Early-onset (pediatric and adolescent) multiple sclerosis (MS) is a chronic autoimmune and neurodegenerative disorder of the central nervous system, which accounts for 3–5% of all MS cases. The major histocompatibility complex (MHC) with its polymorphisms has been the genetic locus with the most robust association with adult MS, since its first discovery in the 1970s. Nowadays, human leukocyte antigen (HLA) typing studies and genome-wide association studies (GWAS) have tried to provide insight into the genetics of early-onset MS and their role in disease diagnosis, prognosis, and therapeutic decision-making. Fundamental genetic similarities have emerged, supporting the assumption that MS shares similar genetic variants and biological processes in all age groups. In this chapter, we considered it useful to collect all the available data concerning the HLA distribution in early-onset MS, given the absence of a review paper with such an approach. We additionally aimed toward the summarization of the association of the HLA frequencies in early-onset MS and the main acquired demyelinating disorders that are considered in differential diagnosis of early-onset MS, like ADEM, NMO/NMOSD, and anti-MOG encephalopathy, for further understanding and current or future research in this promising field.
Part of the book: Human Leukocyte Antigen (HLA)