BRCA1 c.68_69del as a founder variant in the Spanish Roma: prevalence and screening implications

Founder effect of the *BRCA1* c.68_69del variant in the Spanish Roma population, shared with Ashkenazi ancestry

Two cross-sectional prevalence studies show that the BRCA1 c.68_69del (185delAG) variant is frequent in the Spanish Roma population through a founder effect, reaching 3.6% in the community-based sample and 0.8% in the nationwide sample. Haplotype reconstruction reveals an extended haplotype shared with European and Ashkenazi-ancestry carriers (common Iberian founder, estimated 600 years old in the Roma), distinct from the Indian origin. These data support targeted genetic screening for this variant in the Roma community, modeled on the cost-effective Ashkenazi approach.

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Identification of a clinically actionable founder variant in a population often underrepresented in genomic databases — an equity issue in cancer genetics. The high prevalence justifies considering this variant when faced with a suggestive family history in patients of Roma ancestry. The variant is in any case captured by any standard BRCA panel or sequencing; the key issue is referral to consultation and cascade family extension.