IFNA2 and major depressive disorder: Intriguingly, Pierucci-Lagha et al. (2010) investigated the functional role of these alleles (e.g., LGLG, LGS, and SS carriers were designated S’S’ and found low expression levels) and demonstrated that in Hispanic HCV patients with IFN-α treatment, S’ allele homozygotes showed markedly higher depression symptom scores.