Factors may affect the severity of dyslipidemia in patients carrying these mutations include the natural apoE polymorphism which affects the distribution of apoE to different lipoprotein classes [39], interaction of apoE with HSPGs [40] or additional genetic, hormonal, or environmental factors, such as obesity, hypothyroidism, estrogen status, or diabetes [41]. This evidence concerns the gene APOE and obesity due to melanocortin 4 receptor deficiency.