BDNF and Behcet disease: After the patients had been stratified by their BD subtypes (BP-I and BP-II) and their BDNF Val66Met polymorphism genotypes (Val/Val, Val/Met, and Met/Met), the correlation between factor 1 (WCST) and the change of plasma BDNF level was only in patients with BP-I and the BDNF Val66Met Val/Met genotype (r = −0.54, p = 0.008) (Table 3).