Abstract: The invention is based, at least in part, on the discovery that mutations on the chromosome 19q arm can lead to a diagnosis that a human has an elevated likelihood of developing proliferative disorder, such as an oligodendroglioma or prostate cancer, and can further provide a prognosis of a human who has a proliferative disorder. A mutation can include a deletion of at least a fragment of a chromosome 19q arm, particularly at band 13.3, or an insertion or substitution of one or more nucleic acids on the chromosome 19q arm. Deletions and single nucleotide polymorphisms (SNPs) in the GLTSCR1 gene was found to be of particular predictive and diagnostic value.