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Using human DNA sequence, scientists identify mutation for cattle disease
  
By
Edward R. Winstead


Scientists have identified a genetic mutation in cattle that causes a skin and tooth disorder. Versions of the gene, ED1, are present in humans and mice. In all three species, the gene resides on the X-chromosome and causes a similar disorder when mutated.


German Holstein cow with ectodermal dysplasia.

The human gene encodes a protein called ectodysplasin 1, which appears to be involved in the formation of hair follicles and tooth buds in fetal development. In both humans and cattle, mutations in the ED1 gene can result in sparse hair growth, absent sweat glands, and abnormal teeth. The disorder is known as anhidrotic ectodermal dysplasia.

To find the cattle gene, Tosso Leeb, of the School of Veterinary Medicine Hannover, Germany, and colleagues identified regions of the cattle X-chromosome likely to contain the gene based on known locations of the human and mouse genes. They then screened the human DNA sequence against the target region of the cattle chromosome and found a close match. The cattle DNA came from a family of German Holsteins affected by ectodermal dysplasia.

"We have cloned and characterized one of the largest known genes," the researchers write in Genome Research. "The bovine ED1 DNA sequences will add to our understanding of the bovine genome, in which only very limited genomic DNA information is available." The family of affected Holsteins, they add, could serve as a model for investigating the role of the human ectodysplasin 1 protein in development.


X-ray of cattle jaw with abnormal teeth.

In 1997, researchers at the University of Pennsylvania School of Veterinary Medicine reported the birth of a dog with ectodermal dysplasia linked to the X-chromosome. The male German shepherd puppy had symmetrical areas of hairlessness as well as missing and misshapen teeth. There was no family history of a similar condition, so the researchers concluded that the mutation had occurred spontaneously.

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Drögemüller, C. et al. Partial deletion of the bovine ED1 gene causes anhidrotic ectodermal dysplasia in cattle. Genome Res 11,1699-1705 (October 2001).
 
Casal, M.L. et al. X-linked ectodermal dysplasia in the dog. J Hered 88, 513-517 (November-December 1997).
 

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