Two heterozygous mutations associated with type I protein C deficiency in two Chinese independent families

SummaryThe frequency of heterozygous protein C and protein S deficiency, detected by measuring total plasma antigen, in a group (n = 141) of young unrelated patients (<45 years old) with venous thrombotic disease was studied and compared to that of antithrombin III, fibrinogen, and plasminogen deficiencies. Among 91 patients not receiving oral anticoagulants, six had low protein S antigen levels and one had a low protein C antigen level. Among 50 patients receiving oral anticoagulant therapy, abnormally low ratios of protein S or C to other vitamin K-dependent factors were presented by one patient for protein S and five for protein C. Thus, heterozygous Type I protein S deficiency appeared in seven of 141 patients (5%) and heterozygous Type I protein C deficiency in six of 141 patients (4%). Eleven of thirteen deficient patients had recurrent venous thrombosis. In this group of 141 patients, 1% had an identifiable fibrinogen abnormality, 2% a plasminogen abnormality, and 3% an antithrombin III deficiency. Thus, among the known plasma protein deficiencies associated with venous thrombosis, protein S and protein C. deficiencies (9%) emerge as the leading identifiable associated abnormalities.

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Application of Two Neutral Mspl DNA Polymorphisms in the Analysis of Hereditary Protein C Deficiency

Thrombosis and Haemostasis ◽

10.1055/s-0038-1647293 ◽

1990 ◽

Vol 64 (02) ◽

pp. 239-244 ◽

Cited By ~ 8

Author(s):

P H Reitsma ◽

W te Lintel Hekkert ◽

E Koenhen ◽

P A van der Velden ◽

C F Allaart ◽

...

Keyword(s):

Protein C ◽

Stop Codon ◽

Normal Population ◽

Amino Acid Position ◽

Rare Allele ◽

Dna Polymorphisms ◽

Type I ◽

Protein C Deficiency ◽

Gene Deletions ◽

Allelic Frequencies

SummaryScreening of restriction erzyme digested DNA from normal and protein C deficient individuals with a variety of probes derived from the protein C locus has revealed the existence of two neutral MspI polymorphism. One polymorphism (MI), which is located ≈7 kb upstream of the protein C gene, has allelic frequencies of 69 and 31%, and was used to exclude extensive gene deletions as a likely cause of type I protein C deficiency in 50% of cases in a panel of 22 families. Furtherrnore, the same polymorphism has been used in 5 doubly affected individuals establishing compound heterozygosity in 3 of these.The second, intragenic, polymorphism (MII) has allelic frequencies of 99 and 1% in the normal population. The frequency of the rare allele of this RFLP was with 7% much higher in a panel of 22 Dutch families with protein C deficiency. Interestingly, in all three probands that were heterozygous for MII the rare allele of MII coincided with a point mutation that leads to a stop codon in amino acid position 306 of the protein C coding sequence. This mutation may account for 14% of the protein C deficient individuals in The Netherlands.

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Ectopic Transcript Analysis Indicates that Allelic Exclusion is an Important Cause of Type I Protein C Deficiency in Patients with Nonsense and Frameshift Mutations in the PROC Gene

Thrombosis and Haemostasis ◽

10.1055/s-0038-1650386 ◽

1996 ◽

Vol 75 (06) ◽

pp. 870-876 ◽

Cited By ~ 4

Author(s):

José Manuel Soria ◽

Lutz-Peter Berg ◽

Jordi Fontcuberta ◽

Vijay V Kakkar ◽

Xavier Estivill ◽

...

Keyword(s):

Splice Site ◽

Protein C ◽

Stop Codon ◽

Premature Stop Codon ◽

Allelic Exclusion ◽

Polymorphism Analysis ◽

Type I ◽

Protein C Deficiency ◽

Nonsense Mutations ◽

Stop Codons

SummaryNonsense mutations, deletions and splice site mutations are a common cause of type I protein C deficiency. Either directly or indirectly by altering the reading frame, these' lesions generate or may generate premature stop codons and could therefore be expected to result in premature termination of translation. In this study, the possibility that such mutations could instead exert their pathological effects at an earlier stage in the expression pathway, through “allelic exclusion” at the RNA level, was investigated. Protein C (PROC) mRNA was analysed in seven Spanish type I protein C deficient patients heterozygous for two nonsense mutations, a 7bp deletion, a 2bp insertion and three splice site mutations. Ectopic RNA transcripts from patient and control lymphocytes were analysed by RT-PCR and direct sequencing of amplified PROC cDNA fragments. The nonsense mutations and the deletion were absent from the cDNAs indicating that only mRNA derived from the normal allele had been expressed. Similarly for the splice site mutations, only normal PROC cDNAs were obtained. In one case, exclusion of the mutated allele could be confirmed by polymorphism analysis. In contrast to these six mutations, the 2 bp insertion was not associated with loss of mRNA from the mutated allele. In this case, cDNA analysis revealed the absence of 19 bases from the PROC mRNA consistent with the generation and utilization of a cryptic splice site 3’ to the site of mutation, which would result in a frameshift and a premature stop codon. It is concluded that allelic exclusion is a common causative mechanism in those cases of type I protein C deficiency which result from mutations that introduce premature stop codons

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Two Mutations in the Promoter Region of the Human Protein C Gene Both Cause Type I Protein C Deficiency by Disruption of Two HNF-3 Binding Sites

Journal of Biological Chemistry ◽

10.1074/jbc.270.41.24216 ◽

1995 ◽

Vol 270 (41) ◽

pp. 24216-24221 ◽

Cited By ~ 30

Author(s):

C. Arnold Spek ◽

Judith S. Greengard ◽

John H. Griffin ◽

Rogier M. Bertina ◽

Pieter H. Reitsma

Keyword(s):

Binding Sites ◽

Promoter Region ◽

Protein C ◽

Human Protein ◽

Type I ◽

Protein C Deficiency

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Protein C deficiency resulting from possible double heterozygosity and its response to danazol

Blood ◽

10.1182/blood.v71.2.370.bloodjournal712370 ◽

1988 ◽

Vol 71 (2) ◽

pp. 370-374

Author(s):

RA Gruppo ◽

P Leimer ◽

RB Francis ◽

RA Marlar ◽

E Silberstein

Keyword(s):

Functional Activity ◽

Protein C ◽

Anticoagulant Activity ◽

Anticoagulation Therapy ◽

Renal Vein Thrombosis ◽

Type I ◽

Amidolytic Activity ◽

Protein C Deficiency ◽

Protein Levels ◽

Anticoagulant Function

A unique family with protein C (PC) deficiency is described. The proband had a history of renal vein thrombosis as a newborn and iliofemoral thrombosis at the age of 6 years. After 6 months of heparin treatment, discontinuation of anticoagulation therapy was accompanied by persistent hypofibrinogenemia with increased fibrinogen consumption. With continuous infusion of heparin, fibrinogen turnover normalized, and the child has remained free of thrombosis. Both the immunologic level of PC and the functional activity measured by amidolytic assay were moderately reduced (47% and 34%, respectively). Functional activity of PC measured by its anticoagulant activity was disproportionately lower (14%). A 3-year-old asymptomatic sibling had a similar disproportionate reduction of PC anticoagulant activity compared with the amidolytic activity or immunologic level. The mother demonstrated type I PC deficiency with a proportionate reduction in immunologic protein levels (59%), anticoagulant activity (52%), and amidolytic activity (46%), whereas the father had type II PC deficiency with normal immunologic protein levels (102%), normal amidolytic function (98%), but a low anticoagulant function (50%). An abnormal PC molecule was detected by two-dimensional immunoelectrophoresis in the father and two children. These data are consistent with the hypothesis that the children are doubly heterozygous for two different types of PC deficiency inherited from each of the parents. A 14-day trial of danazol in the proband resulted in a rise in the PC antigen concentration from 66% to 98% but no change in PC anticoagulant function.

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THROMBOPHILIA:ITS CAUSES AND A ROUGH ESTIMATE OF ITS PREVALENCE

10.1055/s-0038-1642945 ◽

1987 ◽

Author(s):

E Briët ◽

L Engesser ◽

E J P Brommer ◽

A W Broekmans ◽

R M Bertina

Keyword(s):

Plasminogen Activator ◽

Protein C ◽

Antithrombin Iii ◽

Plasminogen Activator Inhibitor ◽

Protein S ◽

Factor Vii ◽

Type I ◽

Factor V ◽

Protein C Deficiency ◽

Familial Cases

Idiopathic venous thrombosis and embolism have gained widespread interest since the discovery that, deficiencies of antithrombin III, protein C, and protein S are associated with familial venous thrombophilia. The purpose of our study was to obtain an estimate of the prevalence of this syndrome and to establish the etiology in as many cases as possible.We collaborated with specialists from 37 Dutch hospitals, covering about 10% of the Dutch population. A history as well as blood samples were obtained from 113 unrelated cases with familial thrombophilia and from 90 isolated cases. Assuming that each proband in a family with thrombophilia has an average of four affected relatives, a rough estimate of the prevalence of familial thrombophilia in The Netherlands is 40 cases per 100.000. The prevalence of non-familial thrombophilia is probably lower.In 35 out of the 113 familial cases we established a diagnosis of hereditary antithrombin III deficiency (n=5), protein C deficiency (type I: n=9; type II: n=4), protein S deficiency (n=15) and dysfibrinogenemia (n=2). In 36 cases we found no abnormality at all and in the remaining 42 cases abnormalities were found in one or more of the following: heparin cofactor II, factor V, factor VII, factor VIII, von Willebrand factor, plasminogen, tissue plasminogen activator, plasminogen activator inhibitor, alpha 2 antiplasmin and histidine rich glycoprotein. In most of these cases, however, the hereditary nature of the abnormalities could not be demonstrated and the causal relationships remain to be established.In the 90 isolated cases, we diagnosed hereditary deficiencies of anti thrombin III, protein C and protein S each in one case and a lupus anticoagulant in two cases. In 54 cases no abnormality was found and in the remaining 31 cases various abnormalities were found in one or more of the proteins mentioned above.We conclude that the syndrome of thrombophilia is not rare but its true prevalence needs to be established by more rigorous means. An etiological diagnosis can be made with confidence in only one third of the familial cases and in less than 10 percent of the isolated cases.

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