Prenatal Diagnosis Using Chromosomal Microarray Analysis in High-Risk Pregnancies

Area of Science:

• Prenatal Diagnosis
• Genetics
• Medical Diagnostics

Background:

• High-risk pregnancies necessitate accurate diagnostic tools.
• Chromosomal microarray analysis (CMA) is a modern genetic testing method.
• Assessing CMA's utility in prenatal diagnosis is crucial for clinical practice.

Purpose of the Study:

• To evaluate the effectiveness of chromosomal microarray analysis (CMA) in prenatal diagnosis for high-risk pregnancies.
• To compare CMA with traditional G-banding karyotype analysis.
• To determine the diagnostic yield of CMA for various genetic abnormalities.

Main Methods:

• Analysis of 1037 samples (chorionic villi and amniocentesis) from high-risk pregnancies between 2016 and 2021.
• Inclusion criteria: advanced maternal age, fetal structural abnormalities, abnormal screening results, or family history of genetic disorders.
• Both G-banding karyotype analysis and CMA (oligonucleotide array-based comparative genomic hybridization) were performed on extracted DNA.

Main Results:

• Aneuploidies were detected in 4.05% of cases by both methods.
• In cases with normal karyotypes, CMA identified copy number variants (CNVs) in 10.6%, including pathogenic/likely pathogenic CNVs in 2.9%.
• CMA did not detect certain rearrangements like inversions, balanced translocations, and low-level mosaicism, which were identified by G-banding.

Conclusions:

• CMA is an effective initial diagnostic tool for high-risk pregnancies, particularly those with fetal structural anomalies identified via ultrasound.
• CMA provides a higher detection rate for copy number variants compared to karyotyping alone.
• While CMA is powerful, G-banding karyotyping remains important for detecting specific chromosomal rearrangements not identified by CMA.