The invention relates to methods of evaluating MS severity based on analysis of single nucleotide polymorphisms (SNPs) and to products and kits for use in such methods. The methods include a method of assessing a multiple sclerosis disease severity phenotype in a human subject having multiple sclerosis, by determining the genotype of the subject at one or more positions of single nucleotide polymorphism (SNP) selected from: rs2107538, rs1137933, rs1318, rs2069763, rs423904, rs876493, rs10243024, rs10259085, rs1042173, rs10492503, rs10492972, rs12047808, rs12202350, rs12861247, rs13353224, rs1350666, rs1555322, rs1611115, rs17641078, rs1805009, rs2028455, rs2032893, rs2049306, rs2066713, rs2074897, rs2076530, rs2187668, rs2213584, rs2227139, rs2234978, rs2239802, rs2395182, rs260461, rs28386840, rs3087456, rs3135388, rs3741981, rs3756450, rs3781202, rs3787283, rs3808585, rs4128767, rs4404254, rs4473631, rs4680534, rs6077690, rs6457594, rs6570426, rs659366, rs6917747, rs7208257, rs7528684, rs7577925, rs762550, rs7956189, rs7995215, rs8049651, rs8702, rs9808753 and rs987107, and/or a SNP in linkage disequilibrium with any one of said SNPs.