[Gene diagnosis of four patients with protein C deficiency]

Objective: To investigate the molecular etiology of protein C (PC) deficiency. Methods: Routine diagnosis and genetic analysis were performed on four probands with PC deficiency. Results: ①Case 1, female, 40 years old, diagnosed of deep vein thrombosis in left lower limb. PC activity (PC∶C) was 48%, PS activity (PS∶C) was 26.3%, AT activity (AT∶C) was 75.6%. Genetic analysis discovered heterozygous mutation C5156T on promoter of PC gene, together with heterozygous mutation A6578T on Exon2 of PC gene. After anticoagulant, thrombolysis and filter implantation therapies, the patient went home with improvement. ②Case 2, female, 32 years old, diagnosed of deep vein thrombosis in both lower limb, ischemia in both lower and upper limb, and skin infection in both lower limb. PC∶C 27%, PS∶C 22.9%, AT∶C 86.7%. Genetic analysis identified heterozygous mutation C5156T, together with heterozygous mutation A5045T on promoter of PC gene. After anticoagulant and anti-infection therapy, the patient died of respiratory failure, septic shock and DIC. ③Case 3, female, 28 years old, diagnosed of vein thrombosis in right iliac and femoral vein. PC∶C 58%, PS∶C 57.3% , AT∶C 80.8%. Genetic analysis disclosed heterozygous mutation C4867T on promoter of PC gene, AGA 12702-12704del or 12705-12707del on Exon7, the latter one lead to Arg192 or 193del. Heterozygous mutation G15240A on Exon9 was also found. After anticoagulant, thrombolysis and filter implantation therapies, the patient went home with improvement. ④Case 4, male, 30 years old, diagnosed of vein thrombosis in right iliac and femoral vein. PC∶C 50%, PS∶C 75.0%, AT∶C 89.1%. Genetic analysis found homozygous mutation C4867T and G4880A on promoter of PC gene, heterozygous mutation A5045T on promoter and heterozygous mutation T6589C on Exon2. After anticoagulant, thrombolysis and filter implantation therapies, the patient went home with improvement. ⑤ Polymorphism analysis revealed that heterozygous mutation C4867T, homozygous mutation G4880A, and heterozygous mutation C5156T were polymorphism sites of PC gene. Conclusions: Polymorphism sites (G4880A, C4867T, C5156T), missense mutation A5045T, A6578T, G15240A, and deletion mutation AGA12702-12704del, 12705-12707del may be related to deficiency of PC. Missense mutation A5045T, A6578T, G15240A, and deletion mutation AGA12702-12704, 12705-12707del were first reported worldwide.