Hypersensitivity to N-methyl-N'-nitro-N-nitrosoguanidine in fibroblasts from patients with Huntington disease, familial dysautonomia, and other primary neuronal degenerations.

Cells from patients with ataxia telangiectasia, a rare autosomal recessive disease characterized by primary neuronal degeneration, are abnormally sensitive to the DNA-damaging chemical N-methyl-N'-nitro-N-nitrosoguanidine. We have conducted experiments to determine whether more common primary neuronal degenerations also have a hypersensitivity to this radiomimetic chemical. Fibroblast strains from 13 control donors and from 13 patients with inherited primary neuronal degenerations were treated in vitro with the chemical, and the strains' sensitivity to the chemical was then determined by measuring their ability to divide and form colonies. Twelve of the 13 patient strains, including the 6 Huntington disease and the 4 familial dysautonomia strains, were abnormally sensitive. This hypersensitivity, which is believed to reflect defective repair of the chemically-induced DNA damage, might provide the basis for presymptomatic and prenatal diagnostic tests for these disorders and for elucidating their pathogenesis.