BRCA1 (Breast Cancer Gene 1) - GeneticArchaelogy

Overview

BRCA1 is a tumor suppressor gene that plays a crucial role in DNA repair and the maintenance of genomic stability.

📍 Chromosomal Position

17q21.31 (Chromosome 17)

🧬 Gene Category

Tumor Suppressor

🔬 Inheritance

Autosomal dominant

📊 Prevalence

1:400 to 1:800 in the general population

Function & Significance

The BRCA1 protein is involved in the repair of DNA double-strand breaks and plays an important role in regulating the cell cycle. It interacts with various other proteins to recognize and repair DNA damage.

Mutations in this gene can impair the cell’s ability to repair DNA damage, leading to an increased susceptibility to cancer.

🔬 Scientific Background

BRCA1 was identified in 1994 and was one of the first genes linked to hereditary breast cancer. The protein consists of 1,863 amino acids and is involved in numerous cellular processes.

Associated Diseases

Mutations in the BRCA1 gene are associated with an increased risk for several types of cancer:

🎗️ Hereditary Breast and Ovarian Cancer Syndrome

Primary condition associated with BRCA1 mutations
🎗️ Breast Cancer

Up to 70% lifetime risk in mutation carriers
🎗️ Ovarian Cancer

Up to 40% lifetime risk
🎗️ Prostate Cancer

Increased risk in male carriers
🎗️ Pancreatic Cancer

Moderately increased risk

Clinical Relevance

⚕️ Genetic Testing

BRCA1 testing is recommended for individuals with:

A family history of breast or ovarian cancer
Early age of onset (under 50 years)
Multiple cancer cases in the family
Ashkenazi Jewish ancestry (higher carrier rate)

💊 Therapeutic Options

Several prevention and treatment options are available for BRCA1 mutation carriers:

Close-interval screening examinations
Prophylactic surgeries (mastectomy, oophorectomy)
PARP inhibitors (targeted cancer therapy)
Genetic counseling for family planning

🧬 Relevant SNPs

Detailed analysis of pathogenic variants:

rs80357906
17:43094276

Altered

Wild Type

Combinations & Risk:

• TT (Wild Type): Normal risk. The T gene is the wild type (unaltered gene).

• GT (Heterozygous): Increased risk. The G gene is the “altered gene” (pathogenic mutation).

• GG (Homozygous): Very high risk (both alleles altered).

rs80357914
17:43124028

Wild Type 1

Wild Type 2

Significance:

Both A and G are normal/wild type.

⚠️ Risk: Pathogenic frameshift mutation. A risk exists if A or G is missing.

🚨 Risk Examples

If a mutation (altered gene) is present:

Breast Cancer: Risk increases from 12% to up to 70%.
Ovarian Cancer: Risk increases from 1% to up to 40%.
Age: Onset often occurs significantly earlier (before age 50).
Men: Men also have an increased risk for breast and prostate cancer.

✅ Screening Check

What can be done:

Early Detection: MRI and ultrasound in specialized centers.
Counseling: Specialist genetic counseling for the entire family.
Prevention: Close monitoring reduces the risk of severe disease progression.

📚 Data Sources

The information on this page is based on the following scientific sources:

OMIM: #604370 – Online Mendelian Inheritance in Man
ClinVar: Clinical Variant Database (NCBI)
dbSNP: rs80357906, rs80357914 – SNP Database (NCBI)
NCCN Guidelines: Genetic/Familial High-Risk Assessment
PubMed: Peer-reviewed scientific literature

Last Update: February 2026

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BRCA1