What is H antibody?
Anti-H antibody is a type of anti-red blood cell (RBC) antibody that agglutinates with H antigen, which is universally present on human RBCs. The most widely known problem related to the anti-H antibody is the potentially lethal hemolytic transfusion reaction seen in individuals with the Bombay O blood type [1,2,3].
What is the major role of H gene in ABO blood groups?
The H locus (FUT1) Individuals who are homozygous for null alleles at this locus (h/h) do not produce H antigen, and because the H antigen is an essential precursor to the ABO blood group antigens, they cannot produce A and B antigens. Therefore, their serum contains anti-A and anti-B, in addition to potent anti-H.
How does the gene I control ABO blood group?
In humans, the ABO blood groups are controlled by a gene called gene I. It has three alleles, namely IA, IB and i. Two of the three alleles IA and I B dominate over i. But IA and I B express themselves in each other’s presence and hence are co-dominant.
How do you get anti-H?
The rare Bombay phenotype (group Oh; and phenotypically O on serologic testing) results from homozygosity for inactive H(FUT1) and Se(FUT2). Bombay individuals lack the H antigen on RBCs, tissues, and secretions, and make a potent anti-H. These individuals must be transfused with RBCs from other Bombay individuals.
What is H gene?
The H gene encodes an enzyme that is required in the expression of the H antigen on the surface of red blood cells. Translation of the active allele, H, of the FUT1 gene results in formation of the enzyme known as α-1,2-fucosyltransferase (H is also known as FUT1 because the gene product is a FUcosyl Transferase).
What happens if H antigen is absent?
People who lack the H antigen do not suffer from deleterious effects, and being H-deficient is only an issue if they need a blood transfusion, because they would need blood without the H antigen present on red blood cells. The specificity of the H antigen is determined by the sequence of oligosaccharides.
Is hh dominant or recessive?
Individuals with dominant phenotypes can be either homozygous (HH) or heterozygous (Hh). When a recessive (hh) is selected against, a reservoir of recessive alleles remains in the heterozygotes (Hh) of the dominant phenotype.
How does the gene I control ABO blood groups in humans write the effect of gene as on the structure of red blood cells?
Gene i controls ABO blood grouping in humans as there are three different alleles- IA, IB and i. So whenever IA and i alleles are present together it gives a phenotype of blood group A and when IB and i are present together it gives a phenotype of blood group B because IA and IB are dominant over i allele.
Which type of genes alleles control the ABO blood types?
The ABO blood type is inherited in an autosomal codominant fashion. The A and B alleles are codominant, and the O allele is recessive.
What is the H gene?
Is there an H blood type?
H antigen deficiency is known as the “Bombay phenotype” (h/h, also known as Oh) and is found in 1 of 10,000 individuals in India and 1 in a million people in Europe.
Why is the H antigen not produced in ABO blood group?
Because the H antigen is the precursor of the ABO blood group antigens, if it is not produced, the ABO blood group antigens are also not produced. This can be misleading in paternity cases, a fact that has been exploited in soap opera story lines! In the show “General Hospital”, the father of Monica’s child was in doubt.
What is the ABO gene used for?
ABO (gene) ABO determines the ABO blood group of an individual by modifying the oligosaccharides on cell surface glycoproteins. Variations in the sequence of the protein between individuals determine the type of modification and the blood group. The ABO gene also contains one of 27 SNPs associated with increased risk of coronary artery disease.
What is the ABO blood group?
ABO blood group. The ABO gene is located on chromosome 9 and has three alleles, A, B and O. The A allele encodes a glycosyltransferase that adds N-acetylgalactosamine to the glycoprotein H antigen that is expressed on all normal red cells. The B allele encodes a different glycosyltransferase that adds d -galactose.
What are ABO antigens attached to?
The ABO blood group antigens are attached to oligosaccharide chains that project above the RBC surface. These chains are attached to proteins and lipids that lie in the RBC membrane. Molecular basis The ABO gene indirectly encodes the ABO blood group antigens.