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GTP cyclohydrolase deficiency
Pathology:
- tetrahydrobioterin deficiency
- malfunctioning tyrosine hydroxylase, tryptophan hydroxlase
- phenylketonuria
Genetics:
- autosomal recessive
- associated with defect(s) in GTP cyclohydrolase
Clinical manifestations:
- psychomotor retardation
- dystonia
- convulsions
- drowsiness
- irritability
- hyperthermia
- hypersalivation
- difficulty swallowing
Laboratory:
- serum phenylalanine: generally moderately elevated
- urine pteridines
- CSF 5-hydroxyindole acetic acid (5-HIAA)
- CSF homovanillic acid
Special laboratory:
- oral tetrahydrobiopterin-loading test (20 mg/kg)
Management:
- diet: phenylalanine restriction
- pharmaceutical therapy
- tetrahydrobiopterin
- Sinemet
- serotonin
Related
GTP cyclohydrolase (GTP cyclohydrolase 1, GTP dihydrolase, GTP ring-opening enzyme, GTP 8-formylhydrolase, GCH1)
General
inborn error of metabolism
References
- Dhondt J-L
GTP cyclohydrolase deficiency
http://www.orpha.net/data/patho/GB/uk-gtp.pdf