Congenital contractural arachnodactyly (CA), also known as fawn calf syndrome, is an

autosomal recessive In genetics, dominance is the phenomenon of one variant (allele) of a gene on a chromosome masking or overriding the effect of a different variant of the same gene on the other copy of the chromosome. The first variant is termed dominant and t ...

genetic disorder A genetic disorder is a health problem caused by one or more abnormalities in the genome. It can be caused by a mutation in a single gene (monogenic) or multiple genes (polygenic) or by a chromosomal abnormality. Although polygenic disorders ...

cattle Cattle (''Bos taurus'') are large, domesticated, cloven-hooved, herbivores. They are a prominent modern member of the subfamily Bovinae and the most widespread species of the genus ''Bos''. Adult females are referred to as cows and adult mal ...

. The disorder affects the connective tissue of muscles, leading to contracture of the upper limb (most obvious in the hind limbs), and laxity of the joints of the lower limbs. CA affects

Angus Angus may refer to: Media * ''Angus'' (film), a 1995 film * ''Angus Og'' (comics), in the ''Daily Record'' Places Australia * Angus, New South Wales Canada * Angus, Ontario, a community in Essa, Ontario * East Angus, Quebec Scotland * An ...

cattle, and associated breeds such as Murray Greys. The mutation which causes this defect is a deletion on bovine chromosome 21.

Clinical signs

Affected calves are usually born alive with normal body weight, and most can walk and suckle, although 20 percent cannot suckle and die soon after birth. Signs include

proximal Standard anatomical terms of location are used to unambiguously describe the anatomy of animals, including humans. The terms, typically derived from Latin or Greek roots, describe something in its standard anatomical position. This position pro ...

limb

contracture In pathology, a contracture is a permanent shortening of a muscle or joint. It is usually in response to prolonged hypertonic spasticity in a concentrated muscle area, such as is seen in the tightest muscles of people with conditions like spasti ...

, congenital

distal Standard anatomical terms of location are used to unambiguously describe the anatomy of animals, including humans. The terms, typically derived from Latin or Greek roots, describe something in its standard anatomical position. This position pro ...

limb

hyperextension Motion, the process of movement, is described using specific anatomical terms. Motion includes movement of organs, joints, limbs, and specific sections of the body. The terminology used describes this motion according to its direction relative ...

and congenital kyphosis. As the calf grows, signs significantly improve. In mildly affected calves, CA may be less obvious, presenting as tall stature, joint laxity and poor muscling. Joint laxity predisposes affected cattle to the early onset of arthritis.

Prevention

In Australia, affected animals are descended from ''Freestate Barbara 871 of Kaf'', a cow born in Indiana, US, in 1978. This cow is an ancestor of approximately half of all Angus cattle in Australia, limiting the usefulness of

pedigree analysis Genetic genealogy is the use of genealogical DNA tests, i.e., DNA profiling and DNA testing, in combination with traditional genealogical methods, to infer genetic relationships between individuals. This application of genetics came to be used b ...

in identifying potential carriers. If CA is identified in a herd, bulls that have tested negative for CA should be purchased, since both parents must be carriers of the defective gene for affected calves to be born. Angus sires which carry CA include ''Rambo 465T of JRS'', ''Te Mania Kelp K207'', ''Bon View Bando 598'', ''SAF 598 Bando 5175'' and ''Boyd On Target 1083''.

History

The disorder was first identified in

Victoria, Australia Victoria is a state in southeastern Australia. It is the second-smallest state with a land area of , the second most populated state (after New South Wales) with a population of over 6.5 million, and the most densely populated state in Au ...

in 1998, and has since been identified in other countries. A genetic test was developed in 2010.{{cite journal, last1=Tammen, first1=I., last2=Khatkar, first2=M.S., last3=Cavanagh, first3=J.A.L., last4=Windsor, first4=P.A., last5=Thomson, first5=P.C., last6=Raadsma, first6=H.W., title=Mapping of congenital contractural arachnodactyly in cattle, journal=Association for the Advancement of Animal Breeding and Genetics, date=2011, volume=19, pages=215–218, url=http://www.aaabg.org/livestocklibrary/2011/tammen215.pdf

References

Bovine diseases Systemic connective tissue disorders