XCIND as a genetic disease of X-irradiation hypersensitivity and cancer susceptibility.

The XCIND syndrome is named after distinct hypersensitivity to ionizing (X-ray) irradiation, cancer susceptibility, immunodeficiency, neurological abnormality, and double-strand DNA breakage. The disorders comprising XCIND syndrome are usually inherited in an autosomal recessive manner. Ataxia telangiectasia (A-T) is one such disease, and is caused by biallelic germline mutation of the Ataxia telangiectasia mutated (ATM) gene. Heterozygous carriers of the ATM mutation, who do not show A-T-like clinical symptoms, are estimated to comprise 1 % of the population. Thus, understanding the biological basis of XCIND, including A-T, should help shed light on the pathogenesis of genetic diseases with cancer susceptibility.