GDNF and psychiatric disorder: Studies in English and Chinese populations also revealed no functional significance of GDNF polymorphisms: (AGG)n, rs2910709-C/G/T (3′ downstream), rs2973050-C/G/T (intr), rs884344-C (intr), rs2910702-A/T (intr), rs2216710-T (intr), rs3812047-G/T (intr), etc. in the development of mental disorders (Kotyuk et al., 2013).