BH4-Deficient Hyperphenylalaninemia D (PCBD1)
BH4-deficient hyperphenylalaninemia D is an autosomal recessive disorder caused by pathogenic variants in the gene PCBD1. Affected individuals may present with intellectual disability, progressive developmental problems, movement disorders, difficulty swallowing, seizures, behavioral problems, and abnormal body temperature regulation, as well as hypomagnesemia and non-autoimmune diabetes mellitus that can present during puberty. The life expectancy for this disorder is normal with proper management.
For information about carrier frequency and residual risk, please see the residual risk table.