Tripodi A, Franchi F, Krachmalnicoff A, Mannucci P M
A. Bianchi Bonomi Hemophilia and Thrombosis Center, University of Milan, Maggiore Hospital, Italy.
Acta Haematol. 1990;83(3):152-5. doi: 10.1159/000205194.
We report a family in which 2 homozygotes with similarly very low protein C levels have different clinical symptoms. One had recurrent venous thrombosis starting at the age of 28 years, the other is still asymptomatic at 38 years despite exposure to thrombotic risk factors. Our review of 13 additional cases reveals a highly variable phenotypic expression of homozygous protein C deficiency, which can be subdivided into two groups. In the first group are 8 kindreds in which homozygotes presented at birth with unmeasurable protein C levels and life-threatening thrombosis and 1 kindred in which homozygotes are characterized by very low levels of protein C but delayed onset (10 months of age) of thrombosis. In the second group are 4 kindreds characterized by very low, but measurable, protein C levels in homozygotes who survived beyond the neonatal period into adulthood with histories of moderately severe thrombosis. The present case demonstrates that protein C levels lower than 10% are compatible with a negative history for thrombosis, not only in the neonatal period but also during adulthood, and suggests that in some homozygotes other factors need to interact for full clinical penetrance of the defect.
我们报告了一个家族，其中两名蛋白C水平同样极低的纯合子有不同的临床症状。一名从28岁起就反复发生静脉血栓形成，另一名尽管暴露于血栓形成风险因素下，但在38岁时仍无症状。我们对另外13例病例的回顾显示，纯合子蛋白C缺乏症有高度可变的表型表达，可分为两组。第一组有8个家族，其中纯合子出生时蛋白C水平无法测量且有危及生命的血栓形成，还有1个家族，其中纯合子的特征是蛋白C水平极低但血栓形成延迟（10个月大）。第二组有4个家族，其特征是纯合子的蛋白C水平极低但可测量，这些纯合子在新生儿期后存活至成年，有中度严重血栓形成史。本病例表明，蛋白C水平低于10%不仅在新生儿期，而且在成年期也与无血栓形成病史相符，并提示在一些纯合子中，其他因素需要相互作用才能使缺陷完全表现出临床症状。
