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Survival in families with hereditary protein C deficiency, 1820 to 1993
C F Allaart1, F R Rosendaal, W M Noteboom
1Department of Haematology, University Hospital, RC Leiden, Netherlands.
Objectives:
To establish the survival of individuals heterozygous for hereditary protein C deficiency, who have an increased risk of venous thrombotic events, and to compare it with the survival of the general population.
Design:
Retrospective study in pedigrees of 23 families with hereditary protein C deficiency for period 1820 and 1993.
Setting:
23 completed family trees of 24 probands from various parts of the Netherlands with symptoms of protein C deficiency.
Subjects:
All 736 members of the 23 families with a 50% or 100% probability of being (or having been) heterozygous for the genetic defect on the basis of DNA analysis or their place in the pedigrees, following mendelian rules.
Main Outcome Measures:
Observed mortality compared with the mortality of the general Dutch population; the standardised mortality ratio was calculated by dividing the observed mortality by the expected mortality.
Results:
No excess mortality was found in the 206 proved heterozygous individuals and "obligatory transmitters" (those who have definitely passed on the deficiency) (standardised mortality ratio 0.95 (95% confidence interval 0.5 to 1.2)) or in the 530 family members with a 50% genetic probability of heterozygosity (1.10 (0.9 to 1.3)).
Conclusion:
Heterozygous individuals with hereditary protein C deficiency type I have normal survival compared with the general population. Prophylactic anticoagulant treatment may prevent thrombotic events in heterozygous individuals but may not be expected to improve their survival.