Clinical and genetic investigation of ichthyosis in familial and sporadic cases in south of Tunisia: genotype–phenotype correlation

Abstract

Abstract Background Ichthyosis is a heterogeneous group of Mendelian cornification disorders that includes syndromic and non-syndromic forms. Autosomal Recessive Congenital Ichthyosis (ARCI) and Ichthyosis Linearis Circumflexa (ILC) belong to non-syndromic forms. Syndromic ichthyosis is rather a large group of heterogeneous diseases. Overlapping phenotypes and genotypes between these disorders is a major characteristic. Therefore, determining the specific genetic background for each form would be necessary. Methods A total of 11 Tunisian patients with non-syndromic (8 with ARCI and 2 with ILC) and autosomal syndromic ichthyosis (1 patient) were screened by a custom Agilent HaloPlex multi-gene panel and the segregation of causative mutations were analyzed in available family members. Results Clinical and molecular characterization, leading to genotype–phenotype correlation in 11 Tunisian patients was carried out. Overall, we identified 8 mutations in 5 genes. Thus, in patients with ARCI, we identified a novel (c.118T > C in NIPAL4) and 4 already reported mutations (c.534A > C in NIPAL4; c.788G > A and c.1042C > T in TGM1 and c.844C > T in CYP4F22). Yellowish severe keratoderma was found to be associated with NIPAL4 variations and brachydactyly to TGM1 mutations. Two novel variations (c.5898G > C and c.2855A > G in ABCA12) seemed to be features of ILC. Delexon13 in CERS3 was reported in a patient with syndromic ichthyosis. Conclusions Our study further extends the spectrum of mutations involved in ichthyosis as well as clinical features that could help directing genetic investigation.