Current psychiatric diagnoses, although heritable, have not been clearly mapped onto distinct underlying pathogenic processes. The same symptoms often occur in multiple disorders, and a substantial proportion of both genetic and environmental risk factors are shared across disorders. However, the relationship between shared symptoms and shared genetic liability is still poorly understood.

Well-characterised, cross-disorder samples are needed to investigate this matter, but few currently exist. Our aim is to develop procedures to purposely curate and aggregate genotypic and phenotypic data in psychiatric research.

As part of the Cardiff MRC Mental Health Data Pathfinder initiative, we have curated and harmonised phenotypic and genetic information from 15 studies to create a new data repository, DRAGON-Data. To date, DRAGON-Data includes over 45 000 individuals: adults and children with neurodevelopmental or psychiatric diagnoses, affected probands within collected families and individuals who carry a known neurodevelopmental risk copy number variant.

We have processed the available phenotype information to derive core variables that can be reliably analysed across groups. In addition, all data-sets with genotype information have undergone rigorous quality control, imputation, copy number variant calling and polygenic score generation.

DRAGON-Data combines genetic and non-genetic information, and is available as a resource for research across traditional psychiatric diagnostic categories. Algorithms and pipelines used for data harmonisation are currently publicly available for the scientific community, and an appropriate data-sharing protocol will be developed as part of ongoing projects (DATAMIND) in partnership with Health Data Research UK.

22q11.2 deletion syndrome (22q11.2DS) is associated with a high risk of childhood as well as adult psychiatric disorders, in particular schizophrenia. Childhood cognitive deterioration in 22q11.2DS has previously been reported, but only in studies lacking a control sample.

To compare cognitive trajectories in children with 22q11.2DS and unaffected control siblings.

A longitudinal study of neurocognitive functioning (IQ, executive function, processing speed and attention) was conducted in children with 22q11.2DS (n = 75, mean age time 1 (T1) 9.9, time 2 (T2) 12.5) and control siblings (n = 33, mean age T1 10.6, T2 134).

Children with 22q11.2DS exhibited deficits in all cognitive domains. However, mean scores did not indicate deterioration. When individual trajectories were examined, some participants showed significant decline over time, but the prevalence was similar for 22q11.2DS and control siblings. Findings are more likely to reflect normal developmental fluctuation than a 22q11.2DS-specific abnormality.

Childhood cognitive deterioration is not associated with 22q11.2DS. Contrary to previous suggestions, we believe it is premature to recommend repeated monitoring of cognitive function to identifying individual children with 22q11.2DS at high risk of developing schizophrenia.