Coagulation factor XII activity, but not an associated common genetic polymorphism (46C/T),is linked to recurrent miscarriage.

OBJECTIVE: To investigate whether a factor XII genetic polymorphism is associated with first-trimester embryonal loss.

DESIGN: Prospective case-control study. SETTING; Nagoya City University Hospital.

PATIENT(S): Eighty-three patients with a history of two or more unexplained first-trimester recurrent miscarriages and 67 controls with no obstetric complications or history of miscarriage.

MAIN OUTCOME MEASURE(S): Plasma factor XII activity, a genetic polymorphism (46 C-->T) of factor XII, lupus anticoagulant, and beta(2)glycoprotein I dependent anticardiolipin antibodies.

RESULT(S): Ten of the 83 patients and 1 of the 67 controls had decreased factor XII activity; the difference in frequency was statistically significant. Wild-type (CC), heterozygote (CT), and homozygote (TT) allele patterns were observed in 8, 36, and 39 patients, respectively, compared with 11, 20, and 36 of the patients and controls, respectively. The mean (+/- SD) corresponding factor XII activity was 154.8 +/- 44.8%, 112.7 +/- 30.2%, and 66.2 +/- 29.2% in patients and 164.6 +/- 26.7%, 114.3 +/- 28.1%, and 70.4 +/- 18.1% in controls. The two groups did not differ in the frequency of the T allele or categories of factor XII activity.

CONCLUSION(S): Factor XII activity overall, but not the 46C/T common genetic polymorphism, is associated with recurrent miscarriage.