Finally, although the link between vocal cord paralysis and the occurrence 11 months later of severe MPO-ANCA disease cannot be definitively established as causal, the lack of evidence for an alternative origin of the laryngeal disease, the presence of MPO-ANCA from the start, the improvement associated with glucocorticoids and immunosuppressants, and the long-term follow-up confirming the diagnosis of MPA, lead us to believe that the most likely explanation of the cordal paralysis was related to involvement of the recurrent laryngeal nerve by MPA. This evidence concerns the gene MPO and microscopic polyangiitis.