A screening method for identifying an individual having a pre-disposition towards having a cancer is disclosed, which screening method comprises the steps of: (a) obtaining a test sample comprising a nucleotide sequence comprised in a gene in a gene in a base excision repair (BER) pathway of the individual or an amino acid sequence of a polypeptide expressed thereby; and (b) comparing a region of the test sample sequence with the corresponding region of the wild type sequence, whereby a difference between the test sample sequence and the wild type sequence signifies that the individual is pre-disposed to having the cancer; and wherein the difference comprises a specified variation. The specified variation can be the known mutation in the human MYH protein, G382D-hMYH or a nucleotide sequence encoding it, or it can be one or more novel variations, namely, Y165C, E466X, and Y90X, or the respective corresponding nucleotide sequences. The method is particularly suitable for determining a pre-disposition towards bowel cancer.