PNPLA3 and obesity due to melanocortin 4 receptor deficiency: Importantly, the various histological and clinical stages of NAFLD are not only consequences of environmental or modifiable factors, such as diet, obesity, and insulin resistance, but are also tightly intertwined with genetic host factors, such as polymorphisms in the Patatin-Like Phospholipase Domain Containing 3 (PNPLA3) gene [18].