Hemophagocytic lymphohistiocytosis associated with an IgG Cold agglutinin.

Hemophagocytic lymphohistiocytosis (HLH) is a life-threatening disease eventually caused or reactivated by a viral infection, which can also lead to the production of cold agglutinins (CA). The nature of these autoantibodies is usually an IgM, less frequently an IgA or IgG, they agglutinate red blood cells at low temperatures. They can interfere with hematological parameters causing interpretation difficulties. We report a case of a 4-year-old boy who developed an IgG CA during recurrent HLH reactivated by EBV infection. The purpose of this observation is to underline HLH criteria and to analyze CA interference as well as its biological and clinical characteristics.

Fibrinogen Mahdia: A congenitally abnormal fibrinogen characterized by defective fibrin polymerization.

INTRODUCTION: Congenital dysfibrinogenemia is a rare qualitative fibrinogen deficiency. Molecular defects that result in dysfibrinogenemia are usually caused by mutations which affect fibrinopeptide release, fibrin polymerization, fibrin cross-linking or fibrinolysis. AIM: Here, we investigated the genetic basis of hypodysfibrinogenemia in two Tunisian siblings with major bleeding. METHODS: Coagulation-related tests were performed on the patients and their family members. Functional analysis was performed in plasma fibrinogen to characterize fibrin polymerization. The sequences of fibrinogen genes were amplified and analysed by sequencing. RESULTS: Coagulation studies revealed a reduced functional and a borderline low antigenic fibrinogen plasma levels with prolonged thrombin and activated partial thromboplastin times. The fibrinogen is also characterized by a markedly impaired polymerization and could incorporate into fibrin fibres to a smaller extent (22%). Mutational screening disclosed a heterozygous single nucleotide deletion (G) at c.1025, resulting in a frameshift mutation (AαGly323GlufsX79) that is predicted to delete a part of the αC-domain containing some of the FXIII cross-linking sites. Both the normal and the aberrant Aα-chain (approximately 43 kDa) were detected by electrophoretic analysis in the patients. CONCLUSION: The new dysfunctional fibrinogen, Mahdia variant, describes its impact on fibrin assembly after the loss of the αC domains which are involved in the lateral aggregation of protofibrils. The study confirms that the truncated Aα-chain could be incorporated into mature fibrinogen molecules.

[Autoimmune hemolytic anemia in children]. / Anémie hémolytique auto-immune de l'enfant.

Autoimmune hemolytic anemia is a rare condition in children which differs from the adult form. It is defined by immune-mediated destruction of red blood cells caused by autoantibodies. Characteristics of the autoantibodies are responsible for the various clinical entities. Classifications of autoimmune hemolytic anemia include warm autoimmune hemolytic anemia, cold autoimmune hemolytic anemia, and paroxysmal cold hemoglobinuria. For each classification, this review discusses the epidemiology, etiology, clinical presentation, laboratory evaluation, and treatment options.