Solving the CRV puzzle

The study of copy number variations (CRVs) may soon revolutionize the understanding of hundreds of prevalent diseases. Though some genetic diseases have been mapped to specific genes in a specific chromosome location, many still are largely not understood. Many diseases such as mental illnesses, autism, obesity, and others are believed to have a significant genetic component; however scientists have been unable to definitively determine genetic contributions.
New discoveries regarding copy number variations may provide the answer. The concept of varying copies of genetic sequences has existed for some time. In the early 20th century, scientists came to understand that inheriting two copies of an allele can have vastly different effects than the inheritance of a single copy. Also, in the study of aneuploidy, the conclusion was reached that aberrant numbers of chromosome copies can cause significant phenotypic effects. In many cases, multiple gene copies results in over expression of the gene product, leading to possibly deleterious phonotypic effects. Many of these copy variations are responsible for disease.
In recent years, with the increasing availability and efficiency of genome sequencing technology, scientists have been surprised to find that large variation exists between individuals in the copy number of various genomic sequences. Based on previous knowledge, scientists suspect that many of these variations could be responsible for predisposition to a host of various diseases. With each study that is conducted, the estimate of copy number variations per individual rises. The current count is upwards of 60 CRV’s per person.
Continued studies have linked several prevailing diseases such as schizophrenia and Crohn’s disease to abnormal CRV’s in specific genomic regions. It is possible that one such CRV is not enough to cause the disease, but that the total effect of CRV’s in different locations along with other genetic and environmental factors could greatly increase the disease risk. Studies are currently being conducted to identify CRV’s as small as 500bp. Stephen Scherer, a prominent Canadian researcher, is one of the leaders in this area of study.
The future of CRV studies appears promising and may enable scientists to solve the puzzling mysteries of the cause and inheritance of many debilitating diseases.

Article from The Scientific American:
http://www.scientificamerican.com/article.cfm?id=too-little-too-much

More about Dr. Stephen Scherer, one of the leaders in this research:
http://www.tcag.ca/scherer/