Bernard-Soulier syndrome

Bernard-Soulier syndrome (BSS) is an inherited autosomal recessive lethal bleeding disorder occurring in English Cocker Spaniels characterized by low platelet count, unusually large platelets compared to the standard size and substantially worse blood clotting. It is caused by lack of glycoprotein that is normally found on the surface of blood platelets and acts as a receptor of another protein found in the circulating blood called von Willebrand factor (vWF). In case of injury the glycoprotein binds with vWF to stabilize the blood coagulation. In individuals affected with BSS the formation of blood clots is unstable or very difficult.  The clinical signs involve excessive bleeding from cuts and other injuries, gum bleeding, nosebleeds, etc. Life threatened for the individuals suffering from BBS can also be traumatic injuries, childbirth or surgical operation. The frequency of mutant allele in the population is approximately   6 %.

The disease develops only in individuals that inherit the mutation gen from both parents. These individuals are designated BSS^1st/BSS^1st. The carriers of the mutated gene designated BSS^1st/wt have only one mutated gene from one parent and have no clinical signs. However, they pass the disease to their offsprings. If two heterozygotes (BSS^1st/wt) are mated, then theoretically 25 % of the offsprings will be healthy, 50% of the offsprings will be carriers and 25% inherit both mutated genes from their parents and will suffer from BSS. Mating a healthy individual (wt/wt) with a carrier of this mutation (BSS^1st/wt) will result theoretically in a litter consisting of 50% carriers and 50% healthy dogs. When mating a carrier (BSS^1st/wt) with affected individual (BSS^1st/BSS^1st), there will be theoretically 50% affected individuals and 50% carriers.

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Reference:

Gentilini F, Turba ME, Giancola F, Chiocchetti R, Bernardini C, Dajbychova M, Jagannathan V, Drögemüller M, Drögemüller C. A large deletion in the GP9 gene in Cocker Spaniel dogs with Bernard-Soulier syndrome. PLoS One. 2019 Sep 4;14(9):e0220625. doi: 10.1371/journal.pone.0220625. PMID: 31484196; PMCID: PMC6726462.