Chronic inflammatory demyelinating polyradiculoneuropathy (CIDP) is an immune-mediated disorder of peripheral nerves. Intravenous immunoglobulins (IVIg) are a first line therapy for CIDP. The investigators used a transcriptomic approach to compare the gene expression profiles in the peripheral blood of patients having a CIDP or autoimmune diseases, before and after IVIg treatment, in order to identify their mechanism of action in this condition, to lead to a better understanding of CIDP pathophysiology, and potentially determine factors associated with the response to the treatment.

We study the change of the:

• gene profile on transcriptome analysis of peripheral blood
• T cell repertory
• igG dosage
• immunological profile

Before IVIG (T1 time) and and 3 weeks after IVIg treatment (T2 time). On a population of patients having: CIDP, autoimmune muscular disease, Clarkson syndrome, or autoimmune diseases.

We also search for polymorphism of FCgammareceptor, TKPC et CASP3 genes in CIDP patients

Inclusion criteria :

• Age ≥ 18 years old
• Obtained informed consent
• Patient having a definite or probable CIDP according to EFNS/PNS criteria or atypical CIDP corresponding to patients having the EFNS/PNS clinical criteria and at least two EFNS/PNS supportive criteria
• Or
• Patient having a muscular autoimmune disease, or a Clarkson syndrome or other autoimmune disease
• Currently treated by IVIG

Exclusion criteria :

• pregnancy
• breastfeeding