MLH1 and head and neck squamous cell carcinoma: Moreover, there is a study showing that inherited MLH1 (mutL homolog 1) c.-93G>A, MSH2 c.211 + 9C>G, MSH3 c.3133G>A, and EXO1 c.1765G>A anomalies of DNA MMR pathway are essential determinants and important patient outcomes’ predictors of HNSCC, notably among smokers [41].