Prenatal Diagnosis by Chromosome Microarray Analysis, An Indian Experience

Area of Science:

• Prenatal diagnostics
• Genetics
• Medical technology

Background:

• Karyotyping is the standard for prenatal chromosome analysis.
• Chromosome microarray analysis (CMA) offers higher resolution.
• Distinguishing benign, pathogenic (pCNV), and variants of unknown significance (VOUS) is challenging.

Purpose of the Study:

• Evaluate the diagnostic yield and clinical utility of CMA in prenatal samples.
• Stratify CMA results across different prenatal referral groups.
• Compile Indian data on pCNVs and VOUS to aid genetic counseling.

Main Methods:

• Karyotyping and CMA performed on 370 prenatal samples (amniotic fluid and chorionic villi).
• Samples from Indian pregnant women with various risk factors: high maternal age, biochemical screen positive, previous abnormal child, abnormal fetal ultrasound, and heterozygous parents.

Main Results:

• CMA showed a higher diagnostic yield (9.18%) than karyotyping (5.40%).
• Abnormal fetal ultrasound group had the highest percentage of pCNVs (5.40%).
• CMA identified deletion/duplication syndromes and characterized marker chromosomes.

Conclusions:

• CMA is essential for women with abnormal fetal ultrasounds for genotype-phenotype correlation.
• Accumulating CNV data will create an Indian Repository and help resolve VOUS.
• Pre- and post-test genetic counseling is vital for informed decision-making regarding CMA.