Application of chromosomal microarray in fetuses with increased nuchal translucency

Area of Science:

• Prenatal diagnostics
• Human genetics
• Fetal medicine

Background:

• Increased nuchal translucency (NT) is a common finding in fetal ultrasound.
• Conventional karyotyping may miss submicroscopic chromosomal abnormalities.
• Chromosomal microarray (CMA) analysis offers higher resolution for detecting copy number variants (CNVs).

Purpose of the Study:

• To evaluate submicroscopic chromosomal abnormalities in fetuses with increased NT (≥3.0 mm) and normal karyotype.
• To compare the prevalence of pathogenic CNVs in fetuses with increased NT to a low-risk population.
• To assess the utility of CMA in identifying additional pathogenic CNVs beyond conventional karyotyping.

Main Methods:

• Conventional karyotyping was performed on 319 fetuses with increased NT.
• Chromosomal microarray (CMA) analysis was conducted on 137 samples with normal karyotypes.
• Pathologic CNV prevalence was compared between increased NT cases and 926 low-risk controls.

Main Results:

• Chromosomal abnormalities were found in 32.29% of fetuses with increased NT.
• Additional pathogenic CNVs were detected in 5.12% of fetuses via CMA.
• The prevalence of pathological CMA results was significantly higher in the increased NT group (5.12%) compared to the low-risk group (1.19%).

Conclusions:

• Increased NT (≥3.0 mm) is associated with a higher risk of CMA abnormalities.
• Submicroscopic chromosomal abnormalities should be investigated using CMA in fetuses with increased NT and normal karyotype.
• Prenatal counseling should highlight the advantages of CMA for detecting submicroscopic chromosomal abnormalities.