GSTP1 and neurodegenerative disease: Accordingly, in blood cells, it has been demonstrated that D-loop methylation levels are significantly lower in individuals with neurodegenerative disorders [28], the methylation of GSTP1 is associated with susceptibility to DNA damage and increased cancer incidence [29], and the methylation status of LINE-1 is widely used as a surrogate marker of global DNA methylation, affecting the risk of cancer and cardiovascular and neurodegenerative diseases [41,42,43,44].