Estonian Cascade Testing Data Show 19.7% Pathogenic Variant Rate in Relatives, Highest in Men and Pre-Screening Ages

Researchers at Tartu’s Institute of Clinical Medicine examined records of individuals referred because of affected family members. Testing used multigene panels; 87.6% of participants were women and mean age was 41, a decade before Estonia’s routine screening start. The 19.7% detection rate far exceeds population estimates and included 23 distinct variants, nearly 60% in BRCA1 or BRCA2. Younger age groups and those without a known familial variant still showed clinically actionable yields of 8-41.8%.

These figures align with smaller European cascade studies yet exceed rates reported in unselected cohorts from the UK Biobank and US SEER-linked registries. The Estonian data underscore that founder effects and systematic family referral amplify detection, while also revealing that one-third of tested men carried variants linked to prostate and pancreatic risk—risks rarely addressed in national programs focused on women. Current policy that lowers screening age thresholds without proactive relative testing therefore leaves carriers undetected until symptomatic disease.

Next steps require national registries to track cascade uptake and link results to cancer incidence. Pilot programs integrating primary-care prompts after any index case could raise testing coverage above the current 41.8% seen when a familial variant is already known. Without such infrastructure, the observed pre-screening-age identification window will remain under-utilized.