BH4-Deficient Hyperphenylalaninemia C (QDPR)

BH4-deficient hyperphenylalaninemia C is a rare autosomal recessive disorder caused by pathogenic variants in the gene QDPR. The clinical presentation of this disorder includes psychomotor retardation and progressive neurological deterioration and can occur as early as 4 to 5 months of age. Affected individuals may also exhibit microcephaly, low birth weight, tremors, hypotonia, and poor suckling. A special diet is required throughout the patient’s lifetime and despite treatment, some degree of brain abnormalities and developmental delay will persist. While life expectancy information for this disorder is currently unavailable, death generally occurs in infancy or childhood if left untreated.

For information about carrier frequency and residual risk, please see the residual risk table.

This gene is included on the following panel(s):