Distributions and frequencies of pathogenic or likely pathogenic variants in the most frequently affected genes associated with HLH in our cohort. (A) Distributions and frequencies of pathogenic or likely pathogenic variants in PRF1. (B) Distributions and frequencies of pathogenic or likely pathogenic variants in STXBP2. (C) Distributions and frequencies of pathogenic or likely pathogenic variants in UNC13D. Note: the 253-kb inversion is not shown in the graph. (D) Distributions and frequencies of pathogenic or likely pathogenic variants in XIAP. (A-D) The total number of alleles affected with each variant is indicated in the circles. *Novel variants.