HLA-C and myeloid sarcoma: Multiple Sclerosis (MS) is an immunologically associated disorder of the central nervous system (CNS), being characterized by demyelination and degeneration of neural cells.   1  Being considered as a multifactorial disease, genetic plays a major role in MS.   2  The first and most significant genetic association was identified with major histocompatibility complex (MHC) alleles in 1972;   3  where many of the related genes are involved in various immunological processes.