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Gene Effect on Breast Density

A major gene may influence mammographic breast density, a marker of breast cancer risk, scientists report. They say their data are best explained by a mendelian dominant inheritance model, which suggests that about 12% of the population might carry at least one allele of the putative gene and that women who inherit this allele would have a mean breast density about twice that of other women.

Pankow and Sellers et al. (p. 549) evaluated the fraction of breast occupied by radiographically dense tissue on routine mammograms from 1370 women over 40 years of age from 258 families identified through a proband with breast cancer.

The study showed that sister-sister correlations in breast density ranged from .16 to .27 and were all statistically significant. Mother-daughter correlations were smaller (.0 I to .17) and not statistically significant. Segregation analysis provided additional evidence for the inf1uence of a major gene on mammographic breast density.