Molecular characterization of cat factor XII gene and identification of a mutation causing factor XII deficiency in a domestic shorthair cat colony.

Coagulation factor XII (FXII) may be important in cardiovascular and inflammatory diseases. We have identified and characterized a naturally occurring mutation in the feline FXII gene that results in a mutant protein and enzymatic loss of activity. Feline intron/exon gene structure and sequence were acquired by comparing DNA sequences obtained from a fragmented Felis catus genomic sequence and the National Center for Biotechnology Information's Cross Species Megablast of multiple species' FXII gene sequences. Fourteen exons ranging in size from 57 to 222 base pairs were confirmed spanning 8 Kb on chromosome A1. The 1828-base pair feline FXII messenger RNA (mRNA) sequence contains an open reading frame that encodes a protein of 609 amino acids with high homology to human FXII protein. Total RNA and mRNA purified from liver tissue of 4 wild-type/normal and 8 FXII-deficient cats confirmed the predicted mRNA sequence and identified one important single-nucleotide polymorphism (SNP). A single base deletion in exon 11 of the FXII coding gene in our colony of cats results in deficient FXII activity. Translation of the mRNA transcript shows a frame shift at L441 (C441fsX119) resulting in a nonsense mutation and a premature stop codon with a predicted 560-amino acid protein. The mutant FXII protein is truncated in the 3' proteolytic light chain region of the C-terminus, explaining its loss of enzymatic activity. This study is the first molecular characterization of the feline FXII gene and the first identification of an FXII mutation in the domestic cat, providing insights into the origin and nature of feline FXII deficiency.

A phase II prospective open-label escalating dose trial of recombinant interleukin-11 in mild von Willebrand disease.

von Willebrand factor (VWF) is a multimeric glycoprotein that mediates platelet adhesion and is decreased in von Willebrand disease (VWD). 1-8 deamino-d-arginine vasopressin (DDAVP), the most common treatment for VWD, is limited by tachyphylaxis and inconvenience, and in 20% of the patients, unresponsiveness. Recombinant human interleukin-11 (rhIL-11), a gp-130 signalling cytokine with haematopoietic and anti-inflammatory activity, increases VWF antigen and its activity in heterozygous VWF(+/-) mice and dogs. To determine the biological efficacy and safety of rhIL-11 in non-bleeding human subjects with mild VWD, we conducted a phase II prospective open-label trial of rhIL-11 at 10, 25 and 50 mug kg(-1) subcutaneously (s.c.), given daily for 7 days in nine subjects with mild VWD. VWF and factor VIII (FVIII) levels increased gradually and progressively after s.c. rhIL-11, which was sustained through 7 days of dosing to 1.5- to 3-fold over baseline. Following intravenous DDAVP, 0.3 mug kg(-1), on day 7 there was a further boost in VWF and FVIII levels, suggesting that the mechanism of rhIL-11 differs from that of DDAVP. Platelet VWF mRNA expression measured by quantitative PCR increased from two- to eightfold over baseline, suggesting that the mechanism of rhIL-11 effect may be upregulation of VWF mRNA. VWF and FVIII levels returned to baseline by day 14. rhIL-11 was well tolerated with less than grade-1 hypertension, hypokalaemia and fluid retention. Recombinant IL-11 increases VWF levels in humans with mild VWD, justifying future clinical trials to determine its potential in preventing or reducing bleeding in this patient population.