B2M and head and neck squamous cell carcinoma: In a large HNSCC patient cohort published by the TCGA cancer atlas (n = 515), 9% (45/515 of all HNSCC patients have somatic mutations in the MHC class I heavy chain genes (HLA-A, HLA-B, and HLA-C), or the MHC class I light chain gene (β-2 microglobulin, B2M) (Figure 2).