A putative "hepitype" in the ATM gene associated with chronic lymphocytic leukemia risk.

Chronic lymphocytic leukemia (CLL) cells are characterized by several chromosomal lesions. Some of these aberrations imply chromosome breaks as a result of unrepaired double strand breaks (DSBs) in the DNA. The ATM (ataxia telangiectasia-mutated) protein is the principal integrator of cellular responses to DSBs. ATM deletion is also an adverse prognostic factor in CLL. Taking this into account, we evaluated if genetic and/or epigenetic variation in the ATM gene may modulate the individual susceptibility to develop CLL. Our case-control association study was performed in a large Spanish population of 1,503 individuals, including 742 patients with CLL and 761 controls. We identified one haplotype within the ATM gene that confers an increased risk of CLL development (OR = 1.33; 95% CI: 1.10-1.60). Two polymorphisms of this ATM haplotype eliminated one CpG site each in Introns 15 and 61, causing changes in DNA methylation pattern. These data provide the first evidence for the existence of a putative "hepitype" in the ATM gene associated with CLL risk.