Deficiencies of antithrombin, protein C and protein S – Practical experience in genetic analysis of a large patient cohort

Abstract

Deficiencies of natural anticoagulant proteins including antithrombin (AT), protein C (PC) and protein S (PS) are important causes of inherited thrombophilia. This study aimed to report on the practical experience gained in performing genetic analyses of a large cohort of patients with AT, PC and PS deficiencies and to relate this knowledge to clinical application. We genotyped a large cohort of 709 unrelated patients with AT (231), PC (234) and PS (244) deficiencies referred to us by physicians throughout Germany. Mutations were detected by direct sequencing and multiplex ligation-dependent probe amplification (MLPA). The highest mutation detection rate (MDR) was found for the SERPINC1 gene (83.5%), followed by the PROC (69%) and PROS1 (43%) genes. Even at AT activities close to the normal range (75%), the MDR was 70%. Contrastingly, for PC and PS deficiencies, the MDR dropped significantly and mildly lowered to subnormal values. At PS activities >55% for PS no mutations were detected. Mutation profiles of all three genes were similar with the highest prevalence for missense mutations (63-78%), followed by nonsense (7-11%), splice-site mutations (7-13%), small deletions (1-8%), small insertions/duplications (1-4%) and large deletions (3-6%). In conclusion, genetic testing is a useful diagnostic tool for diagnosing thrombophilia. Based on our data, genetic analysis for patients with AT deficiency is indicated for all subnormal activities. In contrast, genotyping is not advisable for PC activities >70% and for PS activities >55%.

Genetic characterization of antithrombin, protein C and protein S deficiencies in Polish patients

“…This is in contrast to a study by Caspers et al, 16 conducted in German patients, in whom the mutation detection rate remained at a level of about 70% for AT activities up to 75%. 16 It seems that in our population, a genetic analysis of the SERPIC1 gene should be performed in patients Mutations were given coordinates according to the HUGO recommendations for mutation nomenclature (http://www.hgvs.org).…”

“…On the other hand, the study on the German population showed that the genetic analysis of the PROC gene should be performed in patients with PC activities below 70%, which worked fine also for our patients. 16 Similarly, in our PS -deficient patients, no mutations were detected above 53% of PS activity, which is in line with the study by Caspers et al 16 The major study limitation was a relatively small sample size; however, we analyzed all eligible patients suspected of these types of thrombophilia in our center. For the new mutations, functional studies should be performed in addition to in silico predictions to prove their detrimental effect.…”

“…It is possible that other genes on chromosome 16q23 and 1q32 influence the PC and PS levels. 16,42,43 PC activity can be modulated also by the genetic variants of EPCR 44 and the polymorphisms of the genes involved in the vitamin K -dependent γ -carboxylation reaction may also influence the activities of PC and PS. 45 It should be also noted that for the measurement of AT activity, both the bovine thrombin-and the FXa inhibition -based tests, together with an antigen method, are advisable to be performed in patients with suspected type II AT deficiency.…”

Distinct frequencies and mutation spectrums of genetic thrombophilia in Korea in comparison with other Asian countries both in patients with thromboembolism and in the general population

“…The overall mutation detection rate (3 genes combined) and the order were similar to those recently reported in a large cohort of patients from Germany (overall 65.8%, with SERPINC1 84%, PROC 69.2%, and PROS1 43.2%). 46 The overall mutation detection rate in the population group in our study was lower than that in the group of patients (36.7% versus 56.7%), but higher than the 15.8% in a population study in China recently reported by Zhu et al 16 In addition, the results from the study by Zhu et al demonstrated the highest mutation detection rate in PROC (31.3%), followed by SERPINC1 (9.7%) and PROS1 (6.3%). This striking difference was in part due to the presence of two prevalent missense mutations (Arg79Cys and Ser148Pro) in the Korean population.…”

Age-specific onset and distribution of the natural anticoagulant deficiency in pediatric thromboembolism

“…Recent advances in the intensive cares, cardiac surgery, and transplantation medicine along with the imaging diagnosis may contribute to the increased number of pediatric patients with thrombosis (2,3). The established genetic risks of venous thromboembolism (VTE) include protein C (PC), protein S (PS), and antithrombin (AT) deficiency, as well as factor V G1691A (FVL) and prothrombin G20210A (FII) variants (4). The high incidence of VTE in Caucasians (5) is explained by the fact that FVL and FII G20210A carriers were found in 20-60% of adult VTE patients in Caucasian but not Asian ancestries (6)(7)(8)(9).…”