Streptococcal infection is common, but occasionally serious. In the winter of 2022, a large increase in severe streptococcal infection due to invasive Group A Streptococcus (also known as S.pyogenes) was identified in the U.K. and elsewhere in Europe, leading to a number of childhood deaths. The human genetic determinants of streptococcal infection are as yet largely unknown, with previous research only identifying associations at one area of the genome (the Human Leukocyte Antigen region). In this project, we want to perform a genome wide association study of Scarlet Fever, a form of infection caused by Group A streptococci. There are approximately 150 cases of self-reported Scarlet Fever in ALSPAC. The summary statistics from this GWAS (not the raw data) will be shared and meta-analysed with other GWAS of scarlet fever (e.g. UK Biobank, 23andMe), in order to help develop an understanding of the determinants of invasive group A streptococcus. This research is a priority for the UK Health Security agency.