Prenatal diagnosis by chromosomal microarray analysis.

Area of Science:

• Prenatal Diagnostics
• Genetics
• Genomics

Background:

• Chromosomal microarray analysis (CMA) complements traditional karyotyping in prenatal settings.
• CMA detects major chromosomal imbalances like aneuploidy and unbalanced rearrangements.
• It also identifies sub-microscopic imbalances (copy number variations, microdeletions, microduplications).

Purpose of the Study:

• To highlight the diagnostic capabilities of CMA in prenatal settings.
• To emphasize the challenges and importance of genetic counseling for interpreting CMA findings.
• To differentiate CMA from non-invasive prenatal testing (NIPT).

Main Methods:

• Utilizing array comparative genomic hybridization or single nucleotide polymorphism arrays for CMA.
• Comparing CMA's diagnostic yield against traditional karyotyping.
• Analyzing the clinical significance of detected microdeletions and microduplications.

Main Results:

• CMA is equivalent to karyotyping for major chromosomal imbalances.
• CMA detects clinically significant subchromosomal deletions/duplications in ~1% of normal karyotype pregnancies and 6% with structural anomalies.
• The clinical significance of microdeletions/duplications can range from benign to unknown.

Conclusions:

• CMA provides significant added value in prenatal diagnosis by detecting sub-microscopic variations.
• Genetic counseling is essential for managing complex results and patient expectations.
• Understanding CMA's scope versus NIPT's screening limitations is vital for informed decision-making.