Identification of XP complementation groups by recombinant adenovirus carrying DNA repair genes.

TO THE EDITOR Individuals with xeroderma pigmentosum syndrome (XP) present an extremely high sensitivity to sunlight, with increased incidence of skin cancer (especially in sun-exposed areas), when compared to the normal population. Some XP patients can also display developmental complications and early aging features. A genetic defect in the nucleotide excision repair pathway (NER) was described as the molecular cause of XP syndrome (Cleaver, 1968), and somatic cell fusion accompanied by functional complementation using unscheduled DNA synthesis (UDS) assays led to the identification of seven complementation groups, which correspond to some of the genes involved in NER (designated XPA to XPG) (Costa et al., 2003; Lehmann, 2003). Among these genes, mutations in XPA and XPC are the most frequent and are responsible for approximately half of all XP cases in the world (Zeng et al., 1997). All described XP mutations can be found in the XP mutations database (http://xpmutations.org). This work describes mutations in fibroblasts obtained from three children with clinical diagnosis of XP, from two nonrelated families. All three patients were born from consanguineous marriages and manifested sunburning on minimal sun exposure, photophobia, and corneal and eye lid deformities. None of them presented neurological abnormalities. The XP02SP patient is 12 years old and displayed several cutaneous tumors in sun-exposed areas, beginning at age 7 (basal-cell carcinomas, squamous-cell carcinoma, malignant fibrohistiocytoma, and atypical