NRXN3 and obesity due to melanocortin 4 receptor deficiency: Interestingly, some genes associated with obesity were also associated with AD by different genetic approaches: candidate gene approach FTO (Li et al., 2018), by differentially expressed genes NRXN3 (Zheng et al., 2018; Hishimoto et al., 2019), NPC1 (Rouillard et al., 2016), NEGR1 (Wray et al., 2018), or by GWAS approach: LEPR, BDNF, TNFα, and MTCH2 (Gao et al., 2015; Karch et al., 2016; Lemche, 2018).