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GENATLAS PHENOTYPE

last update : 07-01-2009

Symbol	GAMTD
Location	19p13.3
Name	guanidinoacetate N-methyltransferase deficiency
Other name(s)	GAMT deficiency creatine deficiency syndrome due to GAMT deficiency
Corresponding gene	GAMT
Main clinical features	muscular hypotonia, severe, with encephalopathy, progressive extrapyramidal movement disorder, seizures and choreoathetosis, drug-resistant epilepsy, extremely low excretion of creatine and accumulation of guanidinoacetate in brain, reversible by oral administration of creatine onset of seizures usually ranges from infancy to 3 years also cases with unexplained developmental delay or regression with dystonia, even without history of seizures occurrence of secondary respiratory chain abnormalities in GAMT deficiency may lead to misdiagnosis, masquerading as a mitochondrial encephalopathy mental retardation, epilepsy and autistic or self-aggressive behavior
Genetic determination	autosomal recessive
Function/system disorder	neuromuscular
	neurology
Type	disease

Gene product

Name	guanidinoacetate methyltransferase

Mechanism(s)

Gene mutation	Chromosome rearrangement	Effect	Comments
missense			in the exon 6, mostly frequent; altering isoform A

Remark(s)