Defective DNA excision repair in cells of patients with homocystinuria

Abstract

Fibroblasts obtained from biopsied material and lymphocytes from patients wwith homocystinuria were studied for repair activity using the criterion of repair of DNA breaks induced by 4-nitroquinoline 1-oxide and γ-irradiation and criteria of reactivation and induced mutagenesis of vaccinia virus. Lymphocytes showed defective DNA repair for all these criteria. In fibroblast cultures, the inhibition of cell-repair activity for the γ-type was retained. The number of spontaneous and γ-induced virus mutations increased as passaging of fibroblasts proceeded.