DOCK8 and hyperinsulinemic hypoglycemia, familial, 4: Two similar cases have been reported: a 30-year-old man with homozygous deletions of DOCK8 on chromosome 9p who developed PML with progressive neurological decline and seizures (Day-Williams et al. 2015) and a neurologically asymptomatic 21-year-old man with cytotoxic T-cell lymphoma and DOCK8 deficiency (variant not detailed) in whom PML was detected and was managed with HSCT (Soldatos et al. 2022).