In a Chinese population, diarrhea-predominant IBS (IBS-D) and depressive disorder showed two shared genetic variants (SYT8 rs3741231 G allele and SSPO rs12536873 TT genotype) associated with neurogenesis and neurotransmission, providing a genetic basis for the high comorbidity of IBS-D and depressive disorder (68). Here, SYT8 is linked to depressive disorder.