Vitamin K deficiency embryopathy: A phenocopy of the warfarin embryopathy due to a disorder of embryonic vitamin K metabolism

Updating an Overview of Teratology

In this chapter, the authors aim to update an overview of the principles of teratology, beginning with the definition of teratology, the critical point at which this process occurs, and some of the most common etiological agents that improve our understanding of teratology.Modern teratology has greatly improved in recent years with advances in new methods in molecular biology, toxicology, animal laboratory science, and genetics, increasing our knowledge of ambient influences. Nevertheless, there is a lot to do to reduce the influence of hazardous intervening agents, whether they target our genetics or not, that can negatively affect pregnancy and induce congenital development disorders, including morphological, biochemical, or behavioral defects.Certain agents might indeed be related to certain defects, but we have not been able to identify the cause of most congenital defects, which highlights the importance of finding and testing out new genetics techniques and conducting laboratory animal science to unravel the etiology and pathogenicity of each congenital defect.

Hyperemesis gravidarum and vitamin K deficiency: a systematic review

Hyperemesis gravidarum (HG), severe nausea and vomiting in pregnancy, can lead to vitamin deficiencies. Little is known about HG-related vitamin K deficiency. We aimed to summarise available evidence on the occurrence of HG-related vitamin K deficiency and corresponding maternal and neonatal complications. A systematic review was conducted, searching Medline and EMBASE from inception to 12 November 2020. We identified 1564 articles, of which we included fifteen in this study: fourteen case reports (n 21 women) and one retrospective cohort study (n 109 women). Nine out of twenty-one women reported in case reports had a prolonged prothrombin time (PT). The cohort study measured PT in 39/109 women with HG, of whom 10/39 women (26 %) had prolonged PT. In total, 30-50 % women received vitamin K supplementation after vitamin K deficiency had been diagnosed. Four case reports (n 4 women) reported corresponding maternal complications, all consisting of coagulopathy-related haemorrhage. Nine case reports (n 16 neonates) reported corresponding neonatal complications including intracranial haemorrhage (n 2 neonates) and embryopathy (n 14 neonates), which consisted of Binder phenotype (n 14 neonates), chondrodysplasia punctata (n 9 neonates) and grey matter heterotopia (n 3 neonates). In conclusion, vitamin K deficiency and related complications occur among women with HG. In our systematic review, we were unable to assess the incidence rate.

Dentofacial manifestations of fetal warfarin syndrome in a paediatric patient

Anticoagulant therapy is commonly indicated during pregnancy to prevent thrombosis and prevention of prosthetic heart valve-associated thromboembolic events. Warfarin is a synthetic anticoagulant with low molecular weight and can cross the placenta resulting in congenital abnormalities termed fetal warfarin syndrome. This paper highlights the case of an 8-year-old boy with warfarin embryopathy. It highlights the extraoral and intraoral findings of the case along with the cephalometric analysis and provides insight into the phenotypic variations among the different cases reported in the literature.

Keutel Syndrome, a Review of 50 Years of Literature

Keutel syndrome (KS) is a rare autosomal recessive genetic disorder that was first identified in the beginning of the 1970s and nearly 30 years later attributed to loss-of-function mutations in the gene coding for the matrix Gla protein (MGP). Patients with KS are usually diagnosed during childhood (early onset of the disease), and the major traits include abnormal calcification of cartilaginous tissues resulting in or associated with malformations of skeletal tissues (e.g., midface hypoplasia and brachytelephalangism) and cardiovascular defects (e.g., congenital heart defect, peripheral pulmonary artery stenosis, and, in some cases, arterial calcification), and also hearing loss and mild developmental delay. While studies on Mgp -/- mouse, a faithful model of KS, show that pathologic mineral deposition (ectopic calcification) in cartilaginous and vascular tissues is the primary cause underlying many of these abnormalities, the mechanisms explaining how MGP prevents abnormal calcification remain poorly understood. This has negative implication for the development of a cure for KS. Indeed, at present, only symptomatic treatments are available to treat hypertension and respiratory complications occurring in the KS patients. In this review, we summarize the results published in the last 50 years on Keutel syndrome and present the current status of the knowledge on this rare pathology.

Neonatal Presentations of Metabolic Disorders

Metabolic disorders in a neonate can present with involvement of any organ system and can be challenging to diagnose. A newborn can present with an acute metabolic crisis such as hyperammonemia or seizures needing immediate management, with a more chronic clinical picture such as cholestatic liver disease, or with structural abnormalities such as skeletal manifestations. Early detection of treatable metabolic conditions is important to improve outcomes. Newborn screening has facilitated early detection and initiation of therapy for many metabolic disorders. However, normal testing does not rule out a metabolic disorder and a high index of suspicion should remain when caring for any critically ill neonate without a diagnosis. Whole exome sequencing (WES) or whole genome sequencing (WGS) can be powerful tools in rapid diagnosis of a potentially treatable metabolic condition in a critically ill neonate. This review presents classic clinical presentations of neonatal metabolic disorders and also highlights some uncommon neonatal manifestations of metabolic disorders to improve the recognition and diagnosis of these conditions.

Rhinitis 2020: A practice parameter update

This comprehensive practice parameter for allergic rhinitis (AR) and nonallergic rhinitis (NAR) provides updated guidance on diagnosis, assessment, selection of monotherapy and combination pharmacologic options, and allergen immunotherapy for AR. Newer information about local AR is reviewed. Cough is emphasized as a common symptom in both AR and NAR. Food allergy testing is not recommended in the routine evaluation of rhinitis. Intranasal corticosteroids (INCS) remain the preferred monotherapy for persistent AR, but additional studies support the additive benefit of combination treatment with INCS and intranasal antihistamines in both AR and NAR. Either intranasal antihistamines or INCS may be offered as first-line monotherapy for NAR. Montelukast should only be used for AR if there has been an inadequate response or intolerance to alternative therapies. Depot parenteral corticosteroids are not recommended for treatment of AR due to potential risks. While intranasal decongestants generally should be limited to short-term use to prevent rebound congestion, in limited circumstances, patients receiving regimens that include an INCS may be offered, in addition, an intranasal decongestant for up to 4 weeks. Neither acupuncture nor herbal products have adequate studies to support their use for AR. Oral decongestants should be avoided during the first trimester of pregnancy. Recommendations for use of subcutaneous and sublingual tablet allergen immunotherapy in AR are provided. Algorithms based on a combination of evidence and expert opinion are provided to guide in the selection of pharmacologic options for intermittent and persistent AR and NAR.

Warfarin-exposed zebrafish embryos resembles human warfarin embryopathy in a dose and developmental-time dependent manner - From molecular mechanisms to environmental concerns

Warfarin is the most worldwide used anticoagulant drug and rodenticide. Since it crosses placental barrier it can induce warfarin embryopathy (WE), a fetal mortality in neonates characterized by skeletal deformities in addition to brain hemorrhages. Although the effects of warfarin exposure in aquatic off target species were already described, the particular molecular toxicological mechanisms during early development are still unclear. Here, we used zebrafish (Danio rerio) to describe and compare the developmental effects of warfarin exposure (0, 15.13, 75.68 and 378.43 mM) on two distinct early developmental phases (embryos and eleuthero-embryos). Although exposure to both developmental phases induced fish mortality, only embryos exposed to the highest warfarin level exhibited features mimicking mammalian WE, e.g. high mortality, higher incidence of hemorrhages and altered skeletal development, among other effects. To gain insights into the toxic mechanisms underlying warfarin exposure, the transcriptome of embryos exposed to warfarin was explored through RNA-Seq and compared to that of control embryos. 766 differentially expressed (564 up- and 202 down-regulated) genes were identified. Gene Ontology analysis revealed particular cellular components (cytoplasm, extracellular matrix, lysosome and vacuole), biological processes (mainly amino acid and lipid metabolism and response to stimulus) and pathways (oxidative stress response and apoptosis signaling pathways) being significantly overrepresented in zebrafish embryos upon warfarin exposure. Protein-protein interaction further evidenced an altered redox system, blood coagulation and vasculogenesis, visual phototransduction and collagen formation upon warfarin exposure. The present study not only describes for the first time the WE in zebrafish, it provides new insights for a better risk assessment, and highlights the need for programming the rat eradication actions outside the fish spawning season to avoid an impact on off target fish community. The urge for the development of more species-specific anticoagulants for rodent pest control is also highlighted.

The complementary role of imaging modalities in Binder phenotype. Can prognostic factors of neonatal respiratory distress be found?

OBJECTIVE

To evaluate the complementarity between prenatal ultrasound, computed tomography, and MRI scans for fetuses with Binder phenotype.

METHODS

We carried out a retrospective study from January 1, 2009, to June 30, 2018, of fetuses with Binder phenotype. Prenatal ultrasound (US) data were collected. A systematic survey of the entire skeleton was performed to look for associated abnormalities such as calcifications, brachytelephalangy, and spinal stenosis. Parents were systematically offered fetal skeletal computed tomography (CT).

RESULTS

Thirteen cases were included. Two cases of perinatal respiratory distress (18%) were observed. Chondrodysplasia punctata was diagnosed from the presence of calcifications, especially of the proximal femoral epiphyses and tarsal bones, in five cases (38%) by US and in 10 cases (83%) by CT. Calcifications of the hyoid bone were detected by CT in three cases (25%) one of which had respiratory distress. Polyhydramnios was associated with the Binder phenotype in four cases (30%) one of which had respiratory distress. One single fetus had combined polyhydramnios and laryngeal calcifications, and he suffered from perinatal respiratory distress.

CONCLUSION

An antenatal diagnosis of Binder phenotype is often associated with chondrodysplasia punctata. We recommend the use of fetal CT as a complement to US in this condition.

An Overview of Teratology

In this chapter, we provide an overview of the basic principles of teratology, beginning with its definition, the critical point for teratogenesis to occur and the most evident etiological agents to improve the understanding of this science.Teratology is a recent science that began in the early twentieth century, and has greatly improved over the recent years with the advancements in molecular biology, toxicology, animal laboratory science, and genetics, as well as the improvement on the knowledge of the environmental influences.Nevertheless, more work is required to reduce the influence of hazardous products that could be deleterious during pregnancy, thus reducing teratogenic defects in the newborn. While some teratogenic defects are attributed to their agents with certainty, the same for a lot of other such defects is lacking, necessitating consistent studies to decipher the influence of various teratogenic agents on their corresponding teratogenic defects. It is here that the laboratory animal science is of great importance both in the present and in the future.

Nonclinical aspects of venous thrombosis in pregnancy

Pregnancy is a hypercoagulable state which carries an excess risk of maternal venous thrombosis. Endothelial injury, alterations in blood flow and activation of the coagulation pathway are proposed to contribute to the hypercoagulability. The risk for thrombosis may be accentuated by certain drugs and device implants that directly or indirectly affect the coagulation pathway. To help ensure that these interventions do not result in adverse maternal or fetal outcomes during pregnancy, gravid experimental animals can be exposed to such treatments at various stages of gestation and over a dosage range that would identify hazards and inform risk assessment. Circulating soluble biomarkers can also be evaluated for enhancing the assessment of any increased risk of venous thrombosis during pregnancy. In addition to traditional in vivo animal testing, efforts are under way to incorporate reliable non-animal methods in the assessment of embryofetal toxicity and thrombogenic effects. This review summarizes hemostatic balance during pregnancy in animal species, embryofetal development, biomarkers of venous thrombosis, and alterations caused by drug-induced venous thrombosis.

Low-dose maternal warfarin intake resulting in fetal warfarin syndrome: In search for a safe anticoagulant regimen during pregnancy

BACKGROUND

Fetal exposure to maternal ingestion of warfarin is known to produce certain dysmorphic features in the neonate, known as fetal warfarin syndrome (FWS). There is a general consensus that maternal intake of warfarin at a daily dose of 5 mg or less is safe both for the infant and the mother.

METHODS

We report four cases of FWS born to mothers with rheumatic heart disease on warfarin prophylaxis during pregnancy at a dose less than 5 mg/day.

RESULTS

Along with typical facial features of FWS and multiple epiphyseal stippling in skeletal x-ray, Case 1 had Dandy-Walker malformation and Case 2 had laryngo-tracheomalacia and patent ductus arteriosus.

CONCLUSION

We emphasize the need for optimizing the choice and dosage schedule of anticoagulants during pregnancy, least harmful for the mother and her developing fetus.

Zebrafish vitamin K epoxide reductases: expression in vivo, along extracellular matrix mineralization and under phylloquinone and warfarin in vitro exposure

Vitamin K (VK) acts as a cofactor driving the biological activation of VK-dependent proteins and conferring calcium-binding properties to them. As a result, VK is converted into VK epoxide, which must be recycled by VK epoxide reductases (Vkors) before it can be reused. Although VK has been shown to play a central role in fish development, particularly during skeletogenesis, pathways underlying VK actions are poorly understood, while good and reliable molecular markers for VK cycle/homeostasis are still lacking in fish. In the present work, expression of 2 zebrafish vkor genes was characterized along larval development and in adult tissues through qPCR analysis. Zebrafish cell line ZFB1 was used to evaluate in vitro regulation of vkors and other VK cycle-related genes during mineralization and upon 24 h exposure to 0.16 and 0.8 µM phylloquinone (VK1), 0.032 µM warfarin, or a combination of both molecules. Results showed that zebrafish vkors are differentially expressed during larval development, in adult tissues, and during cell differentiation/mineralization processes. Further, several VK cycle intermediates were differentially expressed in ZFB1 cells exposed to VK1 and/or warfarin. Present work provides data identifying different developmental stages and adult tissues where VK recycling is probably highly required, and shows how genes involved in VK cycle respond to VK nutritional status in skeletal cells. Expression of vkor genes can represent a reliable indicator to infer VK nutritional status in fish, while ZFB1 cells could represent a suitable in vitro tool to get insights into the mechanisms underlying VK action on fish bone.

Bleeding and non-bleeding phenotypes in patients with GGCX gene mutations

Functional limitations for the vitamin K cycle, caused either by mutations in gamma-glutamyl carboxylase or vitamin K epoxide reductase genes, result in hereditary deficiency of vitamin K-dependent coagulation factors (VKCFD1 and VKCFD2, respectively). Patients suffering from VKCFD often share several other anatomical irregularities which are not related to haemostasis. Here we report on nine patients, eight of them previously unreported, who presented with VKCFD1. All were examined with special attention to vitamin K-dependent coagulation factors as well as to bone and heart development and to other anatomical signs of embryonal vitamin K deficiency. In total, we detected ten mutations in the gamma-glutamyl carboxylase gene of which seven have not been previously reported. Most interestingly, additional non-bleeding phenotypes were observed in all patients including midfacial hypoplasia, premature osteoporosis, cochlear hearing loss, heart valve defects, pulmonary stenosis, or pseudoxanthoma elasticum-like phenotype. Undercarboxylated matrix Gla protein, osteocalcin, and periostin appear to be responsible for these defects which are also observed in cases of fetal warfarin syndrome.

Recent trends in the metabolism and cell biology of vitamin K with special reference to vitamin K cycling and MK-4 biosynthesis

In contrast to other fat-soluble vitamins, dietary vitamin K is rapidly lost to the body resulting in comparatively low tissue stores. Deficiency is kept at bay by the ubiquity of vitamin K in the diet, synthesis by gut microflora in some species, and relatively low vitamin K cofactor requirements for γ-glutamyl carboxylation. However, as shown by fatal neonatal bleeding in mice that lack vitamin K epoxide reductase (VKOR), the low requirements are dependent on the ability of animals to regenerate vitamin K from its epoxide metabolite via the vitamin K cycle. The identification of the genes encoding VKOR and its paralog VKOR-like 1 (VKORL1) has accelerated understanding of the enzymology of this salvage pathway. In parallel, a novel human enzyme that participates in the cellular conversion of phylloquinone to menaquinone (MK)-4 was identified as UbiA prenyltransferase-containing domain 1 (UBIAD1). Recent studies suggest that side-chain cleavage of oral phylloquinone occurs in the intestine, and that menadione is a circulating precursor of tissue MK-4. The mechanisms and functions of vitamin K recycling and MK-4 synthesis have dominated advances made in vitamin K biochemistry over the last five years and, after a brief overview of general metabolism, are the main focuses of this review.

Clinical and radiological pictures of two newborn babies with manifestations of chondrodysplasia punctata and review of available literature

BACKGROUND

Chondrodysplasia punctata (CDP) is a rare, heterogeneous congenital skeletal dysplasia, characterized by punctate or dot-like calcium deposits in cartilage observed on neonatal radiograms. A number of inborn metabolic diseases are associated with CDP, including peroxisomal and cholesterol biosynthesis dysfunction and other inborn errors of metabolism such as: mucolipidosis type II, mucopolysacharidosis type III, GM1 gangliosidosis. CDP is also related to disruption of vitamin K-dependent metabolism, causing secondary effects on the embryo, as well as fetal alcohol syndrome (FAS), chromosomal abnormalities that include trisomies 18 and 21, Turner syndrome.

CASE REPORT

This article presents clinical data and diagnostic imaging findings of two newborn babies with chondrodysplasia punctata. Children presented with skeletal and cartilage anomalies, dysmorphic facial feature, muscles tone abnormalities, skin changes and breathing difficulties. One of the patients demonstrated critical stenosis of spinal canal with anterior subluxation of C1 vertebra relative to C2. The aim of this article is to present cases and briefly describe current knowledge on etiopathogenesis as well as radiological and clinical symptoms of diseases coexisting with CDP.

CONCLUSIONS

Radiological diagnostic imaging allows for visualization of punctate focal mineralization in bone epiphyses during neonatal age and infancy. Determining the etiology of chondrodysplasia punctata requires performing various basic as well as additional examinations, including genetic studies.

Vitamin K-dependent carboxylation of matrix Gla-protein: a crucial switch to control ectopic mineralization

Vascular mineralization has recently emerged as a risk factor for cardiovascular morbidity and mortality. Previously regarded as a passive end-stage process, vascular mineralization is currently recognized as an actively regulated process with cellular and humoral contributions. The discovery that the vitamin K-dependent matrix Gla-protein (MGP) is a strong inhibitor of vascular calcification has propelled our mechanistic understanding of this process and opened novel avenues for diagnosis and treatment. This review focuses on molecular mechanisms of vascular mineralization involving MGP and discusses the potential for treatments and biomarkers to monitor patients at risk for vascular mineralization.

Binder phenotype in mothers affected with autoimmune disorders

OBJECTIVE

To report four foetal cases of the Binder phenotype associated with maternal autoimmune disorders.

PATIENTS AND METHODS

In three mothers with autoimmune diseases, 2D and 3D ultrasonographic measurements were made on four foetuses with the Binder profile, and were compared with postnatal phenotypes.

RESULTS

The Binder phenotype can be detected in early pregnancy (14.5 WG). All foetuses had verticalized nasal bones and midfacial hypoplasia. Punctuate calcifications were found in almost all the cases. No specific maternal auto-antibody has been associated with foetal Binder phenotype.

CONCLUSION

Since the Binder phenotype can be diagnosed at ultrasound examination during pregnancy, it is important to establish the underlying cause so as to assess the foetal prognosis. This study stresses the importance of systematic checks for maternal autoimmune disease in cases of prenatally diagnosed Binder phenotypes.

X-linked brachytelephalangic chondrodysplasia punctata: a simple trait that is not so simple

Brachytelephalangic chondrodysplasia punctata (CDPX1) is an X-linked recessive disorder caused by mutations in the arylsulfatase E (ARSE) gene, characterized by the presence of stippled epiphyses on radiograms in infancy and early childhood. Other features include hypoplasia of the midface and of the nasal bone, short stature, brachytelephalangy, and ectopic calcifications. Patients display marked clinical variability and there is no clear genotype-phenotype correlation. We report on a 14-month-old boy who presented with respiratory stridor due to tracheal calcifications. He had mild midface hypoplasia and brachytelephalangy, but lacked other features of CDPX1, such as short stature and epiphyseal stippling. Analysis of ARSE detected a deletion involving exons 7-10. His maternal grandfather harbored the same defect but lacked any clinical manifestation. These findings underscore two important points. First, the absence of stippled epiphyses on radiograms should not be considered an exclusion criteria for ARSE mutation screening in patients with other features of the disease, especially after the neonatal period. Second, counseling to parents of affected children should be cautious because although the theoretical risk of inheriting the ARSE mutation is 50% for every male child of a carrier mother, it is not possible to determine whether he will develop features of CDPX1 and the eventual severity of symptoms. The actual risk of developing the disease is probably lower than 50%. Conversely, normal prenatal sonography does not rule out potentially severe complications such as tracheal stenosis.

Chondrodysplasia punctata: a clinical diagnostic and radiological review

Chondrodysplasia punctata (CDP) is associated with a number of disorders, including inborn errors of metabolism, involving peroxisomal and cholesterol pathways, embryopathy and chromosomal abnormalities. Several classification systems of the different types of CDP have been suggested earlier. More recently, the biochemical and molecular basis of a number of CDP syndromes has recently been elucidated and a new aetiological classification has emerged. Here we provide an updated version with an overview of the different types of CDP, a discussion of the aetiology and a description of the clinical and radiographic findings. An investigative guideline to help determine the exact diagnosis in new cases is also presented.

Binder phenotype: clinical and etiological heterogeneity of the so-called Binder maxillonasal dysplasia in prenatally diagnosed cases, and review of the literature

OBJECTIVE

Prenatal Binder profile is a well known clinical phenotype, defined by a flat profile without nasal eminence, contrasting with nasal bones of normal length. Binder profile results of a hypoplasia of the nasal pyramid (sometimes referred to as maxillonasal dysplasia). We report 8 fetuses prenatally diagnosed as Binder phenotype, and discuss their postnatal diagnoses.

METHODS

Ultrasonographic detailed measurements in 2D and 3D were done on the 8 fetuses with Binder profile, and were compared with postnatal phenotype.

RESULTS

All fetuses have an association of verticalized nasal bones, abnormal convexity of the maxilla, and some degree of chondrodysplasia punctata. The final diagnoses included fetal warfarin syndrome (one patient), infantile sialic acid storage (one patient), probable Keutel syndrome (one patient), and five unclassifiable types of chondrodysplasia punctata.

CONCLUSION

This series demonstrates the heterogeneity of prenatally diagnosed Binder phenotype, and the presence of chondrodysplasia punctata in all cases. An anomaly of vitamin K metabolism, possibly due to environmental factors, is suspected in these mild chondrodysplasia punctata. We recommend considering early prophylactic vitamin K supplementation in every suspected acquired vitamin K deficiency including incoercible vomiting of the pregnancy.

Maternal mixed connective tissue disease and offspring with chondrodysplasia punctata

OBJECTIVES

To describe the case of a mother with mixed connective tissue disease (MCTD) whose male and female offspring from 2 successive pregnancies had chondrodysplasia punctata (CDP) in the absence of identifiable biochemical or genetic abnormalities or teratogen exposure.

METHODS

Description of a male and female offspring from a mother with MCTD harboring high-titer anti-ribonucleoprotein (RNP) antibodies. Maternal autoantibody assays were performed employing quantitative multiplex suspension arrays and flow cytometry, and autoantibody titer and pattern were determined by indirect immunofluorescence. Assays of phytanic acid, plasmalogen, and very long-chain fatty acids were performed employing commercially available reagents. Chromosomal analysis was performed on both offspring employing standard cytogenetic analysis. Review of the relevant literature was performed (PubMed search 1966 through July 2008).

RESULTS

Two children with CDP born to a mother with MCTD who harbored anti-RNP autoantibodies at high titer are described. Genetic and chromosomal studies and biochemical analysis of peroxisome function and very long-chain fatty acids excluded known biochemical or genetic defects or mutations as the cause of CDP in these children. Furthermore, detailed review of the clinical history failed to disclose any evidence of maternal teratogen exposure during the 2 pregnancies.

CONCLUSIONS

Maternal MCTD is the most likely explanation for the occurrence of CDP in the 2 children reported here. Review of previously published cases of CDP associated with autoimmune disease suggests that placental crossing of maternal autoantibodies during pregnancy specifically affecting the normal development of fetal growth plates is responsible for CDP in the offspring in these cases.

Osteoporosis in celiac disease and in endocrine and reproductive disorders

As the increase in lifespan brings to light diseases that were previously not clinically detectable, osteoporosis has become an issue of worldwide significance. The disease is marked by a loss of bone mass; the bones become less dense, fragile and more prone to fracturing. Because it is regulated by endocrine and environmental factors, osteoporosis presents a multifactorial etiopathogenesis, with the genetic component accounting for 70% of an individual variation in bone mass density (BMD), the principal determinant, with age, of fracture risk. Pathological conditions such as celiac disease (CD) exacerbate the process of bone loss, so that the occurrence of osteoporosis in celiac subjects is of particular note: indeed, the screening of osteoporosis patients for this disease is advisable, since it may be the only sign of undiagnosed CD. An increase in interleukin IL-1β, of the IL-1 system, in the relatives of celiac patients confirms the genetic predisposition to osteoporosis and its presence is evidence of an association between the two conditions. The direct effect on the bones of CD is secondary to poor absorption of calcium and vitamin D. In women osteoporosis is indirectly associated with early menopause and amenorrhea, and it may follow prolonged breast-feeding and frequent pregnancies, while in men it is associated with hypogonadism and GH deficit. These endocrine and non-endocrine factors exert their effects on bones by modulating the RANK/RANK-L/OPG system. An appropriate lifestyle from adolescence onwards, together with early diagnosis of and treatment for CD and primary and secondary endocrine pathologies are important for the prevention of damage to the bones.

The vitamin K cycle

Vitamin K is a collective term for lipid-like naphthoquinone derivatives synthesized only in eubacteria and plants and functioning as electron carriers in energy transduction pathways and as free radical scavengers maintaining intracellular redox homeostasis. Paradoxically, vitamin K is a required micronutrient in animals for protein posttranslational modification of some glutamate side chains to gamma-carboxyglutamate. The majority of gamma-carboxylated proteins function in blood coagulation. Vitamin K shuttles reducing equivalents as electrons between two enzymes: VKORC1, which is itself reduced by an unknown ER lumenal reductant in order to reduce vitamin K epoxide (K>O) to the quinone form (KH2); and gamma-glutamyl carboxylase, which catalyzes posttranslational gamma-carboxylation and oxidizes KH2 to K>O. This article reviews vitamin K synthesis and the vitamin K cycle, outlines physiological roles of various vitamin K-dependent, gamma-carboxylated proteins, and summarizes the current understanding of clinical phenotypes caused by genetic mutations affecting both enzymes of the vitamin K cycle.

Vitamin K-dependent gamma-glutamylcarboxylation: an ancient posttranslational modification

The vitamin K-dependent carboxylase carries out the posttranslational modification of specific glutamate residues in proteins to gamma-carboxy glutamic acid (Gla) in the presence of reduced vitamin K, molecular oxygen, and carbon dioxide. In the process, reduced vitamin K is converted to vitamin K epoxide, which is subsequently reduced to vitamin K, by vitamin K epoxide reductase (VKOR) for use in the carboxylation reaction. The modification has a wide range of physiological implications, including hemostasis, bone calcification, and signal transduction. The enzyme interacts with a high affinity gamma-carboxylation recognition sequence (gamma-CRS) of the substrate and carries out multiple modifications of the substrate before the product is released. This mechanism ensures complete carboxylation of the Gla domain of the coagulation factors, which is essential for their biological activity. gamma-Carboxylation, originally discovered in mammals, is widely distributed in the animal kingdom. It has been characterized in sea squirt (Ciona intestinalis), in flies (Drosophila melanogaster), and in marine snails (Conus textile), none of which have a blood coagulation system similar to mammals. The cone snails express a large array of gamma-carboxylated peptides that modulate the activity of ion channels. These findings have led to the suggestion that gamma-carboxylation is an extracellular posttranslational modification that antedates the divergence of molluscs, arthropods, and chordates. I will first summarize recent understanding of gamma-carboxylase and gamma-carboxylation gleaned from experiments using the mammalian enzyme, and then I will briefly describe the available information on gamma-carboxylation in D. melanogaster and C. textile.

Antioxidative Treatment Diminishes Ethanol-Induced Congenital Malformations in the Rat

BACKGROUND

Intrauterine exposure to ethanol causes embryonic and fetal growth retardation and maldevelopment. Oxidative stress in mother and offspring has been suggested to be part of the teratogenic mechanism, and supplementation of antioxidative agents to the pregnant women may therefore be of value in future prophylactic treatment regimen. There is a need for in vivo experimental work in this field, and in the present study, our aim was to investigate whether chronic ethanol consumption induced congenital malformations in rats and, if so, whether dietary supplementation of vitamin E (alpha-tocopherol) diminished such maldevelopment.

METHODS

Female Sprague-Dawley rats were given drinking water containing 20% ethanol and half of these received food containing 5% vitamin E. Non-ethanol-exposed female rats, with or without vitamin E treatment, served as controls. The pregnancy was interrupted on gestational day 20 when the offspring was evaluated morphologically and fetal hepatic 8-iso-PGF(2alpha) levels were measured to assess the degree of fetal oxidative stress.

RESULTS

Exposure to 20% ethanol increased maternal blood ethanol to 1.5 promille and increased resorption and malformation rates in the offspring. Maternal vitamin E treatment did not affect blood ethanol levels, but normalized fetal development. The fetal hepatic levels of 8-iso-PGF(2alpha) were increased in the ethanol-exposed group and normalized by vitamin E treatment of the mother.

CONCLUSIONS

Ethanol exposure disturbs embryogenesis partly by enhanced oxidative stress, and the adverse effects can be ameliorated by antioxidative treatment.

Low vitamin K status is associated with osteoarthritis in the hand and knee

OBJECTIVE

Poor intake of vitamin K is common. Insufficient vitamin K can result in abnormal cartilage and bone mineralization. Furthermore, osteophyte growth, seen in osteoarthritis (OA), may be a vitamin K-dependent process. We undertook this study to determine whether vitamin K deficiency is associated with radiographic features of OA.

METHODS

We conducted an analysis among 672 participants (mean age 65.6 years, 358 women) in the Framingham Offspring Study, a population-based prospective observational cohort. Levels of plasma phylloquinone (the primary form of vitamin K) had previously been measured in these participants, for whom we also had bilateral hand and knee radiographs. The main outcomes were 1) prevalence ratios (PRs) of OA, osteophytes, and joint space narrowing (JSN) per quartile of plasma phylloquinone level for each joint, adjusting for correlated joints using generalized estimating equations, and 2) adjusted mean number of joints with each feature per quartile of plasma phylloquinone level. Analyses were conducted in hands and knees separately and adjusted for age, sex, body mass index, total energy intake, plasma vitamin D, and femoral neck bone mineral density.

RESULTS

The PRs for OA, osteophytes, and JSN and adjusted mean number of joints with all 3 features in the hand decreased significantly with increasing plasma phylloquinone levels (P<or=0.03 for all). For example, as plasma phylloquinone levels rose, the PR for hand OA decreased from 1.0 to 0.7 (P=0.005). For the knee, only the PR for osteophytes and the adjusted mean number of knee joints with osteophytes decreased significantly with increasing plasma phylloquinone levels (PR decreased from 1.0 to 0.6, P=0.01).

CONCLUSION

These observational data support the hypothesis of an association between low plasma levels of vitamin K and increased prevalence of OA manifestations in the hand and knee.

Biliary lithiasis in early pregnancy and abnormal development of facial and distal limb bones (Binder syndrome): A possible role for vitamin K deficiency

BACKGROUND

Binder syndrome is a maxillonasal dysostosis characterized by midface and nasal hypoplasia, sometimes associated with short terminal phalanges of fingers and toes and transient radiological features of chondrodysplasia punctata. Warfarin- or phenytoin-induced vitamin K deficiency during early pregnancy is a well-established etiology for this syndrome, which occurs nevertheless sporadically in most cases.

CASE(S)

We describe here the first case, to our knowledge, of Binder syndrome in a child whose mother presented with biliary lithiasis in early pregnancy. The mother proved to have a decrease in clotting factors II, VII, and X, and in prothrombin time, at 11 weeks of gestation, which was highly suggestive of vitamin K deficiency.

CONCLUSIONS

The biliary lithiasis-induced vitamin K deficiency in early pregnancy is likely to have resulted in Binder syndrome. This observation should prompt physicians to carefully check for vitamin K deficiency in pregnant women presenting with biliary lithiasis, in order to prevent Binder syndrome in the fetus by providing intravenous vitamin K supplementation as soon as possible. Finally, reassuring genetic counseling regarding the genetic risk for future pregnancies is to be provided to the parents.

Familial multiple coagulation factor deficiencies: new biologic insight from rare genetic bleeding disorders

Combined deficiency of factor (F)V and FVIII (F5F8D) and combined deficiency of vitamin K-dependent clotting factors (VKCFD) comprise the vast majority of reported cases of familial multiple coagulation factor deficiencies. Recently, significant progress has been made in understanding the molecular mechanisms underlying these disorders. F5F8D is caused by mutations in two different genes (LMAN1 and MCFD2) that encode components of a stable protein complex. This complex is localized to the secretory pathway of the cell and likely functions in transporting newly synthesized FV and FVIII, and perhaps other proteins, from the ER to the Golgi. VKCFD is either caused by mutations in the gamma-carboxylase gene or in a recently identified gene encoding the vitamin K epoxide reductase. These two proteins are essential components of the vitamin K dependent carboxylation reaction. Deficiency in either protein leads to under-carboxylation and reduced activities of all the vitamin K-dependent coagulation factors, as well as several other proteins. The multiple coagulation factor deficiencies provide a notable example of important basic biological insight gained through the study of rare human diseases.

Cervical spine stenosis and possible vitamin K deficiency embryopathy in an unusual case of chondrodysplasia punctata and an updated classification system

We describe in this paper a patient with brachytelephalangic chondrodysplasia punctata (BCDP) who has multiple serious medical problems and striking physical abnormalities. These include cervical spine stenosis with resultant quadriplegia, severe nasal hypoplasia, and brachytelephalangy. Radiographs taken shortly after birth demonstrated extensive epiphyseal and vertebral stippling, and distal phalangeal hypoplasia. The pregnancy was complicated by maternal intestinal obstruction due to a small bowel carcinoma and probable malabsorption. The severity of the phenotype in this case may have been influenced by these maternal factors particularly vitamin K deficiency.

Fetus with an unusual form of nonrhizomelic chondrodysplasia punctata: case report and review

Chondrodysplasia punctata (CDP) is a heterogeneous condition mainly characterized by premature and ectopic calcification of cartilage. Many genetic and nongenetic causes have been described leading to a preliminar etiological classification into defects of peroxisomal metabolism, defects in cholesterol metabolism, and vitamin K (vit K) metabolism. However, numerous cases of CDP still remain unclassified. The difficulties in reaching a causal diagnosis are illustrated here by a 23-week-old fetus with nonrhizomelic CDP characterized by extensive cartilage stippling, brachyphalangy, and nasal hypoplasia.

Brodifacoum toxicosis in two neonatal puppies

Eight out of a litter of 13 puppies were either born dead or died within 48 hours of birth. Three puppies that died shortly after birth were necropsied. Two puppies had hemorrhage in the thoracic and peritoneal cavities, intestinal serosa, and meninges. The third puppy was smaller than the other two puppies but did not have detectable hemorrhage. Brodifacoum, a second-generation coumarin anticoagulant, was detected in livers from the two puppies with hemorrhage. The dam did not have clinical signs of coagulopathy before or subsequent to whelping. The owners were confident that the dog had not been exposed to rodenticide for at least 4 weeks before whelping. A presumptive diagnosis of in utero brodifacoum toxicity was made. To the authors' knowledge this is the first time a second-generation coumarin anticoagulant has been detected in the liver of a newborn animal. This case is also unique because the dam was unaffected, suggesting that fetuses are more susceptible to brodifacoum toxicity than adult animals.

Midface hypoplasia, obesity, developmental delay and neonatal hypotonia in two brothers

We describe two brothers born to consanguineous parents, who presented with hypotonia and hypoglycaemia in the neonatal period and later developed obesity and developmental delay. They had brachydactyly and similar facial features including a prominent forehead, low nasal bridge, midface hypoplasia, full lips, a small mouth, and small, low set ears with overfolded helices. Their sister had mild learning disabilities. No additional anomalies were found, and metabolic investigations including peroxisomal functions gave normal results. We suggest the patients have a hitherto unreported condition, with an autosomal or X-linked mode of inheritance.

[Warfarin fetopathy]

We report a case of warfarin embryopathy. This disease affects more than 6% of fetuses exposed in utero to a vitamin K antagonist.

OBSERVATION

A child whose mother was treated with acenocoumarol because of a mechanical heart valve presented with signs of warfarin embryopathy. He showed chondrodysplasia punctata with telebrachydactyly, facial dysmorphism with nasal hypoplasia, a cataract, and a bilateral pyeloureteral junction syndrome.

COMMENTS

Characteristics of this drug induced embryopathy are reminded, while bearing in mind the conflict of interests between the mother and the fetus. The mechanisms of this embryopathy are debated in light of the recent knowledge concerning fetal metabolism of vitamin K.

Recurrent cleft lip and palate in siblings of a patient with malabsorption syndrome, probably caused by hypovitaminosis a associated with folic acid and vitamin B(2) deficiencies

We present a woman with metabolic disorders secondary to malabsorption and renal disease who gave birth to a stillborn male fetus with left unilateral cleft lip and palate and a live born infant with left unilateral cleft lip and palate. We discuss potential cofactors that could be implicated in the abnormal embryonic process.