The Sequence 8/28-9/3
Tennis Star Chris Evert Opens Up About Genetic Testing, New Genes Associated with Reading Ability, Bringing a Tree Back from Extinction, Genetic Insights into the Immortal Jellyfish
Tennis star Chris Evert opens up about her genetic testing experience
Genetic testing is becoming increasingly utilized to assess for hereditary forms of cancer. Genetic mutations in the BRCA1 and BRCA2 genes cause approximately 10% of all ovarian cancer, including the ovarian cancer diagnosed in Evert and her sister.
That’s alarming.
It is. Evert describes that had she not lost her sister, Jeanne Evert, to ovarian cancer, she would have never thought to have gotten genetic testing, and her ovarian cancer wouldn’t have been identified.
Tell me the story.
In this article by David Waldstein, we learn that a few months after her sister Jeanne passed, Evert received a call telling her that a mutation in the BRCA1 gene had been identified in her sister before she passed. Evert underwent genetic testing and learned that she had the same genetic mutation in BRCA1.
In light of this information, Evert underwent a hysterectomy in order to reduce her own chances of ovarian cancer, and it was discovered that she had Stage 1 ovarian cancer. If she had not known about the need for genetic testing and the ovarian cancer had been undiscovered, she would have been in Stage 4 in a matter of months.
Wow. Scary.
Yeah. Evert beat her cancer by undergoing chemo treatments, and continued to work and teach in her role at the USTA (United States Tennis Association) Foundation in-between rounds of treatments. She describes not feeling back to herself, but continues to work and inspire those around her. She intends to help raise more awareness and money for cancer research in the future.
Being the champion she is, Chris Evert is taking this opportunity to empower women to be proactive about their health and receive the appropriate screening.
Think you should talk to a genetic counselor about genetic testing? Find one here.
New genes associated with reading ability identified
Eising et al. studied the genome (entire set of DNA) of 33,959 individuals aged 5 to 26 with various reading, writing and language abilities (i.e. some of these individuals were controls, and some had a known language/reading disorder). The purpose was to identify whether there are certain changes in the DNA that affect language and reading abilities.
How did they do that?
GWAS.
What?
GWAS, or Genome-wide association studies, look at the genome of a large group of people, searching for small genetic variations called single nucleotide polymorphisms (aka SNPs). GWAS look for SNPs associated with certain traits. An example for this study would be, “look, there’s a common SNP in individuals with lower word reading accuracy that’s not in the individuals with expected word reading accuracy”.
The results?
The team identified one SNP that is significantly associated with word reading ability. This SNP affects the DOCK7, ATG4C, ANGPTL3, and USP1 genes. The DOCK7 and ATG4C genes are expressed in the brain. Makes sense.
Interesting. Is any of this different from what we already knew?
Yes! To begin, this genetic variant is brand new. It has never been associated with intelligence or educational attainment. This is important, because prior studies show reading and language-related traits are usually correlated with general cognitive performance.
Secondly, it’s surprising to have found a single genetic change potentially responsible for differences in reading ability. Generally, things like reading ability and language skills are considered complex inheritance, meaning genetic differences in multiple genes likely work together, along with environmental factors, to affect a person’s skills. Genes are just part of the picture. But, this study points to one genetic variant being very relevant.
Thirdly, all five of the reading-/language-related traits the team looked at showed high heritability. Heritability is how much of the variation in a given trait can be attributed to genetic variation. Let’s break that down further: this means that a lot of variation in reading ability (13 to 26% according to this paper) is due to genetic variation. Generally, scientists are able to find the heritability of traits by looking at varying traits in identical twins, who have the same DNA. Makes sense.
What’s the takeaway here?
There is a common genetic variant linked to individual differences in reading-/language-related traits.
Should we bring back the American chestnut tree with genetically modified pollen?
The American chestnut tree- billions of which run along the East Coast from Maine to Mississippi- is in danger of extinction because of an exotic fungus called Cryphonectria parasitica.
What’s the deal with this genetically modified pollen?
Researchers developed genetically engineered pollen that carries DNA that can fight off this toxic fungus. The fungus that is infecting the American chestnut trees secretes a chemical called oxalic acid, which kills cells and then feeds on those dead cells. The genetically engineered pollen has an enzyme that breaks down the oxalic acid. It’s actually something other plants already have to protect them from this fungus (think bananas, strawberries and wheat).
What’s the problem?
Some argue that not enough is known about the risks that the genetically engineered pollen may pose. Chestnut trees can live for centuries, and these genetically modified trees have only been studied for a few years.
The takeaway?
The researchers are now ready to plant these seeds in the wild, potentially becoming the first team in the U.S. to use genetic engineering to bring back a forest full of trees and stop a tree from extinction. However, the public will need to weigh the risks and benefits of proceeding with genetically engineered pollen to save the trees.
Genetic insights into the immortal jellyfish
A team led by scientists from the Universidad de Oviedo sequenced and analyzed the genomes of a jellyfish that is capable of reversing its life cycle (immortality, anyone?) and compared it to the genome of a jellyfish that is normal, i.e., the rest of life as we know it, to understand what genes are potentially involved in immortality.
Did you say immortal?
Yes. A jellyfish with the fancy name T. dohrnii is capable of repeated rejuvenation after sexual reproduction. That means that the full-grown jellyfish reduces back into a polyp (think embryo), which then re-grows into a full-blown jellyfish. And, there’s no evidence that this can’t happen an infinite number of times.
How?
We already know that there are some genes that are involved in the aging process, like genes associated with DNA repair. The team focused on the genes that are associated with genomic instability, which are the most related to DNA replication and repair. Why? Because our genes are replicating ALL THE TIME, and sometimes there are mistakes in the replication. And then the genes have to repair themselves. And it probably happens more often than you think. So, if your cells build up these mistakes that aren’t repaired, there will be consequences in the the overall health of your body.
Did we find the answer to immortality?
Maybe! Results showed the this immortal jellyfish has better DNA repair mechanisms (i.e. can more efficiently fix mistakes in DNA replication) as well as better responses to oxidative stress, and better maintenance of telomeres than the non-immortal jellyfish.
The takeaway?
The study highlighted some genes and chemical pathways that likely contribute aging. Thank you, T. dohrnii .