Plasminogen hemizygosity. Detection of a silent allele in 7 members of a family by determination of plasminogen phenotypes, antigenic levels, and functional activity

Plasminogen missense variants and their involvement in cardiovascular and inflammatory disease

Human plasminogen (PLG), the zymogen of the fibrinolytic protease, plasmin, is a polymorphic protein with two widely distributed codominant alleles, PLG/Asp453 and PLG/Asn453. About 15 other missense or non-synonymous single nucleotide polymorphisms (nsSNPs) of PLG show major, yet different, relative abundances in world populations. Although the existence of these relatively abundant allelic variants is generally acknowledged, they are often overlooked or assumed to be non-pathogenic. In fact, at least half of those major variants are classified as having conflicting pathogenicity, and it is unclear if they contribute to different molecular phenotypes. From those, PLG/K19E and PLG/A601T are examples of two relatively abundant PLG variants that have been associated with PLG deficiencies (PD), but their pathogenic mechanisms are unclear. On the other hand, approximately 50 rare and ultra-rare PLG missense variants have been reported to cause PD as homozygous or compound heterozygous variants, often leading to a debilitating disease known as ligneous conjunctivitis. The true abundance of PD-associated nsSNPs is unknown since they can remain undetected in heterozygous carriers. However, PD variants may also contribute to other diseases. Recently, the ultra-rare autosomal dominant PLG/K311E has been found to be causative of hereditary angioedema (HAE) with normal C1 inhibitor. Two other rare pathogenic PLG missense variants, PLG/R153G and PLG/V709E, appear to affect platelet function and lead to HAE, respectively. Herein, PLG missense variants that are abundant and/or clinically relevant due to association with disease are examined along with their world distribution. Proposed molecular mechanisms are discussed when known or can be reasonably assumed.

Cerebral venous thrombosis with plasminogen deficiency

We describe a patient with inherited plasminogen deficiency who developed extensive cerebral venous thrombosis. Several other conditions that might have contributed to a hypercoagulable state, including mild thrombocytosis, thyrotoxicosis, and a chronic inflammatory lung disorder, were present. We also discuss the evidence linking plasminogen deficiency with a thrombophilic state. The diagnosis of cerebral venous thrombosis in this case was readily established by nuclear magnetic resonance imaging, a technique that is ideally suited for the evaluation and follow-up of patients with this condition.

Polymorphism of plasminogen in Tuscany (Italy)

The distribution of PLG phenotypes in the population of Tuscany (Central Italy) has been investigated by means of isoelectric focusing followed by immunofixation of desialyzed sera. In a random sample of 383 unrelated healthy blood donors registered at the Hospital of Pisa, three common phenotypes, PLG A, A-B, and B, and two rare variants were found. The allele frequencies calculated in our study were: PLG*A = 0.6749, PLG*B = 0.3225, and PLG*rare = 0.0026. The theoretical exclusion rate in cases of disputed paternity is 17.42%.

Application of plasminogen polymorphism to forensic hemogenetics

Plasminogen polymorphism (PLG) has attained considerable importance in forensic hemogenetics. PLG comprises two common, codominant autosomal alleles, PLG*A and PLG*B, more than 18 variants, and the silent allele PLG*Q0. Isoelectric focusing followed by functional or immunochemical detection seems to be the optimal method for the determination of phenotypes. PLG*A is the most common allele in all populations, having its highest frequency in Mongoloids, Amerindians and Eskimos, the lowest in Caucasoids. The functionally inactive plasminogen M5 so far has been seen exclusively in Japanese individuals. Silent PLG alleles were only observed in the heterozygous state. No clear differences in functional activity or plasma level could be ascertained for any of the other allotypes. PLG polymorphism is now widely used for many haemogenetic investigations. From the allele distribution in European Caucasoids a single exclusion chance of 17.2% for non-fathers in paternity testing may be calculated. The major prerequisites of a new genetic marker in the parentage expertise, established Mendelian inheritance, favorable distribution of common alleles, low frequency of silent alleles, and simple reproducible typing technology, are fulfilled.