Fibrinogen Villeurbanne II forms abnormal-appearing polymer. Shown are SEM micrographs taken at the same magnification of fibrin clots produced from a 1.77-mg/mL fibrinogen solution purified from plasma obtained from a healthy donor (A) and the patient (B). Size bars, 20 μm. The patient’s fibrin clot was poorly formed, consisting of long, thin fibers with little bundling and irregularly spaced branch points. (C) Quantitative analyses of a 40-μm × 40-μm section of the micrograph show that the patient’s fibrils are significantly thinner than the control. The data represent the mean and SEM. The P value was generated using a Mann-Whitney U test. (D) Shown are the results of a turbidimetric fibrinolytic assay performed using the patient’s and control (normal) plasma. OD, optical density.