Abstract: Objective We commit phenotype diagnosis and gene diagnosis aiming directly at one case of hereditary antithrombin (AT) deficiency syndrome of proband and their family phenotype, and explore the pathogenesis of family members. Methods The activity of AT(AT:A) , protein S and protein C were detected by chromogenic substrate method, with immune turbidimetry on AT antigen (AT:Ag) detection, the molecules weight and content of AT were detected by Western bloting method, Genomic DNA was extracted from blood, the 7 exons of AT and flanking sequences were amplified by PCR, products of PCR of all family members were conducted by direct sequencing analysising and gene mutation detection, screening 100 cases of normal people to exclude the of polymorphism of gene mutation. Results The AT:A and AT:Ag of proband was 48% and 121mg/L respectively, the proband′sixth exon of AT gene is c.10381T del. Some members of the family were detected the same frameshift mutations. conclusion The pedigree and some members of the first symptoms were type Ⅰ hereditary antithrombin deficiency due to AT gene 10381T del frameshift mutations.

Key words: antithrombin , antithrombin deficiency , gene mutation , thrombophilia