Non-Invasive Prenatal Testing (NIPT) for Aneuploidy in a Setting with a High Consanguineous Rate – A Retrospective Cohort Review of 1,153 Cases

Abstract

OBJECTIVE: To review the outcome of NIPT as a screening test for aneuploidy at a tertiary feto-maternal centre in a population with a high consanguinity rate and to investigate whether consanguinity is a factor in failure to generate results. Methods: A retrospective cohort study of the records of all the women who had NIPT at our centre over the six-year period 2015-2021 inclusive. RESULTS: Over the 6-year period, a total of 1,153 NIPTs were performed on 6 commercial brands. 216 (18.7%) were in consanguineous women. The gestational age at testing varied from 10-34 weeks, with 46 women being tested after 20 weeks. There were 20 true positives and 1 false negative. Results were not reported in 68 cases (5.9%); one of the brands (of the 4 most common) had a significantly (P<0.004) higher failure to generate a result rate (12.8% vs 3.9% and 3.2%). The failure to obtain a result was 8.5% in the consanguineous group, slightly higher (but not statistically significant) than 6.9% in the non-consanguineous group. There were 4 positive cases in low-risk women (who requested the test for assurance purposes), who would otherwise have had aneuploid fetuses, had they not requested testing. CONCLUSION: For the first time, we showed that consanguinity does not appear to be a factor in failure to generate a result or very low cfFDNA. Further studies are required to confirm these important findings.