There is no single gene that determines a dog’s size, according to Dr. Ostrander, a canine genetics expert at the National Institutes of Health. There are about 25. Her and other scientists found the first known dog size gene, and one of the most important, in 2007. It’s called IGF1. The importance of genes has been confirmed in many studies. But how it affects the size is not clear.
“The thorn on my side,” says Dr. Ostrander, is that no one has been able to find the mutation in the gene or the pieces of DNA that controls it to explain the actual changes in the DNA that have affected the size. “It’s not an ex, it’s not a promoter. It is not an enhancer. It’s not a splicing site,” she said, referring to the sections of DNA that control genes. “We couldn’t find it. And Joc (pronounced Joss) arrived on the scene. ”
“And I found it,” he said, with a smile.
Dr. Plassais, who worked at the NIH during the research and is now at the University of Rennes 1, in France, said he was fortunate to work at a time when there were so many genomes of dogs and other dogs, modern. and stock, available. So, by comparing more than a thousand genomes from more than 200 different varieties, he found a piece of DNA that has two versions, or variations, tied to size.
This piece of DNA is not a gene, because by definition a gene must contain the instructions to make a protein. But many other pieces of DNA have instructions for bits of RNA that help control genes. He found a piece of DNA that has instructions for what is known as repressor RNA, which plays an important role in controlling the production of proteins regulated by genes.
His finding is called IGF1-AS and it comes in two variants. Each dog has two copies of this DNA. Two major variations make up a large dog, like the German Shepherd. Two small variations produce a small, terrier-like dog, and one of the two produces a medium-sized dog, resembling one of the popular bush-colored dogs seen around the world. gender.
https://www.nytimes.com/2022/01/27/science/small-dogs-dna-wolves.html In dog DNA, small size has an ancient pedigree