ATM mutations in Finnish breast cancer patients
- M Allinen1,
- V Launonen2,
- K Laake3,
- L Jansen3,
- P Huusko1,
- H Kääriäinen4,
- A-L Børresen-Dale3,
- R Winqvist1
- 1Department of Clinical Genetics, University of Oulu/Oulu University Hospital, Oulu, Finland
- 2Department of Medical Genetics, Biomedicum Helsinki, University of Helsinki, Helsinki, Finland
- 3Department of Genetics, Institute for Cancer Research, The Norwegian Radiumhospital, Oslo, Norway
- 4Department of Medical Genetics, The Family Federation of Finland, Helsinki, Finland
- Correspondence to: Dr R Winqvist, Department of Clinical Genetics, University of Oulu/Oulu University Hospital, Oulu, Finland; robert.winqvist{at}oulu.fi
In Finland, mutations in the two major breast cancer susceptibility genes BRCA11 and BRCA22 appear to account for a considerably lower proportion of hereditary breast cancer than in other western European countries.3–5 In addition, the recently identified new susceptibility locus in 13q21 is expected to explain, at most, one quarter of the hereditary predisposition to breast cancer.6 Inherited breast cancer susceptibility may also be the result of mutations in genes associated with certain rare hereditary syndromes, such as Li-Fraumeni syndrome7 or ataxia-telangiectasia (AT).8–10
AT is a recessive neurodegenerative disorder resulting from mutations in the ATM gene.11 It is characterised by progressive cerebellar ataxia, telangiectasias, sensitivity to ionising radiation, and immunodeficiencies. Furthermore, owing to ATM involvement in double strand break repair, defects in its protein function cause genetic instability and, as a consequence, an increased risk of cancer. AT patients are especially prone to developing lymphatic and leukaemic malignancies, but also breast cancer. Also AT heterozygotes have an increased risk of developing breast cancer,8, 10 yet a clear discrepancy remains between the epidemiological data and the observed low frequency of ATM mutations in breast cancer patients.12
Recently, Laake et al13 screened 41 AT families from the Nordic countries for ATM mutations. In seven Finnish AT families included in the study, they observed eight distinct mutations, some of which were recurrent (partly unpublished results).13 Given the fact that many disease related gene defects are clearly enriched in the Finnish population owing to founder effects, genetic drift, and isolation,14 we anticipated that these “Finnish” ATM mutations might also be found in breast cancer patients in Finland, possibly contributing to increased breast cancer susceptibility. Recurrent ATM mutations have been reported in several countries and within many different ethnic groups.9, …
