[Xeroderma pigmentosum. A study in 40 Algerian patients]

Xeroderma pigmentosum (XP) is a rate autosomal recessive disorder related to DNA repair defects. Recently, modifications of oncogenes and mutations of the p53 suppressor gene have been reported in skin tumors of XP patients. The purpose is to study, through a series of 40 patients admitted to the Dermatologic Clinic of Algiers, the characteristics of XP in Algeria.

For each patient, familiarity, clinical and biological examinations and therapeutic results were studied. Biological studies have been axed mainly on analysis of DNA extracted from skin tumors of 18 patients to detect oncogene modifications by Southern blot and hybridization. A technic, based on single strand DNA conformation polymorphism (SSCP), has been carried out to detect rapidly mutations on the p53 gene.

A consanguinity in the first degree is noted in 95 p. 100 of cases and a familiarity in 63 p. 100 of cases. The median age of patients is 10 years; sex ratio is close to one; 32 patients (80 p. 100) are classic XP and 8 (20 p. 100) are XP variant. In 18 tumors analysed, the Ha-ras gene is amplified and/or modified in 50 p. 100 of cases. Only 3 tumors (16.6 p. 100) show mutations of the p53 gene (transitions C-T). Surgical treatment isolated or associated to polychemotherapy permitted to resolve tumors in 75 p. 100 of cases.

In Algeria, XP are mainly classic with a particularly high frequency of occular (62 p. 100) and neurological manifestations (62 p. 100). Genetic studies confirm modifications of the Haras gene in direct relation with unrepaired UV lesions in classic XP and mutations of the p53 tumor suppressor gene characteristic of mutation spectra induced by UV. Surgery is the treatment of choice for tumors; polychemotherapy is an alternative in advanced cases.