For instance, a case-control study of 546 Finnish male smokers found that low levels of serum adiponectin (common in obesity) were associated with increased risk of RCC even after adjusting for potential confounders including body mass index (BMI) [116], and another report from the same group found associations between both leptin and adiponectin concentrations and the risk of RCC in a case-control study enrolling more than 1600 African American and Caucasian participants from two urban areas in the United States [117]. Here, ADIPOQ is linked to obesity due to melanocortin 4 receptor deficiency.