Plasminogen activator inhibitor type-1 (PAI-1, aka SERPINE1) is a moderately heritable glycoprotein that regulates fibrin clot dissolution (fibrinolysis).
Test whether the heritabilities (h ) of PAI-1 and other hemostatic factors are constant throughout their distribution or whether they are quantile-specific, i.e. a larger or smaller h depending upon whether their concentrations are high or low.
Quantile regression was applied to 5606 parent-offspring pairs and 5310 full siblings of the Framingham Heart Study. Quantile-specific heritability was estimated from the parent-offspring regression slope (β , h =2β /(1+r )) and the full-sib regression slope (β , h ={(1+8r β ) . -1}/(2r )).
Heritability (h ±SE) increased significantly with increasing percentiles of the offspring’s age- and sex-adjusted PAI-1 distribution when estimated from β (P =0.0001): 0.09±0.02 at the 10 , 0.09±0.02 at the 25 , 0.16±0.02 at the 50 , 0.29±0.04 at the 75 , and 0.26±0.08 at the 90 percentile of the PAI-1 distribution, and when estimated from β (P =6.5×10 ). There was no significant evidence for quantile-specific heritability for Factor VII (P =0.35), D-dimer (P =0.08), tPA (P =0.74), or von Willebrand factor (P =0.79).
Higher mean plasma PAI-1 antigen concentrations tend to accentuate genetic effects (quantile-dependent expressivity), which is consistent with the greater reported differences in PAI-1 concentrations between rs1799889 SERPINE1 (4G/5G) genotypes in patients with osteonecrosis, meningococcal sepsis, obesity, prior myocardial infarction, deep vein thrombosis, and polycystic ovarian syndrome than in healthy controls. It is also consistent with the greater increases in PAI-1 concentrations in 4G-allele carriers than 5G/5G homozygotes following fibrinolytic treatment, low-salt intake, and high saturated fat intake.

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