# Copy number variants in fetuses with isolated and non-isolated increased nuchal translucency detected by chromosomal microarray analysis

## TL;DR

This study examines how often chromosomal abnormalities are detected in fetuses with increased nuchal translucency using microarray analysis.

## Contribution

The study compares detection rates of chromosomal abnormalities in fetuses with isolated versus non-isolated increased nuchal translucency.

## Key findings

- Chromosomal abnormalities were detected in 29.9% of fetuses with increased nuchal translucency.
- Fetuses with non-isolated increased nuchal translucency had a higher detection rate of chromosomal abnormalities (46.7%) compared to those with isolated cases (23.2%).
- Chromosomal aneuploidy rates increased with greater nuchal translucency thickness in isolated cases.

## Abstract

The purpose of this study was to explore the detection rate of chromosomal copy number variants (CNVs) in fetuses with isolated and non-isolated increased nuchal translucency (NT) by chromosomal microarray analysis (CMA).

A retrospective study was conducted on 211 fetuses with increased NT diagnosed prenatally at Meizhou People’s Hospital from November 2022 to June 2025. Interventional prenatal CMA testing was conducted on these fetuses. The detection rates of chromosomal abnormalities in fetuses with isolated and non-isolated increased NT, and fetuses with different NT thicknesses (2.5-3.4, 3.5-4.4, and ≥4.5 mm) were analyzed.

Among the fetuses, hromosomal aneuploidy, pathogenic or likely pathogenic (P/LP) CNVs, and variants of uncertain significance (VOUS) were detected in 23, 14, and 26 fetuses respectively, with a total detection rate of 29.9%. A total of 151 fetuses (71.6%) had increased NT, and 60 fetuses (28.4%) had non-isolated increased NT. There was a statistically significant difference in the detection rate of chromosomal abnormalities between the two groups (23.2% vs. 46.7%, χ2=11.311, p=0.001). In fetuses with isolated increased NT, with the increase of NT thickening, the rate of chromosomal aneuploidy shows an increasing trend. And there was statistically significant difference in detection rate of chromosomal aneuploidy in fetuses with different NT thicknesses (p=0.045).

A notable difference existed in the detection rate of chromosomal abnormalities between fetuses with isolated and non-isolated increased NT. For those with isolated increased NT, chromosomal aneuploidy rates tended to rise with increasing NT thickness, while this trend was not observed for P/LP CNVs.