Manx cat
Another example of a recessive lethal allele occurs in the Manx cat. Manx cats possess a heterozygous mutation resulting in a shortened or missing tail. Crosses of two heterozygous Manx cats result in two-thirds of surviving offspring displaying the heterozygous shortened tail phenotype, and one-third of surviving offspring of normal tail length that is homozygous for a normal allele. Homozygous offspring for the mutant allele cannot survive birth and are therefore not seen in these crosses.