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Homozygous protein C deficiency with moderately severe clinical symptoms
Insights
Severe protein C deficiency, even at 5% activity, may not cause life-threatening neonatal symptoms. This finding is crucial for understanding thrombotic risk in inherited protein C deficiency.
Area of Science:
- Genetics
- Hematology
- Molecular Biology
Background:
- Protein C deficiency is an inherited thrombophilia associated with an increased risk of venous thromboembolism.
- Severe deficiency, particularly homozygous forms, is often linked to severe neonatal thrombotic events.
Observation:
- A large family study identified two individuals with homozygous protein C deficiency (5% and 9% activity).
- Thirteen heterozygotes exhibited partial deficiency (36-66% activity) with low protein C antigen levels.
- The homozygous individuals experienced recurrent deep-vein thromboses and pulmonary emboli but survived into adulthood (ages 26 and 37).
Findings:
- Homozygous protein C deficiency with activity levels as low as 5% did not result in fatal neonatal complications.
- Clinical presentation in homozygotes included recurrent thrombotic events, but survival to adulthood was achieved.
Implications:
- Protein C levels of 5% may be sufficient to prevent life-threatening neonatal thrombotic complications.
- This suggests a potential threshold for severe clinical manifestations in protein C deficiency.
- Further research into genotype-phenotype correlations in protein C deficiency is warranted.
Abstract:
We report a large family with two members homozygotes for protein C deficiency, with activity levels of 5% and 9%. Thirteen additional members were heterozygotes, with protein C activity ranging from 36-66% and equally low levels of protein C antigen. The homozygotes presented with recurrent deep-vein thromboses and pulmonary emboli, but have reached the ages of 26 and 37 years. Hence, protein C levels of 5% appear sufficient to avoid life-threatening clinical symptoms in the neonatal period.