PUBLIC RELEASE DATE:

25-Oct-2013

Contact: Vanessa McMains vmcmain1@jhmi.edu 410-502-9410 Johns Hopkins Medicine

INVESTIGATING THE GENETIC MECHANISM BEHIND DELUSIONS IN SCHIZOPHRENICS

Wednesday, October 23, 3:30 PM EST SESSION 15 Psychiatric Disease: GWAS to Genes Room 253, Level 2, Convention Center Speaker: Mariela Zeledon, Predoctoral Training Program in Human Genetics, Johns Hopkins University School of Medicine

Johns Hopkins researchers say they have identified changes in a person's DNA sequence that can affect what kinds of schizophrenia symptoms they experience. The DNA changes either ramp up or down a gene associated with delusions. The researchers still aren't sure how having too much and too little of the gene's product triggers delusions, but they have taken a step toward determining why people with schizophrenia can have very different symptoms.

Single DNA letter changes, or mutations, in the gene NRG3 have been linked to susceptibility to delusions in schizophrenic patients. But these mutations don't affect the portion of the gene used as a template to make NRG3 protein, so the researchers initially didn't know how the mutations were having an effect.

To home in on the cause, researchers first looked at whether single DNA letter variations could change NRG3 expression levelshow many times the gene is "read" to make protein. One NRG3 variant was turned on too high, meaning the gene makes too much NRG3 protein, and another too low, meaning it doesn't make enough. Next, the researchers looked at what proteins stick to the NRG3 DNA sequence of the variants associated with delusion compared to the normal version, specifically searching for proteins that turn genes on or off. They did this in two ways: by using a computer program to predict which DNA sequence would stick to which proteins, and by taking a whole slew of gene control proteins spotted individually onto a chip and seeing which DNA sequences bound to which spots. The computer program predicted one set of gene-activating proteins, which the researchers are confirming with the chip analysis. The physiological mechanism has yet to be fully elucidated, but the researchers say that knowing how each genetic variant causes delusions could yield information about disease progression and what treatments will be most effective.

DISCORDANT DATA BETWEEN GENETIC DATABASES --Study suggests case for standardization of data storage and information-sharing policies for genetic diseases

Thursday, October 24, 3:30 PM EST SESSION 32 Genetic Testing for Neurodevelopmental Disease: Genotype: Phenotype Challenges Room 205, Level 2, Convention Center Speaker: Julie Jurgens, Predoctoral Training Program in Human Genetics, Johns Hopkins University School of Medicine

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Johns Hopkins Medicine news tips from the 2013 American Society of Human Genetics conference

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