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.

A 1.77 Mb deletion in 3p26.3 encompassing CNTN6 and CNTN4 genes: case report

Chromosome microarray analysis is a powerful diagnostic tool and is being used as a first-line approach to detect chromosome imbalances associated with intellectual disability, dysmorphic features and congenital abnormalities. This test enables the identification of new copy number variants (CNVs) and their association with new microdeletion/microduplication syndromes in patients previously without diagnosis. We report the case of a 7 year-old female with moderate intellectual disability, severe speech delay and auto and hetero aggressivity with a previous 45,XX,der(13;14)mat karyotype performed at a younger age. Affymetrix CytoScan 750K chromosome microarray analysis was performed detecting a 1.77 Mb deletion at 3p26.3, encompassing 2 OMIM genes, CNTN6 and CNTN4. These genes play an important role in the formation, maintenance, and plasticity of functional neuronal networks. Deletions or mutations in CNTN4 gene have been implicated in intellectual disability and learning disabilities. Disruptions or deletions in the CNTN6 gene have been associated with development delay and other neurodevelopmental disorders. The haploinsufficiency of these genes has been suggested to participate to the typical clinical features of 3p deletion syndrome. Nevertheless inheritance from a healthy parent has been reported, suggesting incomplete penetrance and variable phenotype for this CNV. We compare our patient with other similar reported cases, adding additional value to the phenotype-genotype correlation of deletions in this region.

The clinical significance of 15q11.2 BP1-BP2 duplications: - Where do we stand?

The 15q11.2-q13 region has been well characterized, being associated with a range of syndromatic copy number variants (CNVs), and comprises five established break points sites (BP1 to BP5). While the clinical effect for BP1-BP3, BP2-BP3 and BP4-BP5 CNVs is well established, the same cannot be said for BP1-BP2 CNVs. Recently the 15q11.2 BP1-BP2 deletion has been reviewed, emerging as a microdeletion syndrome with low penetrance and variable expressivity being the CNV frequently inherited from a healthy parent. This microdeletion is considered to be a risk factor for several neurodevelopment disorders. For the reciprocal duplication the picture has been less conclusive. Aiming for a better understanding of the clinical significance of this CNV, we collected patients with intellectual disability and/or other clinical features, referred for microarray testing, gathering clinical details for the ones with the duplication. Data was collected from two genetic laboratories. With a total of 1545 patients, we identified eleven carrying the duplication at 15q11.2 BP1-BP2. It was possible to assess inheritance in only four cases, all inherited from a healthy parent. All patients presented intellectual disability,and facial dysmorphism was the second most common feature observed. Microcephaly, autism, congenital abnormalities, dystonia and cataplexy where reported individually. The magnitude of the effect of 15q11.2 duplication remains elusive, and the outcome unclear, posing a major challenge to genetic counseling. Nevertheless, we expect the collection of more of these cases will establish this gain, as it happened with the reciprocal deletion, as a microduplication syndrome with low penetrance and variable expressivity.