MSH3 and Huntington disease: In GWAS, disease-accelerating loci in HD include MLH1 (MutL homolog 1), PMS1 (post meiotic segregation increased 1 homolog), MSH2 and MSH3 (MutS homologs which dimerize to form MutSβ), PMS2 (post meiotic segregation increased 2) and LIG1 (DNA Ligase 1)44,45.