Adenine Phosphoribosyltransferase Deficiency: An Underdiagnosed Cause of Lithiasis and Renal Failure

Abstract

We describe an infant affected by adenine phosphoribosyltransferase (APRT) deficiency diagnosed at 18 months of age with a de novo mutation that has not been previously reported. APRT deficiency is a rare defect of uric acid catabolism that leads to the accumulation of 2,8 dihydroxyadenine (2,8-DHA), a highly insoluble substance excreted by the kidneys that may precipitate in urine and form stones. The child suffered from renal colic due to a stone found in the peno-scrotal junction of the bulbar urethra. Stone spectrophotometric analysis allowed us to diagnose the disease and start kidney-saving therapy in order to avoid irreversible chronic kidney damage. APRT deficiency should always be considered in the differential diagnosis of pediatric urolithiasis.

The authors Giuseppina Marra and Paolo Gilles Vercelloni equally contributed to the article.

Competing interests: None declared.

Take-Home Message

Pediatric lithiasis (especially in the first years of life) is a relatively rare condition, and may be a major indicator of high morbidity congenital or metabolic disorders that could be diagnosed and treated, sometimes with good clinical results. For this reason, a multidisciplinary approach including a scrupulous metabolic evaluation is always mandatory in every case of child with urinary stones. APRT deficiency can be diagnosed by means of a urinary sediment examination, an affordable and reliable method that should represent the first diagnostic step in every child with lithiasis. However, a correct diagnosis requires a high index of suspicion that is possible only with a good knowledge of the disease.