ABO blood group system gives type O. As both "I" and "I" are dominant over "i", only "ii" people have type O blood. Individuals with "II" or "Ii" have type A blood, and individuals with "II" or "Ii" have type B. "II" people have both phenotypes, because A and B express a special dominance relationship: codominance, which means that type A and B parents can have an AB child. A couple with type A and type B can also have a type O child if they are both heterozygous ("Ii","Ii"). The "cis-AB" phenotype has a single enzyme that creates both A and B antigens.
Jehovah's Witnesses and blood transfusions decide whether they could conscientiously accept fractions used from blood for purposes such as vaccination. This position has been expanded on since; the pre-formatted Durable Power of Attorney form provided by the Watch Tower Society includes an option for Jehovah's Witnesses to "accept all fractions derived from any primary component of blood." In 1964, Jehovah's Witnesses were prohibited from obtaining transfusions for pets, from using fertilizer containing blood, and were even advised (if their conscience troubled them) to write to dog food manufacturers to verify that their products were blood-free. Later that year, it was stated that doctors or nurses