X-linked lymphoproliferative syndrome (XLP or Duncan disease) is characterized by extreme sensitivity to Epstein-Barr virus (EBV), resulting in a complex phenotype manifested by severe or fatal infectious mononucleosis, acquired hypogammaglobulinemia and malignant lymphoma. We have identified a gene, SH2D1A, that is mutated in XLP patients and encodes a novel protein composed of a single SH2 domain. SH2D1A is expressed in many tissues involved in the immune system. The identification of SH2D1A will allow the determination of its mechanism of action as a possible regulator of the EBV-induced immune response.

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Ligneous conjunctivitis (McKusick 217090) is a rare form of chronic conjunctivitis characterized by the development of firm fibrin-rich, woody-like pseudomembraneous lesions mainly on the tarsal conjunctivae. Less frequently, similar lesions may occur on other mucous membranes of the body indicating that these manifestations are part of a systemic disease. Histopathological findings from affected humans and (plasminogen-deficient) mice indicate that wound healing, mainly of injured mucosal tissue, is impaired due to markedly decreased (plasmin-mediated) extracellular fibrinolysis. Pseudomembraneous lesions of the eyes and other mucosal tissue mainly contain clotted fibrin(ogen). Actually, systemic plasminogen deficiency has been linked to ligneous conjunctivitis in humans and mice. In one case, ligneous conjunctivitis has been induced by antifibrinolytic treatment with tranexamic acid. Further rare associated disorders of ligneous conjunctivitis are congenital occlusive hydrocephalus and juvenile colloid milium. This review outlines the historical background, clinical characteristics of ligneous conjunctivitis and its associated complications, histological abnormalities of pseudomembraneous lesions, inheritance, hemostasiologic and molecular genetic findings in affected patients, current treatment approaches, and the plasminogen-deficient mouse as an animal model.

Severe type I plasminogen (PLG) deficiency has been causally linked to a rare chronic inflammatory disease of the mucous membranes that may be life threatening. Here we report clinical manifestations, PLG plasma levels, and molecular genetic status of the PLG gene of 50 patients. The most common clinical manifestations among these patients were ligneous conjunctivitis (80%) and ligneous gingivitis (34%), followed by less common manifestations such as ligneous vaginitis (8%), and involvement of the respiratory tract (16%), the ears (14%), or the gastrointestinal tract (2%). Four patients showed congenital occlusive hydrocephalus, 2 with Dandy-Walker malformation of cerebellum. Venous thrombosis was not observed. In all patients, plasma PLG levels were markedly reduced. In 38 patients, distinct mutations in the PLG gene were identified. The most common genetic alteration was a K19E mutation found in 34% of patients. Transient in vitro expression of PLG mutants R134K, delK212, R216H, P285T, P285A, T319_N320insN, and R776H in transfected COS-7 cells revealed significantly impaired secretion and increased degradation of PLG. These results demonstrate impaired secretion of mutant PLG proteins as a common molecular pathomechanism in type I PLG deficiency. IntroductionPlasminogen (PLG) plays an important role in intra-and extravascular fibrinolysis, wound healing, cell migration, angiogenesis, and embryogenesis. 1 Plg is primarily synthesized by liver tissue. 2 However, other minor sources identified in mice include adrenal gland, kidney, brain, testis, heart, lung, uterus, spleen, thymus, and gut tissue. 3 In humans, the cornea has been described as an extrahepatic site of PLG synthesis. 4 Inherited PLG deficiency in humans can be divided into 2 types: true PLG deficiency (type I, or hypoplasminogenemia) and dysplasminogenemia (type II). In the former, both immunoreactive PLG level and functional activity are reduced, while the latter shows a normal or slightly reduced level of immunoreactive PLG while functional activity is significantly decreased. It has been shown by several authors since 1995 that homozygous or compound-heterozygous type I PLG deficiency is a major cause of a rare inflammatory disease affecting mainly mucous membranes in different body sites. 5,6 The most common clinical manifestation is ligneous conjunctivitis, characterized by development of fibrin-rich, woodlike ("ligneous") pseudomembranous lesions. Involvement of the cornea may result in blindness. Other, less common manifestations are ligneous gingivitis, otitis media, ligneous bronchitis and pneumonia, involvement of the gastrointestinal or female genital tract, juvenile colloid milium of the skin, and congenital occlusive hydrocephalus. 6 In severely affected patients, prognosis is poor and treatment options are few. Worldwide, more than 150 patients with this disease have been reported since 1847, the date of first description. 6,7 From the Hospital for Children and Adolescents, University of Leipzig, Leipzig, Germany; For personal use o...

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