Mosaic TLR8 gain-of-function in an elderly female treated with JAK inhibitor and adjunctive therapy.

We report severe neutropenia in a 77-year-old female with mosaic TLR8 gain-of-function due to a novel variant. Treatment with ruxolitinib, prednisone, and GM-CSF resulted in clinical improvement. This case expands the phenotypic spectrum beyond pediatric and male cohorts, highlighting mosaicism in late-onset immune dysregulation.