vitamin-k-semiquinone-radical and Abnormalities--Multiple

Ectopic mineralization disorders comprise a broad spectrum of inherited or acquired diseases characterized by aberrant deposition of calcium crystals in multiple organs, such as the skin, eyes, kidneys, and blood vessels. Although the precise mechanisms leading to ectopic calcification are still incompletely known to date, various molecular targets leading to a disturbed balance between pro- and anti-mineralizing pathways have been identified in recent years. Vitamin K and its related compounds, mainly those post-translationally activated by vitamin K-dependent carboxylation, may play an important role in the pathogenesis of ectopic mineralization as has been demonstrated in studies on rare Mendelian diseases, but also on highly prevalent disorders, like vascular calcification. This narrative review compiles and summarizes the current knowledge regarding the role of vitamin K, its metabolism, and associated compounds in the pathophysiology of both monogenic ectopic mineralization disorders, like pseudoxanthoma elasticum or Keutel syndrome, as well as acquired multifactorial diseases, like chronic kidney disease. Clinical and molecular aspects of the various disorders are discussed according to the state-of-the-art, followed by a comprehensive literature review regarding the role of vitamin K in molecular pathophysiology and as a therapeutic target in both human and animal models of ectopic mineralization disorders.

Topics: Abnormalities, Multiple; Animals; Calcinosis; Cartilage Diseases; Genetic Diseases, Inborn; Hand Deformities, Congenital; Humans; Pulmonary Valve Stenosis; Vitamin K

 Matrix γ-carboxyglutamate protein (MGP), a vitamin K-dependent protein, is recognized as a potent local inhibitor of vascular calcification. Studying patients with Keutel syndrome (KS), a rare autosomal recessive disorder resulting from MGP mutations, provides an opportunity to investigate the functions of MGP. The purpose of this study was (i) to investigate the phenotype and the underlying MGP mutation of a newly identified KS patient, and (ii) to investigate MGP species and the effect of vitamin K supplements in KS patients..  The phenotype of a newly identified KS patient was characterized with specific attention to signs of vascular calcification. Genetic analysis of the MGP gene was performed. Circulating MGP species were quantified and the effect of vitamin K supplements on MGP carboxylation was studied. Finally, we performed immunohistochemical staining of tissues of the first KS patient originally described focusing on MGP species..  We describe a novel homozygous MGP mutation (c.61+1G>A) in a newly identified KS patient. No signs of arterial calcification were found, in contrast to findings in MGP knockout mice. This patient is the first in whom circulating MGP species have been characterized, showing a high level of phosphorylated MGP and a low level of carboxylated MGP. Contrary to expectations, vitamin K supplements did not improve the circulating carboxylated mgp levels. phosphorylated mgp was also found to be present in the first ks patient originally described..  Investigation of the phenotype and MGP species in the circulation and tissues of KS patients contributes to our understanding of MGP functions and to further elucidation of the difference in arterial phenotype between MGP-deficient mice and humans.

Topics: Abnormalities, Multiple; Arteries; Calcinosis; Calcium-Binding Proteins; Cartilage Diseases; Extracellular Matrix Proteins; Hand Deformities, Congenital; Homozygote; Humans; Matrix Gla Protein; Mutation; Pulmonary Valve Stenosis; Vitamin K

Prenatal exposure to oral anticoagulants during pregnancy may result in defective fetal development or life-threatening hemorrhage. Fetal exposure during the first eight weeks of pregnancy may cause abnormal development of the facial structures, hypoplastic digits, strippled epiphyses, and mental retardation. Midtrimester exposure may result in optic atrophy, faulty brain growth, and developmental retardation. Third-trimester exposure may produce fetal anticoagulation, predisposing the infant to life-threatening hemorrhage in the perinatal period. Anticoagulation with heparin sodium does not provide a clearly safe alternative, since this therapy has been associated with excessive fetal loss.

Topics: Abnormalities, Drug-Induced; Abnormalities, Multiple; Administration, Oral; Adult; Anticoagulants; Body Weight; Chondrodysplasia Punctata; Female; Fetus; Gestational Age; Humans; Infant, Newborn; Maternal-Fetal Exchange; Optic Atrophy; Pregnancy; Pregnancy Complications, Cardiovascular; Rheumatic Heart Disease; Vitamin K; Warfarin