Polydactyly - Great Pyrenees Type

Acronym:	POLYD
Gene:	ALX4
Mutation:	g.44922456_44922506del
Inheritance:	Autosomal Dominant
Sample type:	CHS (Cheek Swab), WBE (Whole Blood EDTA)
Method:

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Genetics and characteristics

Canine Polydactyly is a genetic developmental trait found in dogs and cats when they develop additional digits (one or two) in the forelimb or hind limb. Dogs have five digits on their front paws and four digits on their hind paws. It is believed the first digit of the hindlimb known as the hind dewclaw was lost due to evolutionary adaptation. Congenital malformations of the vertebrate limb are often caused by alterations in the anteroposterior patterning of limb development. Polydactyly has been detected in many breeds such as the Beagle, Belgian Malinois, Cocker Spaniel, Rottweiler, etc. and it has been associated with a mutation in the LMBR1 gene. However, in a few breeds, including Great Pyrenees, five or six digits have been intentionally maintained through breeding and are caused by a different mutation – deletion within the ALX4 gene. ALX4 is a member of the homeobox protein family that direct the formation of body structures during early embryonic development, including limbs.

This type of dominant genetic alteration commonly called „dewclaw“ found in Great Pyrenees dogs is inherited as an autosomal dominant trait meaning even dogs with only one mutated ALX4 gene will develop extra digits, not only dogs that carry two mutated genes. Early genetic testing can help identify dogs that carry the gene with the specific mutation and help breeders in further breeding by proper selection of mating pairs.

 

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Results Reported As

 

 

 

 

 

 

 

 

 

 

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References:

Fondon, J. W., 3rd, Garner, H. R. (2004). Molecular origins of rapid and continuous morphological evolution. Proceedings of the National Academy of Sciences of the United States of America, 101(52), 18058–18063. https://doi.org/10.1073/pnas.0408118101

Park, K., Kang, J., Subedi, K. P., Ha, J. H., Park, C. (2008). Canine polydactyl mutations with heterogeneous origin in the conserved intronic sequence of LMBR1. Genetics, 179(4), 2163–2172. https://doi.org/10.1534/genetics.108.087114