Disease-related genes associated with reduced volume in certain regions at birth

By Laura Sanders

Web edition: January 10, 2013
Print edition: February 9, 2013; Vol.183 #3 (p. 9)

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BIRTHMARK

Newborns carrying the ε4 version of the ApoE gene had decreased brain volume (blue) in the medial temporal lobe of the brain compared with newborns who carried a different version. Other brain areas showed an increase in brain volume (yellow).

Credit: R. Knickmeyer et al.

At birth, some infants are already saddled with brains that carry features of Alzheimer’s disease and schizophrenia. Newborns who carry certain versions of genes already show brain shrinkage reminiscent of that in adults with brain illnesses, a study of 272 newborn babies reveals.

The new results, published online January 2 in Cerebral Cortex, illuminate what happens to the brain in the earliest stages of life, says neuroscientist Jay Giedd of the National Institute of Mental Health in Bethesda, Md., who was not involved in the study. “As we go through life, there are so many uncontrollable factors,” he says. “This is a way to see gene influences before the world steps in.”

Until this study, scientists didn’t have a good idea of whether certain brain signatures — such as reduced volume in parts of the brain — were present from birth or whether they accumulated over a lifetime, says study coauthor Rebecca Knickmeyer of the University of North Carolina at Chapel Hill.

To test this, Knickmeyer and her colleagues looked for the influence of 10 versions of seven genes on newborns’ brains. The researchers chose genes that affect how the brain grows and develops. These gene variants have also been linked to adult brain diseases, such as the ε4 version of the ApoE gene, which triples the risk of getting Alzheimer’s, and a version of the COMT gene, which has been implicated in schizophrenia.

Brains of newborns with some versions of these genes had features similar to those seen in the brains of adults with diseases, the team found. Newborns with the ε4 version of the ApoE gene had less brain tissue volume in the temporal cortex, a part of the brain that thins in elderly people and adults who have ε4. Newborns with a variant in COMT also had reduced volume in the temporal cortex, a brain characteristic that turns up in people with schizophrenia.

The implications are that these brain features are a consequence of genetic influences, Giedd says. “I’m trying not to be doom and gloom, but it’s not lifestyle. It’s not parenting.” Things like that won’t change the lower brain volume in a newborn baby, he says.  

But Giedd points out that genes aren’t destiny, and that having a high-risk gene variant doesn’t mean a person will definitely get an illness. Many other things influence how the brain grows and develops, and these factors undoubtedly influence the risk of a disease, he says.

The researchers plan on following the infants in the study until age 8, and perhaps even longer, to see the consequences of these brain features. Such a long-term study could reveal why some people with a higher genetic risk succumb to a disease, and how others avoid it.