CDKN1A and myeloid sarcoma: The aims were to analyze whether the selected seven variants are associated with MS severity, whether they affect the mRNA expression levels of the top three ferroptosis-related DEGs (CDKN1A, MAP1B and EGLN2) in RRMS and SPMS patients, and whether they are associated with MS neurological deficit and severity parameters (EDSS, MSSS, gARMSS), taking into account the existing haplotypes.