April 27, 2006
Gene Variation Influences Human Intelligence

Genetic variations associated with different risks of schizophrenia also influence intelligence levels among healthy volunteers.

GLEN OAKS, NY -- Psychiatric researchers at The Zucker Hillside Hospital campus of The Feinstein Institute for Medical Research have uncovered evidence of a gene that appears to influence intelligence. Working in conjunction with researchers at Harvard Partners Center for Genetics and Genomics in Boston, the Zucker Hillside team examined the genetic blueprints of individuals with schizophrenia, a neuropsychiatric disorder characterized by cognitive impairment, and compared them with healthy volunteers. They discovered that the dysbindin-1 gene (DTNBP1), which they previously demonstrated to be associated with schizophrenia, may also be linked to general cognitive ability. The study is published in the May 15 print issue of Human Molecular Genetics, available online today, April 27.

"A robust body of evidence suggests that cognitive abilities, particularly intelligence, are significantly influenced by genetic factors. Existing data already suggests that dysbindin may influence cognition," said Katherine Burdick, PhD, the study's primary author. "We looked at several DNA sequence variations within the dysbindin gene and found one of them to be significantly associated with lower general cognitive ability in carriers of the risk variant compared with non-carriers in two independent groups."

The study involved 213 unrelated Caucasian patients with schizophrenia or schizoaffective disorder and 126 unrelated healthy Caucasian volunteers. The researchers measured cognitive performance in all subjects. They then analyzed participants' DNA samples. The researchers specifically examined six DNA sequence variations, also known as single nucleotide polymorphisms (SNPs), in the dysbindin gene and found that one specific pattern of SNPs, known as a haplotype, was associated with general cognitive ability: Cognition was significantly impaired in carriers of the risk variant in both the schizophrenia group and the healthy volunteers as compared with the non-carriers.

"While our data suggests the dysbindin gene influences variation in human cognitive ability and intelligence, it only explained a small proportion of it -- about 3 percent. This supports a model involving multiple genetic and environmental influences on intelligence," said Anil Malhotra, MD, principal investigator of the study.

As DNA sequencing costs fall and larger amounts of genetic sequence differences are collected in humans many more genetic variations that influence intelligence and other cognitive characteristics will be found. The rate at which such genetic variations are identified will go up by orders of magnitude in the next 10 years.

Share |      Randall Parker, 2006 April 27 10:47 PM  Brain Intelligence

CASpears said at April 28, 2006 1:06 PM:

What I'm most curious about concerning genes and IQ is...do 3 individuals, one Chinese, one Nigerian, and one Swedish who have identical IQ scores select for the same genes?

If not, this could mean that different genes have evolved to do the same thing in various populations or that in some populations one gene compensates for another that might be expressed in a weaker way.

Brett Bellmore said at April 29, 2006 5:42 AM:

It also suggests that by combining genes from a smart Chinese, Nigerian, and Swede, you might produce somebody who was *really* smart.

Or mentally ill, or subject to seizures, of course. While I'm a great believer that genetic engineering will allow considerable increases in human intelligence, (Assuming it isn't superceded by other technologies before it ever gets that far.) just playing mix and match with existing genes isn't nearly as powerful as creating new ones. They may interact badly, or simply push exceed various margins in the nervous system.

Tj Green said at April 29, 2006 6:54 AM:

Schizophrenia is found in all populations. It is likely that the dyslexia/schizotypal mutation,combined with the bipolar mutation,to produce a child with the schizophrenic genome. We would all be the descendents of that child. We are all aware of what happened next,some of us became schizophrenic,some bipolar,and some psychopathic. Evolution has sent our species in different directions,yet these conditions remain in all populations,the foundations,and therefore the beginning of human intelligence.

ShawnMills said at November 2, 2006 9:58 PM:

I call bullshit. For one, were the schizophrenics medicated during the test? And if they weren't medicated then how can you not assume that their disorder played a role in cognitive ability? In other words, is it that they have reduced intelligence or that they are mentally ill which caused them to do poorly on the tests? Oh and secondly, a 3% correlation?? NEED TO DO BETTER THAN THAT....

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