A new test may be better at detecting potentially harmful genetic changes in children before they are born than current methods, researchers say.

The test, called a chromosomal microarray, detected more irregularities that could result in genetic diseases such as missing or repeated sections of genetic code than did karyotyping, which is the current standard method of prenatal testing.

For instance, children who are missing a small portion of chromosome 22 will be born with DiGeorge syndrome, which can cause severe heart defects and developmental delays. In the study, a chromosomal microarray detected this missing section and diagnosed the condition, whereas a karyotype is not able to find the change.

Microarrays also identified some genetic changes linked to autism not revealed by karyotyping.

The findings suggest microarray should replace karyotyping as the standard method of finding genetic irregularities in fetuses, said study researcher Dr. Ronald Wapner, an obstetrician and gynecologist at Columbia University in New York. Microarrays are already used to diagnose genetic conditions in children with developmental disabilities and birth defects.

However, experts cautioned that microarrays could provide more information than is useful. Some abnormalities identified by the test are new, and have unknown or uncertain consequences, which can put stress on families. [See 11 Big Fat Pregnancy Myths.]

It is critical that parents who receive this type of testing are counseled before and after the test about what the findings could mean, experts say.

Microarrays vs. karyotype

In karyotyping, fetal cells are analyzed under a microscope, which allows researchers to see whether too many or too few chromosomes are present, or if the chromosomes have an abnormal structure. In contrast, microarrays compare a sample of the fetus' DNA with that of a healthy person, giving researchers a closer look at the genetic code.

Both tests require amniocentesis, a procedure that takes fetal cells from the amniotic fluid and comes with risks, including a small risk of miscarriage.

Read more from the original source:
Genetic Test Could Better Reveal Fetal Abnormalities

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