Molecular Diagnosis of One Pedigree with Protein S Deficiency and Antithrombin Deficiency

To identify gene mutations for one patient and his family members with protein S and antithrombin deficiency.

ELISA were used to detect protein S (PS), protein C (PC) and antithrombin (AT) activities for the proband and family members, respectively. The genomic DNA was extracted from the peripheral blood of proband and family members. All exons and their flanks of protein S gene and antithrombin gene were amplified by polymerase chain reaction (PCR). The PCR products were sequenced directly. The mutation-related exons of his famliy members were amplified by PCR and sequenced directly.

The proband was a 49-year-old male. He presented with sudden left lower extremity swelling and pain without casues. Regular examination revealed that his APTT, PT, and TT were all in normal levels, but D- dimmer was 5. 62mg/L, Color doppler ultrasonography showed thrombosis in his left femoral vein. The activity of PS for his family members was ‡₁ 0%, ‡₂ 0%, ‡₃ 0%, ‡₄ 130. 8%, ‡₅ 8. 4%, ‡₁ 0%, ‡₂ 0%, and that of AT was ‡₁ 129. 1%, ‡₂ 51. 9%, ‡₃ 73.2%, ‡₄ 119. 1%, ‡₅ 136. 2%, ‡₁ 65. 5% and ‡₂ 60. 1%, respectively. The sequencing analysis showed that a heterozygous missense mutation G68395T (NG_009813. 1) was detected in Exon 4 of PS gene leading to the substitution of Arg90 by Leu (NP_000304. 2) for the propositus. The heterozygous mutation (Arg90Leu) was also found in other family members. A heterozygous (nonsense) mutation G12444A (NG_012462. 1) was detected in Exon 4 of AT gene leading to Trp257Ter (NP_000479. 1) for the propositus. The mutation (Trp257Ter) was found in other family members with reduced activity of AT. These two mutations (G68395T in PS gene and G12444A in AT gene) were not reported before and were thus novel ones.

The novel mutation G68395T in PS gene and G12444A in AT gene might be the causes of deficiency of PS and AT for the family.

No relevant conflicts of interest to declare.