In algebra, the letter "A" in conjunction with other letters firstly of the alphabet is used to signify recognized portions.Æ æ Ɑ ɑ Ʌ ʌ Ꞵ ꞵ Ð ð Ɛ ɛ Ə ə Ǝ ə Ɣ ɣ Ƣ ƣ Ɩ ɩ Ɥ ɥ Ꟛ ꟛ Ŋ ŋseven. A On the list of 4 significant blood groups during the ABO system. Folks using this blood group hold the A antigen to the surface