The patient belonged to a family in which human STK4 deficiency had originally been reported (previously published).[9] She had severe periodic neutropenia (600–1700/μL), episodic leukopenia (white blood cells 750–4430/μL, lymphocytes: 266–821/μL, CD3: 177/μL, CD4: 120/μL, CD8: 86/μL, CD19: 57/μL, CD56: 49/μL), high-IgG level (27.1 g/L), and low-IgM level (0.22 g/L) since childhood, receiving treatment with intravenous immunoglobulin (IVIg) 500 mg/kg, on a 3-week regular basis accompanied by clinical follow-up exams.[11]. This evidence concerns the gene STK4 and hyperinsulinemic hypoglycemia, familial, 4.