EIF2AK3 and obesity due to melanocortin 4 receptor deficiency: Accumulating studies have found that abnormal expression of ERS-related proteins, such as GPR78, p-PERK, and ATF6, were detected in liver cells of patients with obesity or NAFLD [28], which were involved in the pathology process of NAFLD, including hepatic steatosis, insulin resistance, inflammation and apoptosis.