Fetal Genetic Disorders Test Being Developed


GRAPEVINE, TEX. — Researchers are attempting to develop a first-trimester cervical swab test to detect fetal genetic disorders.

While the test still is under development, if proven effective, it could provide noninvasive, earlier prenatal screening and possibly eliminate the need for amniocentesis and chorionic villi sampling (CVS).

“Early prenatal diagnosis to detect fetal genetic disorders is desired by both expectant mothers and physicians to make informed decisions,” Farideh Z. Bischoff, Ph.D., of Baylor College of Medicine, Houston, said at a meeting sponsored by the American College of Medical Genetics.

“Current methods of prenatal testing carry a small but finite risk of miscarriage, and the results rarely are available before 12 to 16 weeks of pregnancy, due to the time required for cell culture,” Dr. Bischoff said.

Recovery and analysis of fetal trophoblast cells would provide a safe alternative approach for rapid noninvasive prenatal diagnosis, she said.

The researchers are using micro electro mechanism system (MEMS) channels to isolate, purify, and characterize fetal trophoblasts from maternal transcervical mucous specimens. The trophoblast cells migrate from the placenta to the endocervical canal.

In a pilot study, the researchers were able to take cervical swab specimens from 17 women during the first trimester, and trophoblasts were detected in all.

The swab specimens were taken during the first trimester of pregnancy, between 8 and 12 weeks. Samples were washed and processed using a novel MEMS device coated with a proprietary reagent and trophoblast specific antibody.

Although only 0.02% to 1.94% of the initial total cell populations were trophoblasts, the recovered cell population was determined to be predominately of trophoblast origin. Trophoblast isolation was optimal in samples not contaminated by blood.

Now investigations are underway to detect fetal chromosomal aneuploidy and diagnostic potential using fluorescent in situ hybridization and polymerase chain reaction-based methods, Dr. Bischoff said.

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