TABLE 4-3 Genes Other Than BRCA1 and BRCA2 Involved in Breast Cancer Susceptibility22



Effect on Breast Cancer Risk

Odds Ratio*

Rare genetic syndromes with increased breast cancer risk


Mutation of this gene causes Li-Fraumeni syndrome and is characterized by an increased risk of several cancers. Expressed in three different variants.

Associated with increased risk, particularly in white populations. Risk not shown in Hispanic, African-American, or Pakistani study participants.

1.08 CI 0.88-1.13


Mutation of this gene causes ataxia telangiectasia, a neurodegenerative disease characterized by lack of coordination, red lesions, and immune defects.

Few patients survive to an age at which breast cancer occurs, but a role in increased risk is plausible and has been shown in some small studies.



Mutation of this gene causes Cowden syndrome, characterized by malformations resembling tumors composed of mature tissues, especially of the skin, mucous membranes, breast, and thyroid.

Not likely to have an effect in the sense of classical heredity. Unknown if PTEN plays a role in sporadic breast cancer susceptibility.



Mutation of this gene causes Peutz-Jeghers syndrome and is characterized by freckle-like spots on the lips, mouth and fingers and benign polyps in the intestines.

Only likely to play a role in increased risk among those patients with Peutz-Jeghers syndrome.


Low penetrant cancer susceptibility genes: Proto-oncogenes


Protein product is a protein kinase that transmits signals from growth factor receptors. When mutated can result in abnormal cell cycle control.

Moderately associated with increased risk.


CI 1.73-2.41

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