LY9 and COVID-19–associated multisystem inflammatory syndrome in children: Abuhammour et al. (2022) have previously reported this variant in individuals with MIS-C. LY9 is involved in the IL-2 signalling pathway and is essential for modulating immune responses and activating lymphocytes. In addition, we have identified a non-frameshift deletion in the LY9 gene, namely p.170_171del, which has not been reported in ClinVar and is categorized as benign in ACMG classifications.