[A novel gene mutation in a congenital protein S deficiency pedigree]

To study the phenotype and genotype of a protein S (PS) deficiency pedigree.

Detection of total and free PS antigen was carried out by ELISA, PS activity by coagulation assay, amplification of exon I-XII fragments of PS gene by polymerase chain reaction (PCR), changes of denaturing cDNA by single-strand conformation polymorphism (SSCP) and gene mutation by DNA sequencing.

In the 9 members of the pedigree, free PS was between 10.3%-45.5% (normal range 55%-128%) and PS activity between 13%-37% (normal range 70%-130%), but total PS was normal. A G to T change in exon X of the protein S gene was identified. This mutation resulted in a substitution of stop codon for Ser.

It was demonstrated that the proband is heterozygosity and the existance of G163 T change in exon X of the protein S gene led to a substitution of stop codon for Ser. This mutation is a novel undescribed mutation.