This single-nucleotide polymorphism is considered a functional polymorphism because its A/A genotype has been associated with greater CACNA1C messenger RNA expression in the PFC compared with G/G or A/G genotypes.27 Moreover, it has been reported that BD carriers of the A allele have increased amygdala activity during emotional processing tasks compared to non-carriers. Here, CACNA1C is linked to Behcet disease.