Question: What is (are) Guanidinoacetate methyltransferase deficiency ?
Answer: Guanidinoacetate methyltransferase deficiency is an inherited condition that affects the brain and muscles. Affected people may begin showing symptoms of the condition from early infancy to age three. Signs and symptoms can vary but may include mild to severe intellectual disability, epilepsy, speech development limited to a few words, behavioral problems (i.e. hyperactivity, autistic behaviors, self-mutilation), and involuntary movements. Guanidinoacetate methyltransferase deficiency is caused by changes (mutations) in the GAMT gene and is inherited in an autosomal recessive manner. Treatment aims to increase the levels of creatine in the brain through supplementation with high doses of oral creatine monohydrate.
Source: GARD

Question: What are the symptoms of Guanidinoacetate methyltransferase deficiency ?
Answer: What are the signs and symptoms of Guanidinoacetate methyltransferase deficiency? The Human Phenotype Ontology provides the following list of signs and symptoms for Guanidinoacetate methyltransferase deficiency. If the information is available, the table below includes how often the symptom is seen in people with this condition. You can use the MedlinePlus Medical Dictionary to look up the definitions for these medical terms. Signs and Symptoms Approximate number of patients (when available) Ataxia - Autosomal recessive inheritance - Delayed speech and language development - Hyperreflexia - Hypertonia - Infantile muscular hypotonia - Intellectual disability - Myoclonus - Progressive extrapyramidal movement disorder - Seizures - The Human Phenotype Ontology (HPO) has collected information on how often a sign or symptom occurs in a condition. Much of this information comes from Orphanet, a European rare disease database. The frequency of a sign or symptom is usually listed as a rough estimate of the percentage of patients who have that feature. The frequency may also be listed as a fraction. The first number of the fraction is how many people had the symptom, and the second number is the total number of people who were examined in one study. For example, a frequency of 25/25 means that in a study of 25 people all patients were found to have that symptom. Because these frequencies are based on a specific study, the fractions may be different if another group of patients are examined. Sometimes, no information on frequency is available. In these cases, the sign or symptom may be rare or common.
Source: GARD