Furthermore, two polymorphisms (rs422951 and rs72555375) of the NOTCH4 gene in a susceptibility region for IBM with MHC (from BTNL2 to HLA-DRB1) [28] also had a strong association (OR >2) with IBM in two independent Caucasian cohorts [29]. This evidence concerns the gene HLA-DRB1 and inclusion body myositis.