What if the letters A, B and O went missing? Y_u w_old n_tice. The letters A, B and O also represent blood types and at times they do go missing from hospital shelves. This June, the American Red Cross is launching the Missing Types campaign, part of an international effort, to encourage new blood donors to give and help ensure patients like Tymia have the lifesaving blood products they need. Help fill the gaps - schedule your blood donation appointment today at redcrossblood.org