APOE and obesity due to melanocortin 4 receptor deficiency: Female mice carrying targeted replacement (TR) of the murine Apoe gene with sequences encoding human ApoE4 show impaired glucose tolerance compared with ApoE3-TR mice (Koren-Iton et al., 2020), but this difference may disappear when compounded by the pathologies associated with diet-induced obesity or Aβ accumulation (Christensen and Pike, 2019; Koren-Iton et al., 2020).