Congenital Protein S Deficiency Research Articles

Gene analysis of six cases of congenital protein S deficiency and functional analysis of protein S mutations (A139V, C449F, R451Q, C475F, A525V and D599TfsTer13)

Congenital deficiency of protein S (PS), an anticoagulant factor, leads to venous thrombosis, with onset predominantly beginning in adolescence. In the present study, gene analysis of six unrelated Japanese families diagnosed with congenital PS deficiency identified five missense mutations in the PROS1 gene – c.757C>T (Ala139Val; A139V), c.1346 G>T (Cys449Phe; C449F), c.1352G>A (Arg451Gln; R451Q), c.1424G>T (Cys475Phe; C475F) and c.1574C>T (Ala525Val; A525V) – and one frameshift mutation, c.2135delA (Asp599ThrfsTer13; D599TfsTer13). C449F, R451Q, A525V and D599TfsTer13 are novel mutations. Results from ELISA to measure PS antigen levels in culture supernatant showed that the A139V variant was similar to wild-type, but other variants showed reductions when compared with wild-type. Results from pulse-chase analysis confirmed that the A139V variant exhibited secretion equivalent to wild-type, but for the other variants, there was no extracellular secretion, and it had nearly all been degraded inside the cell within six hours. Results from pulse-chase analysis using proteasome inhibitors also showed that intracellular degradation of mutant protein was inhibited. Activity of the A139V variant was decreased to 71% of wild-type, and the phospholipid binding capacity fell to as low as 45%. These results suggest that although the A139V variant has normal secretion, it has abnormal phospholipid binding capacity, and therefore causes type II PS deficiency, in which PS activity is decreased. It is also thought that with the other variants, misfolding due to amino acid mutations causes nearly all PS to be degraded intracellularly, therefore leading to type I PS deficiency.

High prevalence of congenital thrombophilia in patients with pregnancy-related or idiopathic venous thromboembolism/pulmonary embolism.

Congenital thrombophilia which is characterized by deficiencies in proteins such as antithrombin (AT), protein C (PC) and protein S (PS), is a major cause of venous thromboembolism (VTE). A total of 130 patients with VTE were evaluated for congenital thrombophilia based on the activity of AT, PC, or PS. Fifteen VTE patients with congenital AT deficiency (11.5%), 16 with congenital PC deficiency (12.3%) and eight with congenital PS deficiency (6.2%) were diagnosed using DNA analysis. The frequency of congenital AT deficiency was significantly higher in subjects with pregnancy-related and idiopathic VTE than in those with VTE due to other causes, and congenital PC and PS deficiency were frequently associated with idiopathic VTE. Among the groups examined, the plasma levels of AT were the lowest in subjects with pregnancy-related VTE. Although our findings may have been influenced by some unintentional bias, congenital thrombophilia is nevertheless a major cause of VTE in pregnant patients as well as in young or middle-aged patients without any underlying diseases.

Compound heterozygous mutations in the PROS1 gene responsible for quantitative and qualitative protein S deficiency

Protein S (PS) is a vitamin K-dependent plasma glycoprotein, which plays an important role in the blood anticoagulant system. The PS gene (PROS1) spans some 80 kb of genomic DNA, composed of 15 exons and 14 introns, and is closely linked to a highly homologous pseudogene (PROS2), whose sequence is 96% identical to that of PROS1 [1]. Congenital PS deficiency caused by PROS1 mutations is associated with an increased risk of thromboembolic disease. In this study, we investigated the molecular basis of a patient with both quantitative and qualitative PS deficiency. A 69-year-old man had a medical examination in our hospital because of progressive bilateral leg pain and swelling. He was diagnosed with deep vein thrombosis (DVT) based on the venographs of the legs. Laboratory tests showed normal values of platelet count, prothrombin time, activated partial thromboplastin time, ATIII activity and protein C activity. Test results for lupus anticoagulant and anti-cardiolipin b2GPI antibody were negative. Total PS antigen, free-PS antigen and PS activity levels were 49.0% (normal range 65‐135%), 26.7% (60‐150%) and 10% (60‐150%), respectively. From these findings, he was diagnosed as having PS deficiency.

Plasma protein S activity correlates with protein S genotype but is not sensitive to identify K196E mutant carriers.

Protein S (PS) is an anticoagulant protein that functions as a cofactor for activated protein C (APC), and congenital PS deficiency is a well-known risk factor for the development of deep vein thrombosis (DVT). Recently, we and others identified the K196E missense mutation in the second epidermal growth factor-like domain of PS as a genetic risk factor for DVT in the Japanese population. The incidence of this mutation is high in the Japanese population. In the present study, we investigated the relationship between plasma PS activity and the presence of the K196E mutation. We measured PS activity as a cofactor activity for APC in 1,862 Japanese individuals and determined the PS K196E genotype in this population. Individuals heterozygous for the mutant E-allele had lower plasma PS activity than wildtype subjects (mean +/- SD, 71.9 +/- 17.6%, n = 34 vs. 87.9 +/- 19.8%, n = 1,828, P < 0.0001). However, the PS activity of several heterozygous individuals (n = 8) was greater than the population average. In contrast, multiple wildtype subjects (n = 26) had PS activity less than 2 SD below the population mean, indicating that other genetic or environmental factors affect PS activity. Plasma PS activity itself is not suitable for identifying PS 196E carriers and other methods are required for carrier detection.

Protein S and Congenital Protein S Deficiency: The Most Frequent Congenital Thrombophilia in Japanese

Protein S is a natural anticoagulant. Congenital protein S (PS) deficiency is a confirmed risk factor of venous thromboembolism (DVT) which though occurs infrequently yet is a leading cause of maternal mortality and morbidity. Congenital PS deficiency may also be responsible for obstetric complications such as preeclampsia/eclampsia, recurrent fetal loss and intrauterine fetal restriction. Congenital PS deficiency has been identified in 1-7.5% of patients with DVT and in 0.03-0.13% general Caucasian population. However, Japanese people have higher prevalence both in VTE patients (12.7%) and general population (0.48-0.63%). Because PS deficiency is the most frequent congenital thrombophilia in Japanese people, Japanese obstetricians must understand this thrombophilia and also that women with PS deficiency have an increased risk of VTE and a necessity of prophylactic use of anticoagulant against recurrent VTE during pregnancy and puerperium. This article reviews the literature to understand PS and congenital PS deficiency, especially the association of this thrombophilia with pregnancy.

Decrease in anticoagulant factors in patients with prostate cancer treated with diethylstilbestrol diphosphate

Estrogen has been highly evaluated as one of the most potent endocrine agents for the treatment of prostate cancer. Unfortunately, a high risk of cardiovascular complications is a clinically important adverse effect of estrogen therapy, and occasionally the complications are fatal. In recent years a high incidence (55%) of thrombotic events has been reported in patients with congenital protein S (PS) deficiency. The aim of this study is to determine the relationship between cardiovascular complications of estrogen therapy and anticoagulant factor levels in the serum of patients with prostate cancer. Study 1 employed 99 patients with prostate cancer: 39 were untreated, 25 were treated with LH-RH agonist therapy alone, and 35 were treated with oral diethylstilbestrol diphosphate (DESdP) 300 mg per day. We measured the serum levels of anticoagulant factors, parameters antithrombin III (ATIII), protein C (PC), PS, coagulant and fibrinolytic factors in all patients. In study 2, the adverse effects of DESdP therapy on the serum levels of anticoagulant factors were examined in 8 patients with advanced prostate cancer. In study 1, the ATIII and PS levels of the patients treated with estrogen therapy were significantly lower than those in either the untreated patients or the patients treated with an LHRH agonist alone. Especially, both PS antigen (51.5 +/- 16.0%) and PS activity (42.9 +/- 16.0%) were markedly lower in estrogen-treated patients than in the untreated patients (102 +/- 20.8%, 100.6 +/- 20.7%, respectively) or the patients treated with an LH-RH agonist alone (97.9 +/- 16.8%, 91.5 +/- 17.7%, respectively, both p < 0.0001). PS was decreased to below the normal lower limit of normal in 82% (24/35) of the patients on estrogen therapy. In study 2, all 8 cases showed a significant decrease in PS after DESdP therapy. Our results showed that the PS levels in the oral DESdP group were almost the same as in patients with congenital PS deficiency. We conclude that decreased PS may play a role in the development of cardiovascular complications in prostate cancer patients on estrogen therapy.

Resistance to activated protein c: Evaluation of three functional assays

Resistance to Activated Protein C (APC) was evaluated using 3 different methods: two of them were based on the prolongation of the Activated Partial Thromboplastin Time (APTT) using 2 different APTT reagents in the presence of APC, whereas the third method was based on the prolongation of prothrombin time when APC is added. The three methods were significantly correlated. APTT-based assays were sensitive to factor XII deficiency, whereas thromboplastin-based assay was sensitive to factor VII deficiency (< 0.5 UI/ml), which surestimates the response to APC. In contrast, an increase in factor VIII (F. VIII) level is associated with a decreased response to APC, when APTT-based assays are used, whereas thromboplastin-based assay is unmodified. During pregnancy, a decreased response to APC is observed, which is not only due to the increase in F. VIII, since thromboplastin-based assay is also modified. In Protein S (PS) immuno-depleted plasma, the low response to APC is corrected by addition of free PS: the thromboplastin-based assay was the most sensitive one to PS deficiency. However, in patients with congenital PS deficiency, there was no correlation between APC-resistance and free PS level. In patients with lupus anticoagulant, discrepancies were observed between the 3 methods, but with a high frequency of low response to APC. For the 3 assays, there was a good differentiation and correlation between normal and pathological results, the thromboplastin-based assay being perharps the most discriminating. However, 3 unrelated thrombophilic patients showed normal results using thromboplastin-based assay, although they were APC-resistant using APTT-based assays. For 2 patients, this discrepancy can be explained by high levels of F. VIII. For the last patient, an abnormal F. VIII, resistant to APC can be suspected.

Combined inherited protein s and heparin co-factor II deficiency in a patient with upper limb thrombosis: A family study

A 42-year-old Italian woman presenting with spontaneous deep vein thrombosis of the right arm, was found to have inherited a deficiency of both protein S (PS) and heparin co-factor II (HC II). The two defects seemed to segregate independently, since her son exhibited only a HC II deficiency while one of her sisters manifested only the PS defect. All affected patients appeared heterozygous for one or other or both deficiency states. The proposita and her sister exhibited a congenital PS deficiency consisting of normal or near normal levels of total PS antigen and C4b-binding protein (C4b-BP) but a moderate reduction both of free PS antigen and of PS functional activity. In addition, the proposita and her son had half normal levels of HC II antigen and activity. Except for the proposita,all were asymptomatic. Inherited deficiencies either of PS or of HC II have been associated with thrombotic manifestations. Since the proposita had an inherited combined defect of the two proteins,severe thrombotic events might be expected. However, this was not found to be the case. The role of HC II deficiency in the pathogenesis of thrombosis whether alone or combined remains to be fully investigated.

Protein-S, a vitamin K-dependent protein, is a bone matrix component synthesized and secreted by osteoblasts.

Protein-S is a vitamin K (Vit K)-dependent protein synthesized by hepatocytes, megakaryocytes, and endothelial cells and plays an important role in the regulation of hemostasis. Two cases of free protein-S congenital deficiency were recently reported to be associated with osteopenia. We hypothesized that this osteopenia could be the result of a bone deficit of protein-S synthesized by bone cells. Using enzyme-linked immunoassay, immunocytochemistry, immunoblotting, and immunoprecipitation after labeling with [35S]methionine, we have shown that this protein is secreted by three human osteosarcoma cell lines and by human adult osteoblast-like cells. In addition, protein-S was present in protein extracts of human bone matrix. Protein-S secreted by MG 63 cells increased linearly from 1-7 days of culture, was biologically active, and was regulated by warfarin, as previously described for the other cell types secreting protein-S. Vit K had no direct effect on protein-S secretion or activity, but could overcome the effects of warfarin. In conclusion, in addition to osteocalcin and matrix gamma-carboxyglutamic acid (Gla) protein, osteoblasts secrete another Vit K-dependent protein, which is a constituent of the bone matrix. Our data suggest that osteopenia occurring in patients with congenital protein-S deficiency might be related to a deficiency of protein-S secretion by the osteoblasts. This finding raises the intriguing possibility that protein-S might play a role in bone turnover and bone mass.