TOPICS: ATM gene, double-stranded DNA breaks, nonhomologous end joining repair mechanism, cell cycle, mutations, alpha-fetoprotein (AFP), autosomal recessive, cerebellar atrophy, ataxia, spider angiomas (telangiectasias), IgG, radiation, IgA, lymphopenia, lymphoma, leukemia, T cell disorder, B cell disorder, IgE