The Utility of Whole Exome Sequencing in Fetuses With Isolated Increased Nuchal Translucency

Background To evaluate the utility of prenatal whole exome sequencing (WES) in cases of isolated increased nuchal translucency (NT). Methods Retrospective analysis of the prenatal WES results in fetuses with increased NT (≥ 3.0 mm) and normal fetal anatomy, normal karyotype, and chromosomal microarray analysis (CMA). Subgroup analysis was performed based on NT measurements. Results Diagnostic variants were identified in 3 of 118 fetuses (2.5%) with isolated increased NT (≥ 3.0 mm). The distribution of positive findings was as follows: NT 3.0–3.4 mm group ( n = 13): 1 case (7.7%) with diagnostic genetic variants; NT ≥ 3.5 mm group ( n = 105): 2 cases (1.9%) with diagnostic genetic variants (both in the NT 5.0–6.4 mm subgroup). Fisher's exact test (two‐tailed) showed no statistically significant differences in diagnostic yield between: NT 3.0–3.4 mm versus NT ≥ 3.5 mm ( p = 0.298); NT 3.0–3.4 mm versus NT 5.0–6.4 mm ( p = 1.000); NT ≥ 3.0 mm versus NT ≥ 3.5 mm ( p = 1.000). Conclusion Our analysis revealed a low diagnostic yield (2.5%) for prenatal WES in cases of isolated increased NT ≥ 3.0 mm. Our findings provide valuable evidence for clinical counseling, particularly when patients inquire about the likelihood of isolated findings. These data offer meaningful guidance for their decision‐making process regarding further testing options.