Tay Sachs disease is caused by a defective gene on the 15th chromosome. Both parents must have the defective gene to pass the active disease to a child. If both parents carry the defective gene, children have a 25% chance of having an active form of Tay Sachs. If one parent is affected, the gene may pass to children, but no symptoms occur. The child is then a carrier and can pass the defective gene onto their children.
Who is at Risk?
There are three forms of Tay Sachs disease – infant, juvenile and adult. Infant Tay Sachs disease is the most common form. The fetus is affected by the defective gene in utero with symptoms progressing over time. About one in 27 Ashkenazi Jews carry recessive genes for Tay Sachs. If there is a family history of Tay Sachs, it is suggested that couples have genetic testing before attempting to have children.
Tay Sachs disease is a progressive disorder. Nerve damage begins in utero in cases of infant Tay Sachs. Symptoms quickly progress after birth and may include:
- Loss of hearing
- Loss of muscle tone and strength
- Delayed mental development
- Growth delays
Tay Sachs progresses quickly. Infants quickly lose motor skills and may develop seizures or body tremors. Symptoms grow more severe as the disease progresses. The most severe complication is early death.
Family history is the best tool for doctors to diagnose Tay Sachs disease. If there is a family history, genetic testing may be done to diagnose the condition. Other tests used in diagnosis may include:
- Blood tests
- Eye examination
There is no treatment for Tay Sachs disease. Parents are often counseled on treatments to ease pain and suffering. Parents of children with Tay Sachs are encouraged to seek counseling and support group therapy to help ease the stress associated with the progressive disease.
Patients may benefit from a feeding tube and medications to limit seizures early in the disease, but as the disease progresses these treatments may no longer work.
Life expectancy is reduced dramatically in patients with Tay Sachs disease. The infant form of Tay Sachs reduces life expectancy to four or five years. Other forms of Tay Sachs develop later in life, but tend to progress quickly leading to death in about five years.