Persistent severe immunoglobulin deficiency after treatment with rituximab in a patient with MOGAD: A case report on how rituximab may, or may not, unmask primary immunodeficiencies

We present the clinical scenario of a young female patient, who presented with a progressive sensory motor tetraparesis and fatigue. Upon investigation anti-MOG-associated disease (MOGAD) was diagnosed. After high dose intravenous steroid therapy, an immunosuppressive treatment with rituximab, in six-monthly cycles, was initiated. With this, the neurological condition stabilized without any further relapses. But the patient started to suffer from recurrent respiratory tract infections, even after the treatment with rituximab was paused for two years. Investigations revealed an underlying strikingly severe IgA deficiency alongside an IgG Deficiency.