[The first case of adenine phosphoribosyltransferase deficiency with APRT*Q0 (M1I) mutation in Japan].

Adenine phosphoribosyltransferase (APRT) deficiency is an enzyme deficiency associated with purine metabolism, a hereditary disease that causes recurrent 2, 8-DHA stone formation due to a complete or partial APRT defect and slowly damages the renal function. Since APRT deficiency can be treated to prevent its progression to renal insufficiency, it is important to detect APRT gene mutations and make a definite diagnosis early. A 3.5-year-old girl presented with painful urination and dysuria, and was admitted to our hospital. The analysis of stones collected after spontaneous passage revealed 2, 8-dihydroxyadenine (DHA) urolithiasis. To make a definite diagnosis, we searched for the APRT gene mutations reported in Japanese. However, no APRT Q0 mutation was identified. Only a heterogeneous mutation, APRT J, was noted. Subsequently, we screened the gene mutation regions reported from Europe and the United States and identified a heterogeneous mutation at the start codon of APRT Q0 from methionine to valine. This is the first report of this mutation in Japan. She was diagnosed with APRT deficiency caused by a compound heterogeneous mutation: APRT Q0/(M1V) APRT J (M136T). We believe that the same gene mutation has been inherited among other Japanese. For the future genetic diagnosis of APRT deficiency, this is a valuable case.