RESUMEN
Objective To investigate the phenotypes and genotypes of a hereditary protein C(PC) deficiency pedigree.Methods Imrnunoassay(ELISA)was used for PC antigen and PS antigen; Immunoturbidimetry assay was used for measuring AT antigen;Chromogenic substrate assay was used for measuring the activity of PC,PS and AT in Sysmex 1500 automatic Blood Coagulation Analyzer.Polymerase chain reaction(PCR)for amplification of the fragment of each exon and side sequences of PC gene in 10 members of the 3 generations;Direct DNA sequencing was used to examine the mutation site.Results Among 10 members of the 3 generation pedigree,8 of them had a PC:Ag level of 1.06-1.92 mg/L(normal references 3.00-6.00 rag/L),the activity of PC was between 41% and 67%(normal references 70%- 140%),which was significantly lower than the normal references while the levels of PS:Ag,PS:A,AT:Ag and AT:A were all within normal range.DNA sequencing analysis showed that there was a G to T mutation in exon IX of the PC gene at 12 918 position in 8 members.This mutation resulted in the substitution of terminator TGA for TGG which encoding tryptophan at 372 amino acid.There was a polymorphism in 2 405C/ T,2 418A/G,2 583A/T in the promotor area.Conclusions This pedigree is a type I hereditary protein C deficiency.There is a G12 918T mutation in exon IX of PC gene.This mutation is reported for the first time and there is a polymorphism in 2 405C/T,2 418A/G,2 583A/T in the promotor area.