[Recurrent deep vein thrombosis caused by heterozygous missense mutation of the protein S gene: genetic analysis of a case].

OBJECTIVE: To analyze the molecular pathogenesis of protein S deficiency in an adolescent case of recurrent deep vein thrombosis (DVT). METHODS: Blood samples from the patient and his family members were collected for detection of the coagulation parameters by one-step clotting method, and the protein S (PS) and protein C activities were measured by a chromogenic assay. Enzyme-linked immunosorbent assay was employed for detecting the levels of free PS antigen. All the exons and exon-intron boundaries of the patients PS gene were amplified using PCR and analyzed by direct sequencing. RESULTS: As carriers of hereditary PS deficiency, both the patient and his father showed a heterozygous C82792T point mutation in the 10th exon of their PS gene which resulted in the substitution of arginine314 by cysteine in the polypeptide chain of PS protein. CONCLUSION: Recurrence of DVT in this patient is the result of hereditary PS deficiency caused by a novel heterozygous missense mutation in the PS gene.