Tay-Sachs Disease: Symptoms, Causes, Treatment

Author: Thomas C. Weiss
Published: 2010/02/18 - Updated: 2023/02/01
Topic: Types of Disability - Publications List

Page Content: Synopsis - Introduction - Main

Synopsis: Tay-Sachs disease is a form of fatal genetic lipid storage disorder where harmful amounts of ganglioside GM2 build up in the nerve cells and tissues of the brain. Tay-Sachs disease is particularly prevalent among persons of Eastern European and Ashkenazi Jewish descent. A simple blood test that measures beta-hexosaminidase A activity may identify people with the disease and carriers.

Introduction

Defining Tay-Sachs Disease

Tay-Sachs disease is a form of fatal genetic lipid storage disorder where harmful amounts of a fatty substance known as 'ganglioside GM2' build up in a person's nerve cells and tissues in their brain. The condition is caused by a lack of sufficient activity on the part of an enzyme known as 'beta-hexosaminidase A,' which catalyzes the biodegradation of acidic, fatty materials such as gangliosides. Gangliosides are both made and biodegrade quickly in early life as the person's brain develops.

The U.S. Social Security Administration (SSA) has included Tay Sachs Disease as a Compassionate Allowance to expedite a disability claim.

Main Item

Infants with Tay-Sachs disease seem to develop as usual during the first few months of their lives. However, as their nerve cells become distended with fatty material - a process of deterioration involving their mental and physical abilities happens. Children with the disease become deaf, blind, and unable to swallow. Their muscle starts to atrophy, and paralysis sets in. Additional neurological symptoms experienced by children with Tay-Sachs disease include seizures, dementia, and increased startle response to noise. There is a much rarer form of Tay-Sachs disease, which occurs in people in their twenties to early thirties, characterized by progressive neurological deterioration and an unsteady gait. People with the disease also experience red spots in their eyes.

Tay-Sachs disease is particularly high among persons of Eastern European and Ashkenazi Jewish descent. A simple blood test that measures beta-hexosaminidase A activity may identify people with the disease and carriers. A person's parents must carry the mutated gene for them to be affected. When this occurs, there is a twenty-five percent chance with each pregnancy that the child these parents have will be affected by Tay-Sachs disease.

Causes of Tay-Sachs Disease

Tay-Sachs disease results from defects in a particular gene on chromosome fifteen, which codes for the production of enzyme Hex-A. People have two copies of this particular gene; if either or both Hex-A genes are active, a person's body produces enough enzymes to prevent the buildup of the GM2 ganglioside lipid. People who carry Tay-Sachs disease have one copy of the inactive gene and one copy of the inactive gene; they remain healthy. Carriers do not have the disease, although they can pass the active gene to children.

People who are carriers of Tay-Sachs disease have a fifty-percent chance of passing the active gene for the disease to their children. Children who inherit one inactive gene for the disease are carriers, like their parents. If both parents of a child are carriers, and their child inherits the active gene from each of them, the child will have Tay-Sachs disease.

Anyone can be a carrier of Tay-Sachs disease, although the incidence of the disease is much higher among people of Eastern European Jewish descent. About one in every twenty-seven Jews in America are carriers of the Tay-Sachs disease gene. Non-Jewish French Canadians who live near the St. Lawrence River or in the Cajun community of Louisiana also experience a higher incidence of the disease. Among the general population, approximately one in two-hundred and fifty people carry the gene for Tay-Sachs disease.

Symptoms of Tay-Sachs Disease

There are three forms of Tay-Sachs disease, categorized according to their present symptoms and the age at which the person first experiences them. The most common form of the disease presents symptoms when a child is only three to six months old. The disease progresses from there, rapidly progressing to death by the time the person reaches four or five years old. When the infant is born, they seem healthy and regularly develops for the first few months. As the buildup of ganglioside, GM2, starts to affect their nerves, the symptoms associated with Tay-Sachs start to appear. These symptoms can initially include:

• Seizures
• Listlessness
• Increasing irritability
• Decreased eye contact
• Increased startle reaction
• Delayed mental and social skills
• Slow body growth with increasing head size
• The infant stops smiling, crawling, or rolling over and loses the ability to grasp or reach out

As the disease progresses, the child experiences more dominant symptoms. The child then begins experiencing symptoms that include:

• Deafness
• Blindness
• Feeding difficulties
• Loss of motor skills
• Abnormal body tone
• Loss of intellectual skills

Rarer forms of Tay-Sachs disease that develop later in a person's life are due to low levels of the Hex-A enzyme, instead of a complete deficiency of Hex-A such as in the infantile form of the disease. Children with juvenile Hex-A deficiency often develop symptoms between the ages of two and five years, commonly dying before age five. A milder form of Hex-A deficiency may develop in people between the ages of five and early thirties. The symptoms can include an unsteady gait, tremors, slurred speech, and mental illness.

Late-Onset Tay-Sachs disease, a much rarer form, affects adults and causes intellectual and neurological impairment. This form of Tay-Sachs disease has only recently been identified. The disease has not been extensively described.

Diagnosing Tay-Sachs Disease

Tay-Sachs disease can be identified through a simple blood test. A person's blood samples can be analyzed for DNA studies or enzyme assay. An enzyme assay is a biochemical test that measures the level of Hex-A in the person's blood. People who are carriers of Tay-Sachs disease have less Hex-A in their blood and cells than those who do not.

Carrier testing that is DNA-based looks for particular mutations or changes in the person's gene that codes for Hex-A. The Hex-A gene was isolated in 1985, and since then, more than fifty different mutations in the gene have been identified. Some mutations remain unknown, however. Current tests can detect approximately ninety-five percent of people who are carriers among the Jewish population and approximately sixty percent of people who are carriers among those in the general population. Genetic testing is available for parents who are carriers of Tay-Sachs disease.

Treatment of Tay-Sachs Disease

Medical science has not created a cure for Tay-Sachs disease or effective treatment. Researchers are pursuing several approaches to finding a cure for the disease. One of these involves enzyme replacement therapy to provide the Hex-A that babies with Tay-Sachs disease lack. Bone marrow transplantation has been attempted, although it has not succeeded in reversing or slowing down the damage to a baby's nervous system. An additional path of research being pursued involves gene transfer into cells to replace an abnormal gene. The approach presents promise for people who experience Tay-Sachs disease.

Author Credentials: Thomas C. Weiss is a researcher and editor for Disabled World. Thomas attended college and university courses earning a Masters, Bachelors and two Associate degrees, as well as pursing Disability Studies. As a CNA Thomas has providing care for people with all forms of disabilities. Explore Thomas' complete biography for comprehensive insights into his background, expertise, and accomplishments.