XIAP and hyperinsulinemic hypoglycemia, familial, 4: Given that patients with XIAP deficiency are likely to be more susceptible to complications such as graft-versus-host disease and post-HSCT HLH (48), our experience of a single patient with XIAP deficiency suggests that ruxolitinib may have a beneficial effect in controlling both hyperinflammation and post-HSCT HLH activity; however, larger studies are needed to confirm its efficacy.