A GCC repeat expansion in

GC-rich tandem repeat expansions (TREs) are often associated with DNA methylation, gene silencing and folate-sensitive fragile sites, and underlie several congenital and late-onset disorders. Through a combination of DNA methylation profiling and tandem repeat genotyping, we identified 24 methylated TREs and investigated their effects on human traits using PheWAS in 168,641 individuals from the UK Biobank, identifying 156 significant TRE:trait associations involving 17 different TREs. Of these, a GCC expansion in the promoter of