Abstract
Three children with urinary stones were referred to us for evaluation of adenine phosphoribosyltransferase(APRT) activity in red blood cells(RBCs), mononuclear cells(MNCs), and polymorphonuclear cells(PMNLs). They had no APRT activity in their RBCs, MNCs, and PMNLs. They were the third, forth, and fifth cases with complete deficiency of this enzyme in Japan. In their five asymptomatic relatives, the RBC-APRT activity was more than two standard deviations(SD) below the mean for controls, indicating they seemed to be heterozygotes. The PMNLAPRT activity in heterozygotes was more than one SD below the mean for controls, but the MNC-APRT activity was within the normal range, because of the wide variation of normal values. The determination of MNC- or PMNL-APRT activity can show homozygosity in this disorder, but it may be impossible to distinguish heterozygotes from normal subjects. The measurement of RBC-APRT activity seems to be useful in diagnosing both homozygotes and heterozygotes of APRT dificiency.
