# Frequency of Founder Mutations in BRCA1 and BRCA2 Genes in Hereditary Breast Cancers in Poland vs. Other Countries

## TL;DR

This paper compares the frequency of BRCA1 and BRCA2 founder mutations in hereditary breast cancer in Poland with other countries, highlighting their clinical and diagnostic significance.

## Contribution

The study provides a comparative analysis of BRCA founder mutations in Poland versus other regions, emphasizing their role in genetic testing and counseling.

## Key findings

- Poland has a distinct spectrum of BRCA1 and BRCA2 founder mutations influencing national testing protocols.
- Founder mutations are more prevalent in certain populations due to shared ancestry and regional spread.
- Genetic counseling is crucial for prevention, risk assessment, and treatment decisions in hereditary breast cancer.

## Abstract

Hereditary breast cancer (HBC) accounts for a notable proportion of all breast cancer (BC) cases and is strongly associated with pathogenic variants (PVs) in the BRCA1 and BRCA2 genes. In several populations, certain BRCA PVs occur more frequently due to founder effects, reflecting their origin from a common ancestor and subsequent spread within specific regions. Understanding these population-specific founder mutations is essential for improving diagnostic accuracy, genetic counseling, and personalized surveillance strategies. In Poland, a distinct spectrum of BRCA1 and BRCA2 founder mutations has been identified, influencing national testing protocols and allowing more efficient identification of individuals at high genetic risk. This review summarizes current knowledge on the prevalence of founder mutations in Poland compared with neighboring countries, highlights their clinical implications, and emphasizes the crucial role of genetic counseling in prevention, risk assessment, and therapeutic decision-making for hereditary breast cancer.

Breast cancer (BC) remains one of the most prevalent malignancies worldwide, and genetic factors may influence its development. Approximately 10–15% of all BCs are hereditary and known as Hereditary Breast Cancer (HBC). A remarkable family history and young onset are the strongest risk factors of HBC. The rapid development of genetic testing techniques has increased the detection rate of pathogenic and likely pathogenic variants in several genes associated with high, moderate, or low risk of HBC. This allowed us to identify the whole family at risk of HBC. Among hereditary cases, pathogenic variants (PVs) in the BRCA1 and BRCA2 genes are particularly notable, especially in certain populations where founder mutations (specific genetic variants originating from a common ancestor) are more prevalent. In this article, an overview of the current state of knowledge on HBC is provided, focusing on the frequency of founder mutations in the BRCA1 and BRCA2 genes in HBC in Poland compared to other countries. We will also highlight the role of genetic counseling in the diagnosis and treatment of BC, emphasizing its crucial importance in identifying genetic predispositions, selecting appropriate therapeutic strategies, and supporting patients and their families in making informed medical decisions.