Hyperprolinemia as a clue in the diagnosis of a patient with a psychiatric disorder

Background: Over the last few years, microdeletions of the 22q11.2 region responsible for DiGeorge syndrome, or velocardiofacial syndrome, have been increasingly related to neuropsychiatric disorders including schizophrenia and bipolar disorders. These signs seem to be related to certain genes located in the hemideleted region as the proline dehydrogenase (PRODH) and the catecholo-methyltransferase (COMT) genes. The PRODH or proline oxidase deficiency is responsible for hyperprolinemia type 1 (HPI) also causing psychiatric manifestations. Case Report: We describe a 17 year old boy with previous mild psychomotor and speech delay, mild cognitive impairment, and obsessive behaviours who started his adolescent psychiatric care presenting irritablemood and aggressive behaviour with schizophrenia symptoms that scored a “severely ill” level PANSS assessment. Symptoms got worse when he was treated with valproic acid and plasma aminoacids showing increase in alanine and proline, suggested a mitochondrial involvement of the proline metabolic pathway. Results: Mild dysmorphia suggested a possible 22q11.2 deletion genetically confirmed involving both the PRODH and COMT regions. HPI that can present with psychiatric features is however a recessive disorder and therefore the symptoms could not be solely explained by this genetic deletion. Additional investigations also showed disclosed a p.L289m (c.1865 T > A) mutation in the PRODH gene. Discussion: We believe that the association of this mutation together with the 22q11.2 deletion would lead to a decrease of functional protein. Although it may be difficult to diagnosis chromosomal abnormalities in patients with no clear malformations and mild dysmorphic features as in this patient we emphasize need to investigate the aetiology in patients with psychiatric symptoms, especially if they have other systemic manifestations such as developmental delay or psychotic symptoms, as it may be important in the management of the patients.