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Health and Disease

Tay-Sachs Disease: The Rare Genetic Disorder

Tay-Sachs is a deadly disease that can affect a babies mobility, sight, and hearing. Tay-Sachs is usually found amongst infants who are typically from the ages 3-6 months old and symptoms usually progress from then on out. Children with Tay Sachs don’t live a long life and typically pass away by the age of 5.

Introduction

Tay-Sachs disease is a very rare disorder that destroys nerve cells in the brain. It is found in infants who don’t have enough of an enzyme, known as beta-hexosaminidase. 15 (HEX-A) is a defective gene that prevents the body from making this protein.  The beta-hexosaminidase plays a very important role in the brain as well as the spinal cord. Not having enough of this enzyme can cause this disease to be very severe and can be extremely dangerous.  Tay-Sachs is usually found amongst infants who are typically from the ages 3-6 months old and symptoms usually progress from then on out. There are 3 types of  Tay-Sachs disease: infantile, juvenile, and late-onset/adult. However, the most common type is infantile which can start to appear in only the first few months. As the infant continues to grow, Tay-Sachs will start affecting the baby’s sight, hearing, and movement. Progressions usually happen very quickly and by the age of 2, the child will be completely disabled or have seizures. Children with Tay Sachs don’t live a long life and typically pass away by the age of 5.

Symptoms

Symptoms of Tay Sachs disease include muscle weakness which can also lead to paralysis. The infant may also be startled by sound, which will also start to progress into deafness. Further on, the child may start to see red spots, known as cherry-red spots of the macula, that develop in the back of the child’s eyes. This will start to progress into blindness and they will start to be unresponsive and have delayed mental and social development. If a child is having any problems with seeing, hearing, or moving the child must get tested to see if they have Tay-Sachs. However, Tay-Sachs is a very rare disease (less than 20,000 cases per year) so the chances of a child having it are extremely low. Another symptom of Tay-Sachs would be developmental regression. This means that the infant will most likely lose many developmental milestones, causing the infant to slowly regress physically and also mentally, such as difficulty in speaking and swallowing.

Inheritance

Tay-Sachs is inherited from an autosomal recessive pattern. Autosomal recessive is an inheritance pattern that both copies of the gene in each cell have this mutation. This means that if both parents are a carrier for a disease it is very likely that their child will also be a carrier or have the disease. However, autosomal recessive disorders aren’t usually seen in every generation of a family that is affected. If one of the parents is in fact a carrier for Tay-Sachs, then it is possible that the child will also inherit this mutation. There is a 1 in 4 chance that the child will have the disease, a 1 in 2 chance to be an unaffected carrier like each parent, or there’s a 1 in 4 chance that the child would be unaffected and not a carrier.

Risk

Tay-Sachs is commonly found in people with a certain ancestry, but most commonly found in people who identify as Ashkenazi Jews. Ashkenazi Jews are people who have families that are from the Jewish community that originates from Eastern Europe. Most Ashkenazi Jews are more likely to have autosomal genetic disorders like Tay Sachs but most of them can be preventable. For Tay-Sachs however, there is a 1 in 25 carrier frequency for Ashkenazi Jews. Tay-Sachs is also starting to be found in the Irish American community as well. There is an estimate that 1 in 50 Irish and Irish Americans are carriers for the Tay-Sachs disease.

Diagnosis

Tay-Sachs can be diagnosed by prenatal tests like chorionic villus sampling. It is important for healthcare professionals to look at the person’s medical history as well. The diagnosis will include a blood test that detects whether or not the child has high or low beta-hexosaminidase. This will tell us whether or not the mutation is present or not. However, Tay-Sachs can be detected before birth if parents decide to take a blood test to see if they are a carrier. 

Conclusion

Although there is currently no cure for Tay-Sachs, it is important to take a blood test to see if you are a carrier for any genetic diseases that can be caused by autosomal recessive patterns. Tay-Sachs disease isn’t a very common genetic disease. However, if your family does identify as Ashkenazi Jews, it is recommended that you take blood tests to see if you are a carrier for other genetic disorders like Tay-Sachs. There are treatments for Tay-Sachs but this is only to keep the child comfortable. For example, medicine for pain or anti-epileptics to control seizures. If you have more concerns about being a possible Tay-Sachs carrier, it is important to contact a doctor or healthcare professional.

References

Reference, G., 2020. Tay-Sachs Disease. [online] Genetics Home Reference. Available at: <https://ghr.nlm.nih.gov/condition/tay-sachs-disease#inheritance&gt; [Accessed 25 August 2020].

“HEXA Gene – Genetics Home Reference – NIH.” U.S. National Library of Medicine, National Institutes of Health, 2020, ghr.nlm.nih.gov/gene/HEXA.

“Tay-Sachs Disease.” Genetic and Rare Diseases Information Center, U.S. Department of Health and Human Services, 23 Jan. 2018, rarediseases.info.nih.gov/diseases/7737/tay-sachs-disease.

Herndon, Jaime. “Tay Sachs Disease:Treatments, Symptoms, Risks and More.” Healthline, Healthline Media, 25 July 2012, http://www.healthline.com/health/tay-sachs-disease.

“Tay-Sachs Disease (for Parents) – Nemours KidsHealth.” Edited by Rupal Christine Gupta, KidsHealth, The Nemours Foundation, Oct. 2014, kidshealth.org/en/parents/tay-sachs.html.

Egan, Casey. “Irish Americans Warned about Tay-Sachs Disease Striking Community.” IrishCentral.com, 7 Sept. 2016, www.irishcentral.com/culture/education/irish-americans-warned-about-tay-sachs-disease-striking-community.

“Preventable Jewish Genetic Diseases.” 19 Jewish Genetic Diseases | Nicklaus Children’s Hospital, http://www.nicklauschildrens.org/medical-services/personalized-medicine-(pmi)/the-victor-center/19-preventable-jewish-genetic-diseases.

Mary Mai, Youth Medical Journal 2020

By Mary Mai

Mary Mai is a student at Balboa High School in California. She is interested in fields of medical genetics, neurology, psychiatry, and pediatrics.

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