Lethal mutation

 This is a mutaton that results in the demise of the organism affected . An example of such a mutation can be observed in manx cats. Characterised by their lack of tails and longer hindlegs, manx cats carry a dominant allele (M^L) that severely affects spinal development. All manx cats are heterozygotes; cats that are homozygote for the M^L allele do not survive because the allele is recessive lethal.