What is Tay–Sachs Disease?
Tay-Sachs Disease is an extremely rare genetic disorder in which the enzyme that breaks down fatty acids in the body is absent. Because of this, there is a build up of fatty substances to such an extent that they reach toxic levels in the brain of the child and start affecting the nerve cells causing a variety of symptoms from blindness to eventual death. The symptoms of Tay-Sachs Disease may start to become apparent by the time the baby reaches six months of age. As of now, there is no cure for this condition and the treatments rendered are purely symptomatic and supportive making the child as comfortable as possible and to slow down the progression of Tay-Sachs Disease.
This condition is seen mostly in the Amish Community of Pennsylvania or people from Eastern or Central European descent. Tay-Sachs Disease is an autosomal recessive trait which means that a copy of the defective gene needs to be inherited from both parents in order to get this disorder. In case if a family is at risk for developing this disorder or an individual has a family history of this disorder then it is recommended that he or she seek genetic counseling before planning to have children to see whether their offspring may have the risk for developing Tay-Sachs Disease.
What Causes Tay–Sachs Disease?
As stated above, Tay-Sachs Disease is a genetic disorder which means that the child gets this disease through his or her parents. The gene mutation responsible for development of Tay-Sachs Disease is the mutation in HEXA gene. Because of this gene there is less or no production of enzyme Hexosaminidase-A which is responsible for removing fatty substances from nerve cells. When there is no production of this enzyme then it leads to gradual build up of fatty substances in the brain that starts to hamper with the functioning of the nerve cells causing a variety of symptoms. This is what leads to Tay-Sachs Disease.
The build of fatty substances in the brain resulting in damage to the nerve cells may result in impairment of many bodily functions to include vision, speech, hearing, movement and mental abilities of a child. Tay-Sachs Disease is an autosomal recessive trait meaning that a copy of the defective gene has to be inherited from both the parents for the child to get Tay-Sachs Disease.
What are the Symptoms of Tay–Sachs Disease?
The symptoms of Tay-Sachs Disease may start to become apparent by the time the child is five to six months of age. The first visible sign of Tay-Sachs Disease is the presence of a red colored dot behind the eyes. The vision of the child may also be observed to be poor that may be clearly observed seeing that the child gets startled even with the slightest of movements even while awake and may get frightened and start crying.
The second symptom of Tay-Sachs Disease is that the child will have significant delay in meeting developmental milestones like crawling or sitting up unassisted.
By the time the child is about a year old, additional symptoms may develop which may include:
- Severe muscle weakness progressing to paralysis
- Extremely poor vision
- Hearing loss
- Significant spasticity
- Repeated bouts of seizures.
Additionally, children with Tay-Sachs Disease will have frequent lung infections even little to no stimuli and in majority of the cases this is what leads to the death of the child with Tay-Sachs Disease.
How is Tay–Sachs Disease Diagnosed?
To begin with if an individual is at risk or has a family history of Tay-Sachs Disease, then he or she needs to undergo genetic testing to look for mutation of the HEXA gene before planning to start a family. This is called preconceptual screening. This can be done through a blood test of both the partners looking for HEXA gene mutations. In case if the test results are positive then there are about 30% chances of the offspring developing Tay-Sachs Disease.
If an individual does not undergo preconceptual screening for Tay-Sachs Disease and goes ahead with planning a family then antenatal screening can be performed to check whether the fetus or the child to be born will have Tay-Sachs Disease or not. This can be done during the first trimester by taking out cells from the placenta and checking it for mutations of the HEXA gene. An amniocentesis can be done between 15-20 weeks of pregnancy to check for mutations of the HEXA gene to see if the child will have Tay-Sachs Disease. In case if the test results are positive, it is to the discretion of the parents to either continues with the pregnancy or terminate the pregnancy.
In case if both the above tests are not done, then tests can be done after the child is born based on the symptoms that the child displays. If Tay-Sachs Disease is suspected then blood tests can be done to extract the DNA and check for HEXA gene mutation which will be positive in cases of Tay-Sachs Disease.
How is Tay–Sachs Disease Treated?
As of now, there is no cure for Tay-Sachs Disease and hence treatment is mainly supportive and focuses on keeping the child as comfortable as possible and treating the infections early and to prevent any other complications that may arise due to Tay-Sachs Disease. The treatment usually focuses on preventing any infections of the respiratory system including the airways and lungs. Problems swallowing can be helped with speech therapy or placing an NG tube. The problems with seizures can be controlled with anticonvulsants. Muscle stiffness can be dealt with muscle relaxer. Apart from this there is no further treatment that can be provided for treatment of Tay-Sachs Disease.
What is the Prognosis & Life Expectancy of Tay–Sachs Disease?
The prognosis of a child with Tay-Sachs Disease is extremely poor despite the best of care and at best the child may survive till the age of 5 before succumbing mostly due to frequent infections, especially of the lungs.