Aim
The aim of the study was to describe the clinical manifestations of 22q11.2 deletion syndrome patients in the Finnish paediatric population.

Methods
Nationwide registry data including all diagnoses and procedures of every public hospital in Finland between 2004 and 2018 along with mortality and cancer registry data were retrieved. Patients born during the study period and with an ICD-10 code of D82.1 or Q87.06 were included as having 22q11.2 deletion syndrome. A control group was formed with patients born during the study period and with benign cardiac murmur diagnosed under the age of 1 year.

Results
We identified 100 pediatric patients with 22q11.2 deletion syndrome (54% males, median age at diagnosis <1 year, median follow-up 9 years). Cumulative mortality was 7.1%. Among patients with 22q11.2 deletion syndrome, 73.8% had congenital heart defects, 21.8% had cleft palate, 13.6% had hypocalcaemia, and 7.2% had immunodeficiencies. Furthermore, 29.6% were diagnosed with autoimmune diseases, 92.9% had infections, and 93.2% had neuropsychiatric and developmental issues during follow-up. Malignancy was found in 2.1% of the patients.

Conclusion
The 22q11.2 deletion syndrome is associated with increased mortality and substantial multimorbidity in children. A structured multidisciplinary approach is necessary for managing patients with 22q11.2 deletion syndrome.