MMP9 and Mental deterioration: Patients who carry the HLA-DRB1*15:01 allele have shown positive correlation with oligoclonal bands (OCB) in CSF, early disease onset, risk of cognitive decline, presence of bigger white matter lesions, more advanced brain atrophy, higher lesion load on MRI, and higher concentration of matrix metalloproteinase-9 (MMP-9) in CSF [23,24].