Model Points to Complex Genetic Causes for Complex Diseases

July 12, 2007

Using a probabilistic model, Andrey Rzhetsky of Columbia University and his collaborators hypothesize that numerous, overlapping genetic factors likely contribute to the chance that people will develop a complex disorder. The scientists came to this conclusion by uncovering genetic links between diseases that manifest complex symptoms, such as schizophrenia and autism. Their model, they suggest, should be useful to scientists searching for the genetic origins of diseases that arise from more than one mutation.

Making use of the database at Columbia University's Medical Center — 1.5 million records — the computer model calculated and catalogued genetic connections between pairs of diseases, focusing on the number of genetic aberrations that they shared. Paying special attention to neurological disorders in more than 160 afflictions, the scientists found that there is considerable genetic overlap among autism, schizophrenia, and bipolar disorder. On the other hand, breast cancer sufferers are less likely to develop schizophrenia or a bipolar disorder.

These results fit with the observation that certain genetic variations seem to predispose their bearers to multiple disorders, or to protect them against some disorders while predisposing to others.

The findings are presented in the paper "Probing genetic overlap among complex human phenotypes," which is in the July 10 issue of the Proceedings of the National Academy of Sciences.

Source: PNAS, July 10, 2007.