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Six missense mutations associated with type I and type II protein C deficiency and implications obtained from
Y Z Zheng1, T Sakata, T Matsusue
1Laboratory of Thrombosis Research, National Cardiovascular Center Research Institute, Suita, Japan.
Insights
Genetic mutations causing protein C deficiency were identified in patients with thrombotic complications. Six missense mutations, including three novel ones, were found in the protein C gene, impacting protein structure and function.
Area of Science:
- Genetics
- Molecular Biology
- Biochemistry
Background:
- Protein C deficiency is a genetic disorder predisposing individuals to thrombotic events.
- Understanding the molecular basis of protein C deficiency is crucial for diagnosis and treatment.
Observation:
- Six missense mutations in the protein C gene were identified in patients with protein C deficiency.
- Three of these mutations were novel, and four occurred at CG dinucleotides.
- Structural modeling suggested conformational changes in activated protein C due to these mutations.
Findings:
- Identified six missense mutations, three novel, in protein C gene exons II and IX.
- Demonstrated co-segregation of mutations with protein C deficiency in families.
- Confirmed association of mutations with deficiency by absence in healthy controls.
Implications:
- These findings contribute to understanding the genetic heterogeneity of protein C deficiency.
- The identified mutations provide insights into structure-function relationships of protein C.
- This research may aid in the genetic diagnosis and risk assessment for thrombotic disorders.
Abstract:
The molecular basis of protein C deficiency was studied in three type I and three type II heterozygotes. Three probands showed thrombotic complications. All the exons and intron/exon junctions of the protein C gene were studied using a strategy combining by the polymerase chain reaction (PCR) amplification, single-strand conformational polymorphism (SSCP) analysis, and DNA sequencing of the PCR-amplified fragments. Six missense mutations were identified, including three novel ones. One was located in exon II, in which the initiating translation codon (ATG) encoding for Met at position -42 was replaced by ACG encoding for Thr. The other five were located in exon IX, and included TAC(Tyr399)-->CAC(His), CCG(Pro327)-->CTG(Leu), GAC(Asp359)-->AAC(Asn) in two cases, and GGG(Gly350)-->AGG(Arg). Four of the six missense mutations occurred in CG dinucleotide. Sequence analysis of the other exons excluded additional mutations. By restriction enzyme analysis, co-segregation of the mutation with protein C deficiency was observed in four families. The other two mutations at amino acid positions -42 and 350 were also considered to be associated with protein C deficiency due to the absence of these mutations in 50 normal individuals. A structural model of the protease domain of mutant activated protein C was constructed by the chimeric modelling method, and the resultant model suggested conformational changes due to each missense mutation identified in protein C deficiency. The present data also provide some evidence regarding the genetic heterogeneity of protein C deficiency.