April 2, 2007

Assisted Reproductive Technologies Don't Affect Genetic Code

Photo of a baby girl

Technologies to help women become pregnant have been growing in popularity ever since the birth in 1978 of the first successful "test-tube baby," which was conceived by in vitro fertilization. Many people, however, still worry that assisted reproduction technologies may carry health risks. A new study in mice can partly set their minds at ease. It found that the technologies had no detectable effects on the genetic code.

Assisted reproduction technologies such as in vitro fertilization expose the sperm and egg to physical manipulations and environmental conditions that might potentially alter their DNA, creating future health risks for the child. These manipulations could change the DNA sequence itself or affect factors beyond the DNA sequence called "epigenetic" factors. Most cells in the human body have the exact same genes, yet epigenetic factors cause those genes to be modified and used in different ways by different cells.

A team of researchers, led by Dr. John R. McCarrey at the University of Texas Health Science Center in San Antonio, used transgenic mice to investigate whether these technologies can cause the first of these changes, those to the DNA sequence. The mice carried a stretch of DNA that can be easily recovered and analyzed for alterations.

The researchers analyzed DNA from mice that were produced by three different technologies: in vitro fertilization, intracytoplasmic sperm injection and round spermatid injection. For comparison, they used DNA from mice produced naturally. Their work was supported by NIH's National Institute of Child Health and Human Development (NICHD) along with the American Association of Obstetricians and Gynecologists Foundation.

In the March 20, 2007, issue of the Proceedings of the National Academy of Sciences, the team reported that they found no significant difference in the number or types of DNA changes between naturally conceived mice and those produced by any of the three reproduction technologies.

These findings provide evidence that assisted reproduction technologies don't cause changes to the genetic code itself. However, they still don't put all concern to rest. Whether these technologies might cause harmful epigenetic changes wasn't addressed by these experiments, and is a subject of ongoing research.

— by Harrison Wein, Ph.D.

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