The mapping of the human genome was a monumental achievement; however, it was always intended to be just a starting point. Where has the follow-up work gone? One area is mapping of copy number variants. Normally our (non-sex) chromosomes come in twos (humans are said to be diploid), but the machinery of DNA reproduction relatively often produces a number of copies – copy number variants – that are inheritable and distinctive between individuals. Even identical twins may differ in their copy number variants. Here’s some of what ZenMaster at Cell NEWS reports on a new study:
In research published last week by Nature, an international team describes the finest map of changes to the structure of human genomes and a resource they have developed for researchers worldwide to look at the role of these changes in human disease. They also identify 75 ‘jumping genes’ – regions of our genome that can be found in more than one location in some individuals.
“The genetic ‘blueprint’ of humans is the human genome,” says Sir Mark Walport, Director of the Wellcome Trust. “But we are each unique as individuals, shaped by variation in both genome and environment. Understanding the variation amongst human genomes is key to understanding the inherited differences between each of us in health and disease. A whole new dimension has been added to our understanding of variation in the human genome by the identification of copy number variants.”
“CNV studies have made huge advances in the past few years, but we are still looking only at the most common CNVs,” explains Dr Steve Scherer of the Hospital for Sick Children, Toronto. “We suspect that there are many CNVs that have real clinical consequences that occur in perhaps one in 50 or one in 100 people – below the level we have detected. Success in the hunt for the missing genetic causes of common disease has become possible in the last few years and we expect to find more as higher resolution searches become possible.”