Hereditary thrombophilia: identification of nonsense and missense mutations in the protein C gene.
The structure of the gene for protein C, an anticoagulant serine protease, was analyzed in 29 unrelated patients with hereditary thrombophilia and protein C deficiency. Gene deletion(s) or gross rearrangement(s) was not demonstrable by Southern blot hybridization to cDNA probes. However, two unrelated patients showed a variant restriction pattern after Pvu II or BamHI digestion, due to mutations in the last exon: analysis of their pedigrees, including three or seven heterozygotes, respectively, with approximately 50% reduction of both enzymatic and antigen level, showed the abnormal restriction pattern in all heterozygous individuals, but not in normal relatives. Cloning of protein C gene and sequencing of the last exon allowed us to identify a nonsense and a missense mutation, respectively. In the first case, codon 306 (CGA, arginine) is mutated to an inframe stop codon, thus generating a new Pvu II recognition site. In the second case, a missense mutation in the BamHI palindrome (GGATCC----GCATCC) leads to substitution of a key amino acid (a tryptophan to cysteine substitution at position 402), invariantly conserved in eukaryotic serine proteases. These point mutations may explain the protein C-deficiency phenotype of heterozygotes in the two pedigrees.
D000595:Amino Acid Sequence; D005091:Exons; D005796:Genes; D006801:Humans; D007438:Introns; D009154:Mutation; D011486:Protein C / Q000235:genetics*; D020151:Protein C Deficiency; D012313:RNA / Q000235:genetics*; D016372:RNA, Antisense; D012016:Reference Values; D013924:Thrombophlebitis / Q000097:blood / Q000235:genetics*
D011486:Protein C; D016372:RNA, Antisense; D012313:RNA