Amongst other genes that link depression with obesity, melanin-concentrating hormone receptor 2 (MCHR2), proprotein convertase subtilisin/kexin type 9 (PCSK9), and apolipoprotein A5 (APOA5) may be mentioned, as genes involved in energy-related processes [86]. Here, PCSK9 is linked to obesity due to melanocortin 4 receptor deficiency.