by: Jim Bell, November 28, 2006 12:11:00 am
Scientists who study the human genome are astonished by this discovery, because they've always assumed that the genome -- the human book-of-life -- is largely the same for every person, except for small differences in the way some of the words are spelled. Geneticist James Lupski of Baylor College of Medicine says the findings suggest that the genome -- the book -- actually has sentences, paragraphs and even entire pages of information that vary from one person to another.
"We thought that a lot of what was variation in humans was due to changes in those base pairs, those single nucleotides, those single letters of the alphabet. But what we're seeing instead is that there are chunks of the genome, whole pages that are duplicated and deleted, and there's a lot more of this structural variation than we ever appreciated."
Dr. Lupski says they're finding that the human genome is infinitely more complex than they ever thought. Instead of each person having just two copies of each gene -- one from each parent -- they've learned that people carry many copies of each gene, and the total varies from one person to the next. Lupski says these findings supercede the principals of genetics created by Gregor Mendel in the 19th century, and expanded by James Watson and Francis Crick, who discovered the DNA double helix in 1953. He says this research, and its medical implications, will change the field of human genetics forever.
"We want to know what is the basis of what makes us human and makes us different from other species, but also we want to know why we have different diseases, susceptibility to diseases etcetera, and that will only come from studying the differences in our genomes that you find in people that have those different traits."
Lupski says they're learning that a number of diseases are influenced by and even caused by changes in the number of copies of certain genes, including Parkinson's Disease and Alzheimer's. This discovery could lead to treatments for diseases now thought to be incurable and new ways of diagnosing and treating cancer. These studies were done at Baylor College of Medicine and a dozen other research centers in the United States and Great Britain, and the results are published in the journal Nature. Jim Bell, Houston Public Radio News.