In the most common form of Tay-Sachs disease, classic infantile Tay-Sachs disease, a baby will develop normally until they're around three to six months old.
One of the first noticeable signs of the condition is the appearance of a red dot at the back of their eyes. You may also notice that their vision seems poor, or that they're excessively startled by noises and movement.
It's likely that your baby will be much slower in reaching developmental milestones, such as learning to crawl.
Additional symptoms usually develop after about eight months of age and quickly become more severe. They include:
Children with Tay-Sachs disease become increasingly vulnerable to infection, particularly lung infections. Many children die from a complication of an infection such as pneumonia.
Most children with infantile onset Tay-Sachs disease die before they're four years old, because of complications from repeated infections.
Rarer forms of Tay-Sachs disease
There are two much rarer forms of Tay-Sachs disease.
In the juvenile form, the symptoms don't usually begin until a child is aged 2 to 10 years old.
Initially, problems develop with speech and motor skills, such as balance, walking and holding objects. Some children may also develop problems with vision.
As the condition progresses, the child will have repeated fits and experience dementia.
Most children with the juvenile form of Tay-Sachs disease eventually enter a vegetative state, where they're awake, but showing no signs of awareness. This usually happens between the ages of 10 and 15. The most common cause of death is a complication of an infection.
The symptoms of late-onset Tay-Sachs disease develop later in life, usually during the teenage years or early adulthood.
- slurred speech
- loss of balance and co-ordination
- uncontrollable shaking of the hands (tremor)
- muscle cramps and twitching
- muscle weakness
Around one in three people with late-onset Tay-Sachs disease also develop mental health conditions, such as bipolar disorder or psychosis. They may see or hear things that aren't there (hallucinations) or believe things that aren't true (delusions).
Unlike other forms of the condition, late-onset Tay-Sachs disease doesn't always shorten life expectancy.