A mutant allele common to the type I adenine phosphoribosyltransferase deficiency in Japanese subjects.

Adenine phosphoribosyltransferase (APRT) deficiency is a genetic disorder which causes 2,8-dihydroxy-adenine urolithiasis.The estimated incidence of heterozygosity in Caucasian and Japanese populations is 1%.Mutant alleles responsible for the disease have been classified as APRT*Q0 (type I) and APRT* (type II).In our previous study, we demonstrated in APRT*J a single common base change which accounts for 70% of the Japanese mutants.the present report describes the analysis of an APRT*Q0 mutation in Japanese subjects.Two nucleotide substitutions common to all seven affected alleles from four unrelated subjects (three homozygotes and a heterozygote) were identified: G----A at nucleotide position 1453 and C----T at 1456.The G----A altered the amino acid Trp98 to a stop codon. The C----T did not alter Ala99.These point mutations were demonstrated by sequence analysis of polymerase chain reaction (PCR)-amplified genomic DNA and cDNA.The G----A change at 1453 results in the elimination of a PflMI site in the APRT gene.PflMI digests, which were used to confirm the G----A transition, can be useful in screening for this specific mutation.