Mild haemostatic problems associated with congenital heterozygous α₂-antiplasmin deficiency

A dutch family, of which 13 members are heterozygotes, deficient for α₂-antiplasmin (α₂-AP) is reported. Clinical studies showed that 2 heterozygotes had a mild bleeding tendency, which presented as bleeding episodes after tooth extraction and after surgery and, in one patient, also as excessive menstruation. Laboratory investigations revealed and α₂-AP activity of 62% (51-71) (median and range) and an antigen level of 60% (60-66). The plasminogen binding as well as the fibrin binding properties of α₂-AP were normal. Plasminogen concentrations were significantly higher in the heterozygotes compared to the other family members. However, free plasminogen not bound to histidine-rich glycoprotein was not significantly different between these two groups. We propose that in this family the deficiency of α₂-AP is due to a decreased synthesis of a normal α₂-AP molecule. This present study brings the frequency of heterozygous α₂-AP deficient patients with a bleeding tendency to 13 out of 59 heterozygotes reported in the literature.