A homozygous variant in a consanguineous pedigree with inherited protein S deficiency

Objective: To observe the clinical feature of familiar hereditary protein S deficiency, and to explore the related gene mutation. Methods: The blood samples were obtained from the proband and the family memebers(3 generations,6 persons). PROS1 gene of the proband and the family members was analyzed. The 15 exons and flanking sequence of PROS1 gene were analyzed by PCR and DNA sequencing. Results: Five out of 6 family members were diagnosed as having hereditary protein S deficiency. The proband suffered from pulmonary embolism. The others had no obvious thrombotic event. The gene sequencing revealed that the proband carried a c.-168C>T homozygous variant in the promoter of exon 1. His parents, brother and son all carried c.-168C>T heterozygosis variant at the same position. The gene of his wife was a wild type. Conclusion: A gene variant (c.-168C>T) of PROS1 was discovered in this Chinese family. Gene variant of PROS1 may result in protein S deficiency. Patients with protein S deficiency may suffer from vein thrombosis and(or) pulmonary embolism.