Harvard Mental Health Letter

Copy number variation: The new genetic frontier

A new theory about why psychiatric disorders are so heterogeneous.

Studies in identical twins suggest that autism spectrum disorders, schizophrenia, and many other psychiatric conditions are highly heritable — meaning that genes contribute to their development more than environmental factors do. In schizophrenia, for example, about 80% of disease risk is conferred through genes, while in autism spectrum disorders, 90% of risk is genetic. Yet researchers have been unable to conclusively identify the causative genes after 20 years of searching in various ways.

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