More Than 1 Million Tay-Sachs Carriers in US

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It is a devastating disease that most people know nothing about, yet 1.5 million individuals in the United States are Tay-Sachs carriers, according to the Cure Tay-Sachs Foundation. Your chances of carrying the Tay-Sachs gene range from 1 in 27 to 1 in 250, depending on your background.

Tay-Sachs disease is a hereditary disease in which a mutation in the Hex-A gene causes the body to have little or no amount of the Hex-A enzyme, hexosaminidase A. This enzyme is required by the cells, especially the nerve cells in the brain, to break down fatty waste. When the enzyme is not available, fatty waste products called GM2 ganglioside accumulate inside the cells, causing them to die.

People who are most at risk of carrying the Tay-Sachs gene are eastern Europeans of Jewish (Ashkenazi) descent, Louisiana Cajuns, and French Canadians who live near the St. Lawrence River. Among these populations, 1 in 27 people carry a gene mutation. Experts believe there are between 75 and 100 different mutations that can cause the disease, according to the Cure Tay-Sachs Foundation.

People of Irish-American descent are the next highest risk population, where one in 50 people carry the Tayt-Sachs gene. The chances among the general population of being a carrier is one in 250.

The different mutations can cause different forms of the disease, with infantile being the most common, followed by juvenile and late onset. There is no cure or treatment for infantile and juvenile Tay-Sachs, and everyone affected dies.

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In the infantile form of the disease, babies are usually born without any Hex-A, and so the disease progresses rapidly, typically causing death by age 3 to 5 years. Infants do not display symptoms of the disease right away, however, and so the disease can go undetected for months.

Initial symptoms of infantile Tay-Sachs include seizures, decreased eye contact, listlessness, increasing irritability, delayed mental and social skills, increased startle reaction, slow body growth with increasing head size, and behavior changes, such as the baby stops smiling, crawling, or rolling over.

As the disease progresses, other symptoms appear, such as feeding problems, abnormal body tone, deafness, blindness, and loss of intellectual skills. Children who have juvenile Hex-A deficiency develop symptoms between ages 2 and 5 and usually die by age 15. Late onset disease can appear anytime between 5 years of age and the early 30s. Symptoms usually include unsteady gait, tremors, slurred speech, and in some cases, mental illness.

A person can get Tay-Sachs disease only if he or she inherits a Hex-A gene mutation from both parents. If two carrier parents have a child, three outcomes are possible: neither parent passes along the gene mutation to the child so the child is normal; only one parent passes along the gene mutation so the child is normal but is a carrier of the Tay-Sachs gene; or both parents pass along the gene mutation and the child will have Tay-Sachs.

Right now, 1.5 million Americans are carrying the gene that can cause a deadly disease that has no treatment or cure. The Cure Tay-Sachs Foundation is hoping to help change that. On April 19 it announced that it awarded three grants totalling $208,358 “to further Tay-Sachs and Sandhoff disease research.” The grants will cover research on a type of sheep that have been found to be affected by Tay-Sachs, stem cell research in Sandhoff mice, and investigation into the role of inflammation in the brain in Sandhoff disease. Sandhoff is a severe form of Tay-Sachs.

SOURCES:
Cure Tay-Sachs Foundation
National Institute of Neurological Disorders and Stroke
National Tay-Sachs and Allied Diseases Association

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