However, a recent study reported that PTSD was associated with increased methylation across HLA-DPB1 in a civilian cohort of predominantly African American women, whilst the association between PTSD and HLA-DPB1 methylation was in opposite direction in a military cohort of predominantly Caucasian males (Katrinli et al., 2021). Here, HLA-DPB1 is linked to post-traumatic stress disorder.