Summary
Despite many reports of individuals with congenital plasminogen deficiency and thrombosis,
there is still uncertainty whether heterozygous deficiency represents a real thrombophilic
risk factor or simply a coincidental finding. We have addressed this issue by testing
for plasminogen deficiency in a cohort of 9611 blood donors. Out of 66 donors with
reduced plasminogen activity on two occasions 28 were shown to have a familial deficiency
state (including 3 with dysplasminogen-aemia). Our observed prevalence rate for familial
plasminogen deficiency, calculated at 2.9/1000 (95% Cl = 1.9-4.2 per 1000), was not
significantly different from that calculated from published reports of congenital
plasminogen deficiency in thrombotic cohorts (5.4/1000). Furthermore, with only two
exceptions, all 80 donors and relatives with familial deficiency were asymptomatic
with regard to thrombosis -including a 29 year old donor with suspected compound heterozygous
hypoplasminogenaemia. These findings add further weight to the argument that familial
heterozygous plasminogen deficiency, at least in isolation, does not constitute a
significant thrombotic risk factor. However, it remains uncertain whether plasminogen
deficiency, when combined with other thrombophilic conditions, may become more clinically
important.
