- [Show abstract] [Hide abstract] ABSTRACT: Plasminogen (plg), the circulating proenzyme of plasmin in blood, is a polymorphic protein and most of these natural variants have been identified using isoelectric focusing (IEF) gel electrophoresis. Here, we show that a rare plg gene polymorphism 504R/W is associated with IEF phenotype A3 on the protein level. One healthy individual with homozygous plg gene polymorphism 504W studied so far exhibited low normal plg antigen and slightly decreased plg activity, suggesting that this polymorphism is associated with (mild) hypoplasminogenemia. In addition, we present the findings of IEF phenotyping of plg mutants of 26 patients with severe hypoplasminogenemia, showing one of the following four IEF patterns: A3-like, A3A-like, B-like and AB-like. In the plasma of most compound heterozygous patients, only one of the two plg mutants was detectable by IEF electrophoresis, probably due to undetectable plasma concentration of the 2nd plg mutant. In almost all cases, pI of plg mutants and variants predicted by computer modeling were in good agreement with the observed IEF band pattern. plg phenotyping by IEF in combination with molecular genetic analysis of the plg gene is a useful approach to characterize plg mutants and variants further.
- [Show abstract] [Hide abstract] ABSTRACT: Inherited severe hypoplasminogenaemia is a multisystemic disorder leading to deficient extravascular fibrinolysis. As a clinical consequence wound healing capacity of mucous membranes is markedly impaired leading to ligneous conjunctivitis and several other manifestations. Here we report the molecular genetic and clinical findings on 23 new cases with severe hypoplasminogenaemia. Homozygous or compound-heterozygous mutations in the plasminogen (PLG) gene were found in 16 of 23 patients (70%), three of which were novel mutations reported here for the first time (C166Y, Y264S, IVS10-7T/G). Compared to 79 previously published cases, clinical manifestations of the current group of patients showed higher percentages of ligneous periodontitis, congenital hydrocephalus, and involvement of the female genital tract. In contrast, involvement of the gastrointestinal or urogenital tract was not observed in any of the cases. Patients originated to a large extent (61%) from Turkey and the Middle East, and showed a comparably frequent occurrence of consanguinity of affected families and a greater female to male ratio than was derived from previous reports in the literature. Individual treatment of ligneous conjunctivitis included topical plasminogen or heparin eye drops, topical or systemic fresh frozen plasma, and surgical removal of ligneous pseudomembranes, mostly with modest or transient efficacy. In conclusion, the present study underscores the broad range of clinical manifestations in PLG-deficient patients with a trend to regional differences. Transmission of genetic and clinical data to the recently established Plasminogen Deficiency Registry should help to determine the prevalence of the disease and to develop more efficient treatment strategies.
- [Show abstract] [Hide abstract] ABSTRACT: Leyva-Castillo et al¹ described a Mexican patient with ligneous conjunctivitis. Hemostaseologic studies revealed severe hypoplasminogenemia (type I plasminogen deficiency). Mutation screening of the plasminogen (PLG) gene (chromosome 6q26) suggested a 14–base pair deletion in exon 5 of the PLG gene (deleted sequence, GAACTACTGCAGGA). However, this deletion has already been described before as the result of a methodical error: accidental coamplification of sequences of the plasminogen-related gene B (NCBI accession number AC093616.5) located on chromosome 2.²,3 Furthermore, polymerase chain reaction amplification of PLG gene exons 1, 3, 4, 5, 13, 16, and 17 may lead to “false” distinct nucleotide exchanges owing to coamplified PLG homologous genes.³ Optimizing polymerase chain reaction conditions by, for example, increasing the annealing temperature or changing the primers will probably lead to the disappearance of the alleged deletion and false nucleotide exchanges.³,4 Another method to avoid coamplification of PLG homologous genes is a long polymerase chain reaction amplification strategy as described recently.⁵ In conclusion, the described amplified sequences are not the PLG gene and are possibly derived from PLG-like genes (PLGL) on chromosome 2, or the PLG gene of the patient has undergone a gene conversion with apolipoprotein(a) (LPA) on chromosome 6 or PLGL on chromosome 2.
- [Show abstract] [Hide abstract] ABSTRACT: 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.
- [Show abstract] [Hide abstract] ABSTRACT: Plasmin(ogen) plays an important role in fibrinolysis and wound healing. Severe hypoplasminogenemia has recently been linked to ligneous conjunctivitis. Plasminogen (plg) is known as a polymorphic protein and most of these variants have been identified using isoelectric focusing (IEF) gel electrophoresis. Here, we studied common plg variants from healthy subjects and plg mutants from three patients with hypoplasminogenemia and three subjects with dysplasminogenemia by molecular genetic analysis and IEF. Analysis of 24 healthy subjects showed that subjects with the most common IEF plg phenotype A (n=12) were homozygous for aspartate at position 453 (453D), while both subjects with IEF plg phenotype B were homozygous for asparagine at this position (453N). Subjects with IEF plg phenotype AB (n=10) were compound-heterozygous for 453D/453N. Three patients with severe hypoplasminogenemia and different plg gene mutations exhibited characteristic "abnormal" IEF band patterns when compared with IEF plg phenotypes A and B. In all heterozygous family members the observed IEF plg phenotype was derived from the wild type plg molecule only, probably due to low concentration of the mutant plg molecule in plasma. In contrast, in three unrelated subjects with heterozygous dysplasminogenemia an equal "mixture" of wild type and mutant plg was found by IEF analysis. In conclusion, plg phenotyping by IEF in combination with molecular analysis of the plg gene seems to be a useful method for characterization of plg variants and mutants.
- [Show abstract] [Hide abstract] ABSTRACT: The prevalence of familial plasminogen deficiency in Scotland has recently been calculated at 2.9/1000. However, little is known of the molecular genetic background and the frequency of plasminogen gene mutations in most cases of inherited plasminogen deficiency. Having previously identified 28 unrelated subjects with familial plasminogen deficiency from a cohort of 9611 blood donors, we have now reviewed 19 of these 28 subjects and screened the plasminogen gene in 15 subjects with hypoplasminogenaemia (plus five relatives) and four subjects with dysplasminogenaemia for mutations and polymorphisms. A missense mutation K19E in the plasminogen gene was found in 13 of the 15 propositi with hypoplasminogenaemia, in one of these in a homozygous manner. In two subjects with hypoplasminogenaemia, two new mutations (P353A and R471X) were identified. These three different mutations, if inherited in a homozygous or compound-heterozygous manner, may be associated with the development of ligneous conjunctivitis. In four subjects with dysplasminogenaemia, three heterozygous mutations (C548G, n = 1; A601T, n = 1; G693R, n = 2) were found. None of the propositi with plasminogen deficiency developed venous thrombosis at any time. In conclusion, the K19E mutation in the plasminogen gene is a common cause of hypoplasminogenaemia in Scotland, with an estimated prevalence of around 0.14%.