Immunogenetics of multiple sclerosis and optic neuritis: DNA polymorphism of HLA class II genes

HLA-DR polymorphism and primary biliary cirrhosis: evidence from a meta-analysis

BACKGROUND AND AIMS

We undertook this study to review and quantitatively analyze the association between human leukocyte antigen (HLA) DR polymorphisms and susceptibility of primary biliary cirrhosis (PBC).

METHODS

All relevant publications on the association between HLA-DR polymorphisms and PBC were searched through June 2013. Odds ratios (OR) and confidence intervals (CI) for the comparisons between case and control group were calculated. Statistical analysis was performed using Stata 11.0 software.

RESULTS

Nineteen articles (or 20 studies including the substudies) were identified. For DR*7 allele, the ORs (95% CIs) were 1.530 (1.310, 1.788), 1.757 (1.285, 2.403) and 1.495 (1.211, 1.845) in overall, Asian and European populations, respectively. For DR*8 alleles, the ORs (95% CIs) were 3.158 (1.822, 5.475), 2.803 (2.420, 3.247) and 3.056 (2.573, 3.629) in Asian, American and European subgroups, respectively. The subgroup analysis for DR*11 and DR*13 showed a significant association in Asian and European population. For DR*12 and *15 alleles, the overall ORs (95% CIs) were 0.551 (0.404, 0.753) and 0.721 (0.607, 0.857). However, in subgroup analysis for DR*12 allele, the association was only found in Asian population. In addition, statistical significance exists in American and European populations in the subgroup analysis for DR*15 allele.

CONCLUSION

Our meta-analysis suggested that HLA-DR *7 and *8 allele polymorphisms contributed to the susceptibility of PBC, whereas DR*11, *12, *13 and *15 allele polymorphisms are protective factors in certain population.

CD24 is a genetic modifier for risk and progression of multiple sclerosis

Multiple sclerosis (MS) is a chronic neurological disease of unknown etiology, but a genetic basis for the disease is undisputed. We have reported that CD24 is required for the pathogenicity of autoreactive T cells in experimental autoimmune encephalomyelitis, the mouse model of MS. Here we investigate the contribution of CD24 to MS by studying single-nucleotide polymorphism in the ORF among 242 MS patients and 207 population controls. This single-nucleotide polymorphism results in replacement of alanine (CD24a) with valine (CD24v) in the mature protein. We found that the CD24v/v renders a >2-fold increase in the relative risk of MS in the general population (P = 0.023). Among familial MS, the CD24v allele is preferentially transmitted into affected individuals (P = 0.017). Furthermore, 50% of CD24v/v patients with expanded disability status scale 6.0 reached the milestone in 5 years, whereas the CD24a/v (P = 0.00037) and CD24a/a (P = 0.0016) patients did so in 16 and 13 years, respectively. Moreover, our data suggest that the CD24v/v patients expressed higher levels of CD24 on peripheral blood T cells than did the CD24a/a patients. Transfection with CD24a and CD24v cDNA demonstrated that the CD24v allele can be expressed at higher efficiency than the CD24a alleles. Thus, CD24 polymorphism is a genetic modifier for susceptibility and progression of MS in the central Ohio cohort that we studied, perhaps by affecting the efficiency of CD24 expression on the cell surface.

The influence of HLA-DR and -DQ alleles on progression to multiple sclerosis following a clinically isolated syndrome

A 5-year follow-up study was performed on 70 Caucasian patients presenting with isolated neurological syndromes of the optic nerve, brain stem, or spinal cord to assess the risk of progression to MS. The influence on patient prognosis of HLA-DR and -DQ alleles and presentation with disseminated brain lesions, demonstrated by MRI scanning, was determined. Clinical progression to MS was observed in 61% of optic neuritis patients, 50% of patients with a brain-stem syndrome, and 35% of patients with a spinal cord disturbance. MS and the isolated clinical syndromes were positively associated with DRB1*1501, DQA1*0102, and DQB1*0602; the frequency of these alleles in the latter group was intermediate between that seen in MS patients and healthy controls. Conversion to MS was positively associated with the DRB1*1501.DQA1*0102.DQB1*0602 haplotype, but the influence of HLA was only significant in patients with disseminated brain lesions at presentation (MRI positive); MS developed in 86% of MRI-positive, DRB1*1501-positive patients compared with 55% of MRI-positive, DRB1*1501-negative patients (p < 0.025). The data suggest that these HLA alleles are involved in susceptibility to initial demyelinating lesion formation and are important in the subsequent development of MS in MRI-positive patients.