A method for simple and accurate identification of the multiple sclerosis associated allele HLA-DRB1*1501 in neuroscience research laboratories

HLA associations in South Asian multiple sclerosis

Background:

Previous efforts to identify Human Leukocyte Antigen (HLA) gene associations with multiple sclerosis (MS) in the South Asian population have been underpowered.

Aim:

To identify the primary HLA class II alleles associated with MS in Indians.

Methods:

We typed HLA-DRB1, -DQA1 and -DQB1 in 419 patients and 451 unrelated controls by polymerase chain reaction using sequence specific oligonucleotide probes (PCR-SSOP).

Results:

At the gene level DRB1 showed significant evidence of association ( p=0.0000012), DQA1 showed only marginal evidence of association ( p=0.04) and there was no evidence for association at DQB1 ( p=0.26). At the DRB1 locus association is confirmed with the *15:01 ( p=0.00002) and the *03 ( p=0.00005) alleles.

Conclusion:

Our study confirms that the risk effects attributable to the HLA- DRB1*15:01and DRB1*03 alleles seen in Europeans are also seen in Indians. The absence of any evidence of association with DQB1 alleles reflects the lower linkage disequilibrium between DQB1 alleles and DRB1 risk alleles present in this population, and illustrates the potential value of fine mapping signals of association in different ethnic groups.

Environmental factors related to multiple sclerosis in Indian population

BACKGROUND

Multiple sclerosis (MS) is less prevalent among Indians when compared to white populations. Genetic susceptibility remaining the same it is possible that environmental associations may have a role in determining disease prevalence.

AIMS

To determine whether childhood infections, vaccination status, past infection with Helicobacter pylori (H.pylori), diet, socioeconomic and educational status were associated with MS.

MATERIAL AND METHODS

139 patients and 278 matched control subjects were selected. A validated environmental exposure questionnaire was administered. Estimation of serum H.pylori IgG antibody was done by ELISA. Patients and controls were genotyped for HLA-DRB1*15:01.

RESULTS

In our cohort a significant association was seen with measles (p < 0.007), vegetarian diet (p < 0.001, higher educational status (p < 0.0001) and urban living (p < 0.0001). An inverse relationship was seen with H.Pylori infection and MS (p < 0.001). Measles infection (OR 6.479, CI 1.21-34.668, p < 0.029) and high educational status (OR 3.088, CI 1.212-7.872, p < 0.018) were significant risk factors associated with MS. H.pylori infection was inversely related to MS (OR 0. 319, CI 0.144- 0.706, p < 0.005).

CONCLUSIONS

Environmental influences may be important in determining MS prevalence.

Association of vitamin D and multiple sclerosis in India

BACKGROUND

Vitamin D deficiency is widely prevalent in India. The association between vitamin D status and multiple sclerosis (MS) has not been previously studied in Indians.

OBJECTIVE

The objective of this paper is to determine whether vitamin D status is associated with MS in India.

METHODS

In this study 110 MS patients and 108 matched controls were included. Serum 25-hydroxyvitamin D (25(OH)D) was measured in 63 patients in relapse, 77 patients in remission and all controls. Quantity of sun exposure in childhood and body mass index (BMI) were calculated. Patients and controls were genotyped for HLA-DRB1*1501.

RESULTS

Patients had significantly lower 25(OH)D levels than matched controls (p = 0.003), and patients in relapse had a significantly lower vitamin D level as compared to those in remission (p = 0.001). Vitamin D deficiency (< 50 nmol/l) was seen in a higher proportion of cases (71.8%) than controls (53.7%) (p = 0.01). Higher quartiles of vitamin D (> 58 nmol/l) showed an inverse relationship with MS (OR = 0.28, CI = 0.11-0.68, p= 0.005). This effect persisted after adjusting for sun exposure.

CONCLUSION

The results of our study indicated that serum 25(OH)D shows an inverse relationship with MS in the Indian population. Reverse causality cannot be excluded.

Association of Epstein-Barr virus infection with multiple sclerosis in India

OBJECTIVES

Epstein-Barr virus (EBV) seroprevalence is high from early childhood in Indian populations, though multiple sclerosis (MS) is uncommon. The present study aims to evaluate the association of EBV infection with MS in Indian patients.

METHOD

In this study 140 MS patients and equal number of matched controls were included. Estimation of serum Immunoglobin G (IgG) for EBV Nuclear antigen 1 (EBNA1), viral capsid antigen (EBV-VCA) and early antigen (EB-EA) were obtained by quantitative enzyme linked immunosorbent assay (ELISA). Patients and controls were genotyped for the human leukocyte antigen (HLA) DRB1*1501 allele.

RESULTS

A modest difference was observed for EBNA1 (p=0.02) and EBV-VCA (p=0.03) titres in MS patients as compared to healthy controls. There was no association between EBNA1 titres and MS. High EBNA1 titre (>99.75U/l) was significantly associated with HLA DRBI*15:01 (OR=4.92. CI=1.07-22.57) status in MS patients but not in healthy controls (OR=1.19, CI=0.53-2.63).

CONCLUSION

Evidence for a strong association with remote EBV infection was lacking in this study of Indian patients with MS. Patients who are carriers of HLA DR15 allele may have high EBNA1 titres. These preliminary results need to be reproduced in an independent and larger dataset.