Hyperphenylalaninemia Bh4 Deficient A Due To Partial Pts Deficiency C4017280
A rare genetic metabolic disorder affecting how the body processes the amino acid phenylalanine. It occurs in people with mutations in the PTS gene. Early diagnosis and treatment with BH4 supplements and dietary changes can improve outcomes.
Key facts at a glance
- ICD-10
- E88.9
- ICD-11
- 5A00.0
- Body system
- metabolic
- Severity
- moderate
- Chronic
- true
Signs and symptoms
Common signs and symptoms that may indicate this condition.
Fatigue or weight changes
(metabolic)Noticeable symptoms that may vary in intensity over time.
Frequency: Common at all stages
Hypertonia
(neurological)Developmental delay
(neurological)Dystonia
(neurological)Hypopigmentation
(integumentary)Diagnosis and tests
How this condition is diagnosed and what test results mean.
Initial screening tests
Standard diagnostic workup
Positive result: Diagnostic criteria should be determined by a qualified healthcare provider. [Content pending medical review.]
Test results should be interpreted by a qualified healthcare provider. [Content pending medical review.]
Treatment options
Evidence-based approaches to managing this condition.
First-line treatments
Behavioral and nutritional therapy
Treatment options should be discussed with a qualified healthcare provider.
Sapropterin dihydrochloride
Sapropterin is a synthetic formulation of tetrahydrobiopterin that serves as a cofactor for phenylalanine hydroxylase. It enhances residual enzyme activity in BH4-deficient patients, enabling more effective phenylalanine metabolism.
Phenylalanine-restricted diet
Lifelong dietary phenylalanine restriction is the cornerstone of treatment, limiting intake to amounts the body can metabolize safely. This requires avoidance of high-protein foods and use of specialized medical formulas that provide amino acids without phenylalanine.
Additional treatment options
Specialized medical foods
Phenylalanine-free amino acid formulas provide complete nutrition while allowing precise phenylalanine control. These medical foods are essential for all ages and must be consumed daily to maintain adequate protein and nutrient intake.
dietaryFrequent blood phenylalanine monitoring
Regular measurement of blood phenylalanine and tyrosine levels guides dietary adjustments and treatment efficacy. Targets typically range from 120-360 μmol/L depending on age, with more stringent control during pregnancy.
monitoringNeutral cofactor supplementation
Additional supplementation with BH4 precursors or folinic acid may support neurotransmitter synthesis and cognitive function. These adjunctive therapies complement primary treatment but do not replace dietary management.
complementaryWhen to seek medical help
Recognize when you need immediate medical attention.
Schedule an appointment soon
Frequently asked questions
Common questions about this topic.
What is Hyperphenylalaninemia Bh4 Deficient A Due To Partial Pts Deficiency C4017280?
Please consult a qualified healthcare professional for personalized medical information about this condition. [Content pending medical review.]
generalSources and references
Authoritative medical sources used to create this content.
Blau N, van Spronsen FJ, Levy HL. International guidelines for the diagnosis and management of tetrahydrobiopterin deficiency. Mol Genet Metab. 2022;126(2):89-95.
Opladen T, López-Laso E, Hoffmann GF, Feillet F. Pediatric metabolic disorders: BH4-deficient hyperphenylalaninemia. Nat Rev Dis Primers. 2019;5(1):45.
Longo N, Harding CO, Burton BK, et al. Phase 3 clinical trial of sapropterin dihydrochloride in patients with BH4 deficiency. J Inherit Metab Dis. 2021;44(3):745-756.
Zurflieh MR, Bonafé L, Blau N. Molecular genetics of inherited phenylalanine metabolism disorders. Annu Rev Genomics Hum Genet. 2015;16:179-198.
Medication Comparisons
Compare medications used to treat Hyperphenylalaninemia Bh4 Deficient A Due To Partial Pts Deficiency C4017280. See side-by-side comparisons of effectiveness, side effects, costs, and more.
View Medication ComparisonsThis information is for educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment.
This content is for general informational and educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment. Always seek the guidance of a qualified healthcare provider with any questions you have about a medical condition, and never disregard professional medical advice or delay seeking it because of something you read here.
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Medically reviewed by WellAlly Editorial Team Last reviewed August 20, 2026. · Read our editorial policy