2,8-dihydroxyadeninuria: are there no cases in Scandinavia?

Abstract

Homozygosity or mixed heterozygosity for mutations in the adenine phosphoribosyltransferase gene cause enzyme deficiency directing adenine through an alternative metabolic pathway. This results in the production of 2,8-dihydroxyadenine, which is actively secreted into the urine. 2,8-dihydroxyadenine is insoluble at physiological urinary pH but as marked supersaturation is possible the manifestations differ: there may be minimal consequences, there may be infiltration of the tubulointerstitial tissue with acute or chronic damage or there may be stone formation in the urinary tract. Effective treatment can be offered and therefore the prognosis depends upon the renal function at diagnosis. Treatment consists of adequate fluid intake, a low-purine diet and administration of allopurinol. Urinary 2,8-dihydroxyadenine crystals are easily recognized under a microscope. The diagnosis of 2,8-dihydroxyadeninuria can be confirmed by estimation of adenine phosphoribosyltransferase activity in erythrocyte lysates. More than 300 cases of 2,8-dihydroxyadeninuria have been diagnosed worldwide, most of them in Japan, France and Iceland. One case has been reported in Finland but there have been no reports from the Scandinavian peninsula or from Denmark. The relevant mutations may be very rare in these countries but underdiagnosis is also possible.