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August 19, 2004

Repeated or Missing Genes Discovered

Usually we read about research that has uncovered single letter differences in the human genome, but in the current issue of Nature Genetics Stephen W Scherer & Charles Lee, in their study entitled, Detection of Large-Scale Variation in the Human Genomereport the discovery of huge segments, numbering into the hundreds of thousands of letters, of DNA that repeat or are missing. These segments contain genes, which means that some people have duplicate genes, and the researchers are postulating that these extra or missing genes could influence susceptability to disease.

This was first discovered in a study that used DNA microarrays to analyze DNA of patients with developmental disorders. A group of healthy people were chosen to be the control group, and it was within the control that they found either the missing or the repeating sequences. They found an average of 12 DNA segments that were missing or duplicated in the control group of 39 healthy people.

Scherer & Lee's study fairly duplicates the work of Michael Wigler published in Science in July. In that study, Large-Scale Copy Number Polymorphism in the Human Genome they found that, on average, 11 stretches of DNA that had either missing or repeated sequences of more than 400,000 letters of genetic code.

Wigler's study found that stretches of DNA contained genes associated with drug resistance in breast cancer, leukemia, and matters such as body weight.

Both of these studies of course supplement the work of the HapMap Project which is focusing primarily on single letter differences between populations and not such long sequences between populations.

Here is some supplementary data on large-scale copy number variations that were detected by Scherer & Lee. Here is some supplementary data on large-scale copy number variations near known polymorphic and disease loci such as Muscular Dystrophy, Duchenne (DMD) and Becker (BMD) Muscular Dystrophies, X-linked Mental Retardation, Squamous Cell Carcinoma, and Recessive Hereditary Megaloblastic Anemia 1. Here is a brief on the methods used in the study.

Posted by TangoMan at 11:38 PM