● Lean and obese AT have characteristically different ATM subpopulations that differ in their developmental origins and turnover rates. ● Obesity causes AT remodeling which, in turn, can influence ATM distribution and frequency within AT. ● Mostly, fetal-derived Tim4+CCR2‒MHCII+CD11c‒ ATM are replaced by monocyte-derived Tim4‒CCR2+MHCII+CD11c‒ATM. The gene discussed is ITGAX; the disease is obesity due to melanocortin 4 receptor deficiency.