking psoriasis vulgaris and type 2 diabetes comorbidity.
- Homozygosity for the variant (proband B.IV.1) is associated with earlier disease onset, suggesting a gene-dosage effect.
Strengths
Compelling variant candidacy
Canonical +1 splice donor c.905+1G>T with CADD 33 and high-confidence pLoF, absent from 51 controls; the homozygous proband B.IV.1 shows the earliest onset (age 21-25), consistent with a gene-dosage effect the authors argue for.
Dermatology-informed genetic priors
SERPINA12 was prioritized on convergent biology — reduced vaspin in psoriatic lesions (Saalbach 2016), KLK7-overexpression psoriasiform dermatitis in mice, and recessive PPK from SERPINA12 LoF (Mohamad 2020) — rather than statistics alone.
Longitudinal, multi-family ascertainment
Quantified structural destabilization
Weaknesses
No linkage or statistical analysis anywhere
Central evidence not shown in the paper
Unvalidated mechanistic claim
Phenotype and prediction rigor gaps
Unreconciled contradiction with known SERPINA12 biology
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Scope & Claims
This medRxiv preprint (posted September 17, 2026; not peer reviewed) from Sfax, Tunisia proposes that a heterozygous splice-donor variant, c.905+1G>T, in **SERPINA12** (encoding vaspin) underlies psoriasis vulgaris (PV) in three consanguineous nuclear families, transmitted as an autosomal dominant trait with incomplete penetrance (~58%). Via homology modeling and 100-ns molecular dynamics, it further claims the variant truncates vaspin after residue ~302, destabilizes the C-terminal serpin region and — by extrapolation, without any assay — reduces inhibition of kallikrein 7 (KLK7), bridging PV and type 2 diabetes. The title's promise of "Segregation to Inheritance" anticipates a level of formal genetic proof the paper does not deliver.
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Frequently asked questions
What did this study find in Tunisian psoriasis families?
The authors sequenced the exomes of three psoriasis patients and one healthy relative from consanguineous Tunisian families and found a splice-site variant, c.905+1G>T, in SERPINA12, the gene encoding the adipokine vaspin. Among 19 genotyped family members, 7 of 12 variant carriers had psoriasis and the variant was absent from 51 unrelated controls, leading the authors to propose autosomal dominant psoriasis with about 58% penetrance.
Is the SERPINA12 variant proven to cause psoriasis?
No. The paper reports no linkage analysis or statistical tests, and its own counts (7/12 carriers vs 1/7 non-carriers affected) do not reach nominal significance (Fisher exact one-sided p≈0.08). The claimed loss of KLK7 inhibition was never tested experimentally, and the pedigree figure is not shown in the manuscript. The finding is a plausible candidate observation, not established causation.
How does vaspin connect psoriasis to type 2 diabetes?
The connection is literature-based, not experimentally tested in this paper. Prior work suggests vaspin inhibits the protease KLK7, which contributes to skin inflammation and insulin degradation; the authors hypothesize that loss of vaspin function could promote both epidermal inflammation (psoriasis) and insulin resistance (type 2 diabetes), matching the observed overlap of the two diseases in their family members over age 50.
What are the main limitations of the study?
Very small sample (three families, eight affected cases), no statistical or linkage analysis, one affected individual without the variant, one case counted as affected on scrotal tongue alone, an unverified splice effect predicted only by the dated Fruitfly tool, missing pedigree and supplementary figures, and an unaddressed contradiction with prior reports that biallelic SERPINA12 loss causes recessive palmoplantar keratoderma rather than psoriasis.
About this review
This is an AI-generated preliminary review by Evolve.Pub, produced from the openly available text of the paper. It is not peer review and does not represent the authors' views. The canonical record of the paper is at the publisher link above.
- Figures (pedigree Fig 1 'available upon request', and S1-S3) and Table 1 formatting are absent/garbled in the extraction; figure content was not analyzable.
- The gnomAD allele frequency is garbled in the text ('1.08 e'); its exact value could not be verified.
- Splice-site coordinates conflict between the Results text (205-219/210-224) and Table 2 (265-279/270-284); possibly different coordinate frames.
- This is a non-peer-reviewed medRxiv preprint (CC-BY-ND, posted 2026-09-17); the Fisher p≈0.08 quoted in this review is our recomputation from the paper's Table 1, not a statistic the authors report.
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