Junk DNA: goodbye!: more epigenetics (Introduction)

by David Turell , Wednesday, February 03, 2021, 18:43 (1179 days ago) @ David Turell

How much 'junk' is really there?:

https://medicalxpress.com/news/2021-02-epigenomic-reveals-circuitry-human-disease.html

"Over the past two decades, it has become apparent that those noncoding stretches of DNA, originally thought to be "junk DNA," play critical roles in development and gene regulation. In a new study published today, a team of researchers from MIT has published the most comprehensive map yet of this noncoding DNA.

"This map provides in-depth annotation of epigenomic marks—modifications indicating which genes are turned on or off in different types of cells—across 833 tissues and cell types, a significant increase over what has been covered before. The researchers also identified groups of regulatory elements that control specific biological programs, and they uncovered candidate mechanisms of action for about 30,000 genetic variants linked to 540 specific traits.

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"Layered atop the human genome—the sequence of nucleotides that makes up the genetic code—is the epigenome. The epigenome consists of chemical marks that help determine which genes are expressed at different times, and in different cells. These marks include histone modifications, DNA methylation, and how accessible a given stretch of DNA is.

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"Since the final draft of the human genome was completed in 2003, researchers have performed thousands of genome-wide association studies (GWAS), revealing common genetic variants that predispose their carriers to a particular trait or disease.

"These studies have yielded about 120,000 variants, but only 7 percent of these are located within protein-coding genes, leaving 93 percent that lie in regions of noncoding DNA.

"How noncoding variants act is extremely difficult to resolve, however, for many reasons. First, genetic variants are inherited in blocks, making it difficult to pinpoint causal variants among dozens of variants in each disease-associated region. Moreover, noncoding variants can act at large distances, sometimes millions of nucleotides away, making it difficult to find their target gene of action. They are also extremely dynamic, making it difficult to know which tissue they act in. Lastly, understanding their upstream regulators remains an unsolved problem.

"In this study, the researchers were able to address these questions and provide candidate mechanistic insights for more than 30,000 of these noncoding GWAS variants. The researchers found that variants associated with the same trait tended to be enriched in specific tissues that are biologically relevant to the trait. For example, genetic variants linked to intelligence were found to be in noncoding regions active in the brain, while variants associated with cholesterol level are in regions active in the liver.

"The researchers also showed that some traits or diseases are affected by enhancers active in many different tissue types. For example, they found that genetic variants associated with coronary heart disease (CAD) were active in adipose tissue, coronary arteries, and the liver, among many other tissues."

Comment: This brings us back to errors where a disease happens, but much of it involves 'traits' which may not be bad. This system God designed for adaptation has both good and bad, as we interpret the results. Is God required to produce perfection?