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  Discussion on Research Study: Gene found associated with OCD
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Moderator:
DrO

Posted on Thursday, Jun 11, 2009 - 9:22 am:

Well here we go guys, this is the first instance that a gene mutation has been associated with the increase incidence of OCD in a breed of horse. The last 10 years has been replete with examples that intimated that OCD was likely to be a genetic disorder and here we have what I think is the first in a long line of reports on the genetic component. You want to avoid OCD, you breed lines that don't have a history of it. For more on this see the article associated with this forum.
DrO

J Hered. 2009 Mar 20.

The Candidate Gene XIRP2 at a Quantitative Gene Locus on Equine Chromosome 18 Associated with OsteochonDrOsis in Fetlock and Hock Joints of South German Coldblood Horses.

Wittwer C, Hamann H, Distl O.

the Institute for Animal Breeding and Genetics, University of Veterinary Medicine Hannover, Foundation Bünteweg 17p, 30559 Hannover, Germany.

A whole-genome scan for radiological signs of osteochonDrOsis (OC) and osteochonDrOsis dissecans (OCD) in South German Coldblood (SGC) horses using 250 microsatellite markers identified a genome-wide significant quantitative trait locus (QTL) for fetlock OCD and a chromosome-wide QTL for hock OC on Equus caballus chromosome (ECA) 18 at a relative position of 45.9-78.2 cM. The aim of this study was to analyze associations of single-nucleotide polymorphisms (SNPs) in candidate genes for OC in this QTL region using 96 SGC horses. The OC-QTL on ECA18 could be confirmed and narrowed down to an interval of 13 Mb between GALNT13 and Xin actin-binding repeat containing 2 (XIRP2). SNPs in the XIRP2 gene were significantly associated with fetlock OC, fetlock OCD, and hock OC. The significant associations of SNPs in XIRP2 could be confirmed in linear animal models controlling for systematic environmental and residual quantitative genetic effects. The significant additive genetic effects of the intronic SNPs (AJ885515:g.159A>G, AJ885515:g.445T>C) in XIRP2 were 0.15 (P = 0.01) for fetlock OC, 0.27 (P = 0.01) for fetlock OCD, and 0.15-0.16 (P = 0.01-0.02) for hock OC. Homozygous (A/A or T/T) and heterozygous horses were at a 1.3- to 2.4-fold higher risk for fetlock and hock OC. These results suggest that dominant variants of XIRP2 may be involved in pathogenesis of equine OC.
Moderator:
DrO

Posted on Wednesday, Sep 23, 2009 - 11:01 am:

And further conformation of the above finding:

J Anim Sci. 2009 Aug 14.
Identification of a new quantitative trait locus on equine chromosome 18 responsible for osteochonDrOsis in Hanoverian warmblood horses.

Lampe V, Dierks C, Komm K, Distl O.

Institute for Animal Breeding and Genetics, University of Veterinary Medicine Hannover, Foundation, Bünteweg 17p, 30559 Hannover, Germany.

In this study we present a newly detected QTL associated with osteochonDrOsis in Hanoverian warmblood horses on equine chromosome 18 (ECA18). We developed a highly polymorphic and on ECA18 evenly distributed marker set employing the horse genome assembly EquCab2. The marker set included 11 newly developed microsatellites. Average polymorphism information content was 62.1% at an average spacing of 3 Mb. For genotyping of this marker set comprising a total of 27 highly polymorphic microsatellites, we used the same 14 paternal half-sib families as in the previous whole genome scan. The chromosome-wide linkage analysis revealed a QTL for osteochonDrOsis in fetlock and/or hock joints, as well as for osteochonDrOsis dissecans in hock joints between 74.94 and 82.25 Mb. Within this QTL for equine osteochonDrOsis, the parathyroid hormone 2 receptor gene could be identified as a positional candidate gene. This report is a further step towards the identification of genes responsible for osteochonDrOsis in horses.
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