BabyMap - CMA Prenatal

According to ACMG Microarray methodologies, including array comparative genomic hybridization and SNP detecting arrays, are accepted as an appropriate first-tier test for the evaluation of imbalances associated with intellectual disability, autism, and multiple congenital anomalies1

Chromosomal microarray (CMA) is a sophisticated microarray technology that analyzes the entire genome, detecting submicroscopic chromosomal deletions/duplications known as copy number variants (CNVs). CNVs are commonly associated with various genetic disorders that are often missed by traditional karyotyping. This high-resolution, whole-genome technique is rapidly replacing traditional karyotyping as the primary genetic test for screening suspected chromosomal anomalies. CNVs are linked to a diverse range of genetic disorders, including Autism Spectrum Disorders, autosomal disorders, X-linked Inheritance, UPD (Uniparental Disomy), and more.

Clinical Utility

  • Clinical diagnosis of cytogenetic abnormalities.
  • Differentiation between de novo(new unexplained mutations) and familial history of disorders
  • Prenatal diagnosis of at-risk pregnancies & at-risk family members.
  • To clarify the clinical significance of copy number changes
  • To influence the management of the conditions/disorders in a better way including lifestyle interventions.

When is it recommended

Diagnosis for fetal chromosomal imbalances is important as it is the contributing factor for some adverse obstetric outcomes - pregnancy loss, genetic syndromes etc. The accurate diagnosis of such chromosomal imbalances is a critical component of prenatal genetic evaluation.

    • CMA is recommended for patients undergoing invasive prenatal diagnosis with one or more major fetal structural abnormalities identified by ultrasonographic examination.
    • Abnormal maternal serum screen - improved detection of causative abnormalities.
    • Advanced maternal age.
    • Family history of genetic diseases.
    • Consanguine marriages.

CMA is the first step to get the diagnosis you need for the effective management of genetic conditions and their risk of recurrence.

Mapmygenome - CMA Offerings

  • Chromosomal Microarray genotyping with Illumina 750K Bead chip optimized for efficient cytogenetic analysis.
  • 750000 markers covering ~9000 genes analyzed with emphasis on ~447 disease-associated genes.
  • Copy neutral loss of heterozygosity (Cn-LOH) region detected based on intensity & SNP genotype in order to screen for UPD (Uniparental Disomy) & autosomal recessive disorders.
  • Copy Number Variations as small as 2.3kB CNV regions detected.
  • High-density screening of 324 known cytogenetic regions commonly screened & used as hotspots for cytogenetic testing.
  • 495268 genomic structural variants researched from Database of Genomic Variants for better interpretation.
  • Also covers: Pericenters and Telomeres | Sex Chromosomes | PseudoAutosomal Region (PAR1 and PAR2) | Common Regions of Interest Associated with Known Syndromes

Comparing all the techniques in prenatal testing

Increased resolution (~50-100 kb) in CMA allows for Identification of chromosomal imbalances Resolution limited to around 5 Mb. Can only detect deletions/duplications of regions specifically targeted by the probe
Greater accuracy Greater chance of missing subtle abnormalities Rare very small deletions can not be detected.
Diagnostic yield ~30% 5 – 10% of diagnostic yield 5 – 10% of diagnostic yield
Covers the Whole Genome to detect CNVs Covers the Whole Genome with low resolution to detect CNVs Can only detect deletions/duplications of regions specifically targeted by the probe

Test specification

Technique Variant types TAT Sample requirements
Microarray CNV 3 -4 weeks Extracted DNA samples (1µg - 2µg), POC 100-200g in PBS Solution, EDTA Blood (2-3ml) for MCC assay, CVS Sample/Amniotic Fluid/Cultured Cells - Cell Pellet in 1.5mL tube


  1. South, S., Lee, C., Lamb, A. et al. ACMG Standards and Guidelines for constitutional cytogenomic microarray analysis, including postnatal and prenatal applications: revision 2013. Genet Med 15, 901–909 (2013).


Is CMA a diagnostic test or a screening test?

CMA is primarily considered a diagnostic test rather than a screening test. It has a higher resolution and can provide more detailed information about the presence of chromosomal imbalances compared to traditional karyotyping.

Are there any limitations or drawbacks to CMA?

Does CMA carry any risks or complications for the mother or fetus?

Do I need genetic counseling before undergoing CMA?