Fogdell-Hahn and co-workers examined the role of classical HLA genes including both class I (HLA-A, -B, -C) and class II (HLA-DRB1, -DQ, -DP), indicating that HLA-A*03 confers a risk for MS while HLA-A*02 has a protective effect [7]. The gene discussed is HLA-A; the disease is myeloid sarcoma.