RESUMO
<p><b>OBJECTIVE</b>To study the phenotypes and genotypes of a protein C (PC) deficiency pedigree.</p><p><b>METHODS</b>Immunoassay (ELISA) was used for PC antigen and activated PC (APC) detection, PCR for amplification of the fragment of protein C gene exon II to exon IX, single-strand conformation polymorphism (SSCP) for difference of denatured cDNA and DNA sequencing for gene mutation.</p><p><b>RESULTS</b>Four members in the pedigree were found to be PC antigen levels between 34.3% - 67.8% and PC activity between 22% - 49% which are lower in comparison with normal references (80% - 120% and 70% - 130%, respectively). A G-to-A mutation in exon VII of the protein C gene at 6 219 position was identified in 9 members. This mutation resulted in the substitution of Arg for Gln at 169 amino acid.</p><p><b>CONCLUSION</b>The proband is of heterozygosity. The G6219 A mutation in exon VII of the protein C gene leads to the substitution of Arg 169 Gln. This mutation is reported for the first time in China.</p>