KMT2D and Primary hemophagocytic lymphohistiocytosis: Other pathogenic variants in genes were each found in a single patient, including CDKL5 [16], COL4A1, CPA6, CSNK2A1, DNM1, DYNC1H1, GABRG2, IRF2BPL, KCNQ2, KMT2D, LAMB1, PPT1, PRRT2, SLC2A1, SMARCB1, SYNGAP1, and UNC13D. The latter gene was found to harbor biallelic pathogenic variants in one patient with primary hemophagocytic lymphohistiocytosis who subsequently developed ADEM.