Tay Sachs Disease Overview

Study Notes

Tay-Sachs disease is a rare genetic disorder caused by the absence of an enzyme that helps break down fatty substances, leading to toxic levels in the brain and spinal cord.
It affects the function of nerve cells, leading to developmental delays, muscle weakness, and other major issues.

Tay-Sachs disease is an autosomal recessive disease caused by mutations in both alleles of the HEXA gene on chromosome 15.
The HEXA gene codes for the alpha subunit of the enzyme β-hexosaminidase A, which breaks down GM2 ganglioside.
Mutations in the HEXA gene result in reduced or absent activity of the Hex-A enzyme, leading to the accumulation of GM2 ganglioside within nerve cells.
Individuals who inherit two copies of the mutated HEXA gene, one from each parent, are affected by the disease.
Carriers, who have one mutated copy of the gene, are typically asymptomatic but can pass the mutated gene to their children.

There are three forms of Tay-Sachs disease:
- Infantile Tay-Sachs: the most common form, develops soon after birth, and causes death early in childhood.
- Juvenile Tay-Sachs: affects children aged 2 and older, progresses more slowly, and children may live into their mid-teens.
- Late-onset Tay-Sachs: a rare and milder form, which can start between puberty and the mid-30s, and some individuals may live a normal lifespan.

Symptoms vary in severity and type, and may become more pronounced as the disease progresses.
Common symptoms include:
- Developmental delay
- Muscle weakness
- Loss of motor skills
- Increased startle response
- Hypotonia
- Seizures
- Vision and hearing loss
- Cherry-red spot on the retina
Diagnosis involves:
- HEX-A blood test: to check the levels of hexosaminidase enzyme in the blood.
- Genetic testing: to identify mutations in the HEXA gene.
- Eye exam: to detect the cherry-red spot on the retina.

There is no cure for Tay-Sachs disease, but treatment focuses on managing symptoms and preventing complications.
Supportive treatments include:
- Medication to manage seizures and other symptoms.
- Respiratory care, including chest physiotherapy and exercise, to remove mucus from the lungs.
- Nutrition and hydration support, including assistive feeding devices.
Genetic counseling and testing can help identify carriers and provide information for family planning decisions.

Individuals with Tay-Sachs disease may have specific dental considerations, including:
- Delayed or aberrant tooth eruption.
- Increased risk of dental caries and periodontal disease.
Dental management involves:
- Special care: gentle and careful treatment.
- Prevention: regular cleanings and fluoride treatments.
- Using anesthesia safely.
- Working together with doctors and dentists to plan the best care for patients with Tay-Sachs disease.

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