Copy Number Variant Deletions Linked to Earlier Schizophrenia Onset
Key Clinical Summary
- Individuals with schizophrenia had a significantly higher copy number variant (CNV) burden than healthy controls (P = 9.3e-03).
- A greater number of CNV deletions, but not duplications, was significantly associated with earlier age at onset (AAO; P = 9.28e-04).
- Higher CNV load clustered in patients with early-onset schizophrenia, suggesting a potential neurodevelopmental mechanism.
Copy number variants (CNV), which involve the deletion or duplication of DNA segments, have been associated with both neurodevelopmental and psychiatric disorders. According to findings published in Schizophrenia Research, increased CNV burden, specifically deletions, is associated with earlier age at onset (AAO) of schizophrenia, a key predictor of disease severity and long-term functional outcomes.
Study Findings
The study evaluated 836 individuals, including 323 patients with schizophrenia (31.6% female) and 513 healthy controls (52.1% female). Participants with a confirmed schizophrenia diagnosis were recruited from the inpatient and outpatient psychiatric units at the Hospital Universitari Institut Pere Mata in Spain, while healthy controls were pulled from 2 population-based samples.
As part of the wave 3 schizophrenia genome-wide association study (GWAS) meta-analysis, CNVs were assessed using single nucleotide polymorphisms (SNP) genotyping. The researchers examined overall CNV burden and CNV length, analyzing their association with AAO using linear regression models.
Patients with schizophrenia demonstrated a significantly higher overall CNV burden compared with controls (P = 9.3e-03), reinforcing prior evidence that rare structural genomic variants contribute to schizophrenia risk.
The number of CNV deletions was significantly associated with earlier AAO (P = 9.28e-04). In contrast, CNV duplications did not show a statistically significant relationship with age at onset.
Patients with the earliest onset of schizophrenia exhibited the highest CNV load. The data suggested a graded effect, with CNV burden trending downward as AAO increased. These findings indicate that deletion-type structural variants may play a specific role in accelerating disease onset.
Clinical Implications
Age at onset is a clinically meaningful marker in schizophrenia, with earlier onset consistently associated with more severe symptomatology, poorer functional recovery, and greater long-term disability. Identifying genetic factors that influence AAO may help refine risk stratification and prognostication.
The present findings suggest that CNV deletions may not only increase susceptibility to schizophrenia but also influence disease timing. If validated in larger cohorts, CNV profiling could potentially inform early identification strategies in high-risk populations. Understanding structural genomic burden may help clarify disease heterogeneity and guide investigation into targeted therapeutic approaches that address disrupted neurodevelopmental pathways.
Expert Commentary
“This study highlights the importance of CNV burden in elucidating the genetic architecture underlying schizophrenia and AAO,” wrote Gerard Muntané, PhD, Hospital Universitari Institut Pere Mata, Reus, Catalonia, Spain, and coauthors. The researchers also noted that the study highlights “the value of using genetic tests to detect CNVs in informing future therapeutic approaches.”
“As our findings are based on SNP array data, future research utilizing high-resolution whole-genome sequencing will be essential to define precise breakpoints and identify smaller, potentially pathogenic variants,” they concluded.
