APEX1 and head and neck squamous cell carcinoma: Likewise, germline variants in APEX1 (14th by MUFFINN yet below 13,000th by the gene-centric methods in head and neck squamous cell carcinoma (HNSC) samples) is known to increase the risk of breast cancer development by contributing apurinic/apyrimidinic (AP) site accumulation in DNA [44].