Other mechanisms that have been postulated include the following: (2) antipsychotics inhibit insulin signaling pathways in target cells such as skeletal myocytes, hepatocytes, and adipocytes, thus causing IR in these tissues; (3) atypical antipsychotics cause obesity that can result in hyperlipidemia of the free fatty acid type (lipotoxicity) that can predispose inflammation, which further causes IR; and (4) atypical agents might cause direct damage to β-cells of the pancreas, leading to apoptosis and thus dysfunctioning of these endocrine cells [140]. The gene discussed is INS; the disease is obesity due to melanocortin 4 receptor deficiency.