In 2011, Zhang et al. described 10 adult patients with FHL due to biallelic mutations in PRF1 (n = 7), MUNC13-4 (n = 2), and STXBP2 (n = 1) (24), showing that not only FHL2 could present later in the life. Here, STXBP2 is linked to hemophagocytic syndrome.