Scientists Find Genetic Signature of Down Syndrome in Ancient Bones

 

    Scientists were able to diagnose Down syndrome using DNA from ancient bones. Down syndrome happens to 1 in 700 newborns today, and it results in an extra copy of chromosome 21. Down syndrome is most likely to occur when older mothers give birth in modern times. Back then, Down syndrome was rare because there were higher chances of women dying young, which made Down syndrome rare. 

    The first Down syndrome case using DNA from ancient bones was in 2020. The bones were found to be of a six-month-old boy who had been buried for almost 5570 years. Scientists also found an infant who had Edwards syndrome. Edwards syndrome is when there is an extra copy of chromosome 18. Researchers believe that the baby was only able to survive up to 40 weeks of gestation. This could possibly be the first case of Edwards syndrome found in the ancient remains. 

This is a picture of ancient remains of infants who had Down syndrome. These bones are about 2500 years old. 

References:

https://www.smithsonianmag.com/smart-news/dna-reveals-presence-of-down-syndrome-in-ancient-society-180983835/

https://www.nytimes.com/2024/02/20/science/down-syndrome-dna-bones.html

Is Genetics and Obesity Linked?

    It is well known that obesity is the leading cause of preventable, premature death. So in this article we will explore ways in which genetics may be a contributing factor to the rise in obesity. Obesity occurs when an individual consumes more calories than their body burns. Other factors that may contribute to this is an individual's environment in which it may promote inactivity and/or unhealthy eating habits. Many of these factors include food deserts, poverty, lack of education, and lack of access to gyms. Although these factors do contribute to obesity that does not mean that every individual who is put under these conditions will result in the same outcome. This is where genetics come into play while looking at individuals who may be more susceptible to obesity. A person's metabolic rate affects their ability to digest food under a certain amount of time making it easier to lose more weight than others or an increased tendency to store body fat. Studies have identified variants in several genes that may contribute to obesity by increasing hunger and food intake. Although very little is known about a specific gene that may contribute to obesity, there have been studies that found rare forms of obesity caused by a mutation in a single gene, known as a monogenic mutation. This mutation contributes to appetite control and energy homeostasis carried on chromosome 18. In more “common obesity” types they tend to be polygenic, meaning it is affected by multiple genes. In 2007, researchers identified the first obesity-related gene variant called FTO found on chromosome 16. People who carry this variant tend to be at a 20-30 percent higher risk of obesity. Even though in these articles it shows that some people may be predisposed to obesity that does not mean that obesity is destiny. Meaning there are changes that can be made on a day to day basis to prevent obesity or obesity-related diseases. It is important to learn from any previous family medical history in order to prevent obesity-related diseases.

Sources:

1)  https://www.cdc.gov/genomics/resources/diseases/obesity/index.htm

2) https://www.hsph.harvard.edu/obesity-prevention-source/obesity-causes/genes-and-obesity/

Fathers genes determine sex

 

A study done at Newcastle University by Corry Gellatly studied 927 family trees containing 556,387 people from North America and Europe. The studied showed that men are more likely to have daughters if they have more sisters and more likely to have sons if they have more brothers. The study also suggests that there is an undiscovered gene that controls whether a mans sperm contains more X or Y chromosomes, which would affect the sex of his children.

Gellatly demonstrated that men carry 2 different types of alleles that result in three possible combinations in a gene that controls the ratio of X and Y in sperm. The three possibilities is mm, which produces more Y sperm so have produce sons, mf, which produces an equal number of X and Y sperm and produce an equal number of sons and daughters, and ff, which produces more x sperm so produce more daughters. This gene is passed on from both parents so, this explains why this is roughly an equal amount of men and women throughout the population. If there are to many men, females can find a mate easier so men with more daughters will pass on more of their genes, causing more females to be produced in later generations. This gene could also explain why there is an increase of boys born after wars and an increase of boys in the population in general because more males die in childhood.

This study is a good way of understating the ratio of males and females in our populations. It can also be used to understand how mass events such as war effects the ratios in our population as well, which could help populations overcome drops in either females or males. It could also be helpful in genetic consulting because if a couple if trying to have either a boy or a girl they can look at their family pedigrees and determine if they are more likely to have a boy or a girl.   

The Reason Human Cells Preserve the Correct Amount of Chromosomes.

According to Science Daily, researchers have discovered an important factor during cell division which helps keep human cells in maintaining the correct amount of chromosomes. Researchers from Queen Mary University of London had identified two specific proteins, very tiny, that helps attach the chromosomes and micro tubules correctly. They have found out that these proteins task is very important when it comes to the connection between chromosomes and micro tubules because without or lack of these proteins causes a gain or lost of a chromosome which then affects the human cell indefinitely. Aneuploidy is the term when the cell concludes with the incorrect amount of chromosomes. But, with the finding of this great discovery, this could be the solution towards ending aneuploidy once and for all. The two identified proteins are Aurora-B kinase and BubR1-bound PP2A phosphatase which counteract with each other to successfully give the correct amount of chromosomes for human cells. Aurora kinase adds phosphate groups to the cell while BubR1 removes phosphate groups. In addition, they help control the connection between the micro tubules and chromosomes. Dr Viji Draviam is the senior lecturer in structural cell and molecular biology from QMUL's School of Biological and Chemical Sciences. He has conducted this research with a group of students and discovered this significant breakthrough. Dr. Draviam stated "By contributing to a molecular understanding of the chromosome segregation process, this work will support future development of predictive markers or drug targets for a variety of disorders linked to irregular chromosome numbers." which could mean that prevention of chromosomes and genetic diseases will slowly decay and the future of human cells is looking bright.