ABSTRACT
The clinical picture of Adenine phosphoribosyl-transferase (APRT) deficiency is entirely a function of the excretion of 2,8-dihydroxyadenine and its propensity to cause nephrolithiasis and nephropathy. Plain roentgenograms of the abdomen are usually negative in these patients since 2,8-dihydroxyadenine stones, like those of uric acid, are radiolucent; rarely, admixture of calcium will render these stones radio-opaque. The direct consequence of deficiency of APRT is the accumulation of adenine, which is oxidized in the presence of xanthine dehydrogenase to 2,8-dihydroxyadenine, which is very insoluble. Therapy is aimed at reducing the formation of 2,8-dihydroxyadenine by the use of a low purine diet and allopurinol. A simple fluorescence method has been developed for the identification of 2,8-dihydroxyadenine stones. Calculi have been identified by a reddish-brown appearance when wet of a round friable stone, becoming grey when dry. Mass spectrometry or scanning electron microscopy can be used for the correct identification of calculi.
