Prenatal Testing Comparison

IriSight® CNV Analysis

IriSight® CNV Analysis is a genetic test performed during pregnancy to look for chromosomal conditions in a fetus. It is similar to NIPT/NIPS (NonInvasive Prenatal Testing, NonInvasive Prenatal Screening) and chromosomal microarray (CMA) tests, but there are important differences.

First, NIPT is predictive – it can only suggest that a fetus is at high or low risk of having a certain chromosomal condition. Both CMA tests and IriSight® CNV Analysis are amniocentesis* or chorionic villus sampling (CVS)-based, diagnostic tests that provide definitive answers.

Second, NIPT, CMA and IriSight® CNV Analysis use different sequencing technologies that affect the type and size of chromosomal changes that can be detected. The table below provides a comparison.

*Amniocentesis or CVS is sometimes recommended when ultrasound results are abnormal.

IriSight® Comprehensive Analysis – Prenatal

IriSight® Comprehensive Analysis – Prenatal is a genetic test performed during pregnancy that goes beyond IriSight® CNV Analysis to identify additional types of DNA changes in a fetus that can cause early-onset genetic disorders such as cystic fibrosis and fragile X syndrome. Similar to exome testing, IriSight® Comprehensive Analysis – Prenatal is an amniocentesis* or CVS-based, diagnostic test that provides definitive answers – but there are important differences.

Exome testing and IriSight® Comprehensive Analysis – Prenatal use different sequencing technologies that affect the type and size of DNA changes that can be detected. The table below provides a comparison, highlighting that only IriSight® Comprehensive Analysis – Prenatal can detect variants ranging from small sequence changes to mitochondrial variants and repeat expansions.

*Amniocentesis or CVS is sometimes recommended when ultrasound results are abnormal.

Prenatal testing differences

	NIPT	CMA	IriSight® CNV Analysis	Exome	IriSight® Comprehensive Analysis - Prenatal
Sequencing Technology	SNP technology: sequences <1% of DNA	SNP technology: sequences <1% of DNA	Genome technology: sequences >98% of DNA	Exome technology: sequences 1-2% of DNA	Genome technology: sequences >98% of DNA
Chromosomal changes that can be detected
Down syndrome, Edward syndrome, Patau syndrome
Additional autosomal aneuploidies	Not detected
Monosomy X (Turner syndrome), XXY syndrome (Klinefelter syndrome), Triple X syndrome, XYY syndrome (Jacob's syndrome)
Microdeletions	Subset are detected
CNVs	Not detected	Detected with size limitations		Detected with size limitations
Inversions	Not detected	Varies		Not detected
Additional changes that can be detected
Small sequence changes	Not detected	Not detected	Not detected
Mitochondrial	Not detected	Not detected	Not detected	Varies
Repeat expansions	Not detected	Not detected	Not detected	Not detected

See IriSight® CNV Analysis and IriSight® Comprehensive Analysis – Prenatal test specifications for more information.

Definitions

Aneuploidy – A condition where an abnormal number of chromosomes is present. Trisomy and monosomy are both types of aneuploidy

Trisomy – A condition where an extra copy of a complete chromosome is present

Monosomy – A condition where a complete chromosome is missing

Microdeletion – A type of DNA change where a portion of a chromosome is missing

CNV – Copy Number Variant, a type of DNA change where the number of copies of a DNA segment is changed. CNVs include deletions (where a copy is missing) and duplications (where an extra copy is present)

Inversion – A type of DNA change where a DNA segment is present in reverse orientation or has been relocated to a different position within the genome

Small sequence change – A type of DNA change where a single base or small number of bases is altered

Mitochondrial – Changes in the mitochondrial genome

Repeat expansion – A type of DNA change where a sequence of bases is repeated in an expanded stretch