Quantitative trait locus analysis for hemostasis and thrombosis

Abstract

Susceptibility to thrombosis varies in human populations as well as many in inbred mouse strains. The objective of this study was to characterize the genetic control of thrombotic risk on three chromosomes. Previously, utilizing a tail-bleeding/rebleeding assay as a surrogate of hemostasis and thrombosis function, three mouse chromosome substitution strains (CSS) (B6-Chr5(A/J), Chr11(A/J), Chr17(A/J)) were identified (Hmtb1, Hmtb2, Hmtb3). The tail-bleeding/rebleeding assay is widely used and distinguishes mice with genetic defects in blood clot formation or dissolution. In the present study, quantitative trait locus (QTL) analysis revealed a significant locus for rebleeding (clot stability) time (time between cessation of initial bleeding and start of the second bleeding) on chromosome 5, suggestive loci for bleeding time (time between start of bleeding and cessation of bleeding) also on chromosomes 5, and two suggestive loci for clot stability on chromosome 17 and one on chromosome 11. The three CSS and the parent A/J had elevated clot stability time. There was no interaction of genes on chromosome 11 with genes on chromosome 5 or chromosome 17. On chromosome 17, twenty-three candidate genes were identified in synteny with previously identified loci for thrombotic risk on human chromosome 18. Thus, we have identified new QTLs and candidate genes not previously known to influence thrombotic risk.

Fig. 1

QTL analysis. (a) Hmtb4, peak marker D5Mit338 (59 cM). (b) Hmtb5, peak marker D5Mit320 (70 cM). (c) Hmtb6, peak marker D11Mit336 (75 cM). (d) Hmtb8, peak marker D17Mit 20 (34.3 cM); Hmtb9, peak marker D17Mit39 (45.3 cM). The linkage analysis was performed with MapManager QTX program. (Manly et al. 2001). Solid line indicates significant threshold (0.05). Dashed line indicates suggestive threshold (0.63). The 95% confidence intervals for each QTL are indicated

Fig. 2

The allele distributions at peak markers in the F₂ mice. (a) Hmtb4, clot stability time, chromosome 5, D5Mit338 BB, n = 14; AB, 45; AA, 20. (b) Hmtb5, bleeding time, chromosome 5, D5Mit320 BB, n = 10; AB, 47; AA, 22. (c) Hmtb6, clot stability time, chromosome 11, D11Mit336 BB, n = 27; AB, 34; AA, 15. (d) Hmtb8, clot stability time, chromosome 17, D17Mit20 BB, n = 39; AB, 60; AA, 31. (e) Hmtb9, clot stability time, chromosome 17, D17Mit39 BB, n = 35; AB, 48; AA, 47. A = A/J; B = B6. The lines at the middle indicate the medians. The boxes show the 25th and 75th percentiles. The whiskers show the ranges. Statistical differences are indicated between bars