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Refining the association of MHC with multiple sclerosis in African Americans

Joseph P McElroy1, Bruce A C Cree, Stacy J Caillier

  • 1Department of Neurology, University of California, San Francisco, CA 94143, USA. joseph.mcelroy@ucsf.edu

Human Molecular Genetics
|May 15, 2010
PubMed

Insights

The major histocompatibility complex (MHC) plays a smaller role in multiple sclerosis (MS) susceptibility in African Americans than in Europeans. This finding, based on a large genetic study, may explain lower MS risk in this population.

Area of Science:

  • Neuroimmunology
  • Genetics
  • Epidemiology

Background:

  • Multiple sclerosis (MS) is a central nervous system demyelinating disease with autoimmune and neurodegenerative components.
  • The major histocompatibility complex (MHC) is a key genetic region influencing MS susceptibility, but its specific role is complex due to linkage disequilibrium (LD).
  • African Americans exhibit lower MS risk than European descendants, with distinct genetic diversity potentially offering insights into MS pathogenesis.

Purpose of the Study:

  • To investigate the role of the MHC in multiple sclerosis (MS) susceptibility within the African American population.
  • To fine-map the MHC region in African Americans to identify specific genetic variants contributing to MS risk.
  • To compare the contribution of the MHC to MS susceptibility between African Americans and individuals of European descent.

Main Methods:

  • A case-control association study was conducted using 499 African American MS patients and 750 African American controls.
  • Genotyping of 6040 single nucleotide polymorphisms (SNPs) within the MHC region was performed.
  • Replication analysis involved genotyping selected SNPs in an independent cohort of 451 African American MS patients and 718 controls.

Main Results:

  • Two MHC class II SNPs, rs2647040 and rs3135021, were found to be significant in the replication cohort and partially tagged DRB1*15 alleles.
  • The overall contribution of the MHC region to MS susceptibility appeared smaller in African Americans compared to findings in European descent populations.
  • Genetic heterogeneity across ancestral groups may contribute to observed differences in MS susceptibility.

Conclusions:

  • The MHC plays a less significant role in MS susceptibility among African Americans than previously observed in European populations.
  • Distinct patterns of genetic variation and LD in African Americans influence the MHC's contribution to MS risk.
  • These findings highlight the importance of considering ancestral diversity in understanding the genetic architecture of multiple sclerosis.

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