Mouse chromosome 17 candidate modifier genes for thrombosis.

Two overlapping quantitative trait loci (QTLs) for clot stability, Hmtb8 and Hmtb9, were identified on mouse chromosome 17 in an F2 intercross derived from C57BL/6J (B6) and B6-Chr17(A/J) (B6-Chr17) mouse strains. The intervals were in synteny with a QTL for thrombotic susceptibility on chromosome 18 in a human study, and there were 23 homologs between mouse and human. The objective of this study was to determine whether any of these genes in the syntenic region are likely candidates as modifiers for clot stability. Seven genes, Twsg1, Zfp161, Dlgap1, Ralbp1, Myom1, Rab31, and Emilin2, of the 23 genes with single nucleotide polymorphisms (SNPs) in the mRNA-UTR had differential expression in B6 and A/J mice. Dlgap1, Ralbp1, Myom1, and Emilin2 also had nonsynonymous SNPs. In addition, two other genes had nonsynonymous SNPs, Lama1 and Ndc80. Of these nine candidate genes, Emilin2 was selected for further analysis since other EMILIN (Elastin Microfibril Interface Located Protein) proteins have known functions in vascular structure and coagulation. Differences were found between B6 and A/J mice in vessel wall architecture and EMILIN2 protein in plasma, carotid vessel wall, and thrombi formed after ferric chloride injury. In B6-Chr17(A/J) mice both clot stability and Emilin2 mRNA expression were higher compared to those in B6 and A/J mice, suggesting the exposure of epistatic interactions. Although other homologous genes in the QTL region cannot be ruled out as causative genes, further investigation of Emilin2 as a candidate gene for thrombosis susceptibility is warranted.