Survival in families with hereditary protein C deficiency, 1820 to 1993.

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.