By TIM ALEXANDER
Illinois Correspondent

URBAN, Ill. — The mystery behind the mutation causing Contractural Arachnodactyly (CA), formerly known as Fawn Calf Syndrome, has been solved by a research team from the University of Illinois, which has identified the mutation behind the fatal genetic abnormality affecting Angus and Angus-derived cattle.

Jonathan Beever, UoI associate professor in the Department of Animal Sciences and lead researcher for the nearly yearlong project, said his team completed the correct assembly of the DNA sequence responsible for CA on June 8 and have also developed tests based on the mutation.

“CA is a genetic abnormality inherited as a simple recessive,” said Beever, meaning the defect’s trait is controlled by a single gene and the mutation can persist in populations for a long period of time. “Some debate exists about its classification as a genetic defect because many CA-affected calves survive and can reach reproductive age. However, at the population level, CA behaves as a lethal genetic defect and should be classified as such.”

Fawn Calf Syndrome was first noticed in Australia in the late 1990s, he said. “In fact, (Australian scientists) did a breeding trial in 2003 to see if (CA) was genetic and to determine what the inheritance was. Now that we’ve looked at a lot of pedigrees and a lot of animals, we know the original mutation goes back as far as 1975.”

The increase in knowledge about Fawn Calf Syndrome led to the adoption of its more scientific moniker of CA, a term more recognizable to researchers and physicians than laypersons.

“The name Fawn Calf was based on the calves’ crouching appearance at birth. We have learned the actual pathology is a connective tissue disorder, and the name change came after we identified what the gene was. The name was changed to a more scientific term easily recognized by most practicing veterinarians,” Beever explained.

The 1,256 artificially inseminated sires provided by members of the National Assoc. of Animal Breeders were studied by Beever’s team, with a total of 39 bulls identified as CA carriers. “In the beef cattle industry, one bad gene can cause a death loss,” said Beever, who is also a cattle producer.

Symptoms of CA are marked by lack of significant muscle mass in calves, the researcher explained. “Calves who inherit the mutation from both their mother and their father will be born with classic symptoms such as hind leg contracture; they can’t extend their limbs,” he explained.

“They have some lateral joint flexibility, so if they are able to stand up, the joints in their legs will move from side to side. They tend to have a fairly significant (amount) of muscular hypoplasia, or lack of muscle development. They never develop the muscle mass that is typical of a normal calf.”

Modern tools such as DNA chips that allow researchers to look at more than 50,000 DNA markers at once have helped Beever’s team to find solutions to genetic defects in months, when it once would have taken years.

The year Beever took to identify the mutation behind CA was several months more than he had anticipated spending on the project after locating the CA gene in May 2009. First, the scientist had to generate the necessary DNA sequence on his own.

“We’ve had a complete genosequence of the cow since about 2004, but the word ‘complete’ is a relative term. Not only are some parts not finished, with Murphy at work, it’s exactly the parts you want that are not finished,” Beever said.

The type of research employed by his team typically results in technologies that can “almost immediately” halt the spread of genetic abnormalities in a time of emergency, and can help breeders identify “high genetic merit individuals” within a particular line that may be associated with a defect, Beever added.

This, he said, allows maintenance of good genetics in the population or herd while limiting the defect’s spread.

Research is being undertaken at the UoI to develop a commercially available CA test by this fall, according to a news release. For more information on CA, Beever recommends checking out www.dpi.nsw.gov.au/agriculture/live stock/health/specific/cattle/ca-angus