Background:Antithrombin, PC (protein C), and PS (protein S) are circulating natural anticoagulant proteins that regulate hemostasis and of which partial deficiencies are causes of venous... Show moreBackground:Antithrombin, PC (protein C), and PS (protein S) are circulating natural anticoagulant proteins that regulate hemostasis and of which partial deficiencies are causes of venous thromboembolism. Previous genetic association studies involving antithrombin, PC, and PS were limited by modest sample sizes or by being restricted to candidate genes. In the setting of the Cohorts for Heart and Aging Research in Genomic Epidemiology consortium, we meta-analyzed across ancestries the results from 10 genome-wide association studies of plasma levels of antithrombin, PC, PS free, and PS total. Methods:Study participants were of European and African ancestries, and genotype data were imputed to TOPMed, a dense multiancestry reference panel. Each of the 10 studies conducted a genome-wide association studies for each phenotype and summary results were meta-analyzed, stratified by ancestry. Analysis of antithrombin included 25 243 European ancestry and 2688 African ancestry participants, PC analysis included 16 597 European ancestry and 2688 African ancestry participants, PSF and PST analysis included 4113 and 6409 European ancestry participants. We also conducted transcriptome-wide association analyses and multiphenotype analysis to discover additional associations. Novel genome-wide association studies and transcriptome-wide association analyses findings were validated by in vitro functional experiments. Mendelian randomization was performed to assess the causal relationship between these proteins and cardiovascular outcomes. Results:Genome-wide association studies meta-analyses identified 4 newly associated loci: 3 with antithrombin levels (GCKR, BAZ1B, and HP-TXNL4B) and 1 with PS levels (ORM1-ORM2). transcriptome-wide association analyses identified 3 newly associated genes: 1 with antithrombin level (FCGRT), 1 with PC (GOLM2), and 1 with PS (MYL7). In addition, we replicated 7 independent loci reported in previous studies. Functional experiments provided evidence for the involvement of GCKR, SNX17, and HP genes in antithrombin regulation. Conclusions:The use of larger sample sizes, diverse populations, and a denser imputation reference panel allowed the detection of 7 novel genomic loci associated with plasma antithrombin, PC, and PS levels. Show less
Kruijt, M.; Pol, L.M. van der; Eikenboom, J.; Verburg, H.J.; Cobbaert, C.M.; Ruhaak, L.R. 2021
Antithrombin deficiency diagnostics by first-line activity tests suffer from a lack of sensitivity sometimes resulting in diagnostic uncertainty. We here present a case of a woman with recurrent... Show moreAntithrombin deficiency diagnostics by first-line activity tests suffer from a lack of sensitivity sometimes resulting in diagnostic uncertainty. We here present a case of a woman with recurrent pregnancy loss who was screened for inherited thrombophilia. Antithrombin activity was borderline low, resulting in uncertainty about the correct diagnosis. Using a mass spectrometry-based test, the antithrombin protein of the patient was characterized at the molecular level and a heterozygous p.Pro73Leu mutation was identified. The mutation, also known as antithrombin "Basel," increases the risk of venous thromboembolism and obstetric complications. This case is illustrative of current antithrombin deficiency screening, in which diagnoses may be missed by traditional diagnostics. Next-generation protein diagnostics by mass spectrometry provides molecular insight into the proteoforms present in vivo. This information is essential for laboratory specialists and clinicians to unambiguously diagnose patients and will aid in evolving healthcare from traditional to precision diagnostics. Show less
Ruhaak, L.R.; Romijn, F.P.H.T.M.; Smit, N.P.M.; Laarse, A. van der; Pieterse, M.M.; Maat, M.P.M. de; ... ; Cobbaert, C.M. 2018
