Genome complexity: STR's control gene expression (Introduction)

by David Turell , Tuesday, December 08, 2015, 15:21 (3060 days ago) @ David Turell

Short tandem repeats, presumed to be junk are not. They modify gene expression:-http://medicalxpress.com/news/2015-12-repetitive-dna-hidden-layer-functional.html-"In the first study to run a genome-wide analysis of Short Tandem Repeats (STRs) in gene expression, a large team of computational geneticists led by investigators from Columbia Engineering and the New York Genome Center have shown that STRs, thought to be just neutral, or "junk," actually play an important role in regulating gene expression. The work, which uncovers a new class of genetic variants that modulate gene expression, is published on Nature Genetics's Advance Online Publication website on December 7. -***-"Genomic variants are what makes our DNA different from each other, and come, Erlich explains, "like spelling errors in different flavors." The most common variants are SNPs (single nucleotide polymorphisms). Computational geneticists have been focused mostly on SNPs that look like a single letter typo—mother vs. muther—and their effect on complex human traits.-"Erlich's study looked at Short Tandem Repeats (STRs), variants that create what look like typos: stutter vs. stututututututter. Most researchers, assuming that STRs were neutral, dismissed them as not important. In addition, these variants are extremely hard to study. "They look so different to analysis algorithms," Erlich notes, "that they just usually classify them as noise and skip these positions."-"Erlich used a multitude of statistical genetic and integrative genomics analyses to reveal that STRs have a function: they act like springs or knobs that can expand and contract, and fine-tune the nearby gene expression. Different lengths correspond to different tensions of the spring and can control gene expression and disease traits. He is calling these variants eSTRs, or expression STRs, to note that they regulate gene expression."-Comment: With 0nly 22,000+ genes these extra layers of controls explain how humans got so complex.