Letters Section Editor: Stephen J. Lurie,
MD, PhD, Senior Editor.
To the Editor: Dr de la Hoya and colleagues1 found that in families with breast and/or ovarian
cancer, mutations in BRCA1 but not BRCA2 were associated with a sex ratio skewed against male births.
However, because the authors did not assess for several possible sources of
confounding, their results may not permit the conclusion that BRCA1 mutations are associated with an asymmetrical sex ratio. The
highly penetrant breast and ovarian cancer in BRCA1 families
is an example of an autosomal dominant sex-limited phenotype. That is, only
females carrying a BRCA1 mutation can develop ovarian
cancer, and the majority of cases of breast cancer in families with the BRCA1 mutation also occurs in females.
Mealiffe ME. Sex Ratios in Families With. JAMA. 2003;290(19):2544. doi:10.1001/jama.290.19.2544-a