Biochemical basis of recessive and dominant

Recessive mutations: Loss-of-function mutations, therefore, as there are two alleles, the WT allele is usually sufficient to provide enough WT protein. Dominant mutations: Gain-of-function mutations, the WT allele is still performing its activity, but the mutant allele causes an additional unfavourable action. Semi-dominant mutations: Allele or gene dosage effect, one WT allele doesn’t provide enough active protein on its own to fully perform the required function