About bloody time: Haemophilia A marker gets an A+ mark

Canine Haemophilia A has long been a source of concern for many breeders, owners, and their beloved male dogs who have inherited the recessive bleeding disorder. As an X-linked genetic disorder that prevents blood clotting through the absence of the coagulation factor VIII (pictured bottom), the bitch serves as the carrier and passes the condition to her affected sons – where haemophilia is concerned, blood is definitely not thicker than water. In fact, the condition that results in the spontaneous formation of hematomas at the joints (pictured top right) has generated calls to ‘breed out’ the recessive gene, found on the X chromosome at location Xq28.

Recently, however, geneticists have taken the guess work out of breeding programs by proposing a three-marker panel that will single out the unsuitable female breeding stock. F8-int6, F8-int10 and cF8ms have been identified as the new artillery in the war against haemophilia due to their heterozygosity across numerous breeds. An inclusive approach is necessary as these three focal loci must consider and combat the variability of the genomes of different breeds.

These advancements pave the way for improved carrier detection in cats, horses, chickens and, ultimately, humans – all species that are homologous with the dog. Haemophilia A identification could soon be more accurate and accessible than the testing currently used in medicine.

But what does this mean to the males of the canine populace? With responsible breeding using the genetic guidelines, this discovery should mean no spontaneous bleeding, no haemophilia, and above all – no bloody worries!

Author: Rebekah Donaldson

Student Number: 41770070

Primary reference:

Brooks, MB, MacNguyen, R, Hall, R, Gupta, R & Booth, JG 2008, ‘Indirect carrier detection of canine haemophilia A using factor VIII microsatellite markers’, Animal Genetics, vol. 39, pp. 278-283
http://www.ncbi.nlm.nih.gov/pubmed/18454805?ordinalpos=1&itool=EntrezSystem2.PEntrez.Pubmed.Pubmed_ResultsPanel.Pubmed_RVDocSum
Secondary references:

Cornell University College of Veterinary Medicine 2006, Comparative Coagulation: Canine Hemophilia A Study 2005-2007, viewed 27 May 2008 http://www.diaglab.vet.cornell.edu/coag/research/canine.asp.

OMIA: Online Mendelian Inheritance in Animals n.d., Haemophilia A (Phene ID 56, Group 000437) in Canis familiaris, viewed 16 May 2008 http://omia.angis.org.au/retrieve.shtml?pid=56.

Wikipedia 2008, Factor VIII, viewed 16 May 2008 http://en.wikipedia.org/wiki/Factor_VIII