Inclusion Criteria:  Male or female, 18 years of age or older Patients with CIDP or NMMBC or definite anti-MAG neuropathy according to the criteria defined by EFNS 2010 Signing of an informed consent. Affiliation or beneficiary of the social security system  Exclusion Criteria:  Subjects with a medical condition deemed by the investigator to interfere with the proper conduct of the study. Positive pregnancy test. Pregnant or breastfeeding woman (a urine pregnancy test will be performed for women of childbearing age) A urine The results will be communicated to the patient by a doctor of her choice. Persons deprived of their liberty by a judicial or administrative decision; Persons hospitalised without consent; Persons of full age who are subject to a legal protection measure or who are unable to express their consent. Incapacity of the subject to cooperate.