Bombay phenotype occurs in individuals who have inherited two recessive alleles of the H gene (i.e.: their genotype is<unk> . These individuals do not produce the H carbohydrate that is the precursor to the A and B antigens, meaning that individuals may possess alleles for either or both of the A and B alleles without being able to express them. Because both parents must carry this recessive allele to transmit this blood type to their children, the condition mainly occurs in small closed-off communities where there is a good chance of both parents of a child either being of Bombay type, or being heterozygous for the h allele and so carrying the Bombay characteristic as recessive. Other examples may include noble families, which are inbred due to custom rather than local genetic variety.
Hh blood group
Vel blood group
Rh blood group system
Lan blood group system
Sid blood group system
Junior blood group system
Indian blood group system
P1PK blood group system