Congenital antithrombin Ⅲ deficiency in a korean family

Abstract

Molecular biological techniques were utilized to examine antithrombin III (ATIII) gene status in a Korean family with hereditary ATIII deficiency. The propositus, a 25-year-old male, has been suffered from recurrent deep vein thrombosis. The ATIII activity in the plasma was about half of the normal level. A portion of the family members also has a history of thrombosis. Seven exons of ATIII gene from the patient and from his parents were enzymativally amplified and sequenced. A T to C point mutation (Phe$^{368}$ $\rightarrow$ Ser) was detected in the propositus and the mother, and the thrombophilic tendency was coincided with this base substitution. As observed from the amino acid sequence data on related serine proteinase inhibitor family, the hydrophobic residue, Phe, in position$^{368}$ and the neighboring His$^{369}$ residue which makes hydrogen bonds with main chians were also conserved in the native ATIII. It was thus evident that Phe $\rightarrow$ Ser change in the center of strand which comprises a $\beta$-pleated sheet would sistort the structure of the sheet, and the conformation of the active site located in the adjacent strand would be affected by this mutation.