Rees et al analyzed a cohort of 47,005 individuals for large duplications (1.5-3.0Mb) at 22q11.2 -the reciprocal of the well-known, risk-inducing deletion of this locus. These duplications were found to be substantially less common in schizophrenia cases than in the general population (0.014% vs 0.085%, OR=0.17, P=0.00086).
The authors suggest that duplications of the genomic segment are the first putative protective mutation for schizophrenia that, when deleted, is the most potent genetic risk factor for the disorder.
Evidence that duplications of 22q11.2 protect against schizophrenia. Mol Psychiatry. 2014 Jan;19(1):37-40.
Posted by Yannis Trakadis, MD