Type II antithrombin deficiency caused by a large in‐frame insertion: structural,functional and pathological relevance

Summary. Background: The metastable native conformation of serpins is required for their protease inhibition mechanism, but also renders them vulnerable to missense mutations that promote protein misfolding with pathological consequences. Objective: To characterize the first antithrombin deficiency caused by a large in‐frame insertion. Patients/Methods: Functional, biochemical and molecular analysis of the proband and relatives was performed. Recombinant antithrombin was expressed in HEK‐EBNA cells. Plasma and recombinant antithrombins were purified and sequenced by Edman degradation. The stability was evaluated by calorimetry. Reactive centre loop (RCL) exposure was determined by thrombin cleavage. Mutant antithrombin was crystallized as a dimer with latent plasma antithrombin. Results: The patient, with a spontaneous pulmonary embolism, belongs to a family with significant thrombotic history. We identified a complex heterozygous in‐frame insertion of 24 bp in SERPINC1, affecting strand 3 of β‐sheet A, a region highly conserved in serpins. Surprisingly, the insertion resulted in a type II antithrombin deficiency with heparin binding defect. The mutant antithrombin, with a molecular weight of 59 kDa, had a proteolytic cleavage at W49 but maintained the N‐terminal disulphide bonds, and was conformationally sensitive. The variant was non‐inhibitory. Analysis of the crystal structure of the hyperstable recombinant protein showed that the inserted sequence annealed into β‐sheet A as the fourth strand, and maintained a native RCL. Conclusions: This is the first case of a large in frame‐insertion that allows correct folding, glycosylation, and secretion of a serpin, resulting in a conformationally sensitive non‐inhibitory variant, which acquires a hyperstable conformation with a native RCL.     

Primary Immunodeficiency Diseases in Latin America: The Second Report of the LAGID Registry

This is the second report on the continuing efforts of LAGID to increase the recognition and registration of patients with primary immunodeficiency diseases in 12 Latin American countries: Argentina, Brazil, Chile, Colombia, Costa Rica, Honduras, Mexico, Panama, Paraguay, Peru, Uruguay, and Venezuela. This report reveals that from a total of 3321 patients registered, the most common form of primary immunodeficiency disease was predominantly antibody deficiency (53.2%) with IgA deficiency reported as the most frequent phenotype. This category was followed by 22.6% other well-defined ID syndromes, 9.5% combined T- and B-cell inmunodeficiency, 8.6% phagocytic disorders, 3.3% diseases of immune dysregulation, and 2.8% complement deficiencies. All countries that participated in the first publication in 1998 reported an increase in registered primary immunodeficiency cases, ranging between 10 and 80%. A comparison of the estimated minimal incidence of X-linked agammaglobulinemia, chronic granulomatous disease, and severe combined immunodeficiency between the first report and the present one shows an increase in the reporting of these diseases in all countries. In this report, the estimated minimal incidence of chronic granulomatous disease was between 0.72 and 1.26 cases per 100,000 births in Argentina, Chile, Costa Rica, and Uruguay and the incidence of severe combined immunodeficiency was 1.28 and 3.79 per 100,000 births in Chile and Costa Rica, respectively. However, these diseases are underreported in other participating countries. In addition to a better diagnosis of primary immunodeficiency diseases, more work on improving the registration of patients by each participating country and by countries that have not yet joined LAGID is still needed. Latin American Group for Primary Immunodeficiency Diseases     

Mitochondrial Injury in Human Acute Carbon Monoxide Poisoning: The Effect of Oxygen Treatment

The best oxygen therapy for acute carbon monoxide poisoning (ACOP) remains unestablished. Reported mitochondrial complex IV (mtCIV) inhibition, together with carboxyhaemoglobin (COHb)-induced hypoxia, may influence acute clinical symptoms and outcome. To “mitochondrially” evaluate treatment efficacy, we correlated intoxication severity and symptoms with mitochondrial function (mtCIV activity) and oxidative stress (lipid peroxidation) in 60 poisoned patients and determined ACOP recovery depending on either normobaric or hyperbaric oxygen therapy along a 3-month follow-up. In the present article we positively evaluate mtCIV as a good marker of ACOP recovery, treatment effectiveness, and late neurological syndrome development, which advocates for hyperbaric oxygen therapy as the treatment of choice. However, we discourage its usefulness as a severity marker because of its excessive sensitivity. We additionally evaluate oxidative stress role and prognostic factors for neurological sequelae development.     

Childhood Discoid Lupus in Identical Twins

Abstract: We report the exceptional case of 11‐year‐old identical male twins who both developed discoid lupus erythematosus lesions. Although systemic lupus erythematosus has often been reported in identical twins, discoid lupus erythematosus has only ocassionaly been described, with only one other case in twin children, as far as we are aware.     

Randomized clinical trial on acute effects of i.v. iron sucrose during haemodialysis

Aim: Haemodialysis induces endothelial dysfunction by oxidation and inflammation. Intravenous iron administration during haemodialysis could worsen endothelial dysfunction. The aim of this study was to ascertain if iron produces endothelial dysfunction and the possible neutralizing effect of N‐acetylcysteine when infused before iron. The oxidative and inflammatory effects of iron during haemodialysis were also assessed. Methods: Forty patients undergoing haemodialysis were studied in a randomized and cross‐over design with and without N‐acetylcysteine infused before iron sucrose (50 or 100 mg). Plasma Von Willebrand factor (vWF), soluble intercellular adhesion molecule‐1 (sICAM‐1) levels, malondialdehyde, total antioxidant capacity, CD11b/CD18 expression in monocytes, interleukin (IL)‐8 in monocytes and plasma IL‐8 were studied at baseline and during haemodialysis. Results: Haemodialysis produced significant (P < 0.001) increase in plasma vWF, sICAM‐1, malondialdehyde, IL‐8 and CD11b/CD18 expression in monocytes, as well as decrease in total antioxidant capacity. Iron induced significant increase in plasma malondialdehyde and IL‐8 in monocytes, but had no effect on total antioxidant capacity, CD11b/CD18 expression, plasma IL‐8, vWF and sICAM‐1. The addition of N‐acetylcysteine to 50 mg of iron produced a significant (P = 0.040) decrease in malondialdehyde. Conclusion: Standard (100 mg) and low (50 mg) doses of iron during haemodialysis had no effects on endothelium. Iron only had minor effects on inflammation and produced an increase in oxidative stress, which was neutralized by N‐acetylcysteine at low iron dose. Haemodialysis caused a significant increase in oxidative stress, inflammation and endothelial dysfunction markers.