An insertion within the factor IX gene: hemophilia BEl Salvador.

A patient with moderate to severe hemophilia B has been found to have a large insertion within his factor IX gene. The site of insertion is located in a DNA segment of approximately 0.8 kb between exon IV and an EcoRI site within intron D. The size of the DNA insertion is approximately 6 kb, and it contains at least two TaqI sites, two EcoRI sites, and one HindIII site. The insert probably originates from outside the FIX gene and does not represent an internal duplication. We propose that this abnormal FIX gene be called FIX El Salvador in recognition of the birthplace of the patient.

The effect of L-asparaginase on antithrombin, plasminogen, and plasma coagulation during therapy for acute lymphoblastic leukemia.

Hemostatic function was studied sequentially in 12 children receiving L-asparaginase, vincristine, and prednisone as remission induction chemotherapy for acute lymphoblastic leukemia. The three-week period of L-asparaginase therapy was characterized by progressive decreases in plasma antithrombin, plasminogen, and fibrinogen concentrations, and by progressive increases in plasma clotting times (prothrombin time, partial thromboplastin time, thrombin time). Platelet counts rose rapidly during the third and fourth weeks of therapy as bone marrow remission was achieved. Factor V levels increased steadily during a five-week period, perhaps related to vincristine or prednisone therapy. Recent reports of thrombosis and hemorrhage in children and adults receiving L-asparaginase may be explained by this complex set of abnormalities in coagulation and coagulation control.

Plasminogen and antithrombin III deficiencies in the childhood nephrotic syndrome associated with plasminogenuria and antithrombinuria.

Three of four patients with the childhood nephrotic syndrome were found to have low plasma plasminogen concentrations; all four had low plasma antithrombin III concentrations. In the two patients who were tested, urinary concentrations of these proteins exceeded the plasma concentrations. As the urinary losses of plasminogen and antithrombin III decreased over the course of illness, the plasma concentrations of antithrombin III and plasminogen rose. One patient had multiple thromboembolic episodes. We conclude the deficiencies of antithrombin III and plasminogen, probably secondary to urinary excretion of these proteins, may contribute to the thrombotic diathesis associated with nephrotic syndrome.

Spontaneously acquired factor IX inhibitor in a nonhemophiliac child.

A 2 1/2-year-old, previously healthy child developed progressive swelling of the left leg and a hematoma of the anterior chest wall associated with a falling hemoglobin concentration, as a result of a spontaneously acquired Factor IX inhibitor. Successful management of her condition required a four-volume exchange transfusion and immunosuppressive therapy consisting of cyclophosphamide for four days and prednisone for one month. A brief review of the literature regarding the occurrence and nature of acquired coagulation factor inhibitors and the role of immunosuppressive therapy is also presented.