Genetics On Eye Color

 Genetics on Eye Color

The color of the eyes comes from the iris, specifically from a layer called the stroma. The main pigments that contribute to eye color are melanin, pheomelanin, and eumelanin. Melanin is a yellow-brown pigment that also affects skin tone. Pheomelanin is a red-orange pigment found in people with green or hazel eyes. Eumelanin is a dark brown or black pigment that deepens eye color. These combinations of pigments determine whether a person's eyes appear brown, hazel, green, or blue.

A baby's eye color can change over time, especially during the first year of life. Some babies are born with blue or gray eyes, while others are born with brown eyes. This depends on their genetic background and the amount of pigment present. Pigment production increases during the first six months after birth, and a child’s eye color may not be fully established until around one year of age.

Eye color is influenced by the genes OCA2 and HERC2. These genes control how much pigment is produced and how it is distributed in the iris. Each person inherits two alleles for each gene—one from each parent. If the alleles differ, the dominant one is expressed. Brown eyes tend to be more dominant than blue eyes. Researchers also believe that people with blue eyes may share a distant common ancestor.

It is still possible for two blue-eyed parents to have a child with brown eyes. This can happen because parents may carry hidden genetic variants for brown eyes that can be passed down to their child. Punnett squares can help estimate probabilities based on the parents’ traits, but they are not always reliable because they do not account for how many genes are involved.

In some cases, unusual eye color can provide clues about a person’s health. For example, Waardenburg syndrome can cause heterochromia, a condition in which a person has two different-colored eyes, and it may also be linked to hearing loss. Another condition, ocular albinism, results in very pale blue eyes due to a lack of pigment and is more commonly seen in males.

Source: https://www.verywellhealth.com/genetics-of-eye-color-3421603

Extra Source: https://www.sciencenewstoday.org/the-genetic-secrets-behind-eye-color

Ancient remains provides evidence of some of the earliest recorded ailments .

 Scientists are increasingly using ancient DNA to understand disease in early human populations. In one study, researchers analyzed the remains of a 12,000 year old mother and daughter and identified a rare genetic growth disorder in the NPR2 gene known as acromesomelic dysplasia (dwarfism). Scientist revealed that the daughter inherited two copies of this rare genetic disease, leading to her being short for the time period, while the mother carried only one copy and showed milder effects. This discovery highlights how inheritance patterns influence the expression and severity of genetic diseases.    

    Similarly, another report described how scientists used ancient DNA to trace the origins of infectious diseases in early humans. By extracting and analyzing genetic material from ancient remains, researchers were able to identify diseases and trace their origins. Together, these studies show how modern genetic technology can reveal both inherited and environmental diseases in the past, providing valuable insight into human health, evolution, and the history.

Detecting Early-Onset Dementia Before Symptoms Begin

 

Carmine Martino

BIOL-2110-001

Dr. Guy Barbato

March 28th, 2026

    This article talks about research being done at UT Health San Antonio focused on early on-set dementia, which is a form of dementia that affects people under the age of 65. The researchers are working to better understand the causes of the disease while also working to develop new tools that can help detect it earlier on. 

    One of the main things the article mentions is the use of new diagnostic methods, including blood-based biomarkers and advanced imaging techniques. These tools are being studied as ways to identify signs of dementia long before a person actually starts showing symptoms. The idea is that if doctors can detect the dementia earlier, they can better understand how it develops and potentially improve how it is managed.

    The researchers are also focusing on the genetics side of early-onset dementia. The article explains that many cases of early-onset dementia are still sporadic, meaning the exact cause is unknown. Instead of one specific gene determining whether someone will get the disease, researchers believe that while genetics can increase risk, it may also be a mix of different factors like lifestyle and environmental influences on brain health. Nevertheless, scientists are still looking at genetic patterns to better understand the risks and how the disease develops. 

    While current diagnoses usually happen after symptoms begin, these new approaches aim to change that by identifying the disease much earlier. This could make a big difference in how patients are treated and how the disease is studied overtime.

    I personally liked this article because it shows how research is improving when it comes to diseases that are hard to understand. The idea that doctors might be able to detect dementia years before symptoms start is remarkable. Even though the exact causes are still not fully known, studies like this make it seem possible that in the future, there could be better treatments or even ways to prevent it altogether within the next few decades.

Article:

https://news.uthscsa.edu/researchers-explore-genetic-roots-new-diagnostic-tools-for-early-onset-dementia/

Extra Source:

https://www.alz.org/alzheimers-dementia/what-is-dementia#:~:text=Dementia%20is%20a%20general%20term,most%20common%20cause%20of%20dementia.

Getting Drunk Faster Can be Affected by Genetics

                                                    

    Undenying low tolerance affects getting drunk faster; however, regardless of physical attributes and the number of drinks consumed, Dr. Laura Tran explains in a study from The Scientist that beside tolerance people get drunk faster could have the participation of genetics. Scientists are working to determine how genetic disparities influence alcohol metabolism and to understand how the body absorbs and processes alcohol as well as why among individuals the effects vary. The main point is that certain genes control how quickly alcohol is broken down in the body by the mutations in two main enzymes, alcohol dehydrogenase (ADH) and aldehyde dehydrogenase (ALDH), which alter alcohol metabolism. After getting drunk, ADH takes the first step in turning alcohol into a toxic substance called acetaldehyde, while ALDH breaks them down into a less harmful substance for the body to remove. Therefore, people with slower ALDH activity make metabolite buildup and alcohol stays longer, causing stronger and faster intoxication. Furthermore, the study mentions static ataxia, people with family history of alcoholism tend to show less body sway after drinking. Suggesting their brain may responds differently, especially in the cerebellum, which controls balance and movement.

    It is interesting when something as common as drinking alcohol can be different because of genetics. This study explores the challenge that people do not react the same way even with similar genes, making scientists harder to effectively predict how alcohol will affect each person. However, doctors can give personalized advice to possibly prevent alcohol misuse by identifying higher-risk individuals.

Source: 

https://www.the-scientist.com/why-do-some-people-get-drunk-faster-than-others-72385

Additional Source:

https://www.the-scientist.com/cerebellum-plays-crucial-role-in-metabolizing-alcohol-in-mice-68620

Gene Therapy is Becoming Real

Links:

• https://www.fda.gov/news-events/press-announcements
• https://medlineplus.gov/genetics/understanding/therapy/

Tag: Gene Therapy

Commentary:

Gene therapy is no longer just something being tested, it is actually being used to treat real patients. By replacing or fixing a faulty gene, it targets the root cause of the disease instead of just managing symptoms. That is a huge shift in how treatment works. The downside is that these therapies are extremely expensive and not accessible to everyone. There are also risks, especially with how the body responds to viral vectors used to deliver the gene. Even with that, it shows how powerful genetics can be in medicine and it is likely going to expand a lot in the future.

Hereditary-patterned baldness

Hereditary-pattern baldness is a common, natural form of hair loss caused by genetics, hormones, and aging. It leads to gradual thinning of hair often starting at the temples and crown in men and as overall thinning on the top of the scalp in women. The hair loss is permanent, treatments like minoxidil or finasteride can slow it down or help regrow some hair. The condition tends to worsen over time, especially if it starts at a younger age. 

#Genetics #SportsScience #DNA #HumanTraits #ScienceNews

Source : https://www.health.harvard.edu/a_to_z/hereditary-patterned-baldness-a-to-z

How Genes Affect Heart Function and Lead to Heart Failure

 How Genes Affect Heart Function and Lead to Heart Failure

A recent genetics study published in Nature Communications looked at how genes affect the structure and function of the heart’s ventricles and how this relates to heart failure. Researchers studied genetic data from more than 56,000 people and found over 200 genetic locations linked to heart function, including many that had never been discovered before.

 Some of these genes may help explain why certain people are more likely to develop heart failure. The study also identified possible targets for new medications, which could help doctors treat heart failure more effectively in the future. Understanding the genetic causes of heart disease is important because it can lead to earlier diagnosis, better prevention, and more personalized treatments based on a person’s DNA. This research shows how genome-wide studies can help scientists find new ways to improve patient care and develop therapies for serious conditions like heart failure. 

Citations:

Aung, N., Vargas, J. D., Yang, C., Fung, K., Sanghvi, M. M., Piechnik, S. K., Neubauer, S., Ani Manichaikul, Rotter, J. I., Taylor, K. D., Joao, Bluemke, D. A., Kawut, S. M., Petersen, S. E., & Munroe, P. B. (2022). Genome-wide association analysis reveals insights into the genetic architecture of right ventricular structure and function. Nature Genetics, 54(6), 783–791. https://doi.org/10.1038/s41588-022-01083-2

Nicholls, H. L., Vargas, J. D., Sanghvi, M. M., Ahn, H.-S., Chahal, C. A. A., Khanji, M. Y., Petersen, S. E., Munroe, P. B., & Aung, N. (2026). Genome-wide analysis of cardiac ventricular phenotypes reveals novel loci and therapeutic targets for heart failure. Nature Communications. https://doi.org/10.1038/s41467-026-69982-0

How Snails Can Help Us Grow New Eyes

A species of snail once thought to be an invasive nuisance has become a major stepping stone in the medical felid serving as a great model organism. Recent research shows that the golden apple snail could unlock the secret to regenerating lost or damaged human eyes. It essentially explains that the golden apple snail has eyes which are both structurally and genetically similar to human eyes. However unlike humans, this snail has the ability to completely regenerate its eyes if damaged or lost entirely. Further more both snails and humans need the PAX6 gene to grow eyes, Accorsi found that when she disabled that particular gene that the snails could not grow eyes at all. Understanding how these snail regenerate their eyes could provide insight on how to better treat eye injury and disease. Despite being early in the research process the articles suggests that scientists may be able to utilize these mechanics in order to develop and repair human eyes.

Saey, T. H. (2025, August 6). This snail may hold a secret to human eye regeneration. Science News. https://www.sciencenews.org/article/snail-human-eye-regeneration

Scanza, R. (2024, March 27). An eye for an eye: The apple snail. Stowers Institute. https://www.stowers.org/news/an-eye-for-an-eye-the-apple-snail