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xeroderma pigmentosum, complementation group F (XPF)

Xeroderma pigmentosum is an autosomal recessive pigmentary skin disorder characterized by solar hypersensitivity of the skin, high predisposition for developing cancers on areas exposed to sunlight and, in some cases, neurological abnormalities. Some XP-D patients present features of Cockayne syndrome, including dwarfism, sensorineural deafness, microcephaly, mental retardation, pigmentary retinopathy, ataxia, decreased nerve conduction velocities.

Group F xeroderma pigmentosum had probably been observed only in Japan (Fujiwara et al., 1985) until the report by Norris et al. (1988) of a case in an English woman. Yamamura et al. (1989) described a 61-year-old female patient with XP assigned to complementation group F by the cell fusion-complementation method. Her fibroblasts in culture exhibited a defective DNA repair capacity of 10 to 15% unscheduled DNA synthesis and a 3-fold increased sensitivity to the lethal effects of ultraviolet light. The patient had mild clinical symptoms consisting of numerous pigmented freckles and a small number of seborrheic keratosis-like papules. She had no skin cancers in the sun-exposed areas and no neurologic abnormalities. Yamamura et al. (1989) reviewed 11 Japanese group F patients demonstrating very mild skin symptoms and no ocular or neuropsychiatric abnormalities. Single skin cancers occurred in only 3 of the 11 patients, with an average age of 52 years for their first skin malignancy. Moriwaki et al. (1993) reported the case of a 48-year-old Japanese man suffering from xeroderma pigmentosum associated with mental retardation, cerebral atrophy, and cerebellar ataxia. Genetic complementation tests by cell fusion with polyethylene glycol revealed that the patient belonged to group F. He died of bile duct cancer at the age of 50. Moriwaki et al. (1993) stated that this was the first report of an XPF patient with neurologic abnormalities.


TYPE: sensitivity to radiation, chromosomal instability

Related patway(s): Fanconi anemia (FA) pathway, nucleotide excision repair (NER)

DNAtraffic protein(s) related to disease: ERCC4 (XPF)

OMIM: 278760

Last modification date: Aug. 17, 2011