Genetic background represents another common determinant factor between psoriasis and increased BMI, as various gene polymorphisms associated with obesity have been found with potential roles in psoriasis (e.g., PCSK9, FTO, MC4R genes) or the other way around: genetic determinants involved in psoriasis present possible links with obesity (e.g., susceptibility locus HLA-Cw*06, IL21B gene polymorphism) [36]. This evidence concerns the gene MC4R and obesity disorder.