Studies by comparative genomic hybridization, or CGH-array, allow us to detect alterations in the number of copies of both complete chromosomes and of small chromosomal fragments (i.e., aneuploidies, microdeletions, and microduplications).
This technique has a resolution 10 to 50 times higher than that of conventional karyotyping and produces objective results.
This is why it has become the tool of first choice in pregnancies in which abnormalities are detected by ultrasound.
Step-by-Step
How does it work?
Prenatal CGH-array studies are performed on foetal genetic material, which must be collected through an invasive technique. Either desquamated foetal cells collected from amniotic fluid or cells obtained from a chorionic villus biopsy are used.
Who is it for?
When is it recommended?
Once the presence of foetal chromosomal aneuploidies has been ruled out, it is recommended that a CGH-array be performed when there is:
Elevated nuchal translucency.
Intrauterine growth retardation.
Suspicion of a congenital heart disease by ultrasound analysis.
A family or personal history associated with a genetic alteration.
A nonspecific ultrasound abnormality.
A fast response time (5–7 business days).
This technique has a resolution 10 to 50 times higher than that of conventional karyotyping.
In the case of a normal foetal karyotype and the detection of abnormalities by ultrasound, CGH-array is capable of detecting abnormalities in 8–12% of cases.
