A novel POLH gene mutation in a xeroderma pigmentosum-V Tunisian patient: phenotype–genotype correlation

XP occurs at higher frequency in Tunisia (1:10,000) than in Japan (1:22,000) (Hirai et al. 2006) and the United States (1 per million) (Kleijer et al. 2008). XP-V cells are unable to synthesize intact daughter DNA strands on UV-irradiated templates resulting from an inability to carry out translesion synthesis (Lehmann et al. 1975; Masutani et al. 1999). Approximately 20% of XP patients belong to XP-V complementation group (Gratchev et al. 2003). In Tunisia, XP is classied into three clinical forms: severe, intermediate with or without neurological abnormalities, and moderate.