Test identifies Red Angus who carry marble bone disease

WASHINGTON — A new test that detects a rare and deadly bone disorder in Red Angus is now available to cattle producers, thanks to U.S. Department of Agriculture scientists.

Birth defect

Marble bone disease, also known as osteopetrosis, had not been seen in the United States since the 1960s until it resurfaced in Red Angus cattle three years ago. The 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.

Gene mutation

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

DNA compared

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. In osteopetrosis-affected calves, some of the genetic material of SLC4A2, a gene located on a segment of chromosome 4, had been deleted.

The discovery of the deletion was a first for cattle. SLC4A2 is necessary for proper osteoclast maintenance and function.

Less than one year

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. The test is being used to help manage osteopetrosis and identify possible carriers.