Autosomal recessive
Caused by changes in both copies of the PRODH gene, which makes proline oxidase, the first enzyme in proline breakdown. PRODH lies in the 22q11.2 region, and some affected people have a 22q11.2 deletion on one chromosome with a PRODH variant on the other.
Signs and symptoms
Raised proline levels in the blood, with many people having no symptoms. Some have seizures, intellectual disability or learning difficulties. Less often there are psychiatric features, including an increased risk of schizophrenia-spectrum conditions.
What a diagnosis changes
No specific treatment is established; care focuses on any seizures, developmental or psychiatric needs. Parents of an affected child are usually both carriers, so genetic counselling and carrier testing can be offered, including testing for a 22q11.2 deletion where relevant.
Genes analysed
Also known as
HPI; hyperprolinemia caused by mutation in PRODH; hyperprolinemia, type I; HYRPRO1; PRODH hyperprolinemia; proline oxidase deficiency
