Given the significant implication of a potential dual diagnosis, and that standard of care for DOCK8 deficiency is haematopoietic stem cell transplantation (HSCT) [18, 29–31], it was critical to confirm the pathogenicity of the IFNAR1 variant and investigate the impact of the novel DOCK8 variant to determine the most appropriate diagnosis and patient management strategy. This evidence concerns the gene IFNAR1 and hyperinsulinemic hypoglycemia, familial, 4.