Preconceptional carrier couple screening for cystic fi brosis and hemoglobinopathies An ancestry-based offer in a multi-ethnic society

Purpose: To develop a decisional instrument for ancestry-based cystic fibrosis (CF) and/or haemoglobinopathies (HbPs) carrier couple screening in The Netherlands. Methods: A flow chart (instrument A) and a questionnaire with maps of geographical areas with originally high CF and HbP carrier frequencies (instrument B), were developed to support participants in self-assessing their eligibility as a couple for carrier screening for CF and/or HbPs. The outcome was compared to the self-reported origin of both partners’ ancestors during an in-depth interview. Furthermore, preference for instrument A or B was determined. Results: Of the 112 participants, 88% (99/112, 95% CI 82-94%) (Instrument A) and 91% (102/112, 95% CI 86-96%) (Instrument B), respectively, arrived at a decision in accordance with their ancestral origin, and 57% (64/112, 95%CI 48-66%) preferred instrument B. A false negative proportion of 5.5% suggests that some carriers will exclude themselves from screening. Results might improve with minor changes in the instruments with regard to geographic specification, and availability of translated versions. Conclusion: A decisional instrument to assess ancestry-based eligibility for CF and/or HbPs carrier screening, is now available and can with slight adaptations be used in other countries. The instrument also takes into account the possibility of mixed ancestry.