Normal “healthy” variation in our genome

The human genome contains approximately 30,000 genes. Changes or mutations in the sequence of these genes can produce a different eye color, hair color, or even result in disease.These small differences are what make us who we are. Not all variations or mutations are harmful. Not all lead to the development of disease. But, how much variation in our genes exists in a healthy population? This important question has remained unanswered. Why? Until the technology to sequence the genome (whole genome sequencing) and the ability to determine how much of a specific gene is expressed (RNA sequencing) was developed and advanced enough to make this work affordable, identifying the level of variability in healthy populations has not been possible. It would have taken too long and been too costly.

Things have changed. Both whole genome and RNA sequencing are cheap enough and fast enough that big studies looking at gene variation are feasible. These are still 7-10 year projects and do cost quite a bit, but with the interest and funding of this type of project from the National Institutes of Health (NIH), this work is getting done.

In 2008, the NIH launched the Genotype Tissue Expression (GTEx) project to answer this question. How a specific gene variation translates to a increase or decrease in the amount of that gene is expressed in a given tissue (ie. heart, lung, pancreas) is under intense investigation and the first set of data have been released in Science.  While the answers about gene variations are several years away, this is a giant step forward in our understanding of genes and normal or abnormal states.

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