Tay-Sachs disease usually affects infants who begin to show signs of the disease at approximately six months of age. There are two other forms of the disease, juvenile and late-onset Tach-Sachs disease, which are categorised according to the age of the patients when symptoms present.
Infantile Tay-Sachs Disease
Infantile Tay-Sachs disease is the most common type of the disease and although nerve damage is likely to begin in utero, signs usually become evident later at the age of about six months.
The initial signs of the disease in an infant with the disease may include:
- A red dot visible near center of retina
- Poor vision
- Increased startle response
- Delayed learning development (e.g. sitting and crawling)
The progression of disease tends to occur quickly, with signs and symptoms quickly evolving to become more serious. Other symptoms may include:
- Muscle weakness
- Muscular spasticity
- Disinterest in environment
- Susceptible to infection
- Vision loss
Infants with Tay-Sachs disease are more vulnerable to infections than other children and this risk increases as the disease progresses. An infection of the lungs such as pneumonia is the cause of death for many children with the disease and is the primary cause of the reduced life expectancy of associated with infantile onset of the disease.
Most children with the first signs of Tay-Sachs disease in infancy do not survive beyond the age of four years, as a result of the severity of the symptoms and repeated infections.
Juvenile Tay-Sachs Disease
Some children with Tay-Sachs disease will not begin to notice symptoms until a later date, between the age of two and ten years old.
The initial signs that present usually involve difficulty in the development of speech and motor skills. Affected children commonly struggle learning to move and walk due to problems of balance. Additionally, they may have trouble swallowing and learning to talk as a result of the condition.
Problems with and eventual loss of vision are also commonly evident. Most children suffer from fits when the disease has progressed and have signs of dementia with a difficult memory.
Over time, children with juvenile Tay-Sachs disease tend to lose signs of awareness and are eventually unable to interact with the environment surrounding them. In early adolescence, most children reach a vegetative state and usually die of a complication, such as a lung infection.
Late-Onset Tay-Sachs Disease
In this form of the disease, symptoms tend to present in adolescence or early adulthood. Common symptoms include:
- Speech difficulties
- Reduced coordination and balance
- Severe tremor
- Muscle weakness
- Cramps and twitching
Approximately one-third of patients with late-onset disease tend to develop mental health conditions. These patients usually experience hallucinations or delusions and may also be diagnosed with bipolar disorder or psychosis.
This is the least severe form of Tay-Sachs disease and is not usually associated with fatal complications, instead characterized by symptoms that inhibit quality of life. It is associated with slower progression and the life expectancy of individuals with this form of the disease varies greatly.