GRN and obesity due to melanocortin 4 receptor deficiency: Recent studies have found that serum progranulin levels are elevated in a number of diseases including obesity [20, 21], type 2 diabetes [20, 21], kidney disease [22, 23], cancer [24, 25], systemic lupus erythematosus [26, 27], and rheumatoid arthritis [28, 29].