Atypical immunologic response in a patient with CRIM-negative Pompe disease

► We report the clinical and immunologic response to ERT in a child with Pompe. ► This patient developed anti-rhGAA antibody titers that were blunted yet persistent. ► This immunologic response was unlike previously described groups. ► The persistence of antibodies likely led to her poor clinical outcome. ► Immunomodulatory therapies may be needed in the most severely affected patients.