ABCG2 and hyperuricemia: These observations are in compliance with the concept of Ichida et al. [12] that the currently considered “overproduction type” hyperuricemia should be renamed to “renal overload type,” comprising two subtypes: “extra-renal urate underexcretion” and genuine “urate overproduction.” The common dysfunction of ABCG2 thus can cause a decrease of urate excretion via the extra-renal pathway rather than the renal pathway.