PARP1 and cancer: Thus far, approximately 1,066 single-nucleotide polymorphisms in the PARP-1 gene have been reported; among these polymorphisms, a T to C nucleotide transition results in Val762Ala substitution located in the C-terminal catalytic site and characterizes a commonly occurring PARP-1 polymorphism; this alteration is frequently investigated because of its association with cancer risk [28].