Timothy syndrome

Timothy syndrome is a rare disorder that primarily affects the heart but can affect many other areas of the body. The severity of this condition varies among affected individuals, although it is often life-threatening.

Timothy syndrome is characterized by a heart condition called long QT syndrome, which causes the heart (cardiac) muscle to take longer than usual to recharge between beats. This abnormality in the heart's electrical system can cause severe abnormalities of the heart rhythm (arrhythmias), which can lead to sudden death. Some people with Timothy syndrome are also born with structural heart defects (cardiomyopathy) that affect the heart's ability to pump blood effectively. 

As a result of these serious heart problems, some people with Timothy syndrome live only into childhood. In about 80 percent of cases of Timothy syndrome, the cause of death is a severe form of arrhythmia called ventricular tachycardia, in which the lower chambers of the heart (the ventricles) beat abnormally fast, often leading to cardiac arrest (the heart suddenly stops beating) and sudden death.

Timothy syndrome is also characterized by webbing or fusion of the skin between some fingers or toes (cutaneous syndactyly). About half of affected people have distinctive facial features such as a flattened nasal bridge, low-set ears, a small upper jaw, and a thin upper lip. Children with this condition have small, misplaced teeth and frequent cavities (dental caries). Additional signs and symptoms of Timothy syndrome can include baldness at birth, low muscle tone (hypotonia), frequent infections, episodes of low blood glucose (hypoglycemia), and an abnormally low body temperature (hypothermia). The respiratory system and gastrointestinal tract can also be affected.

Neuropsychiatric features are also common in individuals with Timothy syndrome. Researchers have found that many children with Timothy syndrome have the characteristic features of autism spectrum disorders. Affected children tend to have impaired communication and socialization skills, as well as delayed development of speech and language. Poor coordination is also frequent in affected individuals. Other nervous system disorders that can occur in Timothy syndrome include attention-deficit/hyperactivity disorder, intellectual disability and recurrent seizures (epilepsy); some affected individuals have photosensitive epilepsy, in which seizures are triggered by flashing lights.