A study with 39 MIS-C patients showed that one quarter of MIS-C patients harbored heterozygous missense mutations in primary hemophagocytic lymphohistiocytosis (pHLH) genes (LYST, STXBP2, PRF1, UNC13D, AP3B1) or the HLH-associated gene DOCK8 (four variants) [98]. Here, UNC13D is linked to COVID-19–associated multisystem inflammatory syndrome in children.