Living with GTP cyclohydrolase I deficiency with hyperphenylalaninemia
An inherited metabolic condition in which a missing helper molecule (tetrahydrobiopterin) raises phenylalanine and disrupts brain chemical signals.
Understanding GTP cyclohydrolase I deficiency with hyperphenylalaninemia
Too little tetrahydrobiopterin (BH4) raises levels of the amino acid phenylalanine. BH4 is also needed for enzymes that make brain chemical messengers (monoamines), so low BH4 disrupts nerve signaling. It is noticed in the newborn period or infancy.
Signs & symptoms
GARD doesn't list specific symptoms for this condition yet. The summary describes high phenylalanine and disrupted brain chemical signaling.
- High phenylalanine in the blood (hyperphenylalaninemia)
- Disrupted brain chemical (monoamine) signaling
Not everyone has every symptom. GARD's list comes from the Human Phenotype Ontology.
Diagnosis
- 1Talk with your doctor
Share the symptoms you've noticed, when they started and your family health history. Notes and photos can help.
- 2See a specialist
Specialists who may be involved include brain and nervous system specialists and genetic specialists.
- 3Consider genetic testing
Changes in GCH1 are linked to this condition. Genetic testing and counseling can help confirm a diagnosis and explain what it means for your family.
Care & treatment
- Care team
- Brain and nervous system specialists (neurologists); Genetic specialists (geneticists)
- Expert care
- Ask about multidisciplinary care centers for rare conditions
- Treatment
- GARD doesn't list specific treatments for this condition. Your care team will tailor care to your symptoms.
- Research
- Clinical trials and observational studies may be options. See the research section below.
General information, not medical advice. Your care team makes the decisions.
Everyday life
Living with a rare condition is easier with support.
- Connect with Pediatric Neurotransmitter Disease Association
- Keep notes on symptoms, changes and questions for appointments
- Ask about patient registries that help research
- Look into financial aid and travel resources for care visits
Quick facts
Changes in the GCH1 gene cause this condition. A child inherits a changed copy of the gene from each parent (autosomal recessive).
Also known as: gtpch deficiency; hpabh4b; hyperphenylalaninemia due to gtp cyclohydrolase deficiency; hyperphenylalaninemia, bh4-deficient, b; hyperphenylalaninemia, bh4-deficient, type b; hyperphenylalaninemia, tetrahydrobiopterin-deficient, due to gtp cyclohydrolase 1 deficiency
Patient organizations
- Pediatric Neurotransmitter Disease AssociationGTP cyclohydrolase I deficiency with hyperphenylalaninemia · United States
You are more than your diagnosis
Perspectives from people navigating life with GTP cyclohydrolase I deficiency with hyperphenylalaninemia.
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