WASHINGTON – US Department of Agriculture scientists have developed a new test that detects Marble bone disease, a rare and deadly bone disorder in Red Angus cattle, and it is now available to cattle producers.

Also known as osteopetrosis, Marble bone disease had not been found in the US since the 1960s, but it resurfaced in Red Angus cattle three years ago. This birth defect, which affects humans, cattle and other animals, causes abnormal brain and bone marrow cavity development, leading to overly dense, brittle bones. Calves with the mutation usually are stillborn or die soon after birth, states USDA Agriculture Research Service. ARS is USDA's chief intramural scientific research agency, and this research supports USDA's priority of promoting international food security.

Scientists at the ARS Roman L. Hruska U.S. Meat Animal Research Center (USMARC) in Clay Center, Neb., and the Henry A. Wallace Beltsville Agricultural Research Center (BARC) in Beltsville, Md. collaborated with several university and Red Angus Association of America partners to identify the gene mutation responsible for the disorder in efforts to stop the disease in cattle. They ultimately developed a DNA diagnostic test that identifies osteopetrosis carriers.

Scientists compared DNA from affected Red Angus calves and their carrier parents to unaffected animals. A search of the entire genomes of all the calves for common and uncommon chromosomal segments revealed an abnormality.

ARS writer Sandra Avant relayed that in osteopetrosis-affected calves, some of the genetic material of SLC4A2, a gene located on a segment of chromosome 4. The discovery of the deletion was a first for cattle. SLC4A2 is necessary for proper osteoclast maintenance and function. Osteoclasts are cells that break down old bone during bone development and remodeling.

Scientists were able to develop a polymerase chain reaction test in less than a year, Avant relays. The test is being used to help manage osteopetrosis and identify possible carriers.