GPAT3 and obesity due to melanocortin 4 receptor deficiency: It has been shown that GPAT3 has a key role in the development of hepatic steatosis, obesity, and insulin resistance [61] Expression of GPAT3 gene, an enzyme catalyzing the initial step of fatty acid esterification resulting in synthesis of TG, was markedly upregulated among other genes involved in lipogenesis in HL rats [62].