HTR4 and major depressive disorder: Therefore, we cannot consider how partner status would affect our findings, (3) Since the CSFQ-14 has sex-specific threshold values, we could not meaningfully directly compare men and women (unless they were stratified based on the threshold), (4) Clearly, our findings are not exhaustive, meaning that the 5-HT4R only explains a small proportion of the variance in sexual phenotype in MDD.