AMANDA Flashcards
Landsteiner’s law:
if an antigen is present on the RBC of an individual, the corresponding antibody must be absent in the plasma of the individual and vice versa
antigen on RBC - corresponding antibody is ABSENT
What chromosome is ABO locus located on?
chromosome 9
What causes the group O phenotype?
deletion at residue 261, results in a frameshift
What enzyme do the A and B alleles encode? What about group O?
glycosyltransferases, catalyses the final step in the synthesis of the A and B antigen
group O individuals lack this enzyme
What is the expression of A and B dependent on?
chromosome?
a precursor H substance, determined by the H gene on chromosome 19
What enzyme does the H gene code for?
one that converts carbs into H substances
What enzymes do A and B genes code for in relation to H substance?
specific ones that convert H substances into A and B antigens
What does the O gene produce in relation to H substance?
produces an inactive transferase so H substance remains unchanged, gives the individual the blood O group
What is the Bombay phenotype?
describes individuals whose RBCs lack the H antigen
described as being Ohh
Why do group O individuals also lack A and B antigens?
A and B antigens cannot be formed without the H antigen precursor
Formation of H antigens:
basic precursor + L fucosyl transferase enzyme
Formation of A antigens:
basic precursor + H base + N-acetylgalactosaminyl transferase
Formation of B antigens:
basic precursor + H base + D-galactosyl transferase
Formation of O gene:
what type of allele? H substance?
silent allele, does not alter the structure of the H substance = more H antigens
What antigens and antibodies would a group A have?
antigens - A
antibodies - anti-B
