ABCG1 and obesity due to melanocortin 4 receptor deficiency: Thus, ABCA1 and ABCG1 mRNA levels in adipose tissue from CAD patients are likely to be influenced by additional risk factors, such as smoking, age, diet and obesity [26], which can partially explain the lack of association between ABCA1 and ABCG1 DNA methylation levels and the corresponding mRNA levels in our study.