Clinical and molecular characteristics of autosomal recessive congenital ichthyosis in Thailand

Background: Autosomal recessive congenital ichthyosis (ARCI) is a heterogenous group of rare keratinization disorders. To date, more than 13 causative genes have been identified. However, data on clinical and molecular characteristics including genotype-phenotype correlation are lacking in Thailand.

Objective: We collected cases diagnosed with non-syndromic ARCI and syndromic recessive congenital ichthyosis at the Institute of Dermatology from 2011 to 2021 and performed genetic testing with next-generation sequencing and assessed clinical details.

Methods: Baseline demographic data, birth history, family history, skin manifestations at birth, current cutaneous manifestations, comorbidities, and response to treatments were assessed. DNA was screened for mutations using targeted gene sequencing of 45 genes related to congenital ichthyosis.

Results: A total of 33 patients were analyzed with an average age of 23.8 ± 13.9 years. Congenital ichthyosiform erythroderma (CIE) was most common (60.6%), followed by lamellar ichthyosis (18.2%), self-improving congenital ichthyosis (6.1%), Netherton syndrome (6.1%), ichthyosis prematurity syndrome (3%), Sjögren-Larsson syndrome (3%) and bathing suit ichthyosis (3%). Eight genes were found with pathogenic variants in our cohort as follows: ABCA12 42.4% (14/33), NIPAL4 24.2% (8/33), TGM1 15.2% (5/33), SPINK5 6.1% (2/33), ALDH3A2 3% (1/33), SLC27A4 3% (1/33), CYP4F22 3% (1/33), and ST14 3% (1/33). Clinically, 79% of patients with ABCA12 pathogenic variants in this study had CIE, 79% of w had novel biallelic pathogenic compound heterozygous variants, whereas 21% had homozygous missense variants.

Conclusions: This is the first study to describe clinical and molecular findings of ARCI in a cohort from Thailand. Our findings demonstrate the clinical spectrum of the diseases and expand the molecular findings in a Southeast Asian population.