title: Two novel compound heterozygous mutations associated with types I and II protein C deficiency with unusual phenotypes.
abstract: BACKGROUND
  We diagnosed two Chinese hereditary PC deficiency families and identified two novel compound heterozygous mutations (p.Arg194Cys/Gly324Ser and p.Glu274X/Asp297His) in the protein C (PROC) gene. The probands were classified as types I and II PC deficiency. The aim of this article is to access the influence of the mutations on PC activity, antigen and protein structure, and to evaluate whether there is abnormal PC localization.
  
  
  METHODS
  Genomic DNA of all family members was extracted, PCR amplified, and sequenced. The mutant PC expression plasmids were constructed. Expression assays, intracellular localization, and molecular modeling were performed.
  
  
  RESULTS
  Proband 1, a type II PC defect, harbored a compound heterozygous mutation, p.Arg194Cys/Gly324Ser in the PROC gene, underwent two thromboembolic events. Expression assays indicated that the p.Arg194Cys mutant lead to decreased PC activity and normal PC Ag levels. Intracellular localization showed that both p.Arg194Cys and p.Gly324Ser co-localized with the endoplasmic reticuli and the Golgi apparatus. Molecular modeling suggested that the p.Gly324Ser mutation disturbed the interaction between the heavy and light chains of the PC protein. Proband 2, a type I PC defect, harbored a compound heterozygous PROC gene mutation, p.Glu274X/Asp297His, presented with recurrent spontaneous abortion and right popliteal vein thrombosis. Expression results were in accordance with the PC changes of the patient, and existed in defective PC transport. Structural model suggested p.Glu274X lead to disulfide bond between heavy and light chain cannot form.
  
  
  CONCLUSIONS
  Our results confirm that two novel compound heterozygous PROC gene mutations are causative on the two PC deficiency families.
authors: Division of Hematology, Institute of Molecular Hematology, the Second Xiang-Ya Hospital, Central South University, Changsha, Hunan 410011, PR China.
authors: Ming-Yang
authors: MY
authors: Deng
authors: Division of Hematology, Institute of Molecular Hematology, the Second Xiang-Ya Hospital, Central South University, Changsha, Hunan 410011, PR China.
authors: Zi-Xian
authors: ZX
authors: Liu
authors: Division of Hematology, Institute of Molecular Hematology, the Second Xiang-Ya Hospital, Central South University, Changsha, Hunan 410011, PR China.
authors: Hai-Fan
authors: HF
authors: Huang
authors: Laboratory of Structural Biology, Key Laboratory of Cancer Proteomics of Chinese Ministry of Health, Xiang-Ya Hospital & State Key Laboratory of Medical Genetics, Central South University, Changsha, Hunan, PR China.
authors: Yong-Heng
authors: YH
authors: Chen
authors: Division of Hematology, Institute of Molecular Hematology, the Second Xiang-Ya Hospital, Central South University, Changsha, Hunan 410011, PR China.
authors: Yu-Jiao
authors: YJ
authors: Luo
authors: Division of Hematology, Institute of Molecular Hematology, the Second Xiang-Ya Hospital, Central South University, Changsha, Hunan 410011, PR China.
authors: Nan-Nan
authors: NN
authors: Sun
authors: Division of Hematology, Institute of Molecular Hematology, the Second Xiang-Ya Hospital, Central South University, Changsha, Hunan 410011, PR China.
authors: Zhao
authors: Z
authors: Cheng
authors: Division of Hematology, Institute of Molecular Hematology, the Second Xiang-Ya Hospital, Central South University, Changsha, Hunan 410011, PR China.
authors: Wen-Zhe
authors: WZ
authors: Yan
authors: Division of Hematology, Institute of Molecular Hematology, the Second Xiang-Ya Hospital, Central South University, Changsha, Hunan 410011, PR China. Electronic address: zgsllzy@163.com.
authors: Guang-Sen
authors: GS
authors: Zhang
mesh_terms: D000328:Adult; D006801:Humans; D008297:Male; D008958:Models, Molecular; D009154:Mutation; D010641:Phenotype; D011486:Protein C / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism; D020151:Protein C Deficiency / Q000235:genetics*
chemical_list: D011486:Protein C
keywords: Compound heterozygous mutations; Deep venous thrombosis; Hereditary PC deficiency; Molecular modeling; Mutant PC localization