Because mice with HSL deficiency did not show completely abolished lipolysis and had neither obesity nor cold sensitivity,(8) it was indicated that HSL was not the only enzyme catalyzing TGs, which subsequently led to the discovery of ATGL.(8) ATGL was shown to selectively perform the first step in TG hydrolysis, in which TGs are hydrolyzed to DGs and FFAs. The gene discussed is PNPLA2; the disease is obesity disorder.