User:Oudguy

There is no simple interpretation of what constitutes a "genetic disorder", since most aspects of human biology involve both genetic (inherited) and non-genetic (environmental) causes. Moreover, many genetic effects influence aspects of our biology that are not specifically medical in nature (height, eye color, ability to taste or smell certain compounds, etc). Also, some genetic disorders only yield a medical condition in combination with the relevant environmental factors (such as diet). With these caveats, genetic disorders typically consist of clinically defined diseases with a clearly demonstrable genetic cause. Ideally, the disorder can be associated with DNA sequence variation in a single gene. For example, cystic fibrosis is caused by mutations in the CFTR gene, and is the most common recessive disorder in caucasian populations with over 1300 different mutations known[1]. Severe mutations in specific genes are relatively rare, thus genetic disorders are similarly individually rare. However, since there are many genes that can vary to cause genetic disorders, in aggregate they comprise a significant component of medical conditions, especially in pediatrics. Molecularly characterized genetic disorders are those for which the underlying causal gene has been identified, currently there are approximately 2100 such disorders annotated in the OMIM database