Hereditary breast cancer in Northern Ireland.

The aim of this investigation was to document hereditary breast cancer in Northern Ireland. Family history details from over nine hundred women were obtained by postal survey and one hundred and twenty nine home visits were carried out to collect pedigree information. The families documented varied in the number of affected women from three, which was the minimum criteria for inclusion, to a maximum of nine and many families described other features of hereditary disease such as bilateral breast cancer, ovarian and gastrointestinal malignancies.