<prompt> Group A beta haemolytic streptococci GAbHS cross reacts with?Valves myocardiumAnnular ringEndocardiumPericardium  <response>: Ans. a Valves Myocardium. Ref. Harrisons principles of internal medicine, 18th Chapter 322.Rheumatic heart disease Group A beta haemolytic streptococci GAbHS is implicated as the cause of rheumatic valvular heart disease. Age of occurence: 5-15 years. Pathogenesis: Hypothesis of antigenic mimicry; carbohydrate of GAbHS and glycoprotein of valves and streptococcal cell membrane, M protein sarcolemma and myocardial cell moieties have interactions i.e they cross react with each other. Antigenic relationships have been shown between capsular hyluronic acid human synovial fluid, CE11 wall protein myocardium, group A Carbohydrate Cardiac valves, Cytoplasmic membrane antigens vascular intima, peptidoglycans skin antigens.Streptococcal antigenCross-reacts withCapsular hyaluronic acidHuman Synovial FluidCytoplasmic membrane antigensVascular intimaPeptidoglycansSkin antigensCell wall proteinMyocardiumGroup A carbohydrateCardiac valves 