hyperphenylalaninemia due to DNAJC12 deficiency (MONDO_0044304) can be described as follows. Mild non-BH4-deficient hyperphenylalaninemia (HPANBH4) is an autosomal recessive disorder characterized by increased serum phenylalanine usually detected by newborn screening and associated with highly variable neurologic defects, including movement abnormalities and intellectual disability. Laboratory analysis shows dopamine and serotonin deficiencies in the cerebrospinal fluid, and normal BH4 metabolism. Evidence suggests that treatment with neurotransmitter precursors can lead to clinical improvement or even prevent the neurologic defects if started in infancy (summary by {1:Anikster et al., 2017}).