Cleft Palate (CP1) in Nova Scotia Duck Tolling Retriever

Cleft Palate CP1 is a genetic abnormality that develops in a puppy during gestation. Disturbed skull development leads to missing or abnormally shaped palatal bones and an underdeveloped nasal septum. This type of cleft is usually associated with shortening of the lower jaw (mandible). Clinical signs include discharge of fluid from the nose, sneezing, snorting, coughing, impaired ability to take in food and associated slowed growth and poor weight gain. Due to possible inhalation of food, aspiration pneumonia is quite common and may lead to death.

The cleft in Nova Scotia Duck Tolling Retriever can be caused by two different mutations. The mutation in the ADAMTS20 gene causes a less severe cleft lip/palate referred to as CL/P (CLPS), while the mutation in the DLX6 gene described below causes cleft palate with shortening of the lower jaw and abnormalities up to underdevelopment of the nasal septum.

The CP1 disease is caused by a specific mutation - insertion of a LINE-1 element (2056 bp) in the intron 2 of the DLX6 gene, which occurs exclusively in the Nova Scotia Duck Tolling Retriever.

The mode of inheritance of the mutation is autosomal recessive. This means that only individuals who inherit the mutated gene from both parents will develop the disease. Carriers of the mutated gene are clinically healthy but pass the mutation on to their offspring. In the case of a mating between two heterozygous individuals, theoretically 25% of the offspring will be completely healthy, 50% of the offspring will be carriers and 25% of the offspring will inherit the mutated gene from both parents and will therefore be affected by the disease.

The genetic test can clearly reveal the genotype of the animal and is a useful tool for breeders to prevent unintentional breeding of affected puppies.

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Reference:

Wolf, Z.T., Leslie, E.J., Arzi, B., Jayashankar, K., Karmi, N., Jia, Z., Rowland, D.J., Young, A., Safra, N., Sliskovic, S., Murray, J.C., Wade, C.M., Bannasch, D.L. : A LINE-1 insertion in DLX6 is responsible for cleft palate and mandibular abnormalities in a canine model of Pierre Robin sequence. PLoS Genet 10:e1004257, 2014. Pubmed reference: 24699068