Severe Hematologic Abnormality Associated with an Inborn Error of Immunity (IEI)

Genetic sequencing improves our recognition of IEI's through genotype/phenotype correlations; however, variants of uncertain significance (VUSs) remain an obstacle. Functional assays provide avenues to identify variant pathogenicity but are infrequently commercially available, resulting in delayed diagnosis. We report the case of one such experience, and utilization of research-based functional testing to help characterize variant pathogenicity.