Abo And Secretor Blood Group Genetics Biology Essay

The gland factor ( Se ) might be considered either a physiologic trait or an honorary blood group. The person who is a alleged gland has incontrovertible ABH blood group antigen in the spit and other organic structure fluids ; the nonsecretor does non. Secretor is dominant.

Genetically independent of the ABO blood groups is the gland system which comprises two allelic cistrons, ( Se ) which causes secernment in spit and other fluids of the antigen or antigens matching to the person ‘s ABO group, and ( Se ) which, in the homozygous status determines non-secretion. Heterozygotes are glands. There are broad fluctuations in the frequences of the two cistrons, which could hence be of considerable anthropological value. Besides the gland and non-secretor provinces have important associations with certain diseases. Natural choice is hence thought to be of considerable importance in finding the frequences of the cistrons.

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The Se and se cistrons of the ABH gland system vary widely in frequence in different populations, but our cognition of their distribution is uncomplete and patchy. In peculiar the Se cistron has a really high frequence in American Indians and seemingly a low one in southern India. The system shows chiseled associations with certain diseases and there are indicants that it is involved in major procedures of natural choice.

Secretor map centres around the action of a bunch of cistrons which control the production of enzymes called ‘fucosyltransferases ‘ . The cistrons are called ‘FUT ‘ and are numbered 1-7. The bulk of these are on chromosome figure 19 ( 19q13.3 ) . These enzymes help assemble thefucose strings which so become the H antigen, or are farther glycosylated to A and/or B antigens.

Chromosome 19 does most of the gland work. It carries the the codification for FUT1 and FUT2 ( fucosytransferase enzymes ) of which the ‘null allelomorph ‘ on FUT2 codifications for ‘non-secretor ‘ position. FUT2 codifications for fucosyltransferase activity in organic structure duct gland ( a type of secretory organ ) tissues, which so makes you a gland, since you are pumping blood type antigens into your secernments.

Many of the FUT cistrons are closely involved in the development of the embryo, a fact which helps explicate why many people feel that the primary map of ABO antigens are to move as a scaffold in our inter-uterine life.

One of the cistrons, FUT4, is found on chromosome 11. It appears non-lethal as mice bred to non hold it appear healthy. It seemingly has something to make with the effects of ABO in bone marrow.

Recently, a new fucosyltransferase gen, FUT7, has been linked to 9q34 ( the ABO blood type venue ) . Tissue distribution of FUT7 is really restricted to leucocytes and high endothelial ( blood vas ) cells, and plays a critical function in the map of selectins ( tissue particular lectins involved in the migration of white blood cells to countries of infection or tissue harm. ) Thus the organic structure itself uses ABO and internal lectins to assist aim the immune system.

Functional and Genetic Factors Involved in ABH Secretion

ABH secernment is controlled by two allelomorphs, Seand Se. Se is dominant and Se is recessionary ( or amorphic ) . Approximately 80 % of people are glands ( SeSe or Sese ) .

In the most fundamental sense, the gland cistron ( FUT2 at 19q13.3 ) codifications for the activity of the glycosyltransferases needed to assemble facets of both the ABO and Lewis blood groups. This it does in concert with the cistron for group O, or H ( FUT1 ) . These enzymes are so active in topographic points like goblet and mucose secretory organ cells, ensuing in the presence of the corresponding antigens in organic structure fluids. ( 1 )

The H antigens are indirect cistron merchandises expressed as fucose-containing glycan units, shacking on glycoproteins or glycolipids of erythrocyte membranes or on mucin glycoproteins in secernments and are the fucosylated glycans substrates for glycosyltransferases that give rise to the antigenic determinants for the A, B and Lewis blood group antigens. The major difference between the two cistrons is in their form of look: the FUT1 ( H ) cistron is expressed preponderantly in erythroid tissues giving rise to FUT1 ( H enzyme ) whose merchandises reside on erythocytes, whereas the FUT2 ( Secretor ) cistron is expressed preponderantly in secretory tissues giving rise to FUT2 ( Secretor enzyme ) and to merchandises that reside on mucins in secernments.

When allelomorphs of both cistrons fail to show active enzymes, persons bearing them, in homozygous province, lack the substrates for the A or B glycosyltransferases and do non show the A and B antigenic determinants.

ABO and Secretor Blood group Genetics


Glycosphingolipids transporting A or B oligosaccharides are built-in parts of the membranes of RBCs, epithelial and endothelial cells ; they are besides present in soluble signifier in plasma. Glycoproteins that carry indistinguishable oligosaccharides are responsible for the A and B activity of secreted organic structure fluids such as spit. A and B oligosaccharides that lack bearer protein or lipid molecules are found in milk and piss.

Genes at three separate venue ( ABO, Hh, and Sese ) control the happening and the location of the A and B antigens. Three common allelomorphs -A, B and O- are located at the ABO venue on chromosome9q34. The A and B cistrons encode Glycosyltransferases that produce the A and B antigens, severally. The O cistron is considered to be amorphic since no noticeable blood group antigen consequences from its action. The RBCs of group O individuals lack A and B, but carry an abundant sum of H antigen because this antigen is the precursor stuff on which A and B antigens are built.

Family surveies have shown that the cistrons at the staying two venue, Hh and Sese ( gland ) , are closely linked. The chromosome on which they are located has non yet been identified. It is suggested that one of these venues may hold arisen through cistron duplicate of the other. Two recognized allelomorphs shack at each venue. Of the two allelomorphs at the H venue, one of these, H, produces an enzyme that acts at the cellular degree to build the antigen on which A or B are built. The other allelomorph at this venue, H, is really rare. No antigenic merchandise has been linked to h, so this cistron is besides considered an amorph. The possibility exists that other allelomorphs occur at the Hh venue that differ from H in that they cause the production of lone really little sums of H antigen.

Gland Geneticss

The Sese cistron is straight responsible for the look of H ( and indirectly responsible for the look of A and B ) on the glycoproteins in epithelial secernments such as spit. Eighty per centum of the population are glands because they have inherited the Se cistron and bring forth H in their secernments that can be converted to A and/or B ( depending on the familial background of thesecretor ) . The se cistron, holding no incontrovertible merchandise, is an Amorph.

Oligosaccharide ironss on which the A and B antigens are built can be as simple constructions of a few sugar molecules linked together in additive manner. They can besides be as more complex constructions that are composed of many sugar residues connected together in ramification ironss. It has been proposed that the differences in cellular A, B and H activity seen between specimens from babies and grownups may be related to the figure of bifurcate constructions carried on the cellular membranes of each group. The RBCs of babies are thought to transport A, B and H antigens built preponderantly on additive oligosaccharides. Linear oligosaccharides have merely one end point to which the H, so A and B, sugars can be added. In contrast, the RBCs of grownups appear to transport a high proportion of bifurcate oligosaccharides. Ramifying creates extra parts on the oligosaccharide that can be converted to H and so to A and B antigens.

A and B cistrons do non bring forth antigens straight but alternatively bring forth enzymes calledglycosyltransferases that attention deficit disorder specific sugars to oligosaccharide ironss that have been converted to H by the action of the H cistron. H antigens are constructed on precursor oligosaccharide concatenation terminations called Type 1 and Type 2. The figure 1 C of the terminal 6-carbon sugar b-D-galactose ( Gal ) is linked to the figure 3 C of subterminal N-acetyl-glucosamine ( GlcNAc ) in Type 1 ironss and to the figure 4 C of GlcNAc in Type 2 ironss. Blood group-activeglycoproteins nowadays on cell surfaces or in body fluids carry either Type 1 or Type 2 chains.Glycosphingolipids present in the plasma and those on the membranes of most glandular and parenchymal cells besides have either Type 1 or Type 2 concatenation terminations. In contrast, the glycolipidantigens produced by the RBCs ; look to be formed entirely of Type 2 ironss. These ironss are carried on a category of glycosphingolipids called paraglobosides.

At the cellular degree, the H cistron transferase produces a Fucosyltransferase? that adds fucose ( Fuc ) in alpha ( 1-2 ) linkage to the terminal Gal of Type 2 ironss. The A and B cistron transferases can merely attach their immunodominant sugars when the Type 2 ( or Type 1 ) ironss have been substituted with Fuc ( Internet Explorer, changed to H ) therefore, the A and B antigens are constructed at the disbursal of H. The A gene-specified N-acetyl-galactosaminyl-transferase and the B gene-specified galactosaminyl-transferase attention deficit disorder GalNAc and Gal severally in alpha ( 1-3 ) linkages to the same Gal acted on by the H cistron transferase.

The allelomorphs at the ABO venue that consequence in subgroups ( phenotypes of A and B that differ from each other with regard to the sum of A or B carried on the RBCs ) produce transferases that differ from one another in their ability to change over H antigen. The O cistron is thought to bring forth a protein that can be detected immunologically but has no noticeable transferase activity. As a effect, the RBCs of group O individuals carry readily noticeable, unpersuaded H antigen. The secernment of Sese individuals contain Type I and Type 2 ironss with no H, A or B activity. It has been suggested that the H and Se cistrons each encode a different Fucosyltransferase. The enzyme produced by H Acts of the Apostless chiefly on Type 2 ironss and in RBC membranes. That produced by Se prefers ( but does non restrict its action to ) Type 1 ironss and Acts of the Apostless chiefly in the secretory. Surveies performed on the secernments of individuals with the rare Oh phenotype support the construct that two types of H antigen exist. Persons of this phenotype, who are genetically Hh and Sese, have no H and hence, no A or B antigens on their Red blood cell or in their secernments. However, H, A and B antigens are found in the secernments of genetically hh individuals, who, through household surveies, appear to possess at least one Se cistron.


The ABO cistron codifications for the glycosyltransferases that transfer specific sugar residues to H substance, ensuing in the formation of blood group A and B antigens. This cistron maps to chromosome 9, place 9q34.1-q34.2. It consists of 7 coding DNAs, runing in size from 28 to 688 base brace ( bp ) , and 6 noncoding DNAs with 554 to 12 982 bp ( Figure 1 ) .1-3 The last 2 coding DNAs ( 6 and 7 ) , which comprise 823 of 1062 bp of the canned messenger RNA, encode for the catalytic sphere of ABO glycosyltransferases.

Figure 1. Conventional representation of the genomic organisation of the ABO cistron. The coding DNAs ( black squares ) and regulative parts ( clear squares ) are drawn to scale, as are the intervening noncoding DNAs, although the graduated table of the latter is 10 times smaller. The deliberate Numberss of bases ( National Trusts ) in the coding DNAs and noncoding DNAs are shown. The upstream regulative part, which includes a CBF/NF-Y binding motive, is located around nt -3800 and, depending on the ABOhaplotype, 215 or 344 base brace ( bp ) in size ; the regulative part in the 5 ‘ untranslated part ( UTR ) is located from nt -118 to -1.

The 6 common ABO allelomorphs in white persons are ABO*A101 ( A1 ) , ABO*A201 ( A2 ) , ABO*B101 ( B1 ) , ABO*O01 ( O1 ) , ABO*O02 ( O1v ) , and ABO*O03 ( O2 ) . In coding DNAs 6 and 7 they differ by merely a few base places. ABO*A201, which is responsible for blood group A2, is indistinguishable to ABO*A101 apart from a nonsynonymous permutation at base ( National Trust ) place 467 and a individual omission ( 1060delC ) in exon 7. This omission consequences in break of the halt codon and an A-transferase merchandise with an excess 21 amino acid ( AA ) residue at the C-terminus. ABO*B101 is distinguishable from ABO*A101 at 7 nt places: 3 synonymous mutants at places 297, 657, and 930 ; and 4 nonsynonymous mutants at places 526, 703, 796, and 803. The nt sequence of ABO*O01 differs from that of ABO*A101 by a individual base omission at place 261 in exon 6 ; this omission shifts the reading frame, therefore bring forthing a premature halt codon. ABO*O01 is thought to be either soundless or translated into a abbreviated and catalytically inactive peptide. In contrast, the ABO*O03 allelomorph lacks the 216delG polymorphism but possesses nonsynonymous mutants that may get rid of the protein ‘s enzyme activity by changing the National Trust sugar adhering site.

Eighty-three ABO allelomorphs discriminated at 52 polymorphous sites within the coding part of the ABO cistron have been reported in the literature so far. In most instances the research workers analyzed merely exons 6 and 7. The figure of described ABO alleles additions to 88 when National Trust differences within noncoding DNA 6 are besides considered. It has been shown that surveies of the nt sequence of noncoding DNA 6 are important for elucidation of the beginning of some fresh haplotypes. To our cognition, there is no information available on sequence fluctuation of the noncoding parts upstream from exon 6 and small informations on mutants within the first 5 coding DNAs of the ABO cistron and their relevancy for the ABO phenotypes.14 In the present survey, we therefore examined the complete exon/intron sequences ( except for the immense noncoding DNA 1 consisting 12 982 bp ) and 2 regulative parts of common and rare ABO allelomorphs to measure the familial diverseness and variegation at the ABO venue. The genomic sequence informations were foremost correlated with the associated ABO phenotypes so used for lineage definition.

The presence of a big figure of perennial mutants is characteristic for the considerable diverseness of the ABO cistron. Phenotype-genotype correlativity revealed that an extended heterogeneousness underlies the molecular footing of assorted allelomorphs that generate serologic ABO subgroups. ABO sequence fluctuations besides include phenotypically relevant replacing mutants in coding DNAs 2 to 5. Therefore, ABO genotyping schemes would hold to see all fluctuations distributed across the full cryptography part to accomplish safe phenotype anticipation. Therefore, ABO genotyping remains chiefly reserved as a complement to serology for finding of familial ABO subgroups and exclusion of ABO*B allelomorph markers in the acquired B phenotype. The informations on extremely conserved and lineage-specific noncoding DNA sequence motives provide a powerful base for clarifying the beginning of variant ABO allelomorphs and may turn out valuable for anthropologic surveies on the beginnings and motions of populations.

In a cohort of wheezing kids, we have late shown that the ABO-secretor familial complex influences susceptibleness to asthma in kids. Since old surveies have shown an association of asthma with adenosine deaminase ( ADA ) genotype 2, we have searched for possible interactions between the two systems refering their effects on susceptibleness to asthma in kids. The sample survey has been described in a old paper 1 and was composed of 165 kids, 109 males and 56 females, aged from 1 month-15aˆ…yrs. The standard for inclusion in the survey was the happening of two or more episodes of wheezing in the last 6 months, irrespective of aetiology/pathogenesis of the onslaught.

A back-to-back series of 362 newborn babies from the same Caucasic population in Rome, Italy, was used as the control sample.

The proportion of nonsecretor/O topics with the ADA*1/*1 genotype was much higher in wheezing kids than in controls. On the contrary, the proportion of topics with other phenotypes of secretor-ABO complex transporting the ADA*2 allelomorph was much lower in wheezing kids than in controls. The other two phenotypic classs showed a similar proportion in wheezing kids and controls.

The deficiency of tripartite interaction among secretor/ABO composite, ADA and disease ( tableaˆ…2? ) , suggests that ADA does non act upon the consequence of the secretor-ABO composite and frailty versa, therefore bespeaking that there was non an epistatic consequence. On the contrary, the analysis suggests a concerted consequence of the familial factors on susceptibleness to asthma.

The gland cistron ( FUT2 ) and the ABO system act in concert to construct up oligosaccharide constructions in exocrine secernments, including secernments in the respiratory piece of land. Specific oligosaccharide antigenic determinants are necessary for acknowledgment and attachment of micro-organisms to the cell membrane, proposing that familial fluctuation in these systems may act upon susceptibleness to viral and bacterial respiratory infections.

Based on the different functions of the ABO-secretor composite and ADA in the functional unity of the respiratory piece of land, it is likely that the effects of the two systems on susceptibleness to asthma follow different tracts: the ABO-secretor complex moving on the bacterial-viral morbific constituent and ADA on the cellular responsiveness constituent.


FUT2: fucosyltransferase 2 ( gland position included ) Chromosomal Location: 19q13.3


The merger allelomorph of the FUT2 ( gland type alpha ( 1,2 ) -fucosyltransferase ) cistron at a high frequence and a new se385 allelomorph in a Korean population

Ann Hematol. 2005 Oct ; 84:656-60 Kyoung Un Park, Junghan Song, Kyou Sup Han, Jin Q Kim

The merger cistron ( se ( fus ) ) , a nonfunctional allelomorph of the FUT2 [ gland type alpha ( 1,2 ) -fucosyltransferase ] cistron, was found in Nipponese populations with high frequences ( 4.8-7.9 % ) . In a survey on a Korean population, se ( fus ) was found at a really low frequence ( 0.6 % ) , but it has non yet been revealed in any other cultural population. The purpose of the present survey was to look into FUT2 cistron polymorphisms in a Korean population and to measure their deductions in gland look in spit. From a sum of 696 allelomorphs examined, the frequence of the Se ( fus ) allelomorph in the Korean population was 10.8 % . In add-on, the new se385 allelomorph was found in approximately 7.2 % of the topics, an remarkably frequent happening compared to any other population investigated so far. The void allelomorphs of the FUT2 cistron are another illustration of rare allelomorphs happening with out of the blue high frequences in distinguishable geographic parts or populations.

The Genes

ABO cistrons consist of at least 7 coding DNAs, and the coding sequence in the seven coding coding DNAs spans over 18kb of genomic DNA. The individual nucleotide omission, found in a big figure ( but non all ) of O allelomorphs and responsible for the loss of the activity of the enzyme, is located in exon 6. The first of the seven nucleotide permutations which distinguish the A and B transferases, resides in coding exon 6 ; exon 7, the largest of all, contains the other six nucleotide permutations which result in four amino acid permutations that differentiate the A and B transferases. Among those, permutations responsible for changes at two sites ( residues 266 and 268 ) find the A or B specificity of the enzyme ( Yamamoto and Hakamori ) . In add-on to four common allelomorphs ( A1, A2, B and O ) , legion allelomorphs which encode glycosyltransferases with alterations in activity and/or specificity have been identified.

The primary cistron merchandises of functional allelomorphs are glycosyltransferases. The A alleles encode UDP-GalNAc: Fuc alpha1- & A ; gt ; 2 Gal alpha1- & A ; gt ; 3 N-acetyl-D-galactosaminyltransferase ( alpha 1- & A ; gt ; 3 GalNAc transferase or histo-blood group A transferase ) . The B allelomorphs encode UDP-Gal: Fuc alpha1- & A ; gt ; 2 Gal alpha 1- & A ; gt ; 3 galactosyltransferase ( alpha 1- & A ; gt ; 3 galactosyltransferase or histo-blood group B transferase ) . O alleles encode proteins without glycosyltransferase map. The map of ABH antigens remains unknown.

Location of the FUT2 cistron, which codes for gland position.

Secretion of ABH antigens is under control of two linked cistrons on cistron venue 19q13, another Haplotype: a mutant ( SNP discrepancy ) in one ever goes with a mutant in the other. Presence of the gland cistron adds the H antigen ( fucose ) to ruddy blood cells and organic structure secernments. If this familial codification for releasing H is absent in the familial stuff inherited from both parents, the person will non release their ruddy blood cell antigens into their organic structure tissues, which is what we know as ABH non-secretors. If they inherit the gland cistron from one parent merely, they may still hold some of the features of a non-secretor: even though they secrete their ABH antigens, it was postulated that they may hold some of the metabolic disease associations connected with being a non-secretor ( but non needfully the cell surface antigen-related 1s ) . 19q13 has 288 verified cistrons related to this venue, even more than the ABO venue. Chromosome 19 has the highest cistron denseness of all human chromosomes, and many of these relate to how the immune system works, which explains the difference between immune response of glands and non-secretors: the humoral vs. the cellular response ( TH1 and TH2 ) . Other potentially cistrons on this chromosome relate to insulin-dependent diabetes, familial hypercholesterolaemia, and fix of other cistrons associating to mending DNA harm from exposure to radiation and to other environmental pollutants.

The chance of holding a peculiar combination of two specific allelomorphs at a given venue can be calculated utilizing a mathematical expression, which suggests that 2/3 of the general population will be heterozygous for gland position ( i.e. holding both gland and non-secretor cistrons ) , which may hold a significance in itself when compared with homozygote glands and non-secretors.

9q34 is the location, or venue of the ABO cistron, which codes for the ABO blood group. It is besides the location of many other cistrons that may be associated with the ABO blood group of an single through familial linkage.


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