Adenine phosphoribosyltransferase deficiency identified by urinary sediment analysis: cellular and molecular...

Adenine phosphoribosyltransferase deficiency is an autosomal recessive purine enzyme defect that causes urolithiasis and, in severe cases, renal failure. Most homozygotes with this disorder were identified by analyses of excreted or surgically removed urinary stones, but some were identified only because they were family members of symptomatic individuals. We report here the detection of adenine phosphoribosyltransferase deficiency in two cases by routine analysis of urinary sediments. 2,8-Dihydroxyadenine-like spherical crystals were observed in the urinary sediment, and a diagnosis of homozygous adenine phosphoribosyltransferase deficiency was confirmed by cellular and molecular methods. A molecular diagnostic system using the polymerase-chain reaction and single-strand conformational polymorphism analysis proved to be a rapid and sensitive method to identify the APRT*J allele, a common mutant allele among the Japanese people. These methods will facilitate identification of symptomatic and asymptomatic individuals with homozygous adenine phosphoribosyltransferase deficiency.