Priyanka Saha, Amity University Kolkata
Introduction:
The rarest form of blood type on Earth is ‘Rh-null blood’, also known as ‘Golden blood’. The rationale behind being rare is due to the lack of all the Rh (rhesus) antigens (proteins) on the surface of red blood cells (RBC). RBC of these people has an unusual shape, poor lifespan, and perforated membranes because of the absence of Rh antigens which is taken into account to allow them a correct structure. Till now, it has been identified in less than 50 humans all over the globe. The Rh-null blood was first identified in the year 1961 in an Aboriginal Australian pregnant woman. The scientists thought that fetuses having this blood group will not be able to get delivered and survive.
Human Blood Grouping System:
In 1990, Karl Landsteiner at the University of Vienna performed some blood transfusion experiments which have mixed results as some succeed and some tend to be dangerous. He discovered the ABO blood grouping system by mixing blood cells and serums with each of the staff. The modern human blood grouping system consists of mainly two broad classifications that is ABO blood grouping system and Rh blood grouping system. There are some minor blood grouping systems such as Duffy, KIdd, Xg, Kell, KP, and Lutheran.
The gene, ABO glycosyltransferase that determines the human ABO blood group is located on chromosome 9. A, B, and O are the three different allelic forms of the ABO locus. Each of them is responsible for producing different glycoproteins. Hence, the arrangement of alleles received from parents determines the type of glycoprotein or antigens present on the person’s blood cells, therefore their ABO blood type. The ABO blood group system is divided into four types of blood group, A, B, AB, and O blood type. A blood group possesses A-surface antigens on the RBC membrane and B antibodies in blood plasma. B blood group has B antigens on the RBC membrane and A antibodies in blood plasma. AB blood group contains both A and B antigen on RBC membrane but no antibodies, whereas O blood group contains only A and B antibodies in blood plasma but no antigens.
Likewise, Rh factors are inherited from parents as antigens or proteins on RBCs. The Rh blood group system has 49 Rh antigens, out of which five are most important, namely C, c, D, E, and e. Individuals having Rh factors are referred to as Rh blood group positive and those lacking these factors are Rh blood group negative.
Rh-null blood is also referred to as the ‘Golden blood’:
Many people think that the blood is golden hence it’s named Golden blood, but in fact, it’s not the case! This blood is extremely rare in nature and costliest of all the blood types. Over the past 50 years, only 43 people are diagnosed with it and have an immense role within the field of medical researches and also medicine production. It can be donated to anyone without causing any transfusion complications; thanks to the lack of the Rh antigens. Due to its high demand and scarcity, it’s considered to be precious as gold. That is why Rh-null blood is additionally referred to as ‘Golden blood’.
When do people have this Golden blood type?
Genetic mutation when taken into account has been found to be the main cause of people having golden blood. The mutation within the RHAG gene, which codes Rh-associated glycoprotein, is held to blame for this. This glycoprotein directs Rh antigens to the RBC membrane. The mutation in the RHAG gene is linked to a disease known as ‘hereditary stomatocytosis’, which ends in a decreased life span of RBC and might cause lifelong or short-term hemolytic anemia. People involved in the consanguineous marriage (between cousins, sister-brother, or someone who may be a near or distant relative) or abnormal/autosomal genes having disease traits or alteration/changes of genes like RHD and RHCE or RHAG have a higher risk of getting Rh-null blood.
Inheritance of Rh-null phenotype:
Rh-null phenotype can arise due to two different genetic mechanisms: Amorphic and Regulator. In the amorphic form of mutation, the RHCE gene inherited from each parent undergoes mutation, and the RHD gene gets deleted in maximum cases. These people have inherited the normal RHAG gene. In regulator form of mutation, RHAG gene undergoes mutation which results in the silencing of RhAG protein and RhD or RHCE genes on the RBCs, despite regular inheritance of RHD and RHCE genes. These people can pass normal Rh genes to the next generation.
Rh-null people of both types have a deficiency of LW antigen (an antigen in the LW blood group system) and FY5 antigen (an antigen in the Duffy blood group system). People having Rh-null blood have restricted elimination of the RH gene expression, resulted due to mutations in the RHAG gene. Their RBCs may have other blood group antigens, but possess a weak expression of Rh and LW antigens and impaired expression of S, s, and U antigens (antigens found on glycophorin B).
Complications associated with these particular people:
Early as 1961, scientists believed that individuals having blood, lacking all the Rh antigens can’t be successfully delivered out of the mother’s womb, but it’s not the case! People having this blood group can live, but there are plenty of complications associated with it.
The complications consist of:-
1) Hemolytic anemia since birth: – Hemolysis means the destruction of RBCs and a lower amount of RBC in blood indicates anemia. Here the RBCs are destroyed quite fast and thus have a short lifetime compared to healthy RBCs. It happens because of irregular and abnormal shape of RBC structure, leaky cytomembrane, high fragility because of lack of Rh antigens, and altered cell volume.
Treatment: Symptomatic treatments include blood transfusion at regular intervals. Steroid therapy can be used in case of serious immune-related hemolytic anemia. For patients resistant to steroids, drugs like rituximab and immunosuppressants like azathioprine and cyclophosphamide come into action. Methylprednisolone with immunoglobulin injections is known to be useful in severe hemolytic cases.
2) Difficulties in blood transfusion: – These people can only receive blood from the donor having the same blood type and there are only 9 active donors alive. If they receive blood having Rh antigens, autoantibodies are formed which can cause a severe reaction within the body. They’re asked to donate their blood from time to time to preserve it for his/her own need just in case of any severe injury.
3) Rh incompatibility during pregnancy: – If the mother has Rh-null blood and the baby has Rh-positive blood, then upon mixing of both the blood, the mother’s blood reacts to the antigens of the child’s blood and produce protective proteins (antibody) which cause difficulty in future pregnancy or may result in miscarriage or abortion.
Treatment: If the fetus has been diagnosed with anemia, early delivery followed by regular blood transfusion can be beneficial. However, if it’s too early for the fetus to get delivered, blood transfusion can take place through the uterus of the mother. After the normal delivery, the infants can be treated with series of blood transfusions until it makes their hemoglobin, electrolytes that regulate the mechanism, hydrating fluids, and phytotherapy where fluorescent lights are used to decrease bilirubin level in blood.
4) Hemolytic problems: – Any infection or sepsis within the body results in an increase in RBC destruction which ends up in renal disorder and other organ complications within the body.
Why Rh-null blood is ‘universal’ in nature?
Now we all know the Rh-null blood lacks all the Rh antigens on RBC. It’s considered ‘universal’ because it can be accepted by any people even by those having rare blood types within the Rh systems. Upon receiving this blood, there’s no transfusion reaction because of the lack of common antigens present on the receiver’s blood cells. But because it is extremely rare, the transfusion involving these people is sort of null aside from some severe circumstances like if an individual having Rh-null blood requires a blood transfusion. People having Rh-null blood cannot receive any other blood type due to severe transfusion reactions. Even if they receive O-negative blood, it will result in serious immune responses as it contains Rh antigens on RBCs. They are asked to donate blood as their insurance for future circumstances.
Summary:
The Rh-null blood is the rarest among all the blood groups present in the living world (humans), therefore its usage within the field of medicine and science is tremendous. It’s as precious as gold hence named Golden blood. It’s a universal blood donor but can receive blood from the people having the same blood group which makes their survival difficult. Plenty of more researches are going on this to own a more clear and detailed view of the function of the valuable ‘Golden blood’.
Also read: University of Delhi announces PG admissions 2021
Sources:
- Jaramillo, J. (2020). Rhnull: The ‘Golden blood’ Type. Scientific Scribbles, University of Melbourne, Blogs.unimelb.edu.au. https://blogs.unimelb.edu.au/sciencecommunication/2020/09/08/rhnull-the-golden-blood-type/
- Dickinson, K. (2018). Golden blood: The rarest blood in the world. Big Think. https://r.search.yahoo.com/_ylt=Awrxguq4rOZgQGkAHw3nHgx.;_ylu=Y29sbwMEcG9zAzEEdnRpZAMEc2VjA3Ny/RV=2/RE=1625759032/RO=10/RU=https%3a%2f%2fbigthink.com%2fsurprising-science%2fgolden-blood/RK=2/RS=mA0aJBbhiNyprlrVMCre7lfwg0I-
- Dhnaorkar, A. (2020). What Is the Golden Blood Type? Medicinenet.com. https://www.medicinenet.com/what_is_the_golden_blood_type/index.htm
- Faletto, J. (2019). Rhnull. The Rarest Blood Type on Earth, Has Been called the “Golden Blood”. Discovery.com. https://www.discovery.com/science/Rhnull-Rarest-Blood-Type-on-Earth
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