This is the blog for GW students taking Human Evolutionary Genetics. This site is for posting interesting tidbits on: the patterns and processes of human genetic variation;human origins and migration; molecular adaptations to environment, lifestyle and disease; ancient and forensic DNA analyses; and genealogical reconstructions.

GWHEG figure

GWHEG figure

Wednesday, October 10, 2018

High-Resolution Comparative Analysis of Great Ape Genomes



     Leading as the feature article in Vol. 360 of Science Magazine, the Great Ape Genome project was a multi-institutional study involving over 40 scientist who generated higher quality assemblages of genomes from the great apes; humans, chimpanzee, gorillas, & orangutans. By using single-molecule, real-time (SMRT) long-read sequencing technology, the humanizing bias in previous ape genomes have been reduced allowing a more unambiguous view of genetic similarities and differences that arise as the hominin lineage diverged from the great apes. From their data, 10 million years ago the apes genome underwent a segmental duplication expansion where these sections of DNA that repeated were more prone to deletion and duplication mutations which influenced the evolutions of the various species. This support the hypothesis of bigger brain size in humans compared to other apes being due to the up-regulation of synaptic neurons in the prefrontal cortex because the gene for this neuron have been duplicate numerous times in the human genome. This article is the first step to truly understanding what makes us uniquely human because only by getting higher quality ape genome data and comprehensively comparing them can we understand our own genome and genetic difference.

-Denzel Walker

Recent Success of In Utero Gene Editing






In a recent Popular Science article, author Kat Eschner explains the content and future impacts of the Nature paper "In utero CRISPR-mediated therapeutic editing of metabolic genes".  For the first time researchers used in utero base editing to treat a genetic disorder. The experiment was restricted to mice and many more successful studies need to be completed before researchers are able to begin human trials, but there were hopeful results. The researchers found that the mice who were treated in utero for their rare liver disease (HT1) with base editing, thrived in comparison to those mice not treated and even those treated after birth with nitisinone. Furthermore, the edited cells persisted through development. They discovered that Pcsk9 targeting decreased cholesterol levels and Hpd targeting resulted in 'rescuing' the deadly phenotype of HT1. The long term goal for this research is for base editing to be utilized in humans to prevent life-threatening genetic disorders.

Thursday, October 4, 2018

Genome-edited skin epidermal stem cells protect mice from cocaine-seeking behaviour and cocaine overdose

In this article gene therapy using CRISPR is used to modify the gene that produces the BChE protein. This protein hydrolyzes cocaine in the bloodstream; the unmodified protein is slow and inefficient. Using CRISPR the scientists have modified the gene in stem cells then implanted it back into the body under the skin. It is 4,440 times more efficient at hydrolyzing the drug, cost-efficient, and seems to be a long-term solution to cocaine addiction. The mice with the modified gene no longer craved the drug and were able to survive fatal doses of it. They hope to continue this research by testing on humans and possibly applying the process to other addictions such as alcohol and nicotine.
https://www.nature.com/articles/s41551-018-0293-z.pdf
https://www.theguardian.com/science/2018/sep/17/cure-for-cocaine-addiction-in-reach-say-scientists

Tuesday, October 2, 2018

How Child Abuse Can Impact Your DNA

https://www.independent.co.uk/news/health/child-abuse-dna-trauma-genetics-molecular-scars-sperm-harvard-university-a8563906.html

"Child abuse leaves molecular 'scars' in DNA of victim's sperm, new study suggests"

A Harvard study consisting of thirty-four men, twenty-two of which had suffered abuse as children, found a significant difference in the amount of methylation present in the DNA of the abused men versus in the non-abused. Twelve locations of DNA were identified as being consistently affected by methylation in the men who had experienced abuse as children. While the newly discovered information proves how trauma has a long term impact on the abused individual, it also suggests that future generations can also be affected, due to the presence of methylation in sperm cells. The impact is still relatively unknown, but studies conducted with mice have shown that methylation in sperm cells has proven to have negative health impacts in offspring. While there hasn't been enough research done, it's possible that methylation markers could be used in the future in a legal setting as a tool to determine the approximate age of the person who has left DNA behind at a crime scene. The correlations between methylation and child abuse could also one day allow scientists to calculate the probability that someone has experienced child abuse. This study has provided a lot of information to potentially progress what we know about DNA methylation, but Dr. Andrea Roberts of Harvard says that study still remains to be replicated by others.

The Dangers of DNA Testing

A recent article posted in the New York Times discusses the results of a study posted in Forensic Science International, exploring the possibility of error in forensic laboratory DNA testing. 108 different crime laboratories were sent the same DNA sample mixtures and asked to identify possible suspects in a crime. While almost all the labs correctly identified the major contributors of the "crime", 74 labs implicated an innocent third suspect. This study exposed high levels of variation among results received from various forensic laboratories, suggesting a possible need to standardize aspects such as training, etc. While these results do not necessarily imply innocent people are being sent to jail, they pose a question of preciseness of results in complex sample mixtures.



Allie Henderson

Thursday, September 20, 2018

What Americans Think About Gene Editing for Babies


In an article by Science News, they analyze the Pew Research Center's findings on the attitudes of Americans towards tweaking the genes of unborn babies. 72% of Americans surveyed favored changing an unborn babies' genetic makeup to treat a disease or condition that would be present at birth. On the other hand, Americans are not on board with the idea of "designer babies," with about 80% agreeing that boosting intelligence with gene-editing would be taking medical technology too far. Furthermore, 65% said they did not support gene-editing if it required experimenting on human embryos, however, experiments on embryos are already underway in Europe and China. Only time will tell how the attitude of gene-editing on babies will be in the future.

Tuesday, September 18, 2018

What 13,000 Patents Involving the DNA of Sea Life Tell Us About the Future

This article published by the New York Times discusses a paper from Science Advances on patents on genes of living organisms that are located in the ocean. The articles begins the discussion by introducing a recent debate in the United Nations about how the genes of many living organisms are being used and the development of a global legal framework for genetic resources. Private companies in Germany, USA, Japan, Norway, Britain, France, Denmark, Canada, Israel, and the Netherlands own 98% of the patents involving marine organisms’ DNA; and this is leaving to a new kind of global inequality. These genetic prospectors are looking for organisms with exceptional traits that provide the missing portion of a product that will hopefully develop a new or alternative treatment. After various examples, the article concludes with the experimentation of growing of Omega-3 fatty acids on land modifying genetic codes of a Canola plant with DNA from marine microorganisms. 


Ana Maria Torres Martinez