CTNS and major depressive disorder: Yang et al. [12] used quantitative real-time PCR to assess the mRNA levels of these 48 genes in peripheral blood samples from SSD, MDD and healthy control subjects (n=60/group), and found that three genes: domain-containing 84 (CD84), striatin (STRN) and cystinosin (CTNS) were differentially expressed among the groups.