Blodgrupp a rh
About 30% have (rr) Rh negative and about 60% carry one (r) negative gene. The average among most people is only 15%-Rh negative, while some groups have very little. The Oriental Jews of Israel, also have a high percent Rh negative, although most other Oriental people have only about 1% Rh negative. The Samaritans and the Black Cochin Jew also. The Rh blood group system is a human blood group system. It contains proteins on the surface of red blood cells.
After the ABO blood group system , it is the most likely to be involved in transfusion reactions. The Rh blood group system consisted of 49 defined blood group antigens [ 1 ] in As of , [update] there are over 50 antigens among which the five antigens D, C, c, E, and e are the most important. There is no d antigen. Antibodies to Rh antigens can be involved in hemolytic transfusion reactions and antibodies to the Rh D and Rh antigens confer significant risk of hemolytic disease of the newborn.
The Rh blood group system has two sets of nomenclatures: one developed by Ronald Fisher and R. Race , the other by Wiener.
Blood Types – A, B, AB, O, Rh
Both systems reflected alternative theories of inheritance. This system was based on the theory that a separate gene controls the product of each corresponding antigen e. However, the d gene was hypothetical, not actual. The Wiener system used the Rh—Hr nomenclature. This system was based on the theory that there was one gene at a single locus on each of the two copies of chromosome 1, each contributing to production of multiple antigens.
Notations of the two theories are used interchangeably in blood banking e.
Blood Types
Wiener's notation is more complex and cumbersome for routine use. Because it is simpler to explain, the Fisher—Race theory has become more widely used. Thus, Wiener's postulate that a gene could have multiple specificities something many did not give credence to originally has been proved to be correct. On the other hand, Wiener's theory that there is only one gene has proved to be incorrect, as has the Fisher—Race theory that there are three genes, rather than the two.
The proteins which carry the Rh antigens are transmembrane proteins , whose structure suggests that they are ion channels. Lowercase "d" indicates the absence of the D antigen the gene is usually deleted or otherwise nonfunctional. Rh phenotypes are readily identified through the presence or absence of the Rh surface antigens. As can be seen in the table below, most of the Rh phenotypes can be produced by several different Rh genotypes.
The exact genotype of any individual can only be identified by DNA analysis. Regarding patient treatment, only the phenotype is usually of any clinical significance to ensure a patient is not exposed to an antigen they are likely to develop antibodies against. A probable genotype may be speculated on, based upon the statistical distributions of genotypes in the patient's place of origin. R 0 cDe or Dce is today most common in Africa.
The allele was thus often assumed in early blood group analyses to have been typical of populations on the continent; particularly in areas below the Sahara. Ottensooser et al. However, more recent studies have found R 0 frequencies as low as Rh antibodies are Immunoglobulin G IgG antibodies which are acquired through exposure to Rh-positive blood generally either through pregnancy or transfusion of blood products. The D antigen is the most immunogenic of all the non-ABO antigens.
The percentage of alloimmunization is significantly reduced in patients who are actively exsanguinating. All Rh antibodies except D display dosage antibody reacts more strongly with red cells homozygous for an antigen than cells heterozygous for the antigen EE stronger reaction vs Ee. If anti-E is detected, the presence of anti-c should be strongly suspected due to combined genetic inheritance. It is therefore common to select c-negative and E-negative blood for transfusion patients who have an anti-E and lack the c antigen in general, a patient will not produce antibodies against their own antigens.
Anti-c is a common cause of delayed hemolytic transfusion reactions. The hemolytic condition occurs when there is an incompatibility between the blood types of the mother and fetus. There is also potential incompatibility if the mother is Rh negative and the father is positive. When the mother conceives for the first time, with a positive child, she will become extremely sensitive. When any incompatibility is detected when she conceives the second time in less than two years then, the mother often receives an injection at 28 weeks gestation and at birth to avoid the development of antibodies towards the fetus.
If not given, then the baby will be dead and must be aborted. These terms do not indicate which specific antigen-antibody incompatibility is implicated. The disorder in the fetus due to Rh D incompatibility is known as erythroblastosis fetalis.