Two Novel Mutations Cause Hereditary Antithrombin Deficiency in a Chinese Family

Objective: To study the molecular basis of hereditary antithrombin (AT) deficiency in a Chinese family. It will help us understand the pathogenesis of this type of disease. Method: AT activity (AT:A) and the AT antigen (AT:Ag) level were tested by chromogenic substrate and immunoturbidimetry, respectively. To identify the novel mutations, SERPINC1 gene sequencing was carried out. The possible impact of the mutations was analyzed by model and bioinformatic analyses. Results: AT:A and the AT:Ag level of the proband were 43% and 113 mg/L (normal range: 98–119% and 250–360 mg/L), respectively. Sequencing analysis revealed compound heterozygous mutations, including a frameshift mutation (c.318_319insT) resulting in Asn75stop and a missense mutation (c.922G>T) resulting in Gly276Cys. The bioinformatic and model analyses indicated that these mutations may disrupt the function and structure of the AT protein. Conclusion: We detected 2 novel heterozygous mutations (c.318_319insT and c.922G>T) in the proband, and these were associated with decreased AT:A.