IL17A and arthritic joint disease: Moreover, GAS-specific Th17 cells are found in the tonsils of patients exposed to GAS.26,54 Interleukin-17 is likely a factor associated with the 3 overlapping arthritis types that we see in our cohort55,56 and has also been reported to be present in high levels in pediatric patients with OCD.57 Similar to the PANDAS mouse model, repeated GAS infections may also play a role in psoriasis, thus making the nail pitting finding in our cohort relevant because this is a common finding in psoriasis.58