Rh blood group system
Feb 02, · The Rh factor is one of the proteins on RBCs used to indicate whether the blood of two different people is compatible when mixed – such as blood of a mother and her baby at birth. It is routine and important that the Rh factor for a mother and . Rh Factor The Rhesus factor, or Rh factor, is a certain type of protein found on the outside of blood cells. People are either Rh-positive (they have the protein) or Rh-negative (they do not have the protein). This distinction mostly matters when you are Rh-negative and your child is Rh-positive.
A rheumatoid factor test measures the amount of rheumatoid factor wwhat your blood. Rheumatoid whqt are proteins produced by your immune system that can attack healthy tissue in your body.
High levels of rheumatoid factor in the blood are most often associated with autoimmune diseases, such as rheumatoid arthritis and Sjogren's syndrome.
But rheumatoid factor may be detected in some healthy people, and people with autoimmune diseases sometimes have normal levels of rheumatoid factor. A rheumatoid factor test is one of a group of blood tests primarily used to help pinpoint a diagnosis of rheumatoid arthritis. These other tests may include:. The amount of rheumatoid factor in your blood may also help your doctor choose the treatment approach that will work best for your situation.
During a rheumatoid factor test, a small sample of blood is drawn from a vein in your arm. This typically takes just a few minutes. Your blood sample is sent to a laboratory for testing. A positive rheumatoid factor test result indicates that a high level of what size vivarium for corn snake factor was detected in your blood. A higher level of rheumatoid factor in your blood is closely associated with autoimmune disease, particularly rheumatoid arthritis.
But a number of other diseases and conditions can raise rheumatoid factor levels, including:. Some healthy people — particularly older individuals — have positive rheumatoid factor tests, though it's not clear why.
Fadtor some people who have rheumatoid arthritis will have low levels of rheumatoid factor in their blood. Mayo Clinic does not endorse companies or products. Advertising revenue supports our not-for-profit mission. Don't delay your care at Mayo Clinic Schedule your appointment now for safe in-person care.
This content does not have an English version. This content does not have an Arabic version. Sections for Rheumatoid factor About. Overview A rheumatoid factor test measures the amount of rheumatoid factor in your blood. More Information Juvenile idiopathic arthritis Psoriatic arthritis. Request an Appointment at Mayo Wha. Share on: Facebook Twitter. Show references Firestein GS, et al. Autoantibodies in rheumatoid arthritis. In: Kelley's Textbook of Rheumatology.
Philadelphia, Pa. Accessed May 5, Rheumatoid factor. Lab Tests Online. American Association for Clinical Chemistry. Shmerling RH. Origin and utility of measurement of rheumatoid factor. Ferri FF. Rheumatoid arthritis. In: Ferri's Clinical Advisor Related Juvenile idiopathic arthritis Psoriatic arthritis Rheumatoid arthritis. Rheumatoid factor About. Mayo Clinic Marketplace Check out these best-sellers and special offers on books and newsletters from Mayo Clinic.
What Is The Rh Factor? Why Is It Important?
Jan 19, · The Rhesus factor, also known as the Rh factor, is an antigen that exists on the surface of red blood cells in most people. People who have the Rhesus factor are considered to have a "positive" (+) blood type, such as A+ or B+. Those who don't are considered to have a "negative" (-) blood type, such as "O-" or "AB-.". Feb 14, · Rheumatoid factors are proteins produced by your immune system that can attack healthy tissue in your body. High levels of rheumatoid factor in the blood are most often associated with autoimmune diseases, such as rheumatoid arthritis and Sjogren's syndrome.
The Rh blood group system is a human blood group system. It contains proteins on the surface of red blood cells. It is the second most important blood group system, after the ABO blood group system.
The Rh blood group system consists of 49 defined blood group antigens ,  among which the five antigens D, C, c, E, and e are the most important. There is no d antigen. Rh D status of an individual is normally described with a positive or negative suffix after the ABO type e. 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 fetus and newborn.
The Rh blood group system has two sets of nomenclatures: one developed by Ronald Fisher and R. Race , the other by Wiener. 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 2 copies of chromosome 1, each contributing to production of multiple antigens. Notations of the two theories are used interchangeably in blood banking e. 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 2. The proteins which carry the Rh antigens are transmembrane proteins , whose structure suggest 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 on 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 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. 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 any incompatibility is detected, the mother often receives an injection at 28 weeks gestation and at birth to avoid the development of antibodies towards the fetus.
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. When the condition is caused by the Rh D antigen-antibody incompatibility, it is called Rh D Hemolytic disease of the newborn or Rh disease.
Here, sensitization to Rh D antigens usually by feto-maternal transfusion during pregnancy may lead to the production of maternal IgG anti-D antibodies which can pass through the placenta. This is of particular importance to D negative females at or below childbearing age, because any subsequent pregnancy may be affected by the Rh D hemolytic disease of the newborn if the baby is D positive.
The incidence of Rh disease is mathematically related to the frequency of D negative individuals in a population, so Rh disease is rare in old-stock populations of Africa and the eastern half of Asia, and the Indigenous peoples of Oceania and the Americas, but more common in other genetic groups, most especially Western Europeans, but also other West Eurasians, and to a lesser degree, native Siberians, as well as those of mixed-race with a significant or dominant descent from those e.
The same study concluded that the share of the population with Rh-negative blood type is set to fall further in the future primarily due to low population growth in Europe. The D antigen is inherited as one gene RHD on the short arm of the first chromosome , p Though very much simplified, one can think of alleles that are positive or negative for the D antigen.
The gene codes for the RhD protein on the red cell membrane. The D antigen is a dominant trait. If both of a child's parents are Rh negative, the child will definitely be Rh negative.
Otherwise the child may be Rh positive or Rh negative, depending on the parents' specific genotypes. The epitopes for the next 4 most common Rh antigens, C, c, E and e are expressed on the highly similar RhCE protein that is genetically encoded in the RHCE gene, also found on chromosome 1. Mice have just one RH gene. On the basis of structural homology it has been proposed that the product of RHD gene, the RhD protein, is a membrane transport protein of uncertain specificity CO 2 or NH 3 and unknown physiological role.
RhD-negative compared to RhD-positive subjects without anamnestic titres of anti- Toxoplasma antibodies have shorter reaction times in tests of simple reaction times. And conversely, RhD-negative subjects with anamnestic titres i. The published data suggested that only the protection of RhD-positive heterozygotes was long term in nature; the protection of RhD-positive homozygotes decreased with duration of the infection while the performance of RhD-negative homozygotes decreased immediately after the infection.
The overall change in reaction times was always larger in the RhD-negative group than in the RhD-positive. For a long time, the origin of RHD polymorphism was an evolutionary enigma. RhD-negative women in a population of RhD positives or RhD-positive men in a population of RhD negatives were at a disadvantage as some of their children RhD-positive children born to preimmunised RhD-negative mothers were at a higher risk of fetal or newborn death or health impairment from hemolytic disease.
Natural selection aside, the RHD-RHCE region is structurally predisposed to many mutations seen in humans, since the pair arose by gene duplication and remain similar enough for unequal crossing over to occur. In serologic testing, D positive blood is easily identified. Units that are D negative are often retested to rule out a weaker reaction. This was previously referred to as D u , which has been replaced. Weak D phenotype can occur in several ways. In some cases, this phenotype occurs because of an altered surface protein that is more common in people of European descent.
An inheritable form also occurs, as a result of a weakened form of the R0 gene. The testing is difficult, since using different anti-D reagents, especially the older polyclonal reagents, may give different results. The practical implication of this is that people with this sub-phenotype will have a product labeled as "D positive" when donating blood.
When receiving blood, they are sometimes typed as a "D negative", though this is the subject of some debate. Most "Weak D" patients can receive "D positive" blood without complications. This is important, since most blood banks have a limited supply of "D negative" blood and the correct transfusion is clinically relevant.
In this respect, genotyping of blood groups has much simplified this detection of the various variants in the Rh blood group system. It is important to differentiate weak D due to a quantitative difference in the D antigen from partial D due to a qualitative difference in the D antigen. Simply put, the weak D phenotype is due to a reduced number of D antigens on a red blood cell. In contrast, the partial D phenotype is due to an alteration in D-epitopes. Thus, in partial D, the number of D antigens is not reduced but the protein structure is altered.
These individuals, if alloimmunized to D, can produce an anti-D antibody. Therefore, partial D patients who are donating blood should be labeled as D-positive but, if receiving blood, they should be labeled as D-negative and receive D-negative units.
In the past, partial D was called 'D mosaic' or 'D variant. More than 30 different partial D phenotypes have been described. Only 9 active donors have been reported. Currently, 50 antigens have been described in the Rh group system; among those described here, the D, C, c, E and e antigens are the most important.
The others are much less frequently encountered or are rarely clinically significant. Rh38 have been combined, reassigned to other groups, or otherwise removed. Some of these groups, including f, Ce and CE, describe grouping of some existing groups. V in particular is caused by a mutation on RHCE. The term "Rh" was originally an abbreviation of "Rhesus factor.
Wiener , who, at the time, believed it to be a similar antigen found in rhesus macaque red blood cells. It was subsequently learned the human factor is not identical to the rhesus monkey factor, but by then, "Rhesus Group" and like terms were already in widespread, worldwide use.
Thus, notwithstanding it is a misnomer, the term survives e. Contemporary practice is to use "Rh" as a term of art instead of "Rhesus" e. The significance of their discovery was not immediately apparent and was only realized in , after subsequent findings by Philip Levine and Rufus Stetson.
The antigen that induced this immunization was designated by them as Rh factor to indicate that rhesus blood had been used for the production of the serum. In , Phillip Levine and Rufus Stetson published in a first case report the clinical consequences of non-recognized Rh factor , hemolytic transfusion reaction , and hemolytic disease of the newborn in its most severe form.
No name was given to this agglutinin when described. In , Karl Landsteiner and Alexander S.