ABCG2 and hyperuricemia: Recent clinicogenetic studies have revealed the clinical importance of dysfunctional variations of ABCG2 as genetic risk factors for such urate-related diseases including gout and hyperuricemia (11, 12, 26, 27, 28) and have attracted interest in functional validation of non-synonymous ABCG2 variants even though the allele frequency is extremely low (29, 30, 31).