A novel mutation in protein C gene (PROC) causing severe phenotype in neonatal period

Compound heterozygous protein C deficiency with pulmonary embolism caused by a novel PROC gene mutation: Case report and literature review

RATIONALE

Protein C is an anticoagulation agent, and protein C deficiency results in vascular thrombosis disease. Hereditary protein C deficiency is a risk factor for pulmonary embolism in adults. Pathogenic variants of the Protein C, Inactivator Of Coagulation Factors Va And VIIIa (PROC) gene which encodes protein C have been identified as a cause of protein C deficiency.

PATIENT CONCERNS

We describe a patient with a novel mutation in the PROC gene who was diagnosed with pulmonary embolism in a Chinese family.

DIAGNOSIS

According to the results of the pulmonary computed tomography angiography (CTA) and the level of blood protein C, the patient was diagnosed with pulmonary embolism caused by protein C deficiency.

INTERVENTIONS

Whole-exome sequencing (WES) was performed for the molecular analysis.

OUTCOME

The results of patient's deoxyribonucleic acid revealed a heterozygous mutation (c.237 + 5G > A) in intron 3 of the PROC gene. His father also harbored the same mutation in the PROC gene. We also reviewed the protein C deficiencies caused by PROC gene mutations in cases.

LESSONS

A novel mutation in intron 3 of PROC gene has not been previously reported in patients with pulmonary embolism caused by protein C deficiency. After anticoagulation therapy, the patient recovered, and CT showed resolution of the thrombosis. Pulmonary embolism may be caused by protein C deficiency and the rare compound heterozygous mutation in intron 3 of the PROC gene could cause protein C deficiency via impairment of the secretory activity of protein C.

Genetics of Spontaneous Intracerebral Hemorrhage: Risk and Outcome

Spontaneous intracerebral hemorrhage (ICH) is a common fatal event without an effective therapy. Of note, some familial aggregation and inherited tendency is found in ICH and heritability estimates indicate that genetic variations contribute substantially to ICH risk and outcome. Thus, identification of genetic variants that affect the occurrence and outcome may be helpful for ICH prevention and therapy. There are several reviews summarizing numerous genetic variants associated with the occurrence of ICH before, but genetic variants contributing to location distribution and outcome have rarely been introduced. Here, we summarize the current knowledge of genetic variants and pay special attention to location distribution and outcome. So far, investigations have reveled variations in APOE, GPX1, CR1, ITGAV, PRKCH, and 12q21.1 are associated with lobar ICH (LICH), while ACE, COL4A2, 1q22, TIMP1, TIMP2, MMP2, MMP9, and TNF are associated with deep ICH (DICH). Moreover, variations in APOE, VWF, 17p12, HP, CFH, IL6ST, and COL4A1 are possible genetic contributors to ICH outcome. Furthermore, the prospects for ICH related genetic studies from the bench to the bed were discussed.

Genotypic and phenotypic character of Chinese neonates with congenital protein C deficiency: a case report and literature review

Background

Our objective was to study the phenotype of and molecular genetic mechanisms underlying congenital protein C (PC) deficiency in Chinese neonates. We report the case of a neonate who presented 4 h after birth with purpura fulminans of the skin and thrombosis in the kidney. We also carried out a through literature review to study the genotype and phenotype, relevance, diagnosis, management, and prognosis of neonates with congenital PC deficiency in China.

Case presentation and literature review

Following a septic work-up and check of PC and protein S (PS) levels that showed PC deficiency, we investigated the patient’s and her parents’ genotypes. Our patient was found to have a plasma PC level of 0.8%. Molecular testing revealed a compound heterozygous mutation of the PROC gene: From the father, a c._262 G > T p. ASP88Tyr mutation in exon 4; from the mother, a C. 400 + 5G mutation in intron 5 that had been previously reported as likely pathogenic. Both parents were found to have heterozygous mutations for PC deficiency. In China, 5 other cases of congenital PC deficiency in the neonatal period were reported in the literature. In those cases, purpura fulminans and thrombosis were the main symptoms, and homozygous or compound heterozygous mutations of the PROC gene were identified.

Conclusion

Congenital PC deficiency should be ruled out for neonates presenting with purpura fulminans and thrombosis.

Activation-resistant homozygous protein C R229W mutation causing familial perinatal intracranial hemorrhage and delayed onset of thrombosis

INTRODUCTION

We describe a family with two first-degree cousins who presented with similar phenotypes characterized by neonatal intracranial hemorrhage and subsequent onset of thrombosis.

PATIENTS/METHODS

We enrolled the two affected patients, five unaffected family members and fifty-five normal controls. Clinical, laboratory, and radiological characteristics of patients were obtained. Exome sequencing was performed for the older affected child. PROC c.811 C>T was genotyped by PCR in patients, family members, and controls. Protein C amidolytic activity and antigen were measured using the STACHROM® protein C kit and ELISAs. To define functional abnormalities caused by the patients' mutation, recombinant wildtype protein C and its mutants R229W, R229Q and R229A were studied.

RESULTS

For the two cousins, protein C amidolytic activity was 61% and 59% and antigen was 57% and 73% (nl 70-140%), respectively. Exome sequencing revealed a homozygous variant in exon 9 of the protein C (PROC) gene c.811 C>T (R229W). The R229W mutation is located in the calcium binding loop of protein C's protease domain that mediates thrombomodulin interactions. Recombinant R229W-protein C mutant was strikingly defective in rate of activation by thrombin: thrombomodulin, suggesting an in vivo deficit in these children for generation of activated protein C.

CONCLUSIONS

These cases emphasize that protein C and activated protein C are important in maintaining the integrity of the brain vascular endothelium in humans. Moreover, routine protein C assays utilizing snake venom protease fail to detect protein C mutants that are resistant to thrombin:thrombomodulin activation.

Compound heterozygous protein C deficiency in a family with venous thrombosis: Identification and in vitro study of p.Asp297His and p.Val420Leu mutations

Hereditary protein C deficiency (PCD) is an autosomal inherited disorder associated with high risk for venous thromboembolism (VTE). This study aimed to explore the functional consequences of two missense mutations, p.Asp297His and p.Val420Ile, responsible for type I/II PCD and recurrent deep vein thrombosis (DVT) in a Chinese family. The plasma protein C activities (PC:A) of the proband and his sister were reduced to 4% and 5% of normal activity. However, protein C antigen (PC:Ag) concentrations were not equally decreased, with levels of 90.5% and 88.7%, respectively. Two missense mutations p.Asp297His and p.Val420Leu were identified in the protein C gene (PROC). The PC:A and PC:Ag levels in heterozygous state for p.Asp297His were 66% and 64.8%, whereas in heterozygous state for p.Val420Leu, these levels were 67% and 145%, respectively. Wild type (WT) and two mutant PROC cDNA expression plasmids were constructed and transfected into HEK 293T cells. Western blot analysis revealed that both p.Asp297His and p.Val420Leu showed a normal intracellular protein level. The extracellular protein level and specific activity of p.Asp297His were equally reduced to 37.7 ± 4.3% and 22.1 ± 2.5%, respectively. Mutant p.Val420Leu showed a relatively higher PC:Ag level and undetectable PC:A. Immunofluorescence staining revealed that WT and p.Val420Leu proteins were largely co-localized with both the protein disulfide isomerase (PDI) and cis-Golgi Marker (GM130), while the PC p.Asp297His mutant protein was mainly co-localized with PDI and much less co-localized with GM130. The thrombosis symptom in this family was associated with the two missense mutations in the PROC gene.