Genetics

This blog post examines a recent study assessing how well European-derived polygenic risk scores (PRS) predict multiple sclerosis (MS) risk in individuals of South Asian ancestry using the Genes & Health cohort, and contrasts this performance with European-ancestry analyses in UK Biobank. It explains the study’s design (including MHC vs non-MHC scoring), summarizes key results showing reduced cross-ancestry predictive accuracy—particularly the limited incremental value of MHC-inclusive PRS in the South Asian cohort—and interprets these findings through established principles of linkage disequilibrium and allele-frequency differences that constrain PRS transferability. The post concludes by outlining methodological and equity implications, emphasizing the need for larger, ancestrally diverse MS GWAS and improved multi-ancestry PRS approaches to ensure genomic prediction benefits are distributed fairly across populations.