Genetic Risk Factors for Multi-system Inflammatory Syndrome in Children and Pediatric Post COVID Condition

We will perform Whole Exome Sequencing on DNA from saliva. We will include: Children with a history of MIS-C; children with post-COVID condition; and controls in order to identify rare, high impact genetic variants in immunological genes and pathways in children with a history of MIS-C or pediatric post-COVID condition.

Inclusion Criteria:Children (<19 years) with a history of MIS-C: as defined according to WHO criteria.Children (<19 years) with post-COVID condition: as defined according to the WHO case definition. This includes a history of probable or confirmed prior SARS-CoV-2 infection, with signs and symptoms (including fatigue, shortness of breath, cognitive dysfunction) that are present after 12 weeks, last at least 2 months, have an impact on daily functioning and are not explained by an alternative diagnosis.'Exposed' control group: children (<19 years of age): a history of proven SARS-CoV-2 infection (RT-PCR, antigen test or serology positive). If the child has been vaccinated against SARS-CoV-2, the first documented infection must have been prior to the vaccination.Exclusion Criteria:No informed consentGroup 1 (MIS-C): no specific exclusion criteriaGroup 2 (post-COVID condition): other plausible cause of symptoms AND/OR a history compatible with chronic fatigue syndrome prior to infection with SARS-CoV-2.Children with a history of MIS-C who suffer prolonged signs and symptoms will be included in the MIS-C group.Group 3 ('exposed' control group): MIS-C or post-COVID condition; AND/OR Moderate or severe course of COVID-19, as defined in the COPP-study (N20.043) (need for supplemental oxygen and/or intensive care admission because of COVID-19 and/or death) AND/OR first degree relative with long COVID or MIS-C.