Moreover, SNPs (rs16139, rs3037354, rs2234759, and rs11100494) in NPY, NPY2R, and NPY5R have been found to be associated with AO in HD patients, major depressive disorder, and dyslipidemia (Coletta et al., 2007; Wang et al., 2013; Kloster et al., 2014). Here, NPY2R is linked to Huntington disease.