The use of UHF probes allows better visualization of the nerve's internal structure and, based on our data, we could hypothesize that an increase in f-CSA with or without an increase in n-CSA would point the diagnosis towards CIDP or a variant thereof, whereas an increase in n-CSA even in the most distal parts of the nerve without an increase in f-CSA could be a marker of anti-MAG neuropathy. The gene discussed is MAG; the disease is chronic inflammatory demyelinating polyradiculoneuropathy.