Humans And Dogs Might Develop Cleft Lip, Palate Because Of Mutations In Shared Gene

Man and dog
Mutation in a gene common to both humans and dogs has been associated with cleft palate in both species. Photo courtesy of Shutterstock

A new study exploring birth defects in man and man's best friend has found that a gene present in both species may be associated to cleft palate and cleft lip, birth defects that cause the lips and mouth to fail to develop properly. 

"These results have potential implications for both human and animal health, by improving our understanding of what causes these birth defects in both species," lead researcher Zena Wolf said in a statement. The study, which found mutations in the gene ADAMTS20 could contribute to cleft lip and palate, was conducted at the University of California, Davis, School of Veterinary Medicine.  The results will be presented on Sunday at the American Society of Human Genetics 2014 Annual Meeting in San Diego, Calif. 

Humans and dogs shared a common ancestor about 100 million years ago. Previous studies have shown that 25 percent of our genome matches that of a dog's, thus explaining why diseases like diabetes, cancer, and epilepsy affect both species. Cleft lip and cleft palate are two other conditions that occur naturally in both species, and their severity depends on several genetic and environmental factors. Because pure bred dogs tend to mate with only other pure breds, there isn't much genetic varation, Wolf said, which makes it easier to study them. 

Mutations in the two genes DLX5 and DLX6, which are involved in development of the skull and the face, had already been implicated in causing cleft palates in 12 of 22 dogs. But mutations in similar genes in humans accounted for just one in 30 cleft cases. So, the researchers set out to identify other genes. They conducted a genome-wide association study, comparing the genomes of dogs with cleft lip and cleft palate to those of healthy dogs. They found that it occurred frequently when there was a mutation in the ADAMTS20 gene. The mutation caused the protein that the gene encodes to shorten by 75 percent, resulting in cleft defects. A similar study in humans also found that mutations in ADAMTS20 increased chances of getting the condition. 

"Cleft lip and cleft palate are complex conditions in people, and the canine model offers a simpler approach to study them," Wolf said. "Not only does this research help people, but it helps dogs, too." The team now plans to explore other genes that may cause cleft defects in humans and dog breeds, such as Labrador Retrievers and Whippets. 

Source: Wolf Z, et al. Parallel studies in humans and dogs implicate ADAMTS20 in cleft lip and palate formation. American Society of Human Genetics 2014 Annual Meeting. 2014.

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