The correlation reported previously, as well as our current findings, suggest that further investigations are warranted to understand the possible linkage of the ER gene locus to hereditary breast cancer.
There are, however, at least three loci known to be associated with familial breast cancer (p53, BRCA1, and an as yet unpublished locus) and the frequencies and penetrances of these genes are not likely to be the same.
The gene encoding this enzyme, EDH17B2, has been mapped to chromosome 17, region q12-q21, in the vicinity of BRCA1, as as yet unidentified gene that appears to be involved in familial breast cancer and in familial ovarian cancer.
The gene encoding this enzyme, EDH17B2, has been mapped to chromosome 17, region q12-q21, in the vicinity of BRCA1, as as yet unidentified gene that appears to be involved in familial breast cancer and in familial ovarian cancer.
The gene encoding this enzyme, EDH17B2, has been mapped to chromosome 17, region q12-q21, in the vicinity of BRCA1, as as yet unidentified gene that appears to be involved in familial breast cancer and in familial ovarian cancer.
Three loci have been implicated in the etiology of familial breast cancer; the BRCA1 locus on 17q, the p53 gene on 17p, and the androgen receptor gene on the X chromosome.
No mutation was found in any patient, confirming that germline mutations of the P53 gene are very rare in familial breast cancer (apart from Li Fraumeni families).
Compared with non-HBC, invasive BRCA1-related HBC had a lower diploidy rate (13% vs. 35%; P = 0.002), lower mean aneuploid DNA index (1.53 vs. 1.73; P= 0.002), and strikingly higher proliferation rates (mitotic grade 3; odds ratio [OR]= 4.42; P= 0.001; aneuploid mean S-phase fraction 16.5% vs. 9.3%, P < 0.0001).
The present study confirms the involvement of BRCA1 in disease predisposition for a subset of hereditary breast cancer families often characterized by ovarian cancers.
The hereditary breast cancer gene BRCA2 was recently cloned and is believed to account for almost half of site-specific breast cancer families and the majority of male breast cancer families.
This suggests that mutations in the BRCA1 gene may play a significant role in the tumorigenesis of familial breast cancer but not of sporadic breast cancer.
However, it is not yet clear what proportion of hereditary breast cancer is explained by BRCA1 and BRCA2 or by some other unidentified susceptibility gene(s).
However, it is not yet clear what proportion of hereditary breast cancer is explained by BRCA1 and BRCA2 or by some other unidentified susceptibility gene(s).