Recent insights into the pathogenesis of hyperuricaemia and gout.

Gout is a common rheumatic disease in humans which is characterized by elevation in serum uric acid levels, and deposition of uric acid crystals in the joint. Hyperuricaemia is the primary risk factor for the development of gout and primates have uniquely high levels of serum uric acid due to missense mutations in the uricase gene. Levels of serum uric acid are known to be highly heritable, and mutations in genes which encode enzymes in the purine salvage pathway have long been recognized as rare causes of gout. Until recently, however, little has been known about the genetic determinants of urate metabolism and susceptibility to gout in the general population. Over recent months, a series of large scale genome wide association studies have been performed which have shed new light on the genes which regulate serum uric acid levels and susceptibility to gout. Most of these genes seem to be involved in regulating the renal excretion of uric acid which underscores the importance of reduced urate excretion as opposed to increased endogenous production as a cause of gout. Further work will now be required to investigate the mechanisms by which these genetic variants regulate urate excretion and serum urate levels. However, it seems likely that the genes so far identified will represent new molecular targets for the design of drugs to enhance urate excretion and the genetic variants that predispose to gout might be of value as genetic markers of susceptibility to gout.