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Case Reports
. 2025 Apr 22;18(4):e263687.
doi: 10.1136/bcr-2024-263687.

Double heterozygosity for BRCA1 and BRCA2 in breast cancer: considerations in surveillance and cancer risk management

Nonoko Wakaki  1 , Tatsunori Shimoi  2 , Shogo Nakamoto  3 , Yuichiro Kikawa  4 , Aki Ito  5 , Takayuki Iwamoto  6
Affiliations
Case Reports

Double heterozygosity for BRCA1 and BRCA2 in breast cancer: considerations in surveillance and cancer risk management

Nonoko Wakaki et al. BMJ Case Rep. .

Abstract

This case report examines a premenopausal woman in her 30s with double heterozygosity (DH) for BRCA1 and BRCA2 The patient's DH led her parents to undergo genetic testing as well, and new carriers were found, highlighting the importance of genetic counselling and surveillance for the entire family. Due to the rarity of DH, cancer risk and optimal surveillance strategies are not addressed in current guidelines or other sources. This report summarises existing evidence and highlights the need for further research to better understand cancer risks and to develop effective management strategies for individuals with this unique genetic profile.

Keywords: Breast surgery; Genetic screening / counselling; Heterozygote; Surgical oncology.

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Conflict of interest statement

Competing interests: None declared.

Figures

Figure 1
Figure 1. Pedigree chart showing the patient’s family history of hereditary breast cancer with BRCA test results.
Figure 2
Figure 2. Imaging tests: Top left—mammography, top right—contrast-enhanced MRI, bottom left—ultrasound blood flow evaluation and bottom right—ultrasound strain evaluation.
Figure 3
Figure 3. Comparison of the characteristics and risks of breast, ovarian and other cancers associated with BRCA1 single mutation, BRCA2 single mutation and BRCA1+BRCA2 double heterozygosity.
See this image and copyright information in PMC

References

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