SURVIVAL IN FAMILIES WITH HEREDITARY PROTEIN-C DEFICIENCY, 1820 TO 1993

Objectives-To establish the survival of individuals heterozygous for h ereditary protein C deficiency, who have an increased risk of venous t hrombotic events, and to compare it with the survival of the general p opulation. 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 Nether lands 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 analysi s or their place in the pedigrees, following mendelian rules. Main out come measures-Observed mortality compared with the mortality of the ge neral Dutch population; the standardised mortality ratio was calculate d by dividing the observed mortality by the expected mortality. Result s-No excess mortality was found in the 206 proved heterozygous individ uals 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%, geneti c probability of heterozygosity (1.10 (0.9 to 1.3)). Conclusion-Hetero zygous individuals with hereditary protein C deficiency type I have no rmal survival compared with the general population. Prophylactic antic oagulant treatment may prevent thrombotic events in heterozygous indiv iduals but may not be expected to improve their survival.