A newly identified genetic condition known as Developmental Duplications or DD has been announced today by the American Angus Association as the result of work by Dr. Jonathan Beever with the University of Illinois. The homozygous state of this allele almost always results in early embryonic death which would be observed as a reduction in pregnancy rates. However in a rare number of mildly affected cases, calves with additional limbs have been born and survived, usually exhibiting duplication of the front legs and originating from the neck or shoulder region.
A small number of calves with this phenotype were initially observed and reported in Australia in 2011. At the Request of the Angus Society of Australia, Dr. Jonathan Beever has been investigating the condition over the last three years. Utilizing those calves, a few more recent calves in the US, and the archive of AI sires provided by NAAB members he has been able to very recently determine that the condition is inherited as a simple recessive trait and has successfully developed a DNA diagnostic test to identify carrier animals.
The individual results of this test on the archived AI sire population have been provided to the American Angus Association and the Angus Society of Australia for posting. More current bulls in several breeds are still pending and will be released as soon as they are available. The results for current and former ABS sires are on the ABS Beef website and can be downloaded in the pdf’s below. These results indicate a carrier frequency of approximately 6%. As we receive pending results, updates will be made here and the ABS Beef website.
The ABS carrier bulls listed will continue to be available but on a special order basis only through the ABS Beef Department.
ABS Beef 
[…] Earlier this week, we announced a newly identified genetic condition known as Developmental Duplication. […]