A recent alternative hypothesis suggests that depression results from alterations in receptor activity due to formation of homoreceptor and heteroreceptor complexes involving receptor types including 5HT1A, 5HT7, galR1, and fibroblast growth factor receptor 1 (FGFR1) (Borroto-Escuela et al., 2010, 2012; Renner et al., 2012). This evidence concerns the gene HTR1A and major depressive disorder.