The function of the 17C>T polymorphism in the extracellular space of the N-terminal is yet unknown. The frequency of the 17T allele varies significantly between populations. It is very rare in subjects of European descent, Hispanics, Middle Eastern subjects (Gelernter et al. 1999), and Asian subjects (dbSNP) (Tan et al. 2003; Xu et al. 2002) and common (15–20%) in subjects of African descent (Crowley et al. 2003; Gelernter et al. 1999; Luo et al. 2003). A relatively high allele frequency was also reported in Indian males from Delhi, India (Kapur et al. 2007).
