Missense mutation in the adenine phosphoribosyltransferase gene causing 2,8-dihydroxyadenine urolithiasis

Adenine phosphoribosyltransferase (APRT) catalyzes the synthesis of AMP from adenine and 5-phosphoribosyl-l-pyrophosphate. Deficiency of APRT can lead to an autosomal recessive disorder called 2,8-dihydroxyadenine (2,8-DHA) urolithiasis (1). The APRT gene is located at 16q24.3. A number of point mutations and small deletions and insertions have been identified in the APRT gene as a cause of 2,8-DHA urolithiasis (2). Here we report a missense mutation (CTG-to-CCG, LI 10P) in APRT in a patient with 2,8-DHA urolithiasis from Newfoundland. A younger sister has the same mutation but she is disease-free. SF had an attack of renal colic with hematuria in 1981 at the age of 42 (3). She underwent a right pyelolithotomy and a small calculus, identified as 2,8-DHA, was removed from the renal pelvis. She has been on allopurinol (600 mg/day) for the pas