[Hereditary protein S deficiency: survey results from a Chinese pedigree].

Objective: To investigate the clinical characteristics and gene mutation, and analyze the association between genotype and phenotype of hereditary protein S deficiency in a Chinese pedigree. Methods: Hereditary protein S deficiency was diagnosed in January 2016 in our hospital. A total of 26 family members were surveyed in this study. Blood samples and clinical data were collected from them, and mutations were identified by Sanger sequencing. Pathogenicity of gene mutations was predicted by protein function prediction software including SIFT, PolyPhen_2, nsSNPAnalyzer and MutPred2. Swiss Model (https://swissmodel.expasy.org/) was used to perform homology modeling of the tertiary structure of the protein S wild-type and mutant-type, and observe the impact of gene mutation on the tertiary structure of the protein. Results: Four out of 26 family members of 4 generations were clinically diagnosed with hereditary protein S deficiency. The proband presented with recurrent pulmonary embolism and venous thromboembolism of the lower extremities, and her uncle and mother had a history of venous thromboembolism. Sequencing revealed a mutation in the c.200A>C gene in the second exon of the PROS1 gene of proband and part of her families (Ⅱ2, Ⅱ6, Ⅲ4, Ⅳ2). The prediction results of this gene mutation performed by SIFT, PolyPhen_2, nsSNPAnalyzer, MutPred2 were all harmful. The results of Swiss-Model homology modeling showed that the 67th amino acid was mutated from glutamic acid to alanine because of this gene mutation. Conclusion: A gene mutation cDNA (c. 200A>T) is identified in a Chinese pedigree with hereditary protein S deficiency. This gene mutation may reduce protein S activity, which may cause recurrent pulmonary embolism and venous thromboembolism of the patients.