Genetic investigation of XPA gene: high frequency of the c.682C>T mutation in Moroccan XP patients with moderate clinical profile

Abstract

Objective: Xeroderma pigmentosum (XP) is a genetically and clinically heterogeneous disease, associated with an inherited defect in one of eight different genes (XPA to XPG and XPV). In addition to the early onset of the skin manifestations, the XP group A is marked by the presence of a mild to severe neural disorders which appear tardily and worsens with age. In this study, 9 patients with moderate clinical profile belonging to 6 XP families were recruited to determine the XPA mutational spectrum in Morocco, using the direct sequencing of the whole coding region of the XPA gene.

Results: The genetic investigation of the XPA gene showed that 7 from 9 patients were homozygous for the c.682C>T, p.Arg228X mutation, while all their investigated family members were heterozygous. The frequency of this mutation was estimated to be 83.33% (5/6 families) .The molecular analysis of the 5 other exons of the XPA gene, showed that the 2 negative siblings carried no mutation in the XPA gene. This finding suggests that c.682C>T (p.Arg228X) mutation is relatively associated with moderate phenotype in XP group A Moroccan families; this result will also contribute to improve the molecular diagnosis of XP disease in Moroccan patients.

Keywords: Morocco; Mutation; XPA; Xeroderma pigmentosum.

Fig. 1

a Pedigree of the family XP43. b Localization of the mutation C.682C>T (P.R228X)

Fig. 2

Mapping of XPA gene structure showing XPA exons and different XPA reactive domains (adapted from Ref. [19])