Focus on Causality in ESC/iPSC-Based Modeling of Psychiatric Disorders

Area of Science:

• Neuroscience
• Genetics
• Stem Cell Biology

Background:

• Genome-wide association studies (GWAS) have identified numerous genetic variants linked to psychiatric disorders.
• Understanding the causal role and functional impact of these variants, especially common low-risk ones, remains a significant challenge.
• Embryonic stem cells (ESCs) and induced pluripotent stem cells (iPSCs) offer powerful models for studying these genetic associations in relevant cell types.

Purpose of the Study:

• To analyze the contribution of ESC and iPSC models to understanding causal relationships between genetic risk variants and neuronal phenotypes.
• To review progress in studying both rare, highly penetrant variants and common, low-risk variants in psychiatric disorders like schizophrenia (SCZ) and bipolar disorder (BD).
• To discuss the implications and challenges of using (epi-) genetic editing techniques in these stem cell models.

Main Methods:

• Utilizing patient-specific induced pluripotent stem cells (iPSCs) derived from individuals with psychiatric disorders.
• Employing (epi-) genetic editing techniques to investigate the functional consequences of specific genetic variants.
• Analyzing neuronal phenotypes in vitro to establish cause-effect relationships between genetic risk and cellular function.

Main Results:

• ESC and iPSC models have facilitated the investigation of genetic risk variants in disease-relevant human cells.
• The shift towards studying common low-risk variants using advanced editing techniques provides new insights into complex psychiatric disorders.
• These approaches are crucial for dissecting the functional impact of genetic associations identified through GWAS.

Conclusions:

• ESC/iPSC-based modeling, particularly with advanced genetic editing, is revolutionizing the study of causality in psychiatric disorders.
• While offering new insights, these methods also present challenges related to interpretability and experimental design.
• Future developments in stem cell biology and genetic technologies will further enhance our ability to model and understand psychiatric disease pathogenesis.