November 22, 2013. While scientists sift through human DNA to find genes that increase risk for psychiatric disorders, they occasionally run across something that seems to protect a person from these maladies. Just this kind of protective effect for schizophrenia has been reported in a study published November 12 in Molecular Psychiatry.
Researchers led by Michael Owen and Michael O’Donovan at Cardiff University, United Kingdom, surveyed the genomes of 47,005 people to look for an extra piece of chromosome 22, called 22q11.2. This region contains at least 30 different genes, and previous research has found that when it is missing, it drastically increases a person’s chances of developing schizophrenia. The researchers wanted to know the effects of having an extra copy of this 22q11.2 region.
Extra copies of 22q11.2 were rare in both controls (0.085 percent) and in people with schizophrenia (0.014 percent), but were much rarer in schizophrenia, occurring one-sixth as often as in controls. This suggests that having extra copies of genes within 22q11.2 protects from schizophrenia, whereas having too few copies promotes it. Future research will have to zero in on which gene or genes in particular, but the new finding provides a fuller picture of how different factors—risk and protective alike—combine to tilt a person toward or away from mental illness.—Michele Solis.