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Somatic mutations in the ATM gene are known to be implicated in the development of some cancers, including some types of leukemia (see summary on Cancer in the Information database for discussion of the genetic basis of cancer). People who have two mutated germ-line copies of ATM suffer from the rare disease ataxia telangiectasia, whose features include increased susceptibility to lymphoid cancers. Researchers at the University of Birmingham have now found that six patients out of a group of 32 with B-cell chronic lymphocytic leukemia had somatic ATM mutations [Stankovic, T. et al. (1999) Lancet 353, 26-29]. Surprisingly, two of the six also carried a germ-line (i.e. inherited) mutation in the ATM gene, compared with a carrier frequency of less than 1 in 200 for ATM mutations in the general population. This suggests that carriers of ATM mutations may be at increased risk of this form of leukemia.

Comment: The numbers in the study were small, so conclusions must be tentative. A much larger study will be needed to determine accurately what percentage of people with B-CLL carry a germ-line ATM mutation. There have also been reports that ATM mutation carriers have an increased risk of breast cancer, though this is still controversial. Mutational analysis of the ATM gene is technically difficult and carrier testing is likely to be confined - at least in the short- to medium-term - to a research setting, and to members of families known to be affected by ataxia telangiectasia. This situation would only be likely to change if firm evidence were obtained that ATM mutation carriers have a substantial absolute risk of developing cancer, and if effective treatments and/or preventive measures were available.