Occurrence of both breast and ovarian cancer in a woman is a marker for the BRCA gene mutations: a population-based study from western Sweden.

AIM: This study aimed to analyze whether the occurrence of both breast and ovarian cancer in a woman serves as a marker for BRCA gene mutations. MATERIAL AND METHODS: This population-based study included 256 women in western Sweden who developed both invasive breast and ovarian tumors between 1958 and 1999. Archival paraffin tissue blocks of their tumors were retrieved for DNA-extraction to analyze the founder mutation, BRCA1 c.3171_3175dup (c.3171ins5), which is most common in this geographic area and four other common Scandinavian BRCA1 gene mutations and one BRCA2 mutation. Together, account these mutations for approximately 75% of the BRCA1/2 gene mutations in the clinical unit. RESULTS: Ninteen percent (95% confidence interval (CI) 14-24%) of the women carried one of the analyzed BRCA1 gene mutations but none of the women were positive for the analyzed BRCA2 mutation. One-third of the women with both tumors before age 60 were mutation carriers. BRCA1 c.3171_3175dup (c.3171ins5) constituted 84% of all identified mutations. Although the majority of breast cancers were invasive ductal and atypical medullary types, a variety of other breast malignancies were seen among mutation carriers. Serous ovarian carcinomas predominated among ovarian tumors. A variety of other ovarian tumors, including three granulosa-theca cell tumors, were also observed among mutation carriers. CONCLUSIONS: The occurrence of both breast and ovarian cancer in a woman is associated with a high likelihood of a constitutional BRCA1 mutation. These women and their families might therefore be considered for mutation screening after appropriate genetic counselling.

A high frequency of germline BRCA1/2 mutations in western Sweden detected with complementary screening techniques.

Dominant inheritance is presumed in 6-10% of breast and ovarian cancers. Mutations in BRCA1 and BRCA2 genes are the most commonly identified causative genes in such families. The frequency of mutation carriers with breast/ovarian cancer depends on the population studied, and display considerable variation that coincides with ethnic and geographical diversity. Mutation analyses were performed in 143 families registered at the Cancer Genetic Counseling Clinic of western Sweden. In a thorough mutation screening procedure, the entire BRCA1 and BRCA2 genes were analyzed using a combination of complementary mutation detection techniques. Mutations in either BRCA1 or BRCA2 were detected in 36% (52 out of 143) of all screened families. All families were clinically evaluated regarding age at diagnosis, type of cancer and number of cancer cases in the family. Among high-risk families, the mutation detection rate was 39% (46 out of 117). The detection rate observed among families with cases of ovarian cancer (42 out of 62, 68%), was substantially higher than in families with only breast cancer (10 out of 81, 12%). Age at ovarian cancer did not seem to have an effect on the detection rate. The analyses revealed 11 frameshift mutations, 4 nonsense mutations and 2 large deletions. Notably, the BRCA1 c.3171ins5 mutation accounted for 34 of 52 (65%) identified mutations. Seven mutations are novel: BRCA1c.409_410del; c.1912T>G; c.2228_2229del; c.3029delA; c.3433delA, a large deletion covering exons 1-3 of BRCA1and one BRCA2 mutation; BRCA2c.6287_6290del. We have shown that the founder mutation BRCA1 c.3171ins5 has a great influence on western Swedish breast/ovarian cancer families along with a high number of mutations unique for the region. In order to achieve a high mutation detection rate we suggest a combination of several detection techniques.

High-resolution analysis of the subtelomeric regions of human embryonic stem cells.

The use of human embryonic stem cells (hESCs) in most applications is dependent on their undifferentiated proliferation in vitro. Recent studies have illustrated the possibility that chromosomal changes may occur in hESCs during in vitro propagation of these cells. However, no studies so far have screened for chromosomal abnormalities in hESCs using high-resolution techniques that can detect alterations on a few base-pair levels. We have used the recently developed multiplex ligation-dependent probe amplification procedure to analyze the possible occurrence of deletions or duplications in the subtelomeric regions of hESCs in early and late passages. In this study we show that no subtelomeric anomalies were detected in any of the nine hESC lines investigated, supporting the conclusion that hESCs, under appropriate conditions, maintain genomic stability during in vitro propagation.