ANXA1 and obesity due to melanocortin 4 receptor deficiency: Studies on twins offer valuable insights into the acquired nature of obesity.32 We first assessed whether there were differences in ANXA1 mRNA levels in the subcutaneous adipose tissue (SAT) between monozygotic co-twins discordant for body mass index (BMI) (within-pair difference in BMI ≥ 3 kg·m−2).