Polydactyly in Maine Coon

Polydactyly is a congenital defect characterized by an increased number of toes (more often on the front paws) and a change in their shape. It is the result of a defect in the regulation of the developmental gene Sonic Hadgehog (SHH). This disorder is caused by a mutation in the ZRS regulatory sequence that affects SHH expression in the developing limb bud. Polydactyly does not usually cause serious medical complications, but freely hanging fingers need to be amputated due to the increased risk of entrapment and injury.

Several mutations in the LMBR1 gene have been found to cause polydactyly. The g.169532844T>C mutation has been detected in Maine Coon cats, while g.169532842T>A or g.169533066C>G mutations have been encountered in other cat breeds.

Inheritance of mutations is autosomal dominant with incomplete penetrance and variable expressivity. This means that a single copy of the mutated gene inherited from either parent is sufficient to cause symptoms, but the extent of expression of the trait may vary between individuals. A genetic test can clearly reveal the genotype of an animal and is a useful tool for breeders to prevent unintentional breeding of individuals with this defect.

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Литература:

Lettice, LA., Hill, AE., Devenney, PS., Hill, RE. : Point mutations in a distant sonic hedgehog cis-regulator generate a variable regulatory output responsible for preaxial polydactyly. Hum Mol Genet 17:978-85, 2008. Pubmed reference: 18156157