Achille Manirakiza, Clinical Oncology Specialist, Research Director at King Faisal Hospital Rwanda, shared on LinkedIn:
“New in PLOS Genetics: A prehistoric BRCA1 founder variant in Rwanda
We followed seven unrelated Rwandan women with breast cancer with the same BRCA1 mutation. We found a shared ancestor who lived roughly 4,000–10,000 years ago.
Among 175 women with breast cancer, 1 in 25 carried BRCA1 c.4065_4068del, which accounted for more than 1 in 5 of all pathogenic variant carriers. It is extremely rare in global databases and about 60 times rarer across the broader African population.
We performed:
- Whole-exome sequencing of all seven carriers, with statistical phasing against the 1000 Genomes reference
- Haplotype analysis: all seven shared an ancestral block of about 581 kb around the variant. Extended haplotype homozygosity and haplotype network analyses pointed to a single common origin.
- Relatedness testing across more than 730,000 SNPs ruled out any close family ties, so the shared segment is ancient rather than recent.
- Age estimation from haplotype decay places the founder event in the Neolithic to Bronze Age.
- Population comparison with 1000 Genomes and the MADCaP African cohort found no exact match for the Rwandan founder haplotype anywhere.
The same variant appears in the broader East Africa and elsewhere.
Whether Rwanda’s copy shares an ancestor with those or arose independently is still open.
That’s the next question.”
Title: A common pathogenic founder variant in Rwandan breast cancer cases
Authors: Achille V. C. Manirakiza, Shakuntala Baichoo, Annette Uwineza, Damas Dukundane, Eulade Rugengamanzi, Janviere Mutamuliza, Allison M. O. Niragira, Raissa Muvunyi, Jeffrey Besada, Sarah M. Nielsen, Brianna Bucknor, Diane R. Koeller, Caroline Andrews, Leon Mutesa, Temidayo Fadelu, Timothy R. Rebbeck.
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