ALDH1A1 and obesity due to melanocortin 4 receptor deficiency: However, more recent studies have identified Raldh1 as the only RA‐synthesizing enzyme in the mouse hypothalamus (Helfer et al., 2012; Shearer et al., 2010) and therefore the downregulation of hypothalamic RA signalling in Raldh1−/− mice may also play a role in prevention of obesity.