People with schizophrenia differ greatly in their clinical symptoms. 2012 NARSAD Young Investigator Grantee Sarah Bergen, Ph.D., of Karolinska Institutet, led an international team of scientists in an examination into the genetic basis for differences in age of onset of illness and illness severity, and the specific influence of gender and family history. Involving data from thousands of subjects, this was the first reported study on this scale of genetic associations for these characteristics in schizophrenia.
The research, funded in part by Dr. Bergen’s NARSAD Grant and published in the April issue of Schizophrenia Research, was made possible by the enhanced power of genome-wide association studies (GWAS) to detect and identify disease-susceptibility genetic sites called loci. The team, whose members included NARSAD Grantees Ayman H. Fanous, M.D.; Patrick F. Sullivan, M.D.; Jordan W. Smoller, Sc.D., M.D.; and Shaun M. Purcell, Ph.D., conducted GWAS using data from 2,762 patients with schizophrenia and 3,187 healthy controls enrolled in the International Schizophrenia Consortium.
Among the results of the study, earlier age at onset and more severe disease course were observed in male subjects, although no sex-specific genetic factor was found for overall risk of schizophrenia. For all subjects, earlier onset was associated with increased severity. While family history is a strong risk factor for schizophrenia, it did not appear to be a risk for earlier age at onset.
The authors of the paper state: “Since the vast heterogeneity observed in schizophrenia is at least partially genetically mediated, a better understanding of the specific genetic factors impacting this variability is a vital step in developing new prevention and treatment strategies.”