Assume that a mutation occurs in the gene responsible for the production of hexosaminidase a, such that only about 50% of the enzyme activity is found in the heterozygote compared with a homozygous normal individual. if heterozygotes are phenotypically normal, we would say that the mutant allele is recessive to its normal allele. assume that a mutation occurs in the gene responsible for the production of hexosaminidase a, such that only about 50% of the enzyme activity is found in the heterozygote compared with a homozygous normal individual. if heterozygotes are phenotypically normal, we would say that the mutant allele is recessive to its normal allele. true false