An efficient diagnosis: A patient with X‐linked inhibitor of apoptosis protein (XIAP) deficiency in the setting of infantile hemophagocytic lymphohistiocytosis was diagnosed using high serum interleukin‐18 combined with common laboratory parameters. Issue 8 (21st February 2022) - Higuchi, Toru; Izawa, Kazushi; Miyamoto, Takayuki; Honda, Yoshitaka; Nishiyama, Atsuko; Shimizu, Masaki; Takita, Junko; Yasumi, Takahiro