Progressive choreodystonia in X-linked hyper-IgM immunodeficiency: a rare but recurrent presentation.

An association between movement disorders and immune-system dysfunction has been described in the context of rare genetic diseases such as ataxia telangiectasia as well as infectious encephalopathies. We encountered a male patient who presented immunodeficiency of unknown etiology since childhood. A medication-refractory, progressive choreodystonic movement disorder emerged at the age of 42 years and prompted an exome-wide molecular testing approach. This revealed a pathogenic hemizygous variant in CD40LG, the gene implicated in X-linked hyper-IgM syndrome. Only two prior reports have specifically suggested a causal relationship between CD40LG mutations and involuntary hyperkinetic movements. Our findings thus confirm the existence of a particular CD40LG-related condition, combining features of compromised immunity with neurodegenerative movement abnormalities. Establishing the diagnosis is crucial because of potential life-threatening immunological complications.