HLA-DRB1 and myeloid sarcoma: Furthermore, from 246 MS patients and 295 healthy controls we had data from smoking habit; from 233 MS patients and 194 healthy controls we measured vitamin D levels at basal sample and at 24 month sample; from 315 MS patients and 270 healthy controls we assessed the HLA-DRB1*15:01 allelic variant; class II HLA-DR and -DQ were genotyped from 288 MS patients; 304 MS patients were genotyped for the SNPs shown at Supplementary Table 1; finally, from 215 MS patients we had MRI data.