Hypodontia of Maxillary Lateral Incisors

 Hypodontia, also known as tooth agenesis, is a frequent variation found in dental development and could occur as a part of a syndrome or in a nonsyndromic form. Genetic factors are a major component of the formation of these teeth in terms of size and shape. This particular study focuses on a specific variant of MSX1 (MSX1 rs8670). A sample of patients with isolated, maxillary, lateral incisor agenesis and matched controls had the measurements and morphology of their teeth noted. The methods of this analysis were: genotyping the MSX1 rs8670 genetic variant and morphometric measurements with a 2D image analysis. They were both performed for 26 hypodontia patients and 26 matched controls. This genotyping showed that the presence of the T allele increased the risk of upper lateral incisor agenesis to about 6.9 times the risk of individuals without the allele. There were also easily identifiable morphological differences between hypodontia patients and controls and between the unilateral and bilateral agenesis cases. Of all the teeth affected by hypodontia, the crown of the bucco-lingual dimension was the most affected. There was also evidence indicating that there was significant variation in the crown shape with the Carabelli trait of the upper first molars. The overall findings conclude that the MSX1 rs8670 variant does have associations with variations of the morphological outcomes in dentition. However, epigenetic and environmental factors interact with this variant to cause the variation in morphology, not just the variant itself.

The article highlights how genetics is intertwined with environmental factors, creating variation in morphology; in this case, specifically teeth. This demonstrates that a reliance on a singular factor for an outcome is not very common. Further linking of factors are needed to truly understand the observable traits in an individual, beyond just one or the other. I find the results of this analysis to be a beneficial supplement in studying similar variants in dentition in future analysis.

Link to the article “Genetic and Morphological Variation in Hypodontia of

Maxillary Lateral Incisors”: https://doi.org/10.3390%2Fgenes14010231

another related article: https://doi.org/10.1177/154405910808700715

Accuracy of Genotyping Chips Called into Question

Genotyping chips are used to detect single-nucleotide polymorphisms, the type of DNA used by consumer genetic testing companies to detect variants in a persons genome. These genotyping chips have a false discovery rate of more than 85 percent when screening for rare variants, according to an article from BioRxiv. This finding highlights the danger of direct-to-consumer genetic testing, where customers could “interpret the results at these rare variants literally, without accounting for any possible laboratory errors,” Chiang, a human geneticist at the University of South California Keck School of Medicine, says. “That would be a legitimate concern.”

The chips in which this study came from were supplied by a manufacture named Affymetrix, owned by Thermo Fisher Scientific. They supply their chips to direct-to-consumer companies such as LivingDNA. The companies claim to warn customers not to take their results as a medical diagnosis, but most consumers are not aware of the level of uncertainty in this consumer genetic tests. Other direct-to-consumer companies like 23andMe claim to have a higher accuracy but are still susceptible to false positives in very rare variants.  

An example of a rare variant that may bring about false positives are the BRCA genetic variants. BRCA1 and BRCA2 variants are linked to breast and ovarian cancers, to which there are thousands of known rare variants. The direct-to-consumer companies MyHeritage and 23andMe both announced that they will soon begin providing genetic tests for three variants found on the BRCA1 and BRCA2 genes.

I believe that direct-to-consumer genetic companies are a great way to get the general public interested in genetics and their own genome. It has amazing potential to help people find family and see what part of the world their heritage originates from, but testing for rare genetic variants may still be out of the reach of consumer genetic testing companies. I think that being able to see that if someone has a variant of the BRCA gene would be very helpful in being able to start testing regularly and early to catch any sign of cancer, but with the present rate of false positives in rare variants I believe that we should wait to make this information available to the public until it becomes more accurate.

Genes Responsible for Marriage Quality

In an article posted by Science Daily, it focuses on a research team led by Binghamton University Associate Professor of Psychology Richard Mattson who have been looking at how whether different genotypes of the OXTR gene are responsible for how people support one another. This gene was chosen because it includes the hormone oxytocin which is associated with love, attachment, and relevance to social cognition. From past research, results have shown that marital quality can indeed be impacted by genetic factors.

 This experiment was done with 79 couples who were individually asked to discuss for 10 minutes a problem they identify as personal and next to explain how support was provided to each partner. The couples were also asked to respond to several questions including the quality of support they receive from their partners followed by a saliva test for genotyping.

The results showed a variation of OXTR locations that differed both from husbands and wives with differences in behavior amongst couples, having small effects on evaluations of support and marital quality. What the team found interesting was overall marital quality for both partners was based off the genotypic variation of husbands; those who had a particular genotypic variation on OXTR had signs of social deficits and were less satisfied with support they were provided from their wives, also being less satisfied with their marriage.

As for future studies, the researchers hope they have provided a foundation for replication and more studies on OXTR to endure marital functions, as well as to evaluate the role of genetics that could be important to overall marital quality.

Identifying genes key to human memory: Insights from genetics and cognitive neuroscience

scientists have discovered 100 genes that contribute to human memory. This is such an important find because now scientist are getting closer to understanding the molecular mechanisms that have to do with memory. Once we find out this information we can help fix all kinds of mental illnesses. This study is a part of the new but growing study in how genetic variation relates to variation in brain anatomy and function. figuring out how genes affects the brain can also lead to major discoveries on how genetics affects behavior. This new study is possible because genotyping has gotten cheaper and easier.

Ant Genome Provides Evidence that Could Rewrite the History of Panama Land Bridge

It is an accepted fact that the land bridge that connects North and South America formed around 3 million years ago due to a collision of tectonic plates. However, new evidence suggests that this might not be the case, and instead the bridge actually formed much earlier, around 4-8 million years ago.  The spark of this geological controversy being nothing other than  research on the evolutionary and population genetics of Eciton army ants.

The study on the ants was conducted by Corrie Moreau, who was looking into the diversity present among the different ant species. She conducted her research by analyzing different DNA samples of the ants from each of the 9 species through a technique known as genotyping. This allowed Moreau to compare the genetic variation between ants belonging to different species, as well as individuals belonging to the same species. The genomic data suggests that the ants crossed over from South America to North America far earlier than 3 million years. The ants don't have wings, so in order for this to be possible they would need to have traveled the distance on dry  land.

This doesn’t mean for certain that the ants crossed over by means of a land bridge though, as they could have floated across the water on a tree branch or other form of debris. However, other geologic and biological data also support the idea that the Panama land bridge formed earlier than 3 million years ago. Such evidence includes fossilized teeth belonging to ancient primates that suggests they traveled across continents far earlier than 3 million years ago.

Although nothing concrete can be determined from this study as of yet it is interesting to see how genetic research is applicable across many different fields. It just goes to show that you never know where research will take you. You start out looking into the diversity of ants and end up in a major geological controversy.

http://www.nature.com/news/ant-genomes-rewrite-history-of-panama-land-bridge-1.20924

http://onlinelibrary.wiley.com/doi/10.1111/mec.13846/abstract;jsessionid=3FB002C162ECC42154EC9C9E88DD3F95.f04t04