Loss of function of OTUD7A in the schizophrenia- associated 15q13.3 deletion impairs synapse development and function in human neurons

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.

Mechanisms of copy number variants in neuropsychiatric disorders: From genes to therapeutics

Copy number variants (CNVs) are genomic imbalances strongly linked to the aetiology of neuropsychiatric disorders such as schizophrenia and autism. By virtue of their large size, CNVs often contain many genes, providing a multi-genic view of disease processes that can be dissected in model systems. Thus, CNV research provides an important stepping stone towards understanding polygenic disease mechanisms, positioned between monogenic and polygenic risk models. In this review, we will outline hypothetical models for gene interactions occurring within CNVs and discuss different approaches used to study rodent and stem cell disease models. We highlight recent work showing that genetic and pharmacological strategies can be used to rescue important aspects of CNV-mediated pathophysiology, which often converges onto synaptic pathways. We propose that using a rescue approach in complete CNV models provides a new path forward for precise mechanistic understanding of complex disorders and a tangible route towards therapeutic development.

Patent highlights October-November 2022

A snapshot of recent noteworthy developments in the patent literature of relevance to pharmaceutical and medical research and development.

Neurodevelopmental disturbances in schizophrenia: evidence from genetic and environmental factors

Since more than 3 decades, schizophrenia (SZ) has been regarded as a neurodevelopmental disorder. The neurodevelopmental hypothesis proposes that SZ is associated with genetic and environmental risk factors, which influence connectivity in neuronal circuits during vulnerable developmental periods. We carried out a non-systematic review of genetic/environmental factors that increase SZ risk in light of its neurodevelopmental hypothesis. We also reviewed the potential impact of SZ-related environmental and genetic risk factors on grey and white matter pathology and brain function based on magnetic resonance imaging and post-mortem studies. Finally, we reviewed studies that have used patient-derived neuronal models to gain knowledge of the role of genetic and environmental factors in early developmental stages. Taken together, these studies indicate that a variety of environmental factors may interact with genetic risk factors during the pre- or postnatal period and/or during adolescence to induce symptoms of SZ in early adulthood. These risk factors induce disturbances of macro- and microconnectivity in brain regions involving the prefrontal, temporal and parietal cortices and the hippocampus. On the molecular and cellular level, a disturbed synaptic plasticity, loss of oligodendrocytes and impaired myelination have been shown in brain regions of SZ patients. These cellular/histological phenotypes are related to environmental risk factors such as obstetric complications, maternal infections and childhood trauma and genetic risk factors identified in recent genome-wide association studies. SZ-related genetic risk may contribute to active processes interfering with synaptic plasticity in the adult brain. Advances in stem cell technologies are providing promising mechanistic insights into how SZ risk factors impact the developing brain. Further research is needed to understand the timing of the different complex biological processes taking place as a result of the interplay between genetic and environmental factors.

Brain Lipids and Lipid Droplet Dysregulation in Alzheimer's Disease and Neuropsychiatric Disorders

Background

Lipids are essential components of the structure and for the function of brain cells. The intricate balance of lipids, including phospholipids, glycolipids, cholesterol, cholesterol ester, and triglycerides, is crucial for maintaining normal brain function. The roles of lipids and lipid droplets and their relevance to neurodegenerative and neuropsychiatric disorders (NPDs) remain largely unknown.

Summary

Here, we reviewed the basic role of lipid components as well as a specific lipid organelle, lipid droplets, in brain function, highlighting the potential impact of altered lipid metabolism in the pathogenesis of Alzheimer's disease (AD) and NDPs.

Key Messages

Brain lipid dysregulation plays a pivotal role in the pathogenesis and progression of neurodegenerative and NPDs including AD and schizophrenia. Understanding the cell type-specific mechanisms of lipid dysregulation in these diseases is crucial for identifying better diagnostic biomarkers and for developing therapeutic strategies aiming at restoring lipid homeostasis.

Modeling common and rare genetic risk factors of neuropsychiatric disorders in human induced pluripotent stem cells

Recent genome-wide association studies (GWAS) and whole-exome sequencing of neuropsychiatric disorders, especially schizophrenia, have identified a plethora of common and rare disease risk variants/genes. Translating the mounting human genetic discoveries into novel disease biology and more tailored clinical treatments is tied to our ability to causally connect genetic risk variants to molecular and cellular phenotypes. When combined with the Clustered Regularly Interspaced Short Palindromic Repeats (CRISPR)/CRISPR-associated (Cas) nuclease-mediated genome editing system, human induced pluripotent stem cell (hiPSC)-derived neural cultures (both 2D and 3D organoids) provide a promising tractable cellular model for bridging the gap between genetic findings and disease biology. In this review, we first conceptualize the advances in understanding the disease polygenicity and convergence from the past decade of iPSC modeling of different types of genetic risk factors of neuropsychiatric disorders. We then discuss the major cell types and cellular phenotypes that are most relevant to neuropsychiatric disorders in iPSC modeling. Finally, we critically review the limitations of iPSC modeling of neuropsychiatric disorders and outline the need for implementing and developing novel methods to scale up the number of iPSC lines and disease risk variants in a systematic manner. Sufficiently scaled-up iPSC modeling and a better functional interpretation of genetic risk variants, in combination with cutting-edge CRISPR/Cas9 gene editing and single-cell multi-omics methods, will enable the field to identify the specific and convergent molecular and cellular phenotypes in precision for neuropsychiatric disorders.