On the heels of a similar study released last month, Dr. Stephen Quake's lab at Stanford University recently completed a genetic prenatal analysis using fetal DNA derived from maternal blood. Given the less than one month difference in publication dates of the two studies in different journals, it seems clear they were both being run simultaneously by the independent groups.
Rather than decoding the complete sequence of all the DNA A, T, C, G bases in the whole fetal genome, the current study from Stanford, published July 4 in Nature online, focused on analyzing just the parts of the DNA that contain genes (the exome). This greatly reduced the amount of data that needed to generated for the analysis which makes it a more practical approach to use in a healthcare setting.
The current study also went one step farther than the previous one. The Stanford study looked at the reliability of identifying particular genetic diseases using this approach. One of the two test subjects was carrying a child with DiGeorge syndrome. The analysis was able to characterize the specific location of the missing DNA that produced this syndrome in the fetus. The accuracy of the result was confirmed when the same gene region was found deleted when fetal DNA obtained from the umbilical cord was sequenced after the child was born.
The objective of this research is to develop methods for prenatal genetic testing using fetal DNA circulating in the mother's blood. It is much safer and easier to obtain this blood directly from the arm of a pregnant woman for testing, as opposed to invasively drawing fluid or taking a tissue sample from a fetus in the uterus.
The first medical tests using this sort of non-invasive approach were recently released commercially. These very new tests can only identify a limited number of genetic disorders, such as Down's syndrome, that are caused by abnormalities of large fragments of DNA. However, tests for most of the several hundred genetic birth defects requires more highly resolved analysis of the individual A, T, C, G base DNA sequence using methods like the ones described in the two recent publications.
The Fight to Use Maternal Blood for Prenatal Testing provides an overview of this newly developing and competitive market for fetal gene testing.
The group at Stanford has been at the forefront of advanced gene analysis and Dr. Quake himself recently received the Lemelson-MIT Prize for his contributions as an innovator and developer of this sort of technology
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