Prevalence of rearrangements in the 22q11.2 region and population-based risk of neuropsychiatric and developmental disorders in a Danish population: a case-cohort study
Unbiased estimates of the 22q11.2 deletion population prevalence, mortality, disease risks, and diagnostic trajectories are lacking. Hence, we utilized the unbiased, representative Danish iPSYCH population case-cohort to provide the true population prevalence, trajectory of disease risk, and mortality of 22q11.2 CNVs.
About the study
We use epidemiological methods in conjunction with nationwide hospital registers to analyze the iPSYCH case-control cohort - i.e. cases born from 1981 to 2005 (n=57,377) with Attention-Deficit/Hyperactivity Disorder, Major Depressive Disorder, Schizophrenia, Autism or Bipolar Disorder as well as 30,000 randomly drawn individuals – to provide unbiased, population-adjusted estimates and 30-year long disease trajectories for major mental disorders.
Population prevalence in the Danish population was 1:3672 and 1:1606 for deletions and duplications, respectively, the mortality rate was zero and hazard ratios for mental disorders ranged from 1 to 82 comparably for both rearrangements. By age 32, 10% developed Attention-Deficit/Hyperactivity Disorder, Autism or Intellectual Disability; and deletion carriers had higher probability than duplication carriers of co-occurring Intellectual Disability and of epilepsy.
The significantly different prevalence of 22q11.2 duplications and deletions indicate distinct selective pressures on these rearrangements. While risk for congenital abnormalities, developmental delay, and Intellectual Disability is elevated in deletion carriers, the overall prevalence of mental disorders is higher in duplication carriers, which implies that identification and clinical monitoring should extend beyond congenital traits and into child and adolescent psychiatry.
Facts about the study
- This study adds to the existing literature as it is the first to provide the true population prevalence, trajectory of disease risk, and mortality of 22q11.2 CNVs utilizing the unbiased, representative Danish iPSYCH population case-cohort.
- Importantly, this study also reveals the risk of mental illness in non-clinically ascertained (i.e. non-congenital) individuals who harbour 22q11.2 rearrangements and allows us to address the notion that Schizophrenia in CNV carriers is often comorbid with Autism, epilepsy and Intellectual Disability.
- Trajectories highlight that the diverging pattern between duplications and deletions are primarily caused by comorbid Intellectual Disability in deletion carriers, suggesting that modelling duplications might be more appropriate for studies of single diagnoses.
The article "Prevalence of rearrangements in the 22q11.2 region and population-based risk for neuropsychiatric and developmental disorders in a Danish population: a case-cohort study" was published in The Lancet Psychiatry in June 2018.
Further information
Shantel Weinsheimer, Institute of Biological Psychiatry, Mental Health Center, Sct. Hans, Mental Health Services shantel.marie.weinsheimer@regionh.dk
Thomas Werge, Institute of Biological Psychiatry, Mental Health Center, Sct. Hans, Mental Health Services thomas.werge@regionh.dk