Fine-Mapping Array Design for Multi-Ethnic Studies of Multiple Sclerosis.

Area of Science:

• Genetics
• Immunology
• Neuroscience

Background:

• Over 200 autosomal genetic associations for multiple sclerosis (MS) risk outside the MHC have been identified in European populations.
• Identifying the specific causal variants at these associated loci remains a significant challenge.
• Replication data from Hispanic and African American populations can aid in fine-mapping MS risk loci.

Purpose of the Study:

• To develop a customized genotyping array for efficient fine-mapping of multiple sclerosis (MS) susceptibility loci.
• To leverage replication data from diverse populations to identify causal variants.
• To enhance the fine-mapping potential of MS genetic loci in multi-ethnic cohorts.

Main Methods:

• Customized a genotyping array by adding approximately 20,000 bead types (~17,000 variants) to existing arrays (Ilumina Infinium expanded multi-ethnic genotyping array and Infinium ImmunoArray-24 v2 BeadChip).
• Incorporated regulatory and coding variants within 1 Mb of known risk variants to detect causal variation.
• Included variants based on linkage disequilibrium criteria informed by replication status in Hispanic and African American samples.

Main Results:

• A custom genotyping array was designed to maximize fine-mapping potential for identified MS susceptibility loci.
• The array design facilitates the detection of causal variants in the presence and absence of heterogeneity.
• The strategy is particularly suited for multi-ethnic populations and could be applied to other disease phenotypes.

Conclusions:

• The developed custom genotyping array offers an efficient approach for fine-mapping multiple sclerosis (MS) genetic risk loci.
• This strategy enhances the ability to identify causal variants, particularly in diverse populations.
• The methodology has broader implications for fine-mapping genetic associations in other complex diseases.