Cytoband (human 10q22.1 PCBD1) & (mouse 10qB4 Pcbd1).
Here I present: “Hyperphenylalaninemia“, Victor McKusick, Mendelian Inheritance in Man’, 1966. (PCBD1) icd10=E70.1
PRELUDE.
The metabolic distinction between HPA (E70.1) & PKU (E70.0) matters clinically.
INTRODUCTION.
Icd10=E70.1 Hyperphenylalaninemia (HPA)
This refers to elevated blood phenylalanine without classic phenylketonuria.
It includes: Mild PAH enzyme deficiency
BH₄ cofactor defects
Transient neonatal hyperphenylalaninemia.
Benign or non-PKU phenylalanine elevations.
Neurologic injury is not inevitable and dietary restriction may be mild or unnecessary depending on levels.
Phenylketonuria (PKU)
Icd10=E70.0 This is classic PAH deficiency, with:
Markedly high phenylalanine.
Neurotoxicity without treatment.
Mandatory lifelong dietary control.
PKU ⊂ Hyperphenylalaninemia, but not all HPA is PKU.
Phenylalanine Metabolism Disorders
Hyperphenylalaninemia (E70.1)
PKU (E70.0)
Clinical Philosophy
Hyperphenylalaninemia is a biochemical phenotype.
PKU is a neurotoxic disease entity.
Confusing them leads to over-restriction, mislabeling, and unnecessary lifelong dietary burden.
Tetrahydrobiopterin (BH4)-deficient hyperphenylalaninemia–D is an autosomal recessive disorder characterized by mild-transient hyperphenylalaninemia often detected by newborn screening. Patients also show increased excretion of 7-biopterin. Affected individuals are asymptomatic and show normal psychomotor development, although transient neurologic deficits in infancy have been reported. Patients may also develop hypomagnesemia and nonautoimmune diabetes mellitus during puberty.
PCBD1-Hyperphenylalaninemia (PCBD1).
There is evidence that familial hyperphenylalaninemia can be caused by mutation in the pterin carbinolamine dehydratase-1 (PCBD1) gene encoded on genomic coordinate and cytoband 10q22.1 in humans.
