Introduction
Blood groups are inherited permanent characteristics of an individual that gives rise to the antigen-antibody system. They may be detected early in foetal life and with exception of Lewis systems remains unchanged till death (Adeoye, 2007).
ABO blood group system is a system that classify human blood base on the inherited properties of red blood cells as determine by the presence or absence of the antigen A and B which are carried on the surface of the red blood cells. Person may thus have type A, type B, type AB or type O blood.
The ABO blood group system was discovered by an Australian Pathologist, Karl Landsteiner in the year 1900. He discovered the ABO blood groups by carrying out an experiment which involves the mixing of the red cells and serums of each of his staff. He demonstrated that the serum of some individual agglutinated the red cells of others. From this early experiment, he specified three types of blood which are A, B and O (Ogasarawa, Bannai, and Saitou 2004)
The forth much rare blood group (AB) of the ABO blood group system was discovered two years later by Alfred von Decastello and Andriano Sturli Lanstaner students (Beaker, Silver, and Pallister 2009).
An individual with blood type A have antigen A on their red cells and antibodies to B in their plasma, like-wise blood group B individual have antigen B on their red blood cells and antibodies to A in their plasma. Blood type AB individual have both antigen A and B on their red cells so they lacked antibodies to antigen A and B in their plasma. Blood group O individual does not have antigen A and B on their red cells but they have antibodies A and B in their plasma.
The rhesus blood group system was discovered in 1914 by Landsteiner & Weiner. They injected rabbits and guinea pigs with the red cells from Maccus rhesus monkey and the resulting antibody reacted with the red cells of 85% of New York donors. Those who reacted were said to have the Rhesus factor and are referred to as rhesus positive while those that did not react lacked the Rhesus factor and were referred to as rhesus negative (Avent and Rey 2004)
The discovery of ABO and rhesus blood group system has contributed immensely in blood banking service and transfusion medicine in other to avoid morbidity and mortality in both adult and children.
Conceptual framework
Blood is a vital fluid found in human and other animals. It helps to transport nourishments to all the body organs, tissues and remove waste materials. It is pumped from the heart through a network of blood vessels collectively known as the circulating system. It is made up of two parts. 45% formed the cellular element and 55% formed the liquid part called the plasma. The cellular element includes the erythrocyte, leukocyte and the platelets which are suspended in the plasma (Adebayo, 2007).
Blood group is an inherited permanent characteristics of an individual that give rise to the antigen-antibody system. They may be detected early in foetal life (Adebayo, 2007).
The ABO blood group system is the most important blood type system in human blood transfusion. The associated anti-A and anti-B antibodies are usually 1gm antibodies, which are produce in the first years of life by sensitisation to environment substances, such as food , bacteria and viruses. ABO blood types are also present in some other animals, e.g. rodents, apes (such as chimpanzees, bamboos and gorillas (Maton et al 1993).
ABO blood group system
The ABO blood group system is widely credited to have been discovered by the Australian scientist Karl Landsteiner, who identifies the O, A and B blood types in 1900. Landsteiner originally described the O blood type as type C and in part of Europe; it is referred to as O (zero) signifying the lack of A or B antigen. Landsteiner was awarded the noble price in physiology or medicine in 1930 for his work. Alfred von Decastello and Adriano Sturli discovered the forth type AB in 1902 (Von Decastello and sturli, 1902).
Due to inadequate communication, at the time, it was subsequently found that the Czech serologist Jan Jansky had independently pioneered the classification of human blood into four groups but landsteiner’s independent discovery have been accepted by the scientific world while Jansky remained in relative obscurity (Jansky, 1907). Jansky nomenclature is however still used in Russia and states of the formal USSR in which blood types O, A, B, and AB are respectively designated as i, ii, iii, iv.
The designation A and B with reference to blood group was proposed by Ludwik Hirszfeid. In America, W.L Moss published his own work in 1910 (Moss, 1910). Ludwick Hirszfied and E. Von Dungern discovered the heritability of ABO blood group inheritance pattern of multiple alleles at one locust in 1924. Watkins and Morgan, in England, discovered that the ABO epitope were conferred by sugars to be specific, N-Acetylgalactosamine for the A type and galactose for the B type (Watkin and Morgan, 1959).
Blood group genetics
Blood groups are inherited from both parents. The Abo blood type is controlled by a single gene with three types of alleles inferred from practical genetics: i IA and IB. The gene encodes a glycosyltransferase that is, an enzyme that modifies the carbohydrate content of the red blood cell antigens. The gene is located on the long arm of the ninth chromosome (9q34).
The IA allele gives type A, IB gives type B and i gives type O. As both IA and IB are dominant over i, only people have type O blood. Individual with IA IA or IAi have type A blood and individual IBIB or IBi have type B. IA IB people have both phenotype, because A and B express a special dominance relationship co-dominance, which means that type A and B parents can have an AB child (Yazerm Olsson and Palcic 2006) a couple with type A and type B can so have a type O child if they are both heterozygous (IBi,IAi) .
The Cis – AB phenotype has a single enzyme that create both A and B antigens. The resulting red blood cells do not usually express antigen at the same level that will be expected on common group A1 or B red blood cells, which can help solve the problem of an apparently genetically impossible blood group.
Inheritance patterns of ABO blood groups
Blood groups are inherited from parents in the same way as other genetic traits e.g (eye colour). ABO and Rhesus are the most well known among the blood group system. The ABO blood group system is determined by the ABO gene which is found on chromosome 9. The four ABO blood groups; A, B, AB, and O arise from inheriting one or more of the alternative forms of this gene (or alleles) namely, A, B or O.
BLOOD GROUP POSSIBLE GENE
A AA OR AO
B BB OR BO
AB AB
OO OO
Figure 1 showing the genetic combination of ABO blood group.
The A and B alleles are co dominant so both A and B antigen, will be expressed and the red cells whenever either alleles is present. O alleles do not produce either A or B antigens, thus are sometime called “silent” alleles.
PARENTAL BLOOD GROUPS CHILD’S BLOOD GROUP
O and O O
O and A O or A
O and B O or B
O and AB A or B
A and A A or O
A and B O of A or B or AB
A and AB A or B or AB
B and B O or B
B and AB B or A or AB
AB and AB A or B or AB
Note: These are various possible blood groups that children may inherit according to the combination of parental blood groups.
Genetics terms
Alleles: These are two or more genes that are responsible for the same position on the chromosome (Ochie and Kolhatkar 2008).
Gene: this is the Basic unit of genetic material, which is carried on a particular place on a chromosome
Genotype: this is the genetic make up of an individual (Ochie and kolhatkar 2008).
Phenotype: all the observable characteristics of an individual, such as shape, size, colour and behaviour that result from the interaction of its genotype.
Recessive gene: The recessive genes are express when their dominant in the allele is absent (Ochie and kolhater 2008).
Dominant gene: A gene is dominant when an allele is expressed over a second allele at the same locus
Co-dominant gene: Relating to two alleles of a gene pair in a heterozygote that are both fully expressed.
Blood group antigen and antibodies
Antigens
An antigen is a chemical substance, which when introduce parentally into a body that lacks it, stimulate the production of a corresponding anti-bodies. When the antigen is mixed with the anti-body, it reacts with it in observable manners. The observable manners are agglutination, sensitisation, and haemolysis (Adeoye, 2007). Antigen are large molecular substance usually protein, but sometimes, combine with a polysaccharide component. The antigens occur on the surfaces of the red blood cell in a large proportion of human beings
The precursor to the ABO blood group antigen present in people of all common blood types is called the H-antigen. Individuals with the rare Bombay phenotype (hh) do not express antigen-H on their red blood cell. The H-antigen serves as a precursor for producing A and B antigen. The absence of H-antigen means the individual do not have A and B antigen (similar to O blood group).
However unlike blood type O, the H-antigen is absent hence, the individual produces iso antibodies to antigens A and B. In case they receive blood from blood group o donor, the anti-H antibodies will bind to the H-antigen on the red blood cell of the donor blood and destroy the red blood cells by complement mediated lyses. Bombay phenotype can receive blood only from other hh donors (although they can donate as though they are type O). Some individual with the blood group AI may also be able to produce anti-H antibodies due to complete conversion of all the H-antigens to A1 antigen.
The H-antigen is controlled at the H- locus on chromosome 19. The H-locus contains three exons that span 5kb of genomic DNA and encodes the glycosyltransferase that produces the H-antigen on red blood cells. The H-antigen is a carbohydrate linked mainly to protein. It consist of chains of β-D-N-acetyleglucosamine, β-D-galactose and two linked α-L-fucose, the chains are attach to a protein or ceramide.
The ABO locus, which is located on chromosome 9 contains 7 exons that span more than 18kb genomic DNA. Exon 7 is the largest and contains most of the coding sequence. The ABO locus has three main allelic forms; A,B, and O. The A allele encodes a glycotransferase that bonds α-N-acetylgalactosamine to the D-galactose end of the H-antigen producing the A-antigen. The B allele encodes a glycosyltransferase that bonds α-D-galactose to the D-galactose end of the H-antigen, creating the B antigen
In the case of O allele, when compare to the A-allele, exon 6 lack one nucleotide (guanine) which result in a lost enzymatic activity. This difference which occurs at position 261 causes a frame shift that result in premature termination of the translation and thus degradation of the mRNA. This result in the H-antigen remaining unchanges in case of O groups.
The majority of the ABO antigens are express on the end of long polylactosamine chains attach mainly to band 3 protein. The anion exchange protein of red blood cell membrane and a minority of epitopes are express on neutral glycosphingo lipids.
Antibodies
An antibody is a substance in the serum or plasma of an individual as a result of antigenic stimulation. When the antibody mixes with the antigen, it reacts specifically with it. Antibodies are gamma glubulins produced by the bone marrow and lymph gland cells. Most blood group antibodies are either IgG or IgM, but some activity is associated with IgA. IgM antibodies are usually antibodies that agglutinate red cells with corresponding antigens in saline preparation, while IgG antibodies are the incomplete antibodies that sensitize red blood cells, suspended in saline but do not agglutinate. IgG antibodies cross the placenta from mother to baby (Adeoye, 2007).
Naturally occurring antibodies occurs in the plasma of an individual who lack the corresponding antigen and who have not been transfused or been pregnant. The most important are anti A and anti B. They are usually immunoglobin M (IgM) and react optically at cold temperatures (40c), although, reactive at 370c. They are called cold antibodies (Hoffbrand, et al 2006).
Immune antibodies develop in response to the introduction of red cells possessing antigens that the person lacks by transfusion or by transplantation passage during pregnancy. These antibodies may also develop usually in the early phase of immune response. Immune antibodies react optically at 370c (warm antibodies). The most important immune antibody is the Rh antibody (anti-D).
Molecular background of the ABO blood group system
The ABO human blood group system consists of A antigens, B antigens. The antigenic determinants are synthesized in the Golgi apparatus by specific glycosyltransferases which transfer proper sugars to an oligo saccharide acceptor, called H antigen. N-acetylgalactos, amin-transferase (transferase B) uses a UDP-galactos donor to convert H-antigen to B-antigen.
The amino acid sequences of transfrase A and B differ by four residues, of which only two causes a change in enzyme specificity. These residues are lev/met 266 and Gly/ Ala 268 in transferase A and B respectively. Structural studies revealed that the presence of amino acids with bulky side chains (methionine and alanine) in transferase B cause its inability to bind N-acetylgalactosamine. The recessive trait O, in which antigens A and B are not present, is cause by the expression of an incomplete enzyme as a result of a base deletion and subsequent reading frame change (Smolarek, et al 2008).
Rhesus blood group system
The rhesus blood group system is named after the rhesus monkeys in which they were first discovered in 1940, when landsteiner and weiner injected red cells from rhesus monkey into rabbits, thereby stimulating the production of an antibody which not only agglutinated rhesus monkey red blood cells but also the red blood cells approximately 85% of caucasions (Baker, Silverton, and Pallister, 2009).
The rhesus blood group system is the most important blood group system after ABO. At present, the Rh blood group system consist of 5O defined blood group antigens D,Cc,,E and e are the most important. The commonly used term Rh factor, Rh positive and Rh negative refers to the D antigen only. Besides its role in blood transfusion, the Rh blood group system-specifically the D antigen is used to determine the risk of haemolytic disease of the new born (HDN) or erythroblatic disease of the new born (HDN) or (erythroblastic retalls) as a prevetion is the best approach to the management of this condition (Levine, and Stetson 2000)
Individual either belongs to the rhesus positive or rhesus negative blood groups. People with Rhesus positive blood group have D antigen on the surface of their RBCS. While, Rhesus negative individuals do not have it. In contrast to ABO blood group, antibodies are not usually present in the blood under normal condition. They only form in Rh negative individuals who are exposed to Rhesus positive blood. If a Rh negative person receives a Rh positive transfusion, the recipient produce anti-D antibodies since anti–D does not form instantaneously, there is little danger in the first mismatch transfusion. However, because the recipient will now start producing anti-D, a subsequent Rh positive transfusion could agglutinate the donor’s RBCS.
The role of antigen and antibodies in the blood transfusion
For a blood donor and recipient to be ABO – compatible for transfusion, the recipient cannot be able to produce anti-A or anti-B anti bodies that correspond to the A or B antigen on the surface of the donor’s red blood cells. If the antibodies of the recipient blood and antigens on the donor red blood cells do correspond, the donor blood is rejected. Upon rejection, the recipient may experience acute haemolytic transfusion reaction (AHTR).
In addition to the ABO system, the Rhesus blood group system can affect transfusion compatibility. An individual is either positive or negative to the Rh factor, this is donated by a “+” or “–“ after their ABO type. Blood group that is Rh negative, can be transfuse to a person who is Rh- positive, but a Rh-negative individual can create antibodies for Rh- positive.
Because of this, the AB positive blood group is referred to as the universal recipient as it possesses neither anti-A nor anti-B antibodies in its plasma and Rh-negative blood. Similarly, the blood group O negative is called the universal donor, since its red blood cell have no A or B antigens and are Rh-negative, no other blood group will reject it.
Identification of ABO and Rh gene frequencies among human population has various benefits in transfusion medicine, transplantation and disease risk (Fareed, et al, 2014)
Implications of rhesus blood group during pregnancy
A related condition can occur when an Rh negative woman is pregnant with a Rh positive foetus. The first pregnancy is generally uneventful since anti-D does not form right away so that even if the mother is exposed to Rh positive foetal blood via miscarriage or placental tearing at the time of birth, there is no danger to first Rh positive child. However, she does begin to produce anti-D antibodies upon her first exposure to Rh positive foetal. If she becomes pregnant again with a Rh positive foetus, her anti-D antibodies can pass through the placental and agglutinate the foetal red blood cells.
Agglutinated RBCS haemolyse( release their Haemoglobin) and the baby is born with a severe anaemia called haemolytic disease of the new born (HDN) which may kill the infant or leave brain damaged (Saladin, 2004).
HDN is relatively easy to prevent, while very difficult to treat. A Rh negative mother is at risk of having Rh positive baby if the risk baby’s father is Rh positive as a result, it is now common to give immuno globulin at 28-32 weeks of gestation and at birth to any pregnancy involving a Rh negative mother and a rhesus positive father, immune globulin binds foetal RBCS antigens so that they cannot stimulate the mother immune system to produce anti-D, hence preventing HDN (Shewood, 2014).
Distribution of ABO and rhesus blood group
The distribution of ABO and Rh blood group varies across the world according to the population. There are also variations in blood group distribution with human sub population (ethnic group).
In United Kingdom, the distribution through the population still shows some correlation to distribution of place, names and to the successive invasion and migration including Vikings Danes, Saxons cells and Normans who contributed the morphemes to the place names and the genes to the place, names and the genes to the population. The distribution of ABO and Rhesus blood group among individuals shows blood group O as the predominant and accounting for 82%, group B was found 9.2%, group A 7.9% and AB was the least common 0.9%. This pattern is similar to mamma in Kaduna who found a distribution of ABO and Rhesus blood n, group of 21.3% for group A 24.3% for B, 52% for AB and 49.2% for blood group O (Adeyemo, and Soboyego, 2006).
In addition, in Nigeria, among 7653 individuals in Ogbomoso, Oyo State, 50% had type O, type A 22.9%, type B 21.3%, type AB 5.9% (Enosolease, and Bazuaye 2008). Furthermore, in Abraka, Delta State University, Department of Anatomy, Faculty of basic medical science, 795 samples were analysed, it was found out that blood group O ever was most common followed by A,B, and AB respectively.
A distribution study of ABO and rhesus D blood group among 250students of African descendant attending Usman Dan Folio university in Sokoto, North Western, Nigeria, revealed that 103 (41.2%) O, 68(27.2%) were group B, 63(25.6%) group A and 15(6%) group AB. out of the 250 students investigated, 223 (89.2%) were Rhesus D positive and 105(10.8%) were rhesus D negative (Erabor, et al 2014). Also a study was carried out on 193 medical student of Madona university in which the student were divided into 3 major ethnic group i.e 1gbo, Yoruba & Hausa. The study revealed that blood group O was predominant with a percentage frequency of 13.5, 18.1 & 19.2% in Igbo, Hausa & Yoruba respectively followed by A (10.9%, 8.3%, 7.8%), B (6.7%, 4.7%, 4.7%) AB (21.1%, 1.6%)
In haematology department, University of Port Harcourt teaching hospital, 936 students of different tribes in Nigeria (such as Ikwere, Ijaw, Igbo, Ogoris, Efik, Ibibio, Edo, Yoruba, and Hausa) were screened for predominant ABO and Rhesus blood group with the aim of generating data that would assist in the running of an efficient blood transfusion service. the result of ABO Rhesus screening shows that blood group O was the highest with 527(56.3%), followed by blood A, B, and AB with 212(22.65%), 178(19.2%) &18(2.10%) respectively. The highest contribution to blood O was from the Igbo’s with 220(23.50%) while the Ijaw gave the highest contribution of rhesus D antigen with 370(39.53%) followed by the Igbos (0.43%). A rhesus negative value in this study was 7.26% of which the highest contributor was still the Ijaw with 33(3.53%) and Igbo’s with 27 (2.8%) (Nwauche and Ejele 2012)
A study was carried out in different country (Syria, Lebanon, Israel, Jordan). It reveals that blood group A was predominant with a percentage frequency of 46.25%, 47.25%, 40%, 36.36%, respectively. Followed by blood group O (37.5, 36.11, 38, 36.62%), B (13.13, 11.32, 16, 18.04%), AB (3.12, 5.12, 6, 6.98%). (Hanania, and Hassawi 2007).
References
Abayomi, A. (2007). A text book for Medical Laboratory Practice 1ST Ed. Pp 209:212- 219.
Avent, N.D., and Reid, M.E. (2004).The Rh blood group system.;95: 375-384.
Baker, F.J., Silver, R.E. and Pallister, C.J. (2009). Frequency of ABO blood group among medical student. Journal of surgery Pakistan (international). pp51.
Fareed, M., Hussain, R., Shah, A. and Afzal, M. (2014). “A1A2BO and Rh gene frequencies among six population of Jammu and Kashmir, India”.Transfusion and Aphereses science 01:014
Hanania s, Hassawi D, Irshald .N. (2007). Molecular genotype of ABO blood group system in Jordanian population. J.med sci. 7:51-58.
Havey, G.K. and David, J.A. (2010). Mollision’s blood transfusion in clinical medicine 11th edition. Oxford: Black Well Scientific Publications. Pp 114-163.
Jansky, J.(1907).”Haematologic studies .Psychotiku’’.Sborn Klinick(in Czech). 8:85-139.
Jolly, J.G. (2008). Medicolegal significance of human blood groups. J Indian med. 98: 340-341
Levine, P. and Stetson, R.E. (1939). ‘’An usual case of intragroup agglutination ‘’ JAMA. 113:126-7.
Maton, A., Jean, H., Charles, W., Susan, M., Johnson, M., Quon, W., David, I. and Jill, D.W. (1993). Human Biology and Health Engle wood cliffs, New Jersey, USA; Prentice Hall 14.
Matthew, E.E., and Godwin, N.B. (2008). Journal-Asian J transfusion Science. Pp 2. Pmc 2798756.
Moss, W.L. (1910). “studies on isoagglotinis and Isohemolysins”. Bullet in John Hopkins Hospital. 21:63-70
Nwauche, O.A. and Ejele, O.A. (2004). ABO and rhesus antigens in a cospolitan Nigeria population. Niger J.med. 13: 263-266
Ogasawara, K., Bannai, M. and Sartu, N. (1996). Extensive Polymorphism of ABO blood group gene. Itowan Genetic 32: 777-783.
Ochie, J. and Kolhater, W.S.A. (2000). Medical Laboratory Science Theory and Practice. 350-356
Qureshi, M.A. and Bhatti, R. (2003). Frequency of ABO and Rh blood groups in the diabetes mellitus type 2 patients. J. Coll physician Sugs Pak. 13: 453-453.
Von Decastello, A., Sturli, A. and Kranker, M. (1902). Isoagglutins in serum.
Watkins, W.M. (1980). Advances in Human Genetics (Eds Harris, I.T, and Hir Schmorn, .K.) 10:1-136
Yearm, O. M. and Palic, M. (2006). The Cis AB blood group Phenotype fundamental lessons in glycobiology. Transfuse med. 20:2007 -17.
Ziegher, T., Jacobsohn, N. and Funfstock, R. (2004). Correlation between blood group phenotype & virulence properties of Escherichia coli in patients with chronic urinary tract infection. Int J. antimcrob agents. 24: 70 -75.
