Xeroderma pigmentosum is a very rare autosomal recessive skin disorder characterized by photosensitivity, poikilodermic changes predominantly of the light-exposed skin with early aging of the skin and a high incidence of malignant neoplasia of the skin.
Neuroendocrinal and metabolic errors are the frequent associations but the most serious hazard is the liability towards malignant cutaneous growths very early in life which may be responsible for life termination in the first or second decades. Xeroderma pigmentosum has been associated with several forms of skin cancer, and, in some cases, may occur along with dwarfism, mental retardation, and/or delayed development.
Xeroderma pigmentosum has been reported to be unusually frequent among Arab populations.
El-Hefnawi and Smith (1965) and El-Hefnawi et al. (1965) presented useful Egyptian pedigrees, possibly of complementation groups A and C, and suggested linkage with the ABO blood group locus. Bootsma and Keijzer (1979) studied eight patients from six Egyptian families. Three were assigned to complementation group A and five to group C.
[Bootsma D, Keijzer W. Genetic analysis of xeroderma pigmentosum including Egyptian families. (Abstract) Cytogenet Cell Genet. 1979; 25:139.]
Hashem et al. (1980) conducted a survey of DNA repair characteristics among Egyptians with xeroderma pigmentosum. Out of 16 XP patients, biopsies from eight were analyzed for unscheduled DNA synthesis, strand breakage during pyrimidine dimer excision, and complementation groups. The patients were equally distributed between Complementation Groups A and C.
Afili et al. (1972) reported a pair of affected siblings born to consanguineous parents.
Satokata et al. (1992) studied the molecular basis of xeroderma pigmentosum in a Palestinian patient with severe symptoms of XP. The patient was found homozygous for a nucleotide transition altering the Arg-207 codon (CGA) to a nonsense codon (TGA).
Fathy and Khafagy (1986) reported a 28-year old Qatari female who presented with a small, growing swelling on her right cheek. Biopsy specimen revealed XP. Fathy and Khafagy (1986) surmised that the social practice of women in the Gulf countries avoiding sun exposure had resulted in her relatively long survival.
Giraldo et al. (1977) performed HLA-A and -B typing on peripheral blood lymphocytes and platelets in 37 patients and 108 relatives from 16 Tunisian families. No clear association was found in populations between deleterious XP genes and a particular HLA gene. However, an excess of identical HLA among pairs of diseased siblings would suggest that the disease is polymorphic and a form of the XP could be linked to HLA.
Nishigori et al. (1993) studied the XPAC gene alterations in seven Tunisian XPA patients. These patients included two pairs of siblings. Comparison of the clinical features of the Tunisian patients to that of Japanese XPA patients showed a later age of onset of skin cancers in the Tunisian patients. Except for one patient (9-years old), all the others developed skin cancer. Similarly, with the exception of one patient (20-years old), all others developed neurological abnormalities in the form of hearing impairment at about the age of 15-years. Unscheduled DNA synthesis (UDS) was measured after UV irradiation of cell cultures of the patient's muscle fibroblasts. The UDS ranged between 1% and 6% of the normal level, and all the patients were assigned to complementation group A. RFLP analysis of the genomic DNA revealed the presence of the HphI RFLP in the sixth exon of the XPAC gene in six of the seven patients. None of the patients showed the AlwNI or the MseI RFLP. Nishigori et al. (1993) recommended that the HphI RFLP be used to screen the XPA patients and heterozygotes in the Tunisian population, considering that it was responsible for the majority of the mutations.
Acharya and Al Rubai (1987) reported two sibs (one male and one female), nationals of the United Arab Emirates, with xeroderma pigmentosum. The parents were consanguineous. Karotyping in both sibs was normal.
[Acharya UG, Al Rubai SMS. Clinical, histopathological, metabolic and genetic study of xeroderman pigmentosum. Emirates Med J. 1987; 5:249-51.]
In 1990, Al Rubaie and El Darouti reviewed the cases of seven patients with xeroderma pigmentosum. In one case, abnormal karyotyping was suggestive of an increased risk of the development of neoplasia.