Amniotic Fluid/ Chorionic Villus Sample/Peripheral Venous Blood/Cord blood,/Extracted DNA/Dry Blood Spot/POC

Chromosomal Microarray (CMA315k) – Affymetrix CytoScan Optima

Test Overview

Chromosomal Microarray Analysis (CMA315k) using the Affymetrix CytoScan Optima platform is an advanced genetic test designed to detect chromosomal abnormalities at a much higher resolution than conventional karyotyping.

This test identifies:

• Microdeletions
• Microduplications
• Copy Number Variations (CNVs)
• Aneuploidies (extra or missing chromosomes)
• Loss of Heterozygosity (LOH/AOH)
• Uniparental Disomy (UPD)
• Certain mosaic abnormalities

The CytoScan Optima array contains approximately:

• 315,608 CNV markers
• 148,450 SNP markers
  with enhanced coverage of clinically significant prenatal and postnatal genomic regions.

Clinical Applications

This test is commonly recommended for:

• Developmental delay
• Intellectual disability
• Autism spectrum disorders
• Multiple congenital anomalies
• Dysmorphic features
• Recurrent pregnancy loss
• Prenatal abnormal ultrasound findings
• High-risk Double Marker / Quadruple Marker / NIPT results
• Suspected chromosomal syndromes
• Infertility evaluation
• Bad obstetric history

The American College of Medical Genetics (ACMG) recommends CMA as a first-tier test for several unexplained developmental disorders.

Technology Highlights

Affymetrix CytoScan Optima Features

• Whole genome chromosomal screening
• Enhanced interrogation of 396 clinically important regions
• Detects gains/losses not visible in standard karyotyping
• SNP-based analysis for LOH/AOH and UPD detection
• Faster and more comprehensive than multiple targeted FISH tests

Typical reporting resolution:

• ~500 kb–1 Mb for deletions
• ~1–2 Mb for duplications
• ~5 Mb for LOH/AOH regions

Sample Requirements

Common sample types include:

• Peripheral blood (EDTA)
• Amniotic fluid
• Chorionic villus sample (CVS)
• Products of conception (POC)
• Fresh tissue (selected cases)

Turnaround Time

Typical turnaround time:

• 10–14 working days depending on sample type and laboratory workflow.

Advantages

• Higher sensitivity than conventional karyotyping
• Detects submicroscopic chromosomal abnormalities
• Genome-wide analysis
• Useful for prenatal and pediatric genetic diagnosis
• Can identify clinically relevant CNVs missed by FISH

Limitations

This test generally does not detect:

• Balanced translocations
• Inversions
• Small gene mutations / point mutations
• Very low-level mosaicism
• Epigenetic disorders
• Certain tiny indels below assay resolution

Interpretation

Results are categorized as:

• Normal
• Pathogenic
• Likely pathogenic
• Variant of uncertain significance (VUS)

Genetic counseling is often recommended for abnormal or uncertain findings.

Alternative Names

• CMA 315K
• Cytoscan Optima 315K
• Chromosomal Microarray Analysis
• SNP Microarray
• CytoMicroarray Low Resolution (315K)

Reference Technology

The test uses the Thermo Fisher Scientific / Affymetrix CytoScan Optima microarray platform for genome-wide chromosomal analysis.