Developing and optimizing a decisional instrument using self-reported ancestry for carrier screening in a multi-ethnic society

To develop a decisional instrument for ancestry-based cystic fibrosis and/or hemoglobinopathies carrier couple screening in The Netherlands. A flowchart (Instrument A) and a questionnaire with maps of geographical areas with originally high cystic fibrosis and hemoglobinopathies carrier frequencies (Instrument B), were developed to support participants in self-assessing their eligibility as a couple for carrier screening for cystic fibrosis and/or hemoglobinopathies. 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. 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. A decisional instrument to assess ancestry-based eligibility for cystic fibrosis and/or hemoglobinopathies 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.