About the talk: The human genome contains many types of repetitive material including short tandem repeats. Expansions of short tandem repeats can cause rare diseases including Friedreich’s ataxia and Huntington’s disease but are also responsible for GWAS hits such as the C9orf72 repeat expansion in motor neuron disease. In recent years several methods have been developed to detect repeat expansions in short read next generation sequencing data, currently the predominant type of sequencing available with whole exome sequencing now widely used in genomic medicine. These methods are revealing unexpected enrichment of repeat expansions in complex disorders such as epilepsy and motor neuron disease (unpublished) as well as increasing the diagnostic yield in medical genomic sequencing studies. Development of ultra fast methods, such as our new superSTR algorithm, have allowed us to perform the first UK Biobank analysis of repeat expansions in >50K whole exomes, identifying several interesting new associations.