Absence of SLC22A12 gene mutations in Greek Caucasian patients with primary renal hypouricaemia.

OBJECTIVE: Primary renal hypouricaemia is a hereditary clinical disorder characterized by increased renal urate clearance due to isolated renal tubular defect of uric acid transport. There have been only a few studies on primary renal hypouricaemia in Caucasian populations. Defects in the SLC22A12 gene, which encodes the renal urate transporter URAT1, have been reported to be related to the disease pathogenesis. This study was undertaken to elucidate whether SLC22A12 gene mutations are responsible for low serum uric acid levels in Greek people. MATERIAL AND METHODS: Nine Greek Caucasian subjects with primary renal hypouricaemia were included in the study. All had serum uric acid less than 2.5 mg dL(-1) (0.14 mmol L(-1)), fractional excretion of uric acid more than 10% and no other known causes of hypouricaemia. Mutation analysis of the SLC22A12 gene was performed. RESULTS: No mutation was found--only the previously reported silent polymorphism 1246T > C (His 42His) in exon 2 of the SLC22A12 gene. CONCLUSIONS: No previously reported mutation of URAT1 was associated with primary renal hypouricaemia in Greek subjects.

Effect on serum uric acid levels of drugs prescribed for indications other than treating hyperuricaemia.

Beyond allopurinol and the well-established uricosuric drugs, several other agents can decrease serum uric acid (SUA) levels, such as losartan, fenofibrate and some non-steroidal anti-inflammatory drugs (NSAIDs). Some of these drugs increase renal urate excretion. Hyperuricaemia and gout are common problems (at least 1% of Western men are affected by gout). Raised SUA levels increase the incidence of acute gout and renal calculi. Hyperuricaemia may also predict an increased risk of vascular events. Therefore, lowering SUA levels is of clinical relevance. In this review we consider the effect on SUA levels of drugs that are prescribed for indications other than treating hyperuricaemia. These drugs may obviate the need for specific treatment (e.g. allopurinol) aimed at lowering SUA levels. Furthermore, because hyperuricaemic patients may already be on several drugs (e.g. due to associated dyslipidaemia, hypertension and/or arthritis) compliance may be improved by avoiding additional medication. The potential for adverse effects associated with polypharmacy would also be decreased.