Archives for Heredity

Stem Cell Research Sheds Light on Genetic Factor in Bipolar Disorder

A study published last month in a journal called Translational Psychiatry entitled "Transcripts involved in calcium signaling and telencephalic neuronal fate are altered in induced pluripotent stem cells from bipolar disorder patients" reported interesting findings about the development of brain cells in people with bipolar disorder compared to controls — people without bipolar disorder. The study was unique in two important ways:

The study was based on the increasingly accepted concept that even subtle changes in early embryonic brain development can cause symptoms of mental illness that appear later in life.
The researchers took advantage of evolving technology that creates stem cells — the origin cells in embryos that evolve into all the different cells types in the body — from adults rather than taking them from embryos. This allows researchers to have access to many more stem cells and also offers the opportunity to compare the stem cells from adults with certain diseases to those without and to see differences in the way they develop.

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Where’s the Bipolar Gene?

Given all the activity and advances in genetic research, you might expect researchers to have mapped the entire human genome by now and identified the gene or genes responsible for bipolar disorder and other diseases that appear to have a genetic component. Obviously, that hasn't happened. The best that researchers seem to have come up with are associations of certain gene variations with bipolar – hardly the smoking gun we would hope for.

Even the researchers seem to be getting a little discouraged, as is evident in a two articles I have recently come across. The first, published in the April 2011 edition of the American Journal of Psychiatry is entitled "After GWAS: Searching for Genetic Risk for Schizophrenia and Bipolar Disorder," (by Elliot S. Gershon, Ney Alliey-Rodriguez, and Chunyu Liu). In their abstract, the authors explain:
Ten years ago it was widely expected that the genetic basis of common disease would be resolved by genome-wide association studies (GWAS), large-scale studies in which the entire genome is covered by genetic markers. However, the bulk of heritable variance remains unexplained.
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Bipolar Research

New Genetic Link to Bipolar Disorder

Psych Central's Senior News Editor Rick Nauert recently posted a piece entitled "Genetic Variant Heightens Risk for Bipolar Disorder." In it, he calls attention to a recent study published in the American Journal of Human Genetics that's "based on a relatively new technique for the study of the genetics of bipolar disorder" termed genome-wide association studies (GWAS).

We invite you to check out the post, especially if you're interested in keeping up on the latest breakthroughs in identifying the genetic component of bipolar disorder. Although it may be years before these genetic studies translate into any sort of gene therapy, if that's even possible, they deliver an immediate benefit in three important ways:
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A Step Closer to Confirming Genetic Link to Bipolar Disorder

Researchers in Germany may have come closer to confirming one of the possible genetic components that contribute to a vulnerability to bipolar disorder. For some time, we have known two things about bipolar disorder:

It's a brain illness, a neurological disorder.
It has a strong genetic component.

The unknown, until now, was the link between the genetic component and the actual neural abnormalities. Relatively recently, several studies have implicated a variant on chromosome 12, the CACNA1C gene, as increasing the risk for bipolar disorder. So researchers wanted to find out whether this gene variant could be traced to a particular region of the brain.
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The Effects of Chronic Stress on Bipolar Genes

Researchers at Johns Hopkins University School of Medicine have published a study entitled "Chronic Corticosterone Exposure Increases Expression and Decreases Deoxyribonucleic Acid Methylation of Fkbp5 in Mice," Endocrinology, September 2010, in which they claim to have identified a possible epigenetic cause of depression and other mood disorders, including bipolar disorder. For a more layman's account of the study and its conclusions, I recommend the Johns Hopkins press release entitled "Chronic Stress May Cause Long-Lasting Epigenetic Changes."

The prefix epi- means outside, above, over, or on top of. The term epigenetic refers to factors outside the fundamental gene structure that affect a gene's expression. In this study, researchers examined the effects of a common stress hormone on a gene that has been linked to mood disorders and found that "... long-term exposure to a common stress hormone may leave a lasting mark on the genome and influence how genes that control mood and behavior are expressed."
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NIMH: More Data Prove Genetic Link to Bipolar Disorder

Recently, the NIMH (National Institute of Mental Health) distributed a press release entitled "Largest Study of Its Kind Implicates Gene Abnormalities in Bipolar Disorder." According to the press release, this "largest genetic analysis of its kind to date for bipolar disorder has implicated machinery involved in the balance of sodium and calcium in brain cells." As the press release points out, no single gene has been identified as the "bipolar gene." Researchers generally agree that multiple genes contribute to make an individual more...
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