1. DR. MOHAMMED H SAIEMALDAHR Faculty of Applied Medical Science
BOMBAY Blood Group
DR. MOHAMMED H SAIEMALDAHR BB
Faculty of Applied Medical Science
MED TECH DEP.
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2. The Bombay Phenotypes (Oh)
The H gene appears to be necessary for the formation of A and B Ags. It is very common 99.9% of all individuals have an HH or Hh genotype.
The allele h is very rare and does not produce the L-Fucose transferase necessary for formation of the H-Structure.
The genotype (hh) or H null is extremely rare and is known as the Bombay Phenotype or Oh.
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3. H Antigen
The H gene codes for an enzyme (fucosylytranferase) that adds a Fucose to the terminal sugar of a Precursor Substance (PS*). The biochemical structure below constitutes the H Antigen. (h gene is an amorph.)
H gene acts on a Precursor substance(PS)* by adding Fucose
*PS = oligosaccharide chain attached to either glycosphingo-lipid, Type 2 chain (on RBC) or glycoprotein, Type 1 chain (in secretions)
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4. H antigen is the foundation upon which A and B antigens are built.
A and B genes code for enzymes that add an immunodominant sugar to the H antigen.
O allele does not code a functional enzyme
Greatest Least
amount of H O > A2 > B > A2B > A1 > A1B amount of H
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5. The Bombay Phenotypes (Oh)
The Bombay Phenotype was first reported by Bhende 1952 in Bombay, India.
Bombay cells can not be converted to group A or B by the specific transferases.
This support the concept that the H structure serves as the acceptor molecule or precursor substance for the product of the A or B gene -specified tranferases.
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6. The Bombay Phenotypes (Oh)
Bombay individuals lack all normal expression of the A, B, or O genes they inherited.
The Bombay Phenotype Red Cells are devoid of normal A B, H Ags.
Fail to react with anti- A, anti -B , and anti -A,B and anti H.
Bombay Serum contains anti-A, -B and anti-H.
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7. The Bombay Phenotypes (Oh)
The Bombay anti-H is active over a wide thermal range. It is an IgM antibody that can bind complement and cause red cell lysis.
Because the H Ag is common to all ABO blood group, Bombay blood is incompatible with all ABO donors.
In routine forward grouping, using anti-A, anti-B, and anti-AB. The Bombay would phenotype as an O blood group. However, transfusing normal group O would cause immediate cell lysis by the potent anti-H of the Bombay individuals.
Thus, only blood from another Bombay individual can be transfused to a Bombay recipient.
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8. The Bombay Phenotypes (Oh)
Oh (hh) individuals are all non-secretors of ABH substances, because both the H gene and the Se gene must be inherited for the ABH antigens to be found in secretions.
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9. The Bombay Phenotypes (Oh)
Proof that individual lacks the H antigen may be accomplished by typing the Bombay phenotype red cells with a products of the plant Ulex Europacus or with sera containing Anti-H activity from which all anti-A, anti-AB activity has been adsorbed (Removal of Abs)
This plant lectin provide a much simple and more readily available source of anti-H like activity. Thus this plant must used to determine the presence or absence of the H antigen on the surface of RBCs
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10. The Bombay Phenotypes (Oh)
General Characteristics of Bombay Oh (Hnull Phenotypes)
1. Absence of H, A, and B antigens; NO agglutination with anti-A, anti-B, or anti-H lectin
2. Presence of anti-A, anti-B, anti-A,B and a potent wide thermal range of anti-H in the serum
3. A, B, H non-secretor (no A, B, or H substances present in saliva)
4. Absence of α-2-L-fucosyltransferase (H enzyme) in serum and H antigen on red cells
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11. The Bombay Phenotypes (Oh)
5- Presence of A or B enzymes in serum
6- Strong reactivity with anti-I reagents (possibly owing to an increase in number of I receptors)
7. A recessive mode of inheritance.
8. Red cells of the Bombay phenotype (Oh will not react with the anti-H lectin (Ulex europaeus)
9. Red cells of the Bombay phenotype (Oh are compatible only with the serum from another Bombay individual.
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12. The Bombay Phenotypes (Oh)
The Bombay phenotype can been divided into four different categories that depend on the inheritance of the alleles of H (hh) are responsible for the variable expression of H and in turn A and B antigens.
Category I: Classic Bombay
This group arises from the inheritance of the hh genotypes. These cells lack all H antigen and react stronger with examples of anti-I.
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13. The Bombay Phenotypes (Oh)
Category 2: Deficient Bombay Non –Secretors
The red cells of these individuals have a slight amount of ABH antigens that are primarily detected by adsorption and elution (removal of Ab) studies.
Category 3: H-Deficient Bombay Secretor
Recessive Inheritance
These Bombay secretors arise out of the inheritance of a double dose of the recessive gene.
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14. The Bombay Phenotypes (Oh)
Category 4: H-Deficient Bombay Secretors
Dominant Inheritance
These persons inherit H-deficient red cells via a dominant gene; however, they contain normal ABH substance if they are secretors.
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