Guanidinoacetate Methyltransferase
Deficiency (GAMT)

Guanidinoacetate methyltransferase deficiency, also called GAMT deficiency, is an autosomal recessive metabolic disorder that primarily affects the nervous system and muscles. It is the first observed disorder of creatine metabolism.

This disorder usually appears in the first few months of life, when development of new motor and cognitive skills becomes delayed or stops. Eventually, affected children may lose previously acquired skills such as head control or the ability to sit unsupported.

People with guanidinoacetate methyltransferase deficiency have a wide spectrum of neurological symptoms. In addition to mental retardation and muscle weakness, some children with this disorder experience seizures. They may also develop autistic behaviors that affect communication and social interaction. Some affected children exhibit certain involuntary movements such as tremors or facial tics.

Guanidinoacetate methyltransferase deficiency is a very rare disorder. Only a few dozen affected individuals have been reported worldwide.

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