Variations and expression features of CYP2D6 contribute to schizophrenia risk

Area of Science:

• Genetics
• Neuroscience
• Pharmacogenomics

Background:

• Genome-wide association studies (GWAS) have identified 145 loci associated with schizophrenia (SCZ), but the underlying biological mechanisms are not well understood.
• Understanding the genetic basis of SCZ is crucial for developing effective treatments.

Purpose of the Study:

• To identify genes and splicing junctions associated with SCZ risk by integrating RNA-seq and genotype data.
• To pinpoint causal variants and implicated biological pathways contributing to SCZ.
• To explore the role of the CYP2D6 gene in SCZ pathogenesis and drug metabolism.

Main Methods:

• Analysis of 1497 RNA-seq and genotype data to identify expression quantitative trait loci (eQTLs) for genes (eGenes) and exon-exon junctions (eJunctions).
• Colocalization analysis using SMR and fine mapping to integrate eQTLs with SCZ GWAS data.
• Utilized ChIP-seq and DNA methylation data to identify causal variants.
• Hypothesis-free enrichment analysis to identify implicated pathways.

Main Results:

• Identified 171 genes and 8 splicing junctions in 4 genes (SNX19, ARL6IP4, APOPT1, CYP2D6) potentially contributing to SCZ susceptibility.
• CYP2D6 showed significant association with SCZ SNPs in both eGene and eJunction analyses.
• A specific variant (rs16947) in CYP2D6 was strongly linked to increased exon 3 skipping.
• Enrichment analysis revealed CYP2D6's involvement in the metabolism of drugs like codeine, tamoxifen, and citalopram.

Conclusions:

• This study elucidates the genetic architecture of SCZ by identifying novel candidate genes and splicing events.
• The findings highlight CYP2D6 as a potential key player in SCZ, influencing both disease susceptibility and drug response.
• The identified genetic factors and pathways offer promising new targets for therapeutic interventions in schizophrenia.