Microarray analysis improves prenatal diagnosis.

HOUSTON -- (Nov. 17, 2008) -- A "chip" or array that can quickly detect disorders such as Down syndrome or other diseases associated with chromosomal abnormalities proved an effective tool in prenatal diagnosis in a series of 300 cases at Baylor College of Medicine, said researchers in a report that appears in the current issue of the journal Prenatal Diagnosis (see also Baylor College of Medicine).

In the report, a team led by Dr. Arthur Beaudet and Dr. Sau Wai Cheung at BCM, described use of array comparative genomic hybridization to analyze samples taken during amniocentesis or chorionic villus sampling for chromosomal abnormalities. Amniocentesis and chorionic villus sampling allow researchers to obtain fetal cells for testing.

"Larger studies of this test will help us decide whether it should be used as a first line measure to detect chromosome abnormalities in fetuses," said Beaudet, chair of molecular and human genetics at BCM and senior author of the report. "They will also enable us to determine whether such testing should be offered more widely to pregnant women."

Cheung is professor of molecular and human genetics at BCM and director of the College's Cytogenetics Laboratory.

"The array enables you to detect smaller deletions or duplications of genetic material that would not be seen on a regular karyotype (a depiction of the size, shape and number of chromosome and any abnormalities in them)," said Dr. Ignatia B. Van den Veyver, associate professor of obstetrics and gynecology and molecular and human genetics at BCM and first author of the report. Each of these deletions or duplications is rare but added together, the rate of event could be as high as that seen in Down Syndrome.

In some of these cases where small amounts of DNA are lost or duplicated, children often have significant learning disabilities or health problems that could not be picked up with an ultrasound or other means of prenatal diagnosis, she said.

"This test adds information we could not detect by any other means right now in prenatal diagnosis," she said.