Blood type represent contributions from both parents. A total of 36 human blood group systems and 346 antigens are now recognized by the International Society of Blood Transfusion (ISBT). The two most important ones are ABO and the Rh blood group systems; they determine someone's blood type (A, B, AB and O, with +, − or null denoting RhD status) for suitability in blood transfusion. A complete blood type would describe a full set of 30 substances on the surface of red blood cells, and an individual's blood type is one of many possible combinations of blood-group antigens. Across the 36 blood
Jehovah's Witnesses and blood transfusions of outdated medical beliefs. Dissident Witnesses say the Society's use of Leviticus 17:12 to support its opposition to blood transfusions conflicts with its own teachings that Christians are not under the Mosaic law. Theologian Anthony Hoekema claims the blood prohibited in Levitical laws was not human, but animal. He cites other authors who support his view that the direction at Acts 15 to abstain from blood was intended not as an everlasting covenant but a means of maintaining a peaceful relationship between Jewish and Gentile Christians. He has described as "absurd literalism" the Witnesses' use of a scriptural prohibition on