According to single factor analysis reported by Desai and Neuberger [74], age, gender, Caucasian, past malignancies, multiple organ transplantation, alcoholic liver disease, primary sclerosing cholangitis, and nonalcoholic steatohepatitis were associated with primary diseases, obesity, diabetes, age of donors, and use of mTOR inhibitors during transplantation. Here, MTOR is linked to obesity due to melanocortin 4 receptor deficiency.