The objective of this study is to characterize the genetic architecture of a large cohort of CIDP patients to evaluate whether specific alleles/haplotypes are implicated in the risk of CIDP, in its clinical and immunological variability, severity, therapeutic response, and association with diabetes and other autoimmune diseases. We will genotype \>700,000 single nucleotide polymorphisms (SNPs) by using the Illumina Global Screening Array (GSA), of approximately 1000 patients with CIDP. About 3500 healthy controls from the Italian population have been already genotyped using GWAS from our genetic department. Alleles/haplotypes will be also compared between patients with typical CIDP and its variants, between CIDP patients with and without specific antibodies, between CIDP patients with and without comorbidities, between CIDP patients with low and high levels of disability and between CIDP patients with and without response to each individual treatment (IVIg, steroids, plasma exchange)