Bigger muscles, faster whippet

Differences in a muscle gene make some whippets even faster
Whippets are really fast dogs. They can run up to 35 miles per hour. And many of the fastest ones have a genetic mutation that makes them so fast. A new study found that whippets that had a certain change in the myostatin gene were stronger and faster. This isn't surprising as the myostatin gene is important in making muscle in dogs, cows, people and lots of other animals too. Mutations in this gene affect all of these animals (including us). But most of the work done to date has been on the ones with obvious muscle changes like the cow to the right. What makes this story interesting is that the really fast dogs were indistinguishable from regular dogs. Except that they tended to sometimes have brothers and sisters that were bully whippets. A bully whippet is heavily muscled and has a broad chest. Many are put to sleep because they don't live up to what a whippet should look like (at least according to the American Kennel Club). So what's the difference between a really fast whippet and a bully one? The number of mutated genes the dog has. If it has one mutant copy of the myostatin gene, it is really fast. If it has two, then it is a bully whippet. And what makes the story even more interesting is that a similar mutation has similar effects in people too. One mutant copy makes you strong. Two makes you the equivalent of a bully whippet.
One copy vs. two
As you probably remember, we have two copies of most of our genes—one from mom and one from dad. The same is true for dogs. Genes also come in different forms called alleles. For example, the hair texture gene in people comes in two forms, straight and curly. If someone has two curly alleles, they have curly hair. Two straight ones and you get straight hair. And one of each leads to wavy hair. Same thing with the myostatin gene in whippets. Two copies of the normal version and you have a whippet. Two versions of the mutant copy and you have a bully whippet. And one of each leads to a very fast whippet. Both of these examples are different from the dominant and recessive sorts of genes most people are used to. And really, in the case of the whippet, this gene is more similar to something like sickle cell anemia. With humans starring as both sickle cell anemia and malaria. Sickle cell anemia is a painful disease that used to result in a very early death. Nowadays many patients with sickle cell anemia live into their forties or fifties. Usually genetic diseases like this don't stick around because people with the disease version of the gene don't do particularly well. But this isn't the case with sickle cell. Sickle cell anemia happens when people have two copies of the sickle cell version of the hemoglobin gene. One copy makes you a carrier. And, importantly, one copy makes you much more resistant to malaria. What this means is that when malaria is around, people with one copy of the sickle cell gene do better than people with no copies. They do enough better that the gene stays in the population. This is similar to what may have happened with the whippet. Except people are sickle cell anemia and malaria. The fastest whippets were the most successful and had the most puppies. These dogs had a single copy of the fast myostatin gene. The dogs that had no copies weren't too fast and so didn't get to breed. People were like malaria in this case eliminating dogs with no copies of the fast gene. And dogs with two copies of the gene were bully whippets. They were eliminated because they didn't look whippet enough. In this case, the dog breeders are like sickle cell anemia, killing off the dogs with two copies of the fast gene. So the best survivors in this case were the dogs with one copy of the fast gene. Like people in areas rife with malaria who did best with one copy of the sickle cell gene.

More Information

Dogs like people get one gene
from mom and one from dad.
What about people?
Like I said, people have the myostatin gene too. In fact, a few years back, a human equivalent of a bully whippet was born in Germany. This boy has two copies of a mutant version of the myostatin gene. He has bulging muscles and when he was four years old, he could lift 7 pounds with his arms extended. That is one strong kid. But how common are changes like these in the myostatin gene? And are people with just one copy stronger than average? First off, the particular mutation the German boy has is thought to be very rare. Each of his parents has a single copy as do some of his brothers and sisters. The relatives we know about who have a single copy of the mutant gene are stronger than average. Not as strong as the brother with two copies but still really strong. So this is like the whippet. But there aren't any other known cases like this. Which means that this change is relatively new. Or there hasn't been much of an advantage to having it in our past. There are other changes in the myostatin gene that have been selected for though. A comparison of Africans versus Europeans found a couple of mutations in the myostatin gene in around 30% of the Africans. And only around 2% of the Europeans. A closer look showed that these mutations were selected for in the African population. This means that most likely the change has some sort of advantage. But it isn't strength. The change doesn't seem to affect muscle mass or athletic ability. Scientists are trying to figure out what if any advantage there is to the mutation. Scientists have also started to compare the myostatin gene of athletes and non-athletes to see if there are differences specific to one group or the other. So far, no luck. They're now starting to look at other genes that are similar to myostatin (or that affect myostatin) to see if they can explain differences between people's athletic abilities. We'll have to wait and see what they find. In any event, studying the myostatin gene isn't just important for finding or making better athletes. Scientists may be able to come up with new ways to treat muscle wasting diseases if they can learn how to tweak this gene. Of course, this may result in stronger athletes as well…
Mutations in the myostatin
gene affect people too.