Diagnosis of adenine phosphoribosyltransferase deficiency as the underlying cause of renal failure in a renal transplant recipient

Abstract

Adenine phosphoribosyltransferase (APRT) deficiencyis a rare inborn error of metabolism first described inthe UK in 1976 [1]. It is inherited as an autosomalrecessive trait and the gene is located on chromosome16. APRT is a salvage enzyme that normally catalysesthe conversion of adenine to adenine monophosphateusing PP-ribose-P. Deficiency results in adenine accu-mulation with conversion to and excretion of 2,8-dihydroxyadenine (2,8-DHA) in the urine. 2,8-DHA isprotein-bound in plasma, but is extremely insoluble inurine at any pH. Tubular crystal deposition can occurassociated with marked interstitial fibrosis and/orurolithiasis. Since its original description, APRTdeficiency has been recognized increasingly as a causeof chronic renal failure. We report a case of APRTdeficiency that was diagnosed after renal transplanta-tion. This has led to specific treatment for the patienttoreducetheriskoffurthercrystalandstoneformationin the transplanted kidney. Also, additional familymembers with the condition have been identifiedthrough family screening.