Array comparative genomic hybridization provides the tools to scan fetal DNA quickly and automatically to identify copy number variation, which indicates the deletion or addition of genetic material at a particular point on the genome.
The array starts with single-stranded fragments of DNA embedded on a glass slide to form the array, which is then exposed to fluorescently labeled single-stranded DNA. Half of the labeled DNA is from the fetus being tested and is labeled with one fluorescent color. The other is reference DNA, which is labeled with another color. The fluorescently labeled DNA reference and patient binds to DNA on the array. The color of the fragments will vary based on how much DNA from each binds to the DNA on the array. If the fetus has a DNA duplication, then the patient color on the array will be stronger. If the fetus has a deletion, the reference color will show up stronger. A specialized scanner evaluates the color differences, which are then fed into a computer for analysis.
In this study, most of the women sought prenatal testing because they were older and faced a higher risk of having children with certain chromosomal abnormalities, such as Down syndrome. Some had had abnormal ultrasounds and needed more information, and still others had had children with a genetic abnormality previously.
The scientists found 58 copy number variations, which indicate that there is either more or less genetic material than one would expect to find at that location on the chromosome.
Forty of these variations were interpreted as benign. Thirty-nine of them were inherited from a parent who had no evidence of genetic disease. One had been seen before and had not been associated with disease.
In 15 cases when the array detected something that was significant for patient care, the finding was either
|Contact: Glenna Picton|
Baylor College of Medicine