Cytogenetic Profile of Patients Referred for Chromosomal Analysis in Eastern Libya: A Five-Year Retrospective Study

Chromosomal abnormalities are an important cause of congenital 2tmalformation, intellectual disability, disordered sexual development, and infertility, yet population-level cytogenetic data from Libya are scarce. We describe the spectrum of chromosomal findings among patients referred for karyotyping in eastern Libya. We retrospectively reviewed all patients referred for peripheral-blood metaphase karyotyping to the Genome Laboratory, a private clinical cytogenetics laboratory in Benghazi, between 2021 and 2025, using anonymized records. Karyotypes were classified by cytogenetic outcome. Frequencies were expressed with 95% confidence intervals (CIs); the chi-square test compared abnormality rates between subgroups. Of 319 referred individuals, 251 had an interpretable karyotype and formed the analytic cohort (130 female, 51.8%; median age 3.0 years, interquartile range 0.2–27.0). A clinically significant chromosomal abnormality was identified in 106 patients (42.2%; 95% CI 36.3–48.4). Numerical abnormalities accounted for 88.7% of abnormal results. Down syndrome was the most frequent diagnosis (58 patients, 23.1% of the cohort), of which 93.1% were free trisomy 21. Turner syndrome (19, 7.6%), Klinefelter spectrum (8, 3.2%), trisomy 18 (7, 2.8%), and trisomy 13 (2, 0.8%) followed, alongside 11 structural rearrangements (4.4%). The abnormality detection rate fell steeply with age at referral, from 80.4% in neonates to 15.1% in adults, and did not differ by sex (p = 0.60). Mothers of children with Down syndrome were older than mothers of other referred children (median 37.0 vs 31.0 years). Referral-based cytogenetic testing in eastern Libya yields a chromosomal abnormality in over four in ten patients, dominated by free trisomy 21. The strong inverse relationship between age at referral and diagnostic yield points to delayed recognition of sex-chromosome and structural disorders, supporting earlier clinical suspicion and referral.