Spinal cord involvement in multiple sclerosis: a correlative MRI and high-resolution HLA-DRB1 genotyping study

Background: There have been few magnetic resonance imaging (MRI) studies of the spinal cord in large multiple sclerosis (MS) patient cohorts and little is known about correlations between cord lesions and human leukocyte antigen (HLA) alleles.

Objective: To investigate the spectrum of MRI changes in the spinal cord in MS and associations with the HLA-DRB1 genotype.

Methods: Two hundred and fifty two consecutive MS patients from the Perth Demyelinating Diseases Database had MRI of the spinal cord and brain and high-resolution HLA-DRB1 genotyping. The numbers, locations, shape and segmental extent of cord lesions were analysed and were correlated with carriage of individual HLA-DRB1 alleles and diplotypes.

Results: Focal cord lesions were present in 82.9% of cases, with numbers being maximal in the cervical cord and increasing with disease duration. Focal lesions were usually round or oval in shape but in 35% of cases subpial wedge-shaped lesions were present. Diffuse cord involvement was present in 10% of cases and correlated with carriage of HLA-DRB1*1501 and with higher disability. Carriage of the minor allele HLA-DRB1*0701 was significantly associated with numbers of wedge-shaped lesions and lesions in the cervical cord, while HLA-DRB1*1104 and DRB1*0103 were significantly associated respectively with higher and lower numbers of thoracic cord lesions. HLA-DRB1*1501 and the HLA-DRB1*11 sub-alleles DRB1*1101 and DRB1*1104 were significantly associated with the segmental length of cord lesions.

Conclusions: Our study is the first to investigate the frequency of subpial wedge-shaped lesions in the cord in vivo and has provided preliminary evidence that HLA-DRB1 alleles may play a role in determining the severity and extent of spinal cord involvement in MS.