RAB6B and major depressive disorder: Noticeably, only one hub gene (PPP3R1) was commonly associated with difficulty in concentration/indecision in males and females with MDD, with all other hub genes being either uniquely associated with this clinical feature in males (GABRB3, PRKCE) or females (SYNJ1, ATP9A, SNAP91, RAB6B) with MDD (Fig. 6b).