High rates of "atypical" single nucleotide polymorphism-based noninvasive prenatal screening results among consanguineous Arab American patients: A single center retrospective study

Noninvasive prenatal screening (NIPS), using placental cell-free DNA from a maternal blood sample, is currently the most sensitive and specific screening tool for detecting common fetal aneuploidies. The aim of this study was to compare the rates of "atypical" single nucleotide polymorphism (SNP)-based NIPS results and subsequent pregnancy outcomes between Arab American and non-Arab American patients. We conducted a retrospective cohort study of pregnant Arab and non-Arab American patients who had SNP-based NIPS performed between September 2018 and January 2021 at an urban health system in Michigan. The rate of "atypical" results and other perinatal outcomes were compared between groups using descriptive statistics. "Atypical" results due to multifetal gestations, either undisclosed or unknown at time of ordering, were excluded. Five thousand eight hundred and seventy-three patients underwent SNP-based NIPS: 771 (13.1%) were identified as Arab American, 5102 (86.9%) were non-Arab American, and 49 (0.8%) patients received "atypical" results. Arab patients represented only 13.1% of patients screened (771/5873) but had a significantly higher rate of "atypical" results than non-Arab American patients (17/771 [2.2%] vs. 32/5102 [0.6%]; p < 0.001). Of the 17 Arab patients with "atypical" results, 9 (52.9%) were in known consanguineous relationships. No major congenital anomalies or chromosomal aberrations were identified for any patients who had "atypical" results, and no significant differences in other perinatal outcomes were observed between Arab and non-Arab American patients. A better understanding of the association between consanguinity and "atypical" SNP-based NIPS results would aid in appropriate test selection and interpretation and may help physicians and genetic counselors provide better perinatal counseling and follow-up care for patients in consanguineous relationships.