Genetic heterogeneity of early-onset familial breast cancer

A gene for early-onset familial breast cancer has recently been mapped to the chromosome 17q12-23 region. In order to confirm the gene location, we have tested an extensive early-onset breast cancer family with 4 markers in this chromosome region. Linkage was negative with all 4 markers. This study suggests that there is genetic heterogeneity among early-onset breast cancer families.