The decrease in Cu,Zn-SOD contribution to the total SOD activity pool may be due to inactivation of Cu,Zn-SOD by the xenobiotics of the cigarette smoke, such as cadmium—a well-known, specific Cu,Zn-SOD inhibitor [26,71] in this study—found to be of increased concentration in individuals exposed to cigarette smoke, regardless of obesity. The gene discussed is SOD1; the disease is obesity due to melanocortin 4 receptor deficiency.