14 June 2007. Two recent genome-wide association (GWA) studies
support the notion that many genetic variants each contribute a
little to the risk of developing bipolar disorder. The largest
of the new studies, published in Nature on June 7, comes from
The Wellcome Trust Case Control Consortium, a collaboration of
genetics researchers in the United Kingdom, including lead
author Peter Donnelly of the University of Oxford, England, and
Nick Craddock of Cardiff University, Wales. It comes on the
heels of another study, directed by Francis J. McMahon of the
National Institute of Mental Health (NIMH), that appeared online
in Molecular Psychiatry on May 8. Some of the markers implicate
genes or chromosomal regions that have previously been tied to
schizophrenia, which will add grist to the argument that
schizophrenia and bipolar disorder share too many symptoms and
genes to justify defining them as distinct syndromes (see SRF
Live Discussion led by Nick Craddock and Mike Owen; Maier et
al., 2006). In their study, M