Epigenetics and Disease: Thinking Outside the Box - Evolution News & Views

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Epigenetics and Disease: Thinking Outside the Box

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Two articles caught our attention. One, in The Scientist, is on the factors that influence mental disorders. The other, in Nature, considers the causes of leukemia. Both are about epigenetics, the study of how DNA acts as a whole, or what causes certain genes to be expressed, while others are not. (See here for a survey of the state of epigenetic research.)

In the field of intelligent design, epigenetics is of interest because it usually involves the non-coding portions of DNA, which calls into question the earlier paradigm in genetics that only the coding portions of DNA are of significance for phenotype, and because it signifies an additional layer of complexity to the genome, calling into question the neo-Darwinian assumption that life is built from the bottom-up rather than the top-down.

Take leukemia, for example. While great strides have been made in detecting and curing some types of cancers, the question of what causes cancer remains fuzzy. Indeed, lifestyle choices can obviously play a role. Smoking has been linked to lung cancer, and sunbathing to melanoma, but not everyone who smokes gets cancer, and not everyone who is out in the sun gets melanoma. Some people get these cancers without the behavior.

This disparity may be due to a combination of environment and genetics. The incidence of breast cancer, for instance, may be linked to the BRCA genes, but not everyone who has these genes gets breast cancer, while some people get breast cancer who do not have the genes.

Leukemia, for its part, seems to have a genetic component and an environmental component, but scientists are not sure what they are. Now several cancer research centers are looking at epigenetic factors as a possible indicator. In particular, they are looking at methyl groups, which are small chemical components that attach to DNA. These little chemical flags may affect DNA in many ways, including how the DNA folds around a histone. Scientists have found that there seems to be a link between mutations in the enzymes that insert or take away the methyl group and the incidence of leukemia. When these enzymes are not working the right way, the chemical flags are incorrect, causing the DNA to fold improperly.

The prevailing paradigm had been that if a disease has a genetic link, it would be due to either a mutation in the sequence of A's, T's, C's, and G's, or the insertion of a piece of DNA sequence. Current research on epigenetics suggests a different perspective. As Timothy Ley comments in the Nature article: "A couple of years ago, if I had said that to somebody they would have laughed me out of the room... There just was no clear notion that epigenetic modification would be so critically important for the pathogenesis of the disease."

A field rife with similar questions is that of mental disorders. Recent controversy over the definitions of some disorders in the DSM-5 highlights how much we still don't know. New research on the genetic causes of mental disorders looks at how the methyl groups attach and un-attach to DNA in neurons during development. Scientists have found that methylation is a very dynamic process. To add to the levels of complexity in the genome, there are apparently different kinds of methylation which may make a difference in whether the brain develops normally or not.

It's too early to make any definitive statements on the link between epigenetics and brain disorders, but early studies are unearthing some interesting findings on brain development. They are also demonstrating levels of regulation and complexity that call into question the Darwinian paradigm. In the e!Science News update reporting on the methyl-mapping paper, Dr. Ryan Lister comments:

The human brain has been called the most complex system that we know of in the universe...So perhaps we shouldn't be so surprised that this complexity extends to the level of the brain epigenome. These unique features of DNA methylation that emerge during critical phases of brain development suggest the presence of previously unrecognized regulatory processes that may be critically involved in normal brain function and brain disorders.

Both of these examples demonstrate the importance of asking questions and doing research that is outside of the status quo.

Intelligent design gets a bad rap because it is not in line with the supposed scientific consensus that unguided evolutionary processes account for the existence of all of the life that we see today. But there are unanswered questions regarding the origin of the complexity of biological systems and the information content in DNA (both within the genome and the epigenome), as Stephen Meyer has shown in Darwin's Doubt and Signature in the Cell.

Science, indeed, should be about exploring uncharted territories from varying, even unpopular, perspectives rather than confining ourselves to research that has been blessed by convention. The old paradigm focused on the sequence of the coding portion of DNA to find genetic factors for disease. However, when the old paradigm cannot answer questions, it is time to think outside the box.

Image credit: Ian Carroll/Flickr.


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