1. Formation of a sediment at the bottom of a liquid.
2. The phenomenon whereby the phenotype that would ordinarily be manifested at one locus is obscured by the genotype at another epistatic locus; in humans, the phenotype for the ABO blood group locus can be expressed only in the presence of its precursor, H substance. The Bombay factor in the homozygous state blocks H formation and obscures the ABO phenotype.
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