There are three forms of Tay-Sachs disease: infantile, juvenile and late onset/adult. Infantile form In the most common and severe form, called infantile form, an infant typically begins showing signs and symptoms by about 3 to 6 months of age. Survival is usually only a few years. Signs and symptoms can include: 
Exaggerated startle response when the baby hears loud noises
"Cherry-red" spots in the eyes
Loss of motor skills, including turning over, crawling and sitting up
Muscle weakness, progressing to paralysis
Movement problems
Seizures
Vision loss and blindness
Hearing loss and deafness
Problems swallowing
Loss of mental functions and a lack of response to surroundings
Growth in head size (progressive macrocephaly)
 Juvenile form The juvenile form of Tay-Sachs disease is less common. Signs and symptoms vary in severity and begin in childhood. Survival is typically into the teen years. Signs and symptoms can include: 
Behavior problems
Gradual loss of skills and movement control
Frequent respiratory infections
Slow loss of vision and speech
Decline in mental function and responsiveness
Seizures
 Last onset/adult form This is a rare and less severe form with signs and symptoms beginning in late childhood to adulthood. Severity of symptoms varies greatly, and this form does not always impact life expectancy. Signs and symptoms progress slowly and can include: 
Muscle weakness
Clumsiness and loss of coordination
Tremors and muscle spasms
Loss of the ability to walk
Problems speaking and swallowing
Psychiatric disorders
Sometimes loss of mental function
