ABCA1 and obesity due to melanocortin 4 receptor deficiency: ABCA1 mRNA expression had a significant negative correlation with HOMA-IR (r = −0.44, p = 0.0003) and adipose tissue insulin resistance index (adipo-IR, r = −0.35, p =0.005) in patients with obesity (mean BMI = 44.5 kg/m2) [216].