The immune receptor CD300e has been shown to be expressed by macrophages infiltrating the AT of patients with obesity [4] and a study performed on a cohort of 49 monozygotic twin pairs, discordant for body mass index, revealed that the mRNA encoding CD300e is significantly up regulated in AT of the heavier subjects than their co-twin [5]. This evidence concerns the gene CD300E and obesity due to melanocortin 4 receptor deficiency.