الفهرس 
الملخص العربىيوجد فقط 14 صفحة متاحة للعرض العام
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المستخلص
The ABO blood group system was discovered in 1900 by Karl Landsteiner there are four main ABO blood type groupings ; A, B, AB, and O. These blood groups are determined by the antigen on the blood cell surface and the antibodies present in the blood plasma. The A and B alleles code for enzymes that produce the type A and B antigens, respectively. A third version of this gene, the O allele, codes for a protein that is not functional and does not produce surface molecules. The genes that determine human ABO blood types exist as three alleles (A, B, O). These multiple alleles are passed from parent to offspring such that one allele is inherited from each parent. The human major histocompatibility complex HLA is located on the short arm of chromosome 6. It is known to be the most polymorphic genetic system in humans.The MN blood group system is under the control of an autosomal locus found on chromosome 4, with two alleles designated LM and LN. Rh factor is a blood protein that plays a critical role in some pregnancies. People without Rh factor are known as Rh negative, while people with the Rh factor are Rh positive.