Mutational basis of adenine phosphoribosyltransferase deficiency.

The mutational basis of APRT deficiency was studied in non-Japanese and Japanese patients. Fifteen different mutations have been identified altogether. Of these 4 were common, 6 were located in exon 3, and two at the exon 4-intron 4 junction. The common mutations were a missense mutation in exon 3 (asp65----val) and a T insertion at the exon 4-intron 4 junction in non-Japanese patients, a nonsense mutation in exon 3 (trp98----end) in Type I Japanese patients, and an exon 5 missense mutation (met136----thr) in Type II patients. The other mutations in Type I patients consisted mainly of single base changes and small deletions.