Genetics

MS risk alleles are mostly conditional, registering only when the measurement carries the stimulus, compartment or resolution they depend on. Three 2026 papers each supply one. Kari and colleagues show the CD226 rs763361 variant looks inert in healthy donors until vitamin D is added, when it fails to activate LFA-1 or make Tr1 cells. Han and colleagues move methylation profiling from blood to cerebrospinal fluid and find 2,710 positions and 4,330 regions enriched near MS risk loci. Venkatesh and colleagues rebuild TWAS at brain cell subclass resolution, where MS gene-trait associations rise from 145 to 317.