Prekallikrein deficiency in a family of miniature horses.

This research article is about the discovery of a hereditary deficiency in prekallikrein, a coagulation factor, in a family of miniature horses, identified through abnormal blood clotting times and analysis of coagulation factors.

Introduction and Background

• The research focuses on two miniature horses, siblings, that displayed unusual blood clotting metrics.
• Their 1-stage prothrombin time, a measure of how quickly blood clots, was normal, but their activated-partial thromboplastin time (APTT), another clotting measure, was abnormally long.
• Also, return to normal clotting times was observed when as little as 5% of a normal equine plasma (the yellowish liquid component of blood) was mixed with their plasma.

Coagulation Factor Analysis

• Investigation into the coagulation factors (proteins in blood that help stop bleeding) in the horses revealed deficiencies in factor XII when determined with a feline factor XII-deficient plasma substrate.
• However, when a human factor XII-deficient plasma substrate was used, the concentrations were normal.
• It was detected that the horses had a deficiency of another coagulation factor, prekallikrein, when tested with a human prekallikrein-deficient plasma substrate.
• The levels of other intrinsic coagulation factors were found to be normal within these horses.

Additional Tests and Family Analysis

• The researchers conducted a time-dependent activation test, measuring APTT after various periods of incubation with a contact activator before the addition of calcium ions.
• The data revealed that with greater incubation times, the APTT of both horses was akin to that of a normal equine plasma pool.
• Investigation into the pedigree of the deficient miniature horses suggested that several family members could be heterozygous carriers of the prekallikrein deficiency, implying that this a genetic deficiency that can be passed down to later generations.