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[Detection of the mutation responsible for adenine phosphoribosyltransferase deficiency among Japanese patients].
Adenine phosphoribosyltransferase (APRT) deficiency causes 2,8-dihydroxyadenine(DHA) urolithiasis and renal failure. Recently, two different common mutations were identified; one was APRT* J with a substitution of ACG for ATG at codon 136, called "Japanese-type", another was APRT* Q0 with TGA for TGG at codon 98. Approximately 98% of all Japanese patients with this disorder have been estimated to have these mutations APRT* J (approximately 80%) and/or APRT*Q0 (approximately 20%). We developed a diagnostic method to detect these genotypes. After gene amplification by PCR, target DNA was hybridized with a biotinylated specific probe in the presence of the non-labelled competitive probe on a dot-blotted membrane. To detect the APRT* J (or APRT* Q0) mutation, the biotinylated APRT* J (or APRT* Q0) probe and non-labelled normal probe for the same region were used as specific and competitive probes, respectively. After incubation at 60 degrees C for 30 min, the temperature was gradually decreased from 60 degrees C to 40 degrees C during 120 min, and then incubation was continued at 40 degrees C for 30 min. By using method, we were able to omit the posthybridization process, and the detecting signal was clear and highly specific. This method is useful for detecting point mutations in other genes.
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