Copy Number Variations and Schizophrenia

Genetic components of microdeletion syndromes and their role in determining schizophrenia traits

Schizophrenia is a neuropsychiatric disorder characterized by various symptoms such as hallucinations, delusions, and disordered thinking. The etiology of this disease is unknown; however, it has been linked to many microdeletion syndromes that are likely to contribute to the pathology of schizophrenia. In this review we have comprehensively analyzed the role of various microdeletion syndromes, like 3q29, 15q13.3, and 22q11.2, which are known to be involved with schizophrenia. A variety of factors lead to schizophrenia phenotypes, but copy number variants that disrupt gene regulation and impair brain function and cognition are one of the causes that have been identified. Multiple case studies have shown that loss of one or more genes in the microdeletion regions lead to brain activity defects. In this article, we present a coherent paradigm that connects copy number variations (CNVs) to numerous neurological and behavioral abnormalities associated with schizophrenia. It would be helpful in understanding the different aspects of the microdeletions and how they contribute in the pathophysiology of schizophrenia.

Contribution of copy number variants on antipsychotic treatment response in Han Chinese patients with schizophrenia

BACKGROUND

Response to antipsychotic drugs (APD) varies greatly among individuals and is affected by genetic factors. This study aims to demonstrate genome-wide associations between copy number variants (CNVs) and response to APD in patients with schizophrenia.

METHODS

A total of 3030 patients of Han Chinese ethnicity randomly received APD (aripiprazole, olanzapine, quetiapine, risperidone, ziprasidone, haloperidol and perphenazine) treatment for six weeks. This study is a secondary data analysis. Percentage change on the Positive and Negative Syndrome Scale (PANSS) reduction was used to assess APD efficacy, and more than 50% change was considered as APD response. Associations between CNV burden, gene set, CNV loci and CNV break-point and APD efficacy were analysed.

FINDINGS

Higher CNV losses burden decreased the odds of 6-week APD response (OR = 0.66 [0.44, 0.98]). CNV losses in synaptic pathway involved in neurotransmitters were associated with 2-week PANSS reduction rate. CNV involved in sialylation (1p31.1 losses) and cellular metabolism (19q13.32 gains) associated with 6-week PANSS reduction rate at genome-wide significant level. Additional 36 CNVs associated with PANSS factors improvement. The OR of protective CNVs for 6-week APD response was 3.10 (95% CI: 1.33-7.19) and risk CNVs was 8.47 (95% CI: 1.92-37.43). CNV interacted with genetic risk score on APD efficacy (Beta = -1.53, SE = 0.66, P = 0.021). The area under curve to differ 6-week APD response attained 80.45% (95% CI: 78.07%-82.82%).

INTERPRETATION

Copy number variants contributed to poor APD efficacy and synaptic pathway involved in neurotransmitter was highlighted.

FUNDING

National Natural Science Foundation of China, National Key R&D Program of China, China Postdoctoral Science Foundation.

18q Deletion Syndrome-Associated Schizophrenia: A Case Report

INTRODUCTION

18q deletion syndrome is a rare genetic disorder characterized by various neurodevelopmental anomalies and medical issues. Although the occurrence of psychosis has been reported in a small number of cases, details regarding the nature of such symptoms and their response to treatment have not been described.

CASE PRESENTATION

We describe a 31-year-old male with a history of speech delays, autistic features, a tethered spinal cord, bilateral vertical talus, subaortic stenosis and aortic regurgitation, recurrent otitis media, mild hearing loss, and hypospadias, who experienced a first episode of psychosis in his late 20s. His psychotic symptoms included auditory hallucinations, various delusions, and disorganization of thought. Although his presentation is atypical in certain ways (e.g., exhibiting highly fluctuant symptoms), he nonetheless meets criteria for schizophrenia. Given his overall clinical picture, chromosomal microarray analysis was completed, which revealed a 19.78 Mb deletion at 18q21.32 from nucleotide 58,226,713 to 78,015,180 (GRCh37). Despite exhibiting a somewhat idiosyncratic response to numerous antipsychotic medications, he eventually achieved partial remission of symptoms with improved insight on relatively low dose oral aripiprazole therapy.

CONCLUSION

This is the first in-depth description of 18q deletion syndrome-associated schizophrenia. While our patient's atypical presentation and idiosyncratic response to treatment may be mediated by his comorbid diagnosis of autism, his unusual psychiatric phenotype may alternatively be directly related to his underlying genetic disorder. The description of additional cases in the future will hopefully help clarify matters further.

Clozapine Use in 22q11.2 Deletion Syndrome: A Systematic Review of the Literature

BACKGROUND

22q11.2 deletion syndrome confers significant risk for the development of schizophrenia. While current recommendations regarding the management of psychotic symptoms in affected individuals are generally in keeping with treatment guidelines for general schizophrenia populations, evidence for the use of clozapine has come from case reports and retrospective observational data. As no reviews on the topic currently exist, a systematic review of clozapine use in 22q11.2 deletion syndrome was completed.

METHODS

In November 2023, a literature search was completed using both PubMed and Scopus to identify English-language articles that reported the use of clozapine in humans with 22q11.2 deletion syndrome.

RESULTS

Twenty-six articles describing 57 individuals were deemed eligible for inclusion. Most individuals had a diagnosis of treatment-resistant schizophrenia. Where reported, the mean or median dose of clozapine was relatively low, and the majority of individuals exhibited a good response (approximately 65.5% across individual case reports/series). While seizures were unsurprisingly the most commonly reported serious adverse effect, the majority of individuals were able to remain on (or be restarted on) clozapine by having their dose decreased and/or by adding an anticonvulsant (most commonly valproate).

CONCLUSIONS

This review reaffirms that individuals with 22q11.2 deletion syndrome may benefit from clozapine therapy even at a low dose, assuming they meet criteria for treatment-resistant schizophrenia and provided no contraindications exist. However, given the increased incidence of seizures in 22q11.2 deletion syndrome, the use of prophylactic anticonvulsant therapy should be considered, and hypoparathyroidism/hypocalcemia screened for and corrected before the initiation of clozapine. It is also recommended that clozapine blood levels be monitored.

Late onset psychosis in a case of 15q11.2 BP1-BP2 microdeletion (Burnside-Butler) syndrome: A case report and literature review

Burnside-Butler syndrome is an inheritable genetic condition characterized by the partial deletion of specific genetic material located on chromosome 15q11. Individuals diagnosed with this particular medical condition display a variety of neuropsychiatric disorders, including psychosis, aggression, mood disorders, anxiety disorders, developmental disorders involving learning difficulties, language delays, autism spectrum disorders, and attention-deficit/hyperactivity disorder. The authors discuss the case of a 51-year-old Caucasian female diagnosed with Burnside-Butler syndrome at 8 years. The article highlights the importance of raising awareness regarding the complex nature and delayed onset of neuropsychiatric symptoms associated with this syndrome. It also emphasizes the need for comprehensive evaluation and multidisciplinary care for individuals affected by this uncommon condition.

Copy Number Variations in Neuropsychiatric Disorders

Neuropsychiatric disorders are complex conditions that represent a significant global health burden with complex and multifactorial etiologies. Technological advances in recent years have improved our understanding of the genetic architecture of the major neuropsychiatric disorders and the genetic loci involved. Previous studies mainly investigated genome-wide significant SNPs to elucidate the cross-disorder and disorder-specific genetic basis of neuropsychiatric disorders. Although copy number variations represent a major source of genetic variations, they are known risk factors in developing a variety of human disorders, including certain neuropsychiatric diseases. In this review, we demonstrate the current understanding of CNVs contributing to liability for schizophrenia, bipolar disorder, and major depressive disorder.