All Patients (N=34)	Patients Failing Conventional Therapy (n=27)
Age at HLH diagnosis, years (median [range])	0.85 [0.03, 13.0]	1.00 [0.2-13.0]
Sex (n [%])
Male	16 [47.1]	11 [40.7]
Female	18 [52.9]	16 [59.3]
HLH Genetic Confirmation (n [%])	27 [79.4]	22 [81.5]
FHL1	2 [5.9]	0
FHL2	7 [20.6]	5 [18.5]
FHL3	8 [23.5]	7 [25.9]
FHL4	1 [2.9]	1 [3.7]
FHL5	2 [5.9]	2 [7.4]
Griscelli Syndrome type 2	5 [14.7]	5 [18.5]
X-linked Lymphoproliferative Disorder 1	1 [2.9]	1 [3.7]
X-linked Lymphoproliferative Disorder 2	1 [2.9]	1 [3.7]