Bombay phenotype /bombā″/ [Bombay, India, where first reported] , a rare genetic trait in which there is no expression of the A, B, or H antigens on the red blood cells. Bombay phenotypes (genetically hh) lack the H gene which normally produces the H antigen, a precursor for A and B antigens. Since H is not expressed, A or B cannot be expressed. The serum contains anti-A, anti-B, and anti-H. See also ABO blood group.
