|MadSci Network: Genetics|
Generally, based on the ABO blood chart a parent with AB and parent with O will have a child with blood type A or B. For this to happen the H- antigen must be present. However, if each parent has one recessive gene for the H-antigen the blood type the child may receive both recessive H- genes and thus phenotypically express their blood type as O instead of A or B. This is known as the bombay phenotype, named because of a higher occurance in Bombay. The higher occurance has been seen with the marraige of first cousins. Since the family may have one recessive H-antigen gene, marrying in the family increases the possibility of the child to have both genes be recessive H- genes. After many generations, the population has a higher occurance of this phenotype. An excellent website with more information about this is (http://anthro.palomar.edu/blood/ABO_system.html) hope this answers your questions. Michael Watson
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