How do you inherit the BRCA gene

High risk genes BRCA1 and BRCA2

Clinical symptoms

About 5% of all breast cancers are the result of a mutation in the BRCA1- or BRCA2-Gene. The clinical picture caused by the genetic defect is called "familial breast and ovarian cancer" (HBOC) in German-speaking countries. Both a conspicuous family history and, to a certain extent, certain histopathological findings (e.g. grading G3, "triple-negative" tumors) can indicate hereditary breast cancer.

The carrier frequency for a mutation in either BRCA1 or BRCA2 is given for our population with 1: 400.

Clinical symptoms

Typical for the HBOC are:

  • a familial accumulation BRCA-associated tumors (especially breast and ovarian cancer)
  • an average younger age of onset compared to the general population
  • a high risk of secondary cancers.

In addition to the increased risk of gynecological tumor diseases, a slightly increased risk of prostate and pancreatic cancer has also been described.

carcinomaGeneral population riskBRCA1BRCA2
Breast woman12%50-80%40-70%
Ovaries1-2%24-40%11-18%
Chest man0,1%1-2%5-10%
prostate15%< 30%>39%
pancreas0,5%1-3%2-7%


The incidence of breast cancer and ovarian cancer is also among women BRCA1 / 2-Mutation depending on age. At BRCA1-Mutations is the risk of breast cancer from the age of 40. at approx. 3% / year, with the exception of a particularly vulnerable period between the 45th and 49th years of age. Besides, women have with BRCA1-Mutation has the highest risk of independent secondary cancers (> 30% within 15 years of primary tumor). The risk of ovarian cancer does not increase until a little later (from around 40 years of age). At BRCA2-Mutations the risk of breast cancer increases steadily with age. The risk of ovarian cancer appears to be from age 60. to take off again.

Men with a mutation in one of the genes BRCA1 or BRCA2 have an increased risk for Prostate cancer and should be informed about the possibilities of prostate cancer screening (from the age of 40). In addition, men with a BRCA2Mutation has a significantly higher risk of developing breast cancer than the general population (risk 6%). For men with a BRCA1Mutation, the risk of breast cancer is 1-2%.

Because men with a BRCA1 / 2-Mutation but in the majority do not suffer from a tumor, the family tree alone often does not allow any clear conclusions to be drawn about a familial gynecological tumor disease.

You can find detailed information on clinical symptoms, the likelihood of illness and preventive measures in the specialist information FACTS ON BRCA1 AND BRCA2.

Criteria for the indication according to the quality assurance agreement for molecular genetics (agreement of quality assurance measures in accordance with Section 135 (2) SGB V)

Indication for the analysis of the genes BRCA1 and BRCA2

One of the following criteria should be met

  • at least three women with breast cancer, regardless of age
  • at least two women with breast cancer, one of them younger than 50 years
  • at least one woman with breast cancer before her 36th birthday
  • at least one woman younger than 50 years with bilateral breast cancer
  • at least one woman with breast cancer and one woman with ovarian cancer or one woman with breast and ovarian cancer
  • at least two women with ovarian cancer
  • a man with breast cancer and another person with breast or ovarian cancer

A genetic analysis of the genes BRCA1 and BRCA2 should be given as part of a human genetic counseling by a specialist in human genetics.

Fast track analysis

When planning neoadjuvant chemotherapy depending on the BRCA1 / BRCA2 mutation status, we offer for the genes BRCA1 and BRCA2 a "fast-track" gene analysis with an analysis time of 2 weeks.

In order to request a possible fast-track analysis, we ask you to indicate this with a note on our request form.

 

genetics

The gene BRCA1 is on chromosome 17 (17q21) and comprises 22 exons, while the gene BRCA2 mapped on chromosome 13 (13q12) and contains 27 exons. Both genes are involved in DNA repair mechanisms and belong to the group of tumor suppressor genes.

If a genetic analysis is not possible in any affected person in the family, the primary analysis of a healthy first-degree relative can only be considered if the life risk for breast cancer is> 30% or the risk of being heterozygous is> 20% (calculated with Cyrillic). The extensive restriction of the range of genetic tests to sick people is due to the fact that the informative value of negative results for people who are not sick is low. The question of whether a BRCA-Mutation in the family caused the disease is not answered. Therefore, an inconspicuous test result in a non-sick person does not mean a risk exclusion but only a risk reduction for the tested person and their offspring. For other family members (for example siblings of the person tested), however, no risk assessments can be derived from the result.

methodologyNext Generation Sequencing (NGS)

Sequencing multiple genes in parallel


Material 2-4 ml EDTA blood