Although ultrasound has a proven value in mononeuropathy and could be useful in diagnosis of atypical cases of MMN, it is not widely available, and not all neurophysiologists are trained in ultrasound.24Anti-GM1 igM antibodies are very helpful to confirm the diagnosis of MMN, but a nationwide case series in Japan only found their presence in 54% of the cases.25 The gene discussed is CD40LG; the disease is mononeuropathy.