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

Sunday, October 22, 2017

The Origin of Species: Homo sapiens Style

New DNA analysis of 2000 year old bones in South Africa points to an earlier emergence of Homo sapiens, from around 350-260kya, much earlier than the previously estimated 200kya. Through the use of mitochondrial DNA, researchers were able to use this data, along with a revised human mutation rate of 1.25e-8 per base pair per generation, to more accurately estimate the split of the Homo sapiens species. This analysis coincides with findings from another study conducted at the Jebel Irhoud site on fossil remains that estimated the origin of Homo sapiens to be ~300kya.

Diagram of emergence of Homo Sapiens

Tuesday, October 3, 2017

You Can Now Blame Paranthropus Boisei for Genital Herpes

Researchers Underdown, Kumar, and Houldcroft have proposed in a recent study that the robust australopithecine known as Paranthropus boisei might be the reason why genital herpes exists in the human population today.  Genetic analysis done by early researchers revealed that the virus that causes genital herpes, HSV2, is closer to the chimpanzee herpes variant, ChHV2, than it is to its counterpart HSV1 (cold sores).  Using that data, researchers hypothesized that HSV2 was not passed along to hominins from the last common ancestor of humans and chimpanzees, but across species lines later down in evolutionary history between 3 and 1.4 million years ago.  What Underdown, Kumar, and Houldcroft conclude, using the statistical analysis of temporal and spatial relationships between early hominins and ancestral chimpanzees, is that Paranthropus boisei represents the most important, and most plausable intermediate transmitter of the HSV2 into hominin populations.  You can, therefore, blame Zinj giving humans genital herpes.

Amanda Kunkle

Sunday, October 1, 2017

The Genetics of Staying in School

The article “The Genetics of Staying in School” from The Atlantic discusses a GWAS study done on 294,000 individuals from different areas of the world. The study found 74 gene variants that are associated with educational attainment. In other words, the people who have the variants, on average compete more formal schooling than individuals who do not have the variants. The Manhattan plot showed that there were big statistical differences on chromosomes 2, 3, 6, 9, 13, and 15, as well as some smaller differences on a few others. These kinds of studies can create a lot of public backlash, which is exactly what happened. Thus, the researchers also published a “Frequently Asked Questions” article discussing what the GWAS study really meant. The researchers explained that the 74 gene variants only accounted for 3 percent of the differences in education levels across the whole population. Thus, there are many other factors that affect educational attainment, and that nurture and nature go hand in hand when discussing educational success. However, this study will be helpful to social scientists who want to do educational studies about different styles of schooling in different populations.

Flu Season: Could a Protein Be Our Protection?

A recent study done at the University of Maryland School of Medicine discovered the potential ability of a protein known as RC-101 to protect against influenza and other diseases. RC-101 has been previously identified as a protective agent against disease in the animals in which it is found, such as Orangutans. Although the protein was lost in recent primate evolution and is not found in humans, researchers found similar benefits of viral protection when they studied the protein in the context of human immune cells as well as in mice. In human immune cells, they discovered that the protein not only blocked the virus from entering the target cell, but also stopped the inflammation that is responsible for symptoms associated with the flu, such as fever, lethargy, and pain. In mice, they studied two different groups: both groups received a dose of lethal influenza, but only the first group received the RC-101 protein. As a result, only 20% of mice in the first group died, whereas 90% of mice in the control group died. Ultimately, the flu is an ongoing issue causing thousands of deaths annually, despite the existence of vaccines. Based on the findings of this study, researchers now hope to incorporate this unique double function of RC-101 in making medicine for protection not just from the flu, but also a multitude of viral infections that stem from inflammation.

-Julie Thomasian 

Source: Eurkalert, Published 09/29/2017

Wednesday, September 20, 2017

Using "Junk DNA" for Gene Therapy

Researchers at UCLA and the Howard Hughes Medical Institute tested the feasibility of using the non-coding regions of DNA for gene therapy to treat disease. The researchers discovered that the ability of the LeXis gene, found in the liver, has been found to lower the cholesterol and triglyceride levels in the body. When injected with the LeXis, the mice experienced a significant decrease in the lipid accumulation and reduction of the Strepb2 gene (responsible for cholesterol biosynthesis).
 In order to parallel the human conditions of hypercholesterolemia, the mice were on a strict high sodium and high cholesterol diet. Based on their findings, the researchers demonstrated the possibility of using non-coding regions of DNA as an intervention strategy for metabolic diseases. 

Teniola Balogun

Friday, September 15, 2017

Using CRISPR Technology to understand Evolutionary Patterns in Butterfly

CRISPR has been all the craze for scientist around the world since it allows for "relatively easy" manipulation of an organism's genome. CRISPR stands for Clustered Regularly Interspaced Short Palindromic Repeats. This technology essentially mimics the bacterial immune system to make precise changes to the genome. In Professor Martin’s Lab, at The George Washington University, we have been investigating butterfly wing pattern formation via the use of CRISPR technology, specifically in Vanessa cardui, also known as the Painted Lady butterfly. Lepidoptera is an order of insects that includes moths and butterflies. Butterfly wings are composed of wing scales, which serve as the base for wing color patterns.CRISPR is a genome-editing tool that allows for the deletion and insertion of specific genes with high precision. Moreover, the use of CRISPR genome editing techniques allows for the production and characterization of specific mutations in genes of interest. We have established a protocol to analyze gene function during the development of a non-traditional model organism, the Painted Lady butterfly (Vanessa cardui). The ability to do gene knockouts (eliminate a specific gene) in Lepidoptera was not feasible prior to the rise of CRISPR. The molecular mechanisms for the development of scales are fundamentally unknown since the proper technology for analyzing gene function in Lepidoptera was absent prior to CRISPR technology. With CRISPR we are able to explore this field and expand our knowledge on this subject.

Wednesday, September 13, 2017

New, ultra-rare gene mutations implicated in eating disorders

New, ultra-rare gene mutations implicated in eating disorders

September 5th, of 2017 a study was conducted in which scientists were able to observe an extremely rare cluster of mutations, and believe that understanding that pathway better would help in treatment for people with eating disorders. The study was conducted by researchers at the University of Iowa Carver College of Medicine and the Eating Recovery Center in Dallas, Texas. The team was able to show that "targeting the pathway with a drug already approved for diabetes reduces food consumption in a mouse model of binge eating." I thought this article was really cool because there is so much we don't currently understand in regards to how our genes control behaviors like eating disorders. 

Monday, September 11, 2017

Gene Therapy for Cancer Patients

Annie Syed- Cocktail Chatter

how gene therapy works

The FDA has approved the first ever gene therapy treatment for patients with B-cell lymphoblastic leukemia, most commonly found in children and teenagers. The treatment works by injecting patients with their own genetically modified immune cells with a virus that targets the source of the cancer. Current results show that 70% of the patients who undergo this treatment survive for over a year.  Patients with this cancer have a very low prognosis if they relapse, which makes gene therapy a second chance for families who thought there was no other option. 

Is Autism Genetic?

The autism spectrum is a developmental disorder that affects communication, social, verbal, and motor skills. Symptoms generally appear in early childhood, and since autism is a spectrum, this means that severity is widely varied. No two autistic people share the exact same symptoms. The American Autism Association states that 1 in 68 American children have some form of autism.
The exact cause of autism is unknown, but studies have shown the disorder is highly hereditary. In a study conducting identical twins, when one twin is autistic, the other twin is autistic 80% of the time, and 40% in fraternal twins. If a single baby is autistic, the chances of their younger sibling also being autistic are only 2-6%, but if a couple already has two autistic children, the chances of the third child being autistic rise to 35%.
There are several studies confirming that autism is in fact at least a partially genetic condition, as researchers have found there are roughly 65 genes strongly related to autism, and 200 genes that have weaker ties. However, no one single gene mutation guarantees autism, as patients in autism studies don’t all have the exact same mutations.
When it comes to genetic mutations, there are common variant mutations, which is a mutation that at least 1% of the population shares, and rare variant mutations, which less than 1% of the population shares, and usually these mutations have stronger effects. Autism is likely caused by many common variants and rare variants working together. Autism can be, and is usually diagnosed, in patients that have no family history of autism. This is called a de novo mutation, or a gene that appears for the first time in a family.
Mutations can be passed down from parents, but de novo mutations usually come from mutations in the ova, sperm, or fertilized ova. Mutations are likely caused by the environment, but it is unknown as to which environmental factors contribute to autism. Many researchers claim that complications at birth and poor maternal health can raise the risk of autism, but neither of these factors guarantee autism, and autism can also happen in a successful pregnancy and birth. Considering that parents don’t remember every aspect of their child’s gestation and birth, reports may be biased based on what the parents think is the explanation for their child’s autism.
A study conducted in 2014 suggest that genes may just be the beginning. This study observed that RNA-sequencing in the corpus callosum in autistic individuals showed extensive gene mis-expression, and that some of the genes that had been mutated affected oligodendrocyte development, which largely populated the corpus callosum. This suggests that genes themselves do not cause autism, but the mutated genes affect entire segments of brain development, which can lead to autism.
There are a few barriers to autism research. Many autistic individuals are unable to legally consent to studies, so genetic testing of severely autistic individuals is limited. Furthermore, autism is usually comorbid with other disorders such as Down’s syndrome, anxiety, and/or ADHD, which could also skew genetic testing. There is a chance that a person diagnosed as autistic has been misdiagnosed, as autism is very similar to a number of conditions, such as Rett syndrome, Fragile X, and Nonverbal Learning Disorder.
Interestingly, in a study comparing the genes of autistic patients to their non-autistic parents and siblings, a mother can have the genes consistent with autism but not have the disorder, but if her son inherits those same genes, he is affected. Does this imply that women need to have more mutated genes in order to be affected by autism? Does this also explain why there seem to be more autistic men than women? Does this mean the X-chromosome is affected by autism, as women have two but men only have one?

Works Cited:
American Autism Association. "What Is Autism?" N.p., 2016. Web.

Deweerdt, Sarah. "Why Don't We Know What Environmental Factors Cause Autism?" Spectrum | Autism Research News. N.p., 26 July 2017. Web.

Li, J., M. Shi, Z. Ma, S. Zhao, G. Euskirchen, J. Ziskin, A. Urban, J. Hallmayer, and M. Snyder. "Integrated Systems Analysis Reveals a Molecular

Network Underlying Autism Spectrum Disorders." Molecular Systems Biology 10.12 (2014): 774. Web.

Tech Museum of Innovation. "Autism and Genetics." Department of Genetics, Stanford School of Medicine, 2013. Web.

University of Washington Health Services/UW Medicine. "Family Genetics Study Reveals New Clues to Autism." ScienceDaily. ScienceDaily, 12 May 2015. Web.

Wright, Jessica. "Twin Study Unearths Clues to Role of Environment in Autism." Spectrum | Autism Research News. N.p., 09 Oct. 2015. Web.

Zeliadt, Nicholette. "Autism Genetics, Explained." Spectrum | Autism Research News. N.p., 30 June 2017. Web.

Tuesday, September 5, 2017

DTC DNA tests complicate family trees

recent article in the New York Times describes cases of individuals identifying surprising aspects of their ancestry through direct-to-consumer DNA tests (e.g. 23andme, The article also summarizes a study comparing self-reported ancestry (via census) and DNA-based ancestry for 160,000 Americans. About 4% of those who checked "white" on the census had partial African ancestry, and this was highest in the southern states -- e.g. 13% in South Caroline. The article does an great job clarifying that ancestry and race are not the same thing.  Ancestry is a biological concept, race is a social one.