Rh blood group system
- OMIM: 111680
- UniProt: Q02161
- OMIM: 111700
- UniProt: P18577
The rhesus factors are a 1940 by Karl Landsteiner and Alexander Solomon Wiener found erythrocyte antigen system. Rhesus - positive individuals possess the system and specific proteins on the cell membrane of erythrocytes not ( red blood cells), rhesus -negative. The name comes from the extraction of the first test serum from the blood of rabbits which had been treated with red blood cells from rhesus monkeys (Macaca mulatta).
The Rhesus blood group system Rhesus or system refers to the - after the AB0 system - second most important blood group system of humans. It consists entirely of a group of 50 proteins similar to each other, their five most important representative (C, c, D, E, e ) can be tested with test sera. The oldest and most important Rh factor has the abbreviation D in the Rhesus system:
- Has a person the Rhesus D antigen, it is rhesus positive, and we write " Rh ( D) ", " Rh ", " Rh " or - depending on the genotype - " Dd ", " dD ", " DD ", rarely " RH1 ".
- Has a person not a Rhesus D antigen, it is rhesus negative, and is considered " Rh ( D) -", " Rh ", " rh " or " dd".
The affiliation of a person to the five most important factors C, c, D, E, e is called rhesus formula and about as ccD.Ee or ccddee etc. are displayed, see sections inheritance pattern and rhesus system.
About 85 % of white European and American population and almost 100 % of all Africans, Asians and American Indians are Rhesus positive, the remainder in each Rhesus negative. A life-threatening antigen -antibody reaction can occur with repeated blood transfusion of an individual with rh- Rh blood or from the second pregnancy of a woman with a rh- Rh - child ( Rhesus incompatibility ). Here, the rh- organism produces antibodies against the Rh- erythrocytes, and it comes to hemagglutination ( donor blood recipients ) or hemolysis ( child).
Importance for the organism
According to a study of 2009 genetically engineered mice in which the Rhesusgen rhCG and thus Rhesus proteins were missing, the proteins have important functions in the transport of ammonium ions ( NH4 ) and ammonia ( NH3), the excretion of nitrogenous waste products as well as maintaining a constant pH in the blood. The genetically modified rodents showed a shifted into the acidic range blood pH, lower urinary levels of nitrogenous substances in males and less fertile sperm.
Importance in pregnancy
If the mother is Rh negative and the fetus is Rh - positive, which is the case in about one in 10 pregnancy, it may be that the parent antibody, which originated in the sensitization after a previous pregnancy, has against the Rhesus factor of the child that lead to disability and even death of the child. It now ensures that Rh -negative mothers do not form such antibodies by generally transfused Rh - positive blood them no and with a Rh -positive child performs an anti-D prophylaxis in each pregnancy. After birth, the umbilical cord blood is tested. It is determined whether there is an Rh - positive child, then again, if necessary to carry out an anti -D prophylaxis for the mother after a few hours.
Rhesus negative spread
About 17% of Europeans are rhesus - negative, in the eastern fringes of Europe about 4 %, in the Basque Country is 25 %, in Switzerland 15 %. On other continents, it is in part considerably lower. America, Australia and all of East Asia have no rhesus negative natives.
The circulation of individuals with Rh - negative blood plays an important role in determining the genetic distance of people. Large differences between nations in the frequency of rhesus negative blood indicate great genetic distance and leave according to the studies by Cavalli - Sforza and others close to an early branch of the peoples. The studies complement findings arising from the study on lactose intolerance.
Inheritance pattern
The inheritance of the rhesus is dominant- recessive: the factor is being dominant over Rh -negative phenotype.
Unlike the primary discovered Rh factor "D" stand for the gene products of the Rh -CE gene ( most important antigen combinations are CE, Ce, cE and ce ) and the small letters for antigens that can be detected by test sera with corresponding antibodies. There is thus in addition to the anti- C-serum and an anti - C-serum, etc. ( the same also applies to the Kell system ). Therefore, on standards-compliant German blood donation cards rhesus factors are apparently twice as " ccddee ". The possible combination makes the Rh blood group system one of the most complex human blood group systems.
Rhesus system
After the discovery of blood groups A and B Landsteiner and Wiener have continued their work. In the first designation by the Viennese "R " stood for the responsible gene in rhesus monkeys, and the abbreviation " h" for the corresponding antiserum. With a locus was " Rh " Now for the positive test and " rh " for the negative test. Since more blood group yet been found, this name did not prevail as Rh factor, which refers to the present Rhesus D ( RhD or Rh1 also called ). However, due to the large use in the literature the epithet remained.
Fisher and Race recognized the context of other blood group and led the designations C, D and E of the Rhesus system in continuation of the known A and B of the AB0 system. In this race, the statistician Fisher and immunobiologist went from three loci in the genome of each binary forms of genes as C / c, D / d, E / e Only later was it realized that the features of C and E are at the same locus, and thus present in four Alleltypen. The two genes of the rhesus system lie on chromosome 1 at 1p36.2 - p34 ( GeneID 6007 " RHD " and GeneID 6006 " RHCE ").
Often when specifying the D / d genes is only between positive " D. " and negative " dd" differences. Where " D. " both " DD " as well as " Dd ". A more accurate distinction is possible only by an exact genome analysis.
Subsequent genetic studies have so far largely confirm conjectures, in which the blood groups of the Rhesus system are closely related. The resulting proteins of the rhesus system are largely homologous, so that has long been believed that they arise from alternative splicing of a common gene sequence long, sometimes 1, 2 or 3 variants arise as a consequence in an organism. Carritt et al. then demonstrated in 1997 the possibility of that the RhCE created by gene duplication from RhD, especially after the human genome occurred a missing rhesus protein for the first time. (in some remote populations, there is still no RhD -negative blood group ). In contrast to the assumption of Carrit et al then showed Willy A. Flegel and Wagner 2000 that the RhCE was the original gene has been doubled from the RhD. Several teams showed in 2000, moreover, that the genes for RhCE and RhD close together and are in the opposite reading direction ( the 3 'ends are adjacent ). This also explains that a number of rarer rhesus features could be found in which apparently exons of the RhD protein are marked in RhCE protein.
Because in addition to the frequent occurrences of the Rh D and Rh CE gene more wild types exist, can be found in the literature also numerical notation for the blood group of the rhesus system. Here is D = RH1, RH2 = C, E = RH3, RH4 = c, e = RH5, ... Cw = RH8 ... today with more than 50 variants. How these are actually pronounced in the genome is still not finally resolved. Non-human model organisms such as the mouse are not completely suitable for comparison because they do not wear RhCE / RhD - duplication.
The Rhesus factor comes in rare cases only to quantitatively attenuated form ( you or Dweak ). For blood transfusions such patients occupy a middle position between Rh - positive and Rh negative. If they are to receive blood is transfused Rh - negative blood them. In contrast, patients apply a qualitative change in the D antigen, so-called Dpartial, as Rh negative.
Blood group compatibility
When blood transfusion is transfused to the same blood group as a rule, also on the characteristics in the rhesus system. Because of the lack particular rhesus -negative blood donations to a transmission of other blood groups, however, can often not be avoided. Because of the importance in pregnancy is ( with the exception of life-threatening situations) must avoid a transfusion of RhD - positive blood donations to RhD -negative girl and Rh -negative women of childbearing potential. Generally must be a serological follow-up and to be advised on the detection of antibodies to the patient about the risks and this complication are noted in an emergency passport at all transfusion of rhesus positive blood to rhesus -negative patients. Because of these problems, the blood group of the patient is Rhesus negative reported also unclear in RhD - test, which is regarded as fundamentally incompatible with the available rhesus -positive donations. Exceptions to this rule are to be documented separately by the physician. The reversal of the administration of rhesus - negative blood in rhesus -positive patients is not a problem; due to the availability of this situation is, however, usually not before.
Conversion of Rhesus negative Rhesus positive
According to some media reports, a case of conversion at an originally rhesus -negative 15 - year-old girl to rhesus - positive was documented for the first time in Sydney. It had five years previously received a donor liver of a rhesus - positive donor.