This study demonstrates significant differences in the urine metabolomic fingerprinting of BBS patients compared with controls, including high urinary excretion of monocarboxylates, such as lactic acid (LA); these data were paralleled by the evidence of increased LA production in an in vitro model of renal epithelial cells lacking one of the major BBS proteins, suggesting a possible role of BBS proteins in regulating renal metabolism. The gene discussed is BBS2; the disease is Bardet-Biedl syndrome.