ABO blood group system alleles in white individuals of the ABO gene that produce one's blood type: The same study also identified 18 rare alleles, which generally have a weaker glycosylation activity. People with weak alleles of A can sometimes express anti-A antibodies, though these are usually not clinically significant as they do not stably interact with the antigen at body temperature. Cis AB is another rare variant, in which A and B genes are transmitted together from a single parent. The distribution of the blood groups A, B, O and AB varies across the world according to the population. There are also variations
Blood type blood cells and checking if the mixture "agglutinates", or forms clumps. If agglutination is not obvious by direct vision, blood bank technicians usually check for agglutination with a microscope. If agglutination occurs, that particular donor's blood cannot be transfused to that particular recipient. In a blood bank it is vital that all blood specimens are correctly identified, so labelling has been standardized using a barcode system known as ISBT 128. The blood group may be included on identification tags or on tattoos worn by military personnel, in case they should need an emergency blood transfusion. Frontline German Waffen-SS had blood