Purpose of investigation: To determine the performance of nuchal translucency (NT) measurement as a screening test for homozygous α-thalassemia-1 in at-risk pregnant women. Materials and Methods: Fetal NT thickness was measured at 11-13 weeks of gestation in 283 pregnancies at risk of homozygous α-thalassemia-1. The final diagnosis was confirmed by invasive procedures. The NT measurements were compared in affected fetuses and unaffected ones (normal or carriers). The sensitivity and specificity

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... based on the cut-off of 95 th percentile of normal NT ranges were calculated. Results: Out of a total of 283 pregnancies at risk of homozygous α-thalassemia-1, 65 were confirmed to be affected, and 218 were unaffected. The median NT value (median 2.6 mm, 95% CI: 2.357-2.880 mm) in affected cases was significantly higher than that in the unaffected cases (median 1.6 mm, 95% CI: 1.611-1.686 mm) (p < 0.001). Using receiver-operating characteristic (ROC) analysis, the increased NT yielded a detection rate of 52.3 % (95% CI: 39.54%-64.85%) at a 5% false positive rate. Conclusion: NT may be helpful in screening for fetal homozygous α-thalassemia-1 in clinical work.