A rare but fatal skeletal disease in dogs has been traced to a single gene mutation, offering hope that the condition could be treated or eliminated by smart breeding.
A similar condition affects humans, researchers reported July 5 in the journal PLoS ONE. That means developing a cure in dogs could help people with the condition.
The bone disorder, called mucopolysaccharidoses, affects a rare breed of dog called the Brazilian terrier. These dogs, also called Fox Paulistinhas, were first bred from native Brazilian dogs and terriers from Europe. The breed is almost unknown outside of Brazil and Finland.
A tragic disorder
In rare cases, Brazilian terriers are born with a mysterious bone disease that deforms their skeleton, leaving them unable to stand or walk. These puppies fail to thrive, and either die or have to be euthanized. Researchers at the University of Helsinki wanted to find out why. [What Your Dog's Breed Says About You]
Led by researcher Hannes Lohi of the University of Helsinki and the Folkhalsan Research Center, the scientists delved into the Brazilian terrier genome in search of mutations that could be to blame for the disease. They compared seven affected and 11 unaffected terriers, eventually narrowing the search down to a stretch of genes on the sixth chromosome.
Chromosomes are coils of DNA passed down to offspring from parents. Humans have 46 total chromosomes. Dogs have 78.
The section of chromosome 6 that Lohi and his colleagues targeted had more than 220 genes, a huge number to analyze by traditional methods. Instead, the researchers turned to a new approach.
"Instead of analyzing the region gene by gene, we were able to capture and read the entire region simultaneously in the selected samples," Lohi said in a statement. "The mutation was quickly discovered and subsequently confirmed in over 200 dogs."
Identifying a mutation
The mutation, the researchers discovered, occurred in a gene called GUSB. This mutation causes a change in one of the amino acid molecules that makes up an important enzyme for proper bone growth and formation. Without the enzyme, the body is unable to effectively "clean up" the connective tissue in the bones, meaning it can't sweep away damaged cellular detritus or foreign bacteria.
Mucopolysaccharidoses is not confined to dogs. Mice, cats and even humans have similar disorders. In humans, symptoms typically include skeletal deformities, mental retardation and abnormal enlargement of the spleen and liver.
Almost every third Brazilian terrier carries the mutation, the researchers found. To be affected by the disease, however, puppies have to inherit two copies of the bad gene, one from their father and one from their mother. Lohi and his colleagues developed a genetic test for breeders to test their sires and dams for the mutation in order to ensure that two carriers aren't allowed to mate and have puppies.
Studies on dog genetics are also useful for studying rare diseases in humans, the researchers wrote. Thanks to genetic similarities between dogs and humans, our canine companions are already used as guinea pigs in cancer research, getting experimental treatments before they're approved for humans.
- 10 Things You Didn't Know About Dogs
- Genetics by the Numbers: 10 Tantalizing Tales
- In Photos: America's Favorite Pets
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Baby Elephant San Diego Zoo
A newborn Africa elephant lifted his trunk in search of his mother at the San Diego Zoo Safari Park. The male calf was born at 5:45 a.m. on Monday to Umngani (oom-gah-nee). In this rare moment, the calf stood alone after he had wandered off a few steps, but shortly thereafter his mother, 5-year-old sister Khosi (koh-see), and 2-year-old brother Ingadze (in-Gahd-zee) rushed over to tend to the unnamed calf. Throughout the day the family watched over their newest member, letting him only stray a few feet. The Safari Park is now home to 18 elephants8 adults and 10 youngsters. The adults were rescued in 2003 from the Kingdom of Swaziland, where they faced being culled. The average gestation period for African elephants is 649 days or 22 months. A newborn calf averages 200 to 300 pounds. Calves can be weaned at 2 to 3 years old.
Baby Red Pandas
A zookeeper holds up Kit and Kitty, the twin red pandas born in June on the first day of their introduction into their new enclosure at Tierpark Zoo on September 13, 2011 in Berlin, Germany. The red panda (Ailerus fulgens) is a rare mammal native to the eastern Himalayas and southwestern China.
A flamingo baby cleans itself in its enclosure at the zoo of Hanover, northern Germany, on September 1, 2011. In the past three weeks, five flamingo fledgling hatched out at the Hanover zoo. For the next two months the flamingo babies will be fed by their parents from the beak. Only when they reach an age of three to four years, the young flamingoes will be as pink as their parents.
New-born golden-bellied capuchin named Pinu'u sits on the back of his mother Ibama in their enclosure in the Cologne zoo, Germany, Thursday Aug. 11. 2011. Pinu'u was born on July 4, 2011.
This photo released from the Oregon Zoo shows five-week-old Caracal kittens.
In this July 6, 2011 photo provided by the Center for Whale Research, K-44, right, a newborn male orca whale, is shown swimming with his mother, K-27, near Friday Harbor in the San Juan Islands. (AP Photo/Center for Whale Research, Astrid van Ginneken)
Zoo keepers hold three newborn Siberian tigers, Virgil, Thrax and Manu, at the Budapest Zoo and Botanic Garden in the Hungarian capital on July 4, 2011. The eight-week-old tigers were presented to the press for the first time with their health checkup and ID chips implanted by the chief doctor of the zoo.
Melbourne Zoo's newest primate baby, a three week-old Colobus monkey, is held in the arms of her mother Clover, in Melbourne on June 29, 2011. Keepers have not been able to determine the sex of the newborn monkey which is pure white and won't display any black markings until it's several months old. Black and White Colobus Monkeys, native to Angola, Democratic Republic of Congo, Uganda, Rwanda, Burundi, Tanzania and Kenya, have seen their populations suffer from the fur trade during colonial times, but now the greatest threats to their survival are the loss of their habitat and the bushmeat trade, the large-scale hunting to supply meat to towns and cities.
A two-day old Mustang-Arabian colt rushes to keep up with his mom, Maggie, in a corral at Fred Muzi's Millstone Farm in Dover, Mass. Wednesday, June 22, 2011. Maggie, 3, is one of nine feral horses rescued in Western Mass. by the MSPCA, now being fostered with the goal of getting them healthy and ready for adoption.
A 13-days old hippo with his mother Maruska showed to public for the first time at the Prague's Zoo in Prague, Czech Republic, Tuesday, June 21, 2011.
One of 13 newborn ostriches is accompanied by a hen as it explores its enclosure on June 21, 2011 at the zoo in Berlin. The flightless birds are native to Africa.
German Man Turns Apartment Into Bunny Farm
German authorities have accused Ralf Werner, 45, of turning the balcony of his tiny Berlin apartment into a bunny farm. Officials found 122 bunnies on the premises, many with bite wounds. He has been banned from keeping animals and faces a court case for animal cruelty.
Baby Bottle Nose Dolphin
A baby bottle nose dolphin, born last month, swims close to his mother at the Hakkeijima Sea Paradise aquarium in Yokohama, suburban Tokyo on June 7, 2011.
Newborn Asiatic Elephant
Newborn female Asiatic Elephant calf born to Johti, a 44-year-old, plays at Ostrava's Zoo on May 31, 2011. The calf was born on April 15.
Newborn lambs are watched by their mother at Barracks Farm on April 1, 2011 in Fetcham, England. 300 ewes are lambing at the farm owned by the Conisbee family who supply their own butchers shops in nearby Horsley. The business has been run by generations of Conisbees for over 250 years.
Baby Spider Monkey Estela
A baby Spider Monkey named Estela plays with her grandmother Sonya at Melbourne Zoo on May 6, 2011. Estela was abandoned at birth by her mother Sunshine, and it has taken 24/7 care from Primate Department Keepers to pull the tiny newborn through since her birth on January 17, 2011. The baby spider monkey which is native to Central America, is currently receiving six feeds of formula a day and is now slowly being introduced to solid foods.
Baby Duckling Swim Time
In this Wednesday, May 25, 2011 photo, baby ducklings climb up a board ramp to access their "pond" that was made for swimming in the inner courtyard of St. Anne's Retirement Community near Lancaster, Pa. The ducklings have been entertaining the residents of the retirement community with their antics.
Baby Panda in Chengdu
A baby Panda is seen at the Chengdu Research Base of Giant Panda Breeding on April 19, 2011 in Chengdu, China.
Firefly the Rhino
In this photo provided by The Wilds Conservation Center, Firefly a baby rhino stands at the Wilds conservation center in Cumberland, Ohio on April 5, 2011. Facebook fans of The Wilds conservation center in southeast Ohio were asked to select a name for its newest rhino.
Baby Giant Anteater
A newborn baby Giant Anteater rides on the back of his mom, Evita, at the San Francisco Zoo on January 20, 2011 in San Francisco, California. The new infant giant anteater, born on December 22, 2010, made its first public appearance at the Zoo.
Zuri, a one-month old giraffe, walks past her parents in their outdoor yard at the Cincinnati Zoo, Thursday, May 5, 2011 in Cincinnati. Zuri was making her first appearance outside at the zoo.
One of the three snow leopards triplets rests near its mother at Basel Zoo in northwestern Switzerland on June 15, 2011. The zoo showed off the eight-week-old cubs longside their mother, Mayhan and father, Pator. The pair were matched mid-January through a preservation program run by the European Association of Zoo and Aquaria.
A baby baboon plays with an adult one at the Hellabrunn zoo in Munich, southern Germany on June 15, 2011. Baboons are native to Africa and and live in hierarchical groups.
Godfrey Mutuku Jones, a caretaker at Kenya's Wildlife Service orphanage, holds two, 3-month old female Cheetah cubs at the Nairobi Orphanage in Nairobi, Kenya, Monday, June 6, 2011. The two Cheetah cubs were abandoned by their mother, in Tsavo East, South of Nairobi, and were brought to the orphanage to be cared for by the Kenya Wildlife Service in Nairobi National Park.
A lion cub yawns at the Lion Park in Johannesburg, during a visit of the Slovenian national football team on June 14, 2010 during the 2010 World Cup in South Africa.
A three month old bear cub who was born at the zoo in Stavropol looks at ostriches on May 5, 2011.
Asian Small-clawed Otters
An adult Asian Small-clawed Otter, right, and two baby otters sit in their enclosure at the zoo in Heidelberg, southwestern Germany, on March 28, 2011. The animals, also known as Oriental Small-clawed Otter, are the smallest otter species in the World and are native to South-Eastern Asia.
In this handout image provided by Taronga Zoo, Seba, a baby Red Panda, explores his new home at Taronga Zoo on April 7, 2011 in Sydney, Australia. The Red Panda cub was born at Christmas and is the 45th to be born at the zoo since 1977
Two polar bear cubs Gregor and Aleut play at the Tiergarten zoo in Nuremberg, southern Germany, on March 24, 2011.
Ring-tailed coati cubs play at the zoo in Duisburg, western Germany, Friday, May 6, 2011.
Two baby Sumatran tiger cubs doze in their enclosure at the zoo in the central German city of Frankfurt am Main on May 25, 2011.
A three-day-old white lion cub sleeps in Belgrade Zoo, Serbia, Wednesday, April 20, 2011. The four white lions cubs, an extremely rare subspecies of the African lion were recently born in Belgrade Zoo.
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Baby Sea Lion Learns To Swim
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Orange Baby Baboon
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Anuri The Baby Polar Bear
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