Parental Consanguinity and Chromosomal Abnormality Yield in a Five-Year Cytogenetic Referral Cohort from Eastern Libya

Abstract

 Background/Objective: Parental consanguinity is common in eastern Libya and is an established risk factor for autosomal-recessive disease, but its relationship to chromosomal abnormality is less clear; we tested whether consanguinity was associated with karyotype abnormality, reproductive loss, or previously affected children among patients referred to the First International Laboratory in Benghazi (2021–2025) from a 319-record cytogenetic registry. Methods: Consanguinity was coded as present, absent, or unknown; records with unknown status were excluded. The abnormality rate was compared between consanguineous and non-consanguineous referrals with an interpretable karyotype (Fisher's exact test), and reproductive history and parental age with the Mann–Whitney U and Fisher's exact tests. Results: Consanguinity was documented for 150 of 319 records (47.0%); 42 (28.0%) were consanguineous, mostly first-cousin unions. Among 107 patients with known consanguinity and an interpretable karyotype, a chromosomal abnormality was found in 11 of 26 (42.3%) consanguineous versus 37 of 81 (45.7%) non-consanguineous referrals (odds ratio [OR] 0.87, 95% CI 0.36–2.13; P = .82). Reproductive history did not differ: at least one prior miscarriage in 43.6% versus 39.8% (OR 1.17, 95% CI 0.55–2.46; P = .71), and at least one previously affected child in 26.7% versus 26.9% (OR 0.99, 95% CI 0.38–2.56; P = 1.00). Maternal and paternal age were also similar. Conclusion: Consanguinity was not associated with chromosomal abnormality yield or adverse reproductive history, consistent with consanguinity raising risk chiefly for autosomal-recessive single-gene disorders rather than aneuploidy; these findings support molecular rather than cytogenetic testing for consanguineous families with recurrent pregnancy loss.