P2-13-02: Parent of Origin of BRCA Mutation May Determine Age at Breast Cancer Diagnosis.
Authors: Shapira I , Budman DR , Akerman M , Weiselberg L , Vinciguerra V , D'Olimpio J , Devoe C , Cheng KL , Donahue L , John V , Cohen S 
Published: June 2012

Background: Genetic diseases may display parent-of-origin effects. In such cases, the risk depends on the specific parent or origin allele. Imprinting effect is evident in autosomal dominant hereditary paraganglioma leads to tumors only if inherited from paternal germline. Cancer penetrance in mutations carriers may be determined by the parent origin of BRCA mutation.

Methods: From 2007–2010 we analyzed 1889 consecutive (136 ovarian + 1753 breast) breast (BrCa) or ovarian cancer (OvCa) patients presenting for treatment at our outpatient facility. In 130 patients with BRCA 1 or 2 mutations the parent of origin for the mutation was known. Of the 130 patients 2 had both BRCA1 and BRCA2 mutated paternally inherited and were excluded from this analysis. Of the breast cancer patients: 28 patients had paternal and 29 had maternal BRCA1 mutations, 24 had paternal and 21 had maternal BRCA 2 mutations. Of the ovarian cancer patients 6 had paternal and 10 had maternal BRCA1 mutations, 7 had paternal and 3 had maternal BRCA2 mutations. In carriers of BRCA mutations the mean age at diagnosis for ovarian cancer was 51 (range 21–70) and for breast cancer was 43 (range 24–78).

Two-sample t-test was used to compare the mean age at diagnosis in patients with BRCA 1 or 2 mutations of paternal or maternal inheritance.

For breast cancer maternal allele versus paternal allele 2-sample t-test and p-value were compared for the age at first diagnosis. For breast cancer patients BRCA1 maternal inheritance (mean+SD yrs) 45.73+11.22 versus paternal inheritance 38.04+7.14 2-sample t-test p-value p&lt;0.0020. For breast cancer BRCA2 maternal inheritance (mean+SD yrs) 50.65+10.44 versus paternal inheritance 41.68+6.16, 2-sample t-test p-value p&lt;0.0008.

Results: Significantly younger age at breast cancer diagnosis was observed in paternal vs. maternal inheritance of BRCA1 mutation (38 vs 46, respectively, p&lt;0.0020) and BRCA2 mutation (42 vs 51 respectively, p&lt;0.0008). There was no significant difference between paternal and maternal age of ovarian cancer diagnosis of BRCA1 (p&lt;0.1415) or BRCA2 mutation (p&lt;0.3470).

Conclusion: The restrospective nature of the study may introduce ascertainment bias. However, the breast and ovarian cancers cases in BRCA1 & 2 carriers with maternal or paternal inheritance mirror the Mendelian autosomal dominant pattern in our unselected consecutive cohort of patients. Maternal and paternal inherited BRCA alleles may not be exchangeable. Women with paternally inherited mutations in BRCA gene mutations develop breast cancer at younger age compared with women who inherit the gene mutations from their mothers. In this small sample, clear differences at age of cancer diagnosis are apparent in paternal inheritance of BRCA gene mutation. If this observation duplicates in larger cohorts results will have important implications for recommendation of surgical risk reduction in BRCA mutation carriers.

Citation Information: Cancer Res 2011;71(24 Suppl):Abstract nr P2-13-02.