NEIL1 G83D variant is a low frequency polymorphism, estimated to occur in ~1% of US population (Roy et al. 2007), and is associated with primary sclerosing cholangitis and cholangiocarcinoma (Forsbring et al. 2009). NEIL1 G83D does not cleave thymine glycol (Tg) from damaged DNA (Prakash et al. 2014).NEIL1 E28del, an in-frame deletion variant of NEIL1 reported in gastric (stomach) cancer, where glutamate at position 28 is deleted, does not cleave Tg from damaged DNA (Shinmura et al. 2008).