Download Bombay Phenotype or O h

BOMBAY Blood Group
DR. MOHAMMED H SAIEMALDAHR
BB
Faculty of Applied Medical Science
MED TECH DEP.
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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 LFucose transferase necessary for formation of the HStructure.

The genotype (hh) or H null is extremely rare and is
known as the Bombay Phenotype or Oh.
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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
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*PS = oligosaccharide chain
attached to either glycosphingolipid, Type 2 chain (on RBC) or
glycoprotein, Type 1 chain (in
secretions)
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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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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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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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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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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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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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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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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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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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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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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