Causes

• The short limbs of the munchkin cat are caused by a dominant genetic mutation that occurs spontaneously within the gene pool and affects only the legs of the cat. The autosomal (non-sex chromosome) dominant "munchkin gene" is passed down from parent to child, resulting in hypochondroplasia (a form of short-limbed dwarfism) in some kittens.
  
  

Genetics

• Munchkin cats are heterozygous, containing one "munchkin gene" and one normal gene in their genetic makeup. Non-viable embryos receive two of the "munchkin genes" (homozygous), perishing in the uterus or shortly after birth. Munchkin cats bred to other munchkins or normal cats might also result in normal cats (homozygous for normal genes).
  
  

Considerations

• Munchkin cats function as well as normal cats but the breed is prone to lordosis, a downward curvature of the spine, compressing the heart and lungs, and pectus excavatum, which also affects the chest of the cat. Cats with these diseases should not be bred as they may pass the trait onto offspring.