Otopalatodigital syndrome spectrum disorders: otopalatodigital syndrome types 1 and 2, frontometaphyseal dysplasia and Melnick-Needles syndrome

A new case of Melnick-Needles syndrome with skeletal manifestations: A case report

INTRODUCTION AND IMPORTANCE

Melnick-Needles syndrome (MNS) is a rare skeletal dysplasia that affects skeletal and connective tissue. Less than 70 cases of MNS reported in the literature. MNS had various clinical manifestations such as skeletal deformity, cortical bony sclerosis, facial abnormality, and urogenital symptoms.

CASE PRESENTATION

We presented a 5-year-old girl who referred to our orthopedic clinic with knee valgus deformity, spinal kyphoscoliosis, bilateral coxa valga, and humerus cortical irregularity. Based on some facial and skeletal feature, MNS was confirmed with genetic evaluation (heterozygote Filamin A genome).

CLINICAL DISCUSSION

The diagnosis of MNS requires a thorough medical and family history, physical examination, and radiographic evaluation. Differential diagnoses for patients with skeletal and facial deformities like MNS include Camurati-Engelmann disease, cystinuria, Galloway-Mowat syndrome, Joubert syndrome, and mucopolysaccharidosis. Treatment for MNS patients with bony deformities without lethal conditions can be conservative, but corrective surgery may be necessary in some cases.

CONCLUSIONS

MNS was a rare syndrome with common clinical manifestations such as limb and spine deformity. It is important to conduct a careful examination of any patient who presents with limb and skeletal deformity to the orthopedic clinic, as the disease may have some lethal clinical implications.

Skeletal Dysplasia Families: A Stepwise Approach to Diagnosis

Skeletal dysplasias are a heterogeneous collection of genetic disorders characterized by bone and cartilage abnormalities, and they encompass over 400 disorders. These disorders are rare individually, but collectively they are common (approximate incidence of one in 5000 births). Radiologists occasionally encounter skeletal dysplasias in daily practice. In the 1980s, Professor Juergen Spranger proposed a concept suitable for the diagnosis of skeletal dysplasias termed bone dysplasia families. He stated that (a) different bone dysplasias that share a similar skeletal pattern can be grouped into a "family," (b) the final diagnosis is feasible through the provisional recognition of a pattern followed by a more careful analysis, and (c) families of bone dysplasias may be the result of similar pathogenetic mechanisms. The prototypes of bone dysplasia families include dysostosis multiplex family, achondroplasia family, spondyloepiphyseal dysplasia congenita family, and Larsen syndrome-otopalatodigital syndrome family. Since Spranger's proposal, the concept of bone dysplasia families, along with advancing genetic techniques, has been validated and further expanded. Today, this molecularly proven concept enables a simple stepwise approach to be applied to the radiologic diagnosis of skeletal dysplasias. The first step is the categorization of a given case into a family based on pattern recognition, and the second step is more meticulous observation, such as identification of different severities of the same pattern or subtle but distinctive findings. Since major skeletal dysplasias are limited in number, radiologists can be familiar with the representative patterns of these disorders. The authors describe a stepwise radiologic approach to diagnosing major skeletal dysplasia families and review the clinical and genetic features of these disorders. Published under a CC BY 4.0 license. Quiz questions for this article are available through the Online Learning Center. Online supplemental material and the slide presentation from the RSNA Annual Meeting are available for this article.

Filamin A in platelets: Bridging the (signaling) gap between the plasma membrane and the actin cytoskeleton

Platelets are anucleate cells that are essential for hemostasis and wound healing. Upon activation of the cell surface receptors by their corresponding extracellular ligands, platelets undergo rapid shape change driven by the actin cytoskeleton; this shape change reaction is modulated by a diverse array of actin-binding proteins. One actin-binding protein, filamin A (FLNA), cross-links and stabilizes subcortical actin filaments thus providing stability to the cell membrane. In addition, FLNA binds the intracellular portion of multiple cell surface receptors and acts as a critical intracellular signaling scaffold that integrates signals between the platelet's plasma membrane and the actin cytoskeleton. This mini-review summarizes how FLNA transduces critical cell signals to the platelet cytoskeleton.

Bipolar disorder with Melnick-Needles syndrome and periventricular nodular heterotopia: two case reports and a review of the literature

Background

Melnick–Needles syndrome and periventricular nodular heterotopia are two usually mutually exclusive phenotypes of F-actin-binding cytoskeletal phosphoprotein Filamin-A mutations. Melnick–Needles syndrome is a rare X-linked condition that is lethal in males and shows great phenotypic variability in affected females. It is caused by mutations in Filamin-A gene, which encodes the protein Filamin A. Defects of the human Filamin-A gene also cause X-linked periventricular nodular heterotopia, a malformation of neuronal migration characterized by nodules of neurons in inappropriate location adjacent to the walls of the lateral ventricles.

Case presentation

We report on two Caucasian adolescent females, sisters, diagnosed with Melnick–Needles syndrome and bilateral periventricular nodular heterotopia, who developed bipolar disorder and somatic symptoms disorder at a young age. We also present a review of the literature about mental disorders associated with periventricular nodular heterotopia. Our report shows that patients presenting with atypical and heterogeneous psychiatric disease may have an underrecognized anatomical brain abnormality on genetic basis.

Conclusions

We found records of psychiatric disorders associated with periventricular nodular heterotopia; nevertheless, this is the first report of bipolar disorder occurring in individuals with periventricular nodular heterotopia, and the first report of any psychiatric disorder in individuals affected by Melnick–Needles syndrome. In conclusion, this case report may contribute to characterizing the phenotype of this very rare syndrome.

Exon skip-inducing variants in FLNA in an attenuated form of frontometaphyseal dysplasia

Pathogenic variation in the X-linked gene FLNA causes a wide range of human developmental phenotypes. Loss-of-function is usually male embryonic-lethal, and most commonly results in a neuronal migration disorder in affected females. Gain-of-function variants cause a spectrum of skeletal dysplasias that present with variable additional, often distinctive, soft-tissue anomalies in males and females. Here we present two, unrelated, male individuals with novel, intronic variants in FLNA that are predicted to be pathogenic. Their phenotypes are reminiscent of the gain-of-function spectrum without the skeletal manifestations. Most strikingly, they manifest urethral anomalies, cardiac malformations, and keloid scarring, all commonly encountered features of frontometaphyseal dysplasia. Both variants prevent inclusion of exon 40 into the FLNA transcript, predicting the in-frame deletion of 42 amino acids, however the abundance of FLNA protein was equivalent to that observed in healthy individuals. Loss of these 42 amino acids removes sites that mediate key FLNA functions, including binding of some ligands and phosphorylation. This phenotype further expands the spectrum of the FLNA filaminopathies.

Case Report: Pansynostosis, Chiari I Malformation and Syringomyelia in a Child With Frontometaphyseal Dysplasia 1

Frontometaphyseal dysplasia 1 (FMD1) is a rare otopalatodigital spectrum disorder (OPDSD) that is inherited as an X-linked trait and it is caused by gain-of-function mutations in the FLNA. It is characterized by generalized skeletal dysplasia, and craniofacial abnormalities including facial dysmorphism (supraorbital hyperostosis, hypertelorism, and down-slanting palpebral fissures). The involvement of the central nervous system in patients with OPDSD is rare. Herein, we present the case of a 12-year-old boy with facial dysmorphism, multiple joint contractures, sensorineural hearing loss, scoliosis, craniosynostosis, and irregular sclerosis with hyperostosis of the skull. Brain and whole-spine magnetic resonance imaging revealed Chiari I malformation with extensive hydrosyringomyelia from the C1 to T12 levels. Targeted next-generation sequencing identified a hemizygous pathologic variant (c.3557C>T/p.Ser1186Leu) in the FLNA, confirming the diagnosis of FMD1. This is the first report of a rare case of OPDSD with pansynostosis and Chiari I malformation accompanied by extensive syringomyelia.

Frontometaphyseal dysplasia 1 in a patient from Sri Lanka

A Sri Lankan male child with supraorbital hyperostosis, broad nasal bridge, small mandible, severe kyphoscoliosis, distal joint contractures of the hands and long second and third toes is described. A hemizygous pathogenic variant in exon 22 of the filamin A (FLNA) gene [NM_001110556.1: c.3557C>T; which leads to a nonsynonymous substitution of serine by leucine at codon 1186 in the FLNA protein; NP_001104026.1: p.Ser1186Leu] was identified. The clinical features observed in this patient were consistent with the cardinal manifestations seen in frontometaphyseal dysplasia 1 (FMD1). However, characteristic extra skeletal manifestations such as cardiac defects, uropathy, and hearing impairment which have previously been reported in association with this condition were absent in this patient.

A family of Melnick-Needles syndrome: a case report

BACKGROUND

Melnick-Needles syndrome (MNS) is an extremely rare osteochondrodysplasia caused by a mutation of FLNA, the gene encoding filamin A. MNS is inherited in an X-linked dominant manner. In this study, we describe three members of the same family with MNS, who exhibited different phenotypic severity despite having an identical FLNA gene mutation.

CASE PRESENTATION

The patient was 16 months old, with a history of delayed physical development, multiple upper respiratory infections and otitis media episodes. She was referred to our orthopedic clinic because of bowed legs and an abnormal plain chest radiograph. Both upper and lower extremities were bowed. Plain X-rays showed thoracolumbar kyphoscoliosis, with anterior and posterior vertebral scalloping, and thin, wavy ribs. Hypoplasia of the pubis and ischium, with bilateral coxa valga, were also noted. Target exome sequencing revealed a heterozygous mutation of FLNA, c.3578 T > C, p.Lys1193Pro, which confirmed the diagnosis of MNS. Her older sister and mother had minimal deformities of the axial and extremity skeleton, but genetic analyses revealed the same FLNA mutation as the patient. The mutation identified in this family has not been previously reported.

CONCLUSION

This report illustrates the potential inherited nature of MNS and the phenotypic variability of clinicoradiologic characteristics. In patients with traits suggestive of MNS, a careful medical and family history should be obtained, and genetic testing should be performed for the patient, as well as all family members.

Anterior Segment Dysgenesis With Accessory Iris Membranes in an Infant With Otopalatodigital Spectrum Disorder and Mutation in the FLNA Gene

A 4-month-old male infant with frontometaphyseal dysplasia and de novo FLNA gene mutation died of complications of disease. Post-mortem examination revealed accessory iris membranes. This is the first report in the literature of accessory iris membranes in a confirmed case of FLNA mutation and phenotypic anomalies consistent with frontometaphyseal dysplasia. [J Pediatr Ophthalmol Strabismus. 2020;57:e8-e11.].

Otopalatodigital Syndrome Type I: Novel Characteristics and Prenatal Manifestations in two Siblings

Otopalatodigital spectrum disorder (OPDSD) is rare group of X-linked disorders caused by mutations in the filamin A (FLNA) gene. It is characterized by skeletal dysplasia of variable severity and different extra skeletal manifestations. Its presentation in the fetal period is quite unspecific, so diagnosis is usually made after birth. We present prenatal ultrasonography and postmortem findings that led us to a diagnosis of the mildest form of OPDSD (OPD type I) in two consecutive pregnancies. This is the first report on prenatal diagnosis (PND) of OPD type I. Affected fetuses showed facial dysmorphy (hypertelorism, micrognathia, cleft palate) and digital anomalies, features typical of OPD type I. In addition, microphtalmia and early neonatal death due to severe respiratory distress syndrome are described as a novel characteristics of the disorder. Clinical exome sequencing revealed a hemizygous missense pathogenic variant in the FLNA gene (NM_ 001110556.1: c.620C>T). We suggest that the presence of hypertelorism, micrognathia, digital anomalies on prenatal ultrasound examination should alert suspicion to OPDSD. Detailed clinical examination of mother and other female relatives is of great importance in establishing definitive diagnosis of OPD type I.

Critical Structural Defects Explain Filamin A Mutations Causing Mitral Valve Dysplasia

Mitral valve diseases affect ∼3% of the population and are the most common reasons for valvular surgery because no drug-based treatments exist. Inheritable genetic mutations have now been established as the cause of mitral valve insufficiency, and four different missense mutations in the filamin A gene (FLNA) have been found in patients suffering from nonsyndromic mitral valve dysplasia (MVD). The filamin A (FLNA) protein is expressed, in particular, in endocardial endothelia during fetal valve morphogenesis and is key in cardiac development. The FLNA-MVD-causing mutations are clustered in the N-terminal region of FLNA. How the mutations in FLNA modify its structure and function has mostly remained elusive. In this study, using NMR spectroscopy and interaction assays, we investigated FLNA-MVD-causing V711D and H743P mutations. Our results clearly indicated that both mutations almost completely destroyed the folding of the FLNA5 domain, where the mutation is located, and also affect the folding of the neighboring FLNA4 domain. The structure of the neighboring FLNA6 domain was not affected by the mutations. These mutations also completely abolish FLNA's interactions with protein tyrosine phosphatase nonreceptor type 12, which has been suggested to contribute to the pathogenesis of FLNA-MVD. Taken together, our results provide an essential structural and molecular framework for understanding the molecular bases of FLNA-MVD, which is crucial for the development of new therapies to replace surgery.

A genetic-phenotypic classification for syndromic micrognathia

Micrognathia is a common craniofacial deformity which represents hypoplastic development of the mandible, accompanied by retrognathia and consequent airway problems. Usually, micrognathia is accompanied by multiple systematic defects, known as syndromic micrognathia, and is in close association with genetic factors. Now, large quantities of pathogenic genes of syndromic micrognathia have been revealed. However, how these different pathogenic genes could lead to similar phenotypes, and whether there are some common characteristics among these pathogenic genes are still unknown. In this study, we proposed a genetic-phenotypic classification of syndromic micrognathia based on pathogenic genes information obtained from Phenolyzer, DAVID, OMIM, and PubMed database. Pathogenic genes of syndromic micrognathia could be divided into four groups based on gene function, including cellular processes and structures, cell metabolism, cartilage and bone development, and neuromuscular function. In addition, these four groups exhibited various clinical characteristics, and the affected systems, such as central nervous system, skeletal system, cardiovascular system, oral and dental system, respiratory system and muscle, were different in these four groups. This classification could provide meaningful insights into the pathogenesis of syndromic micrognathia, and offer some clues for understanding the molecular mechanism, as well as guiding precise clinical diagnosis and treatment for syndromic micrognathia.

A recurrent mutation causing Melnick-Needles syndrome in females confers a severe, lethal phenotype in males

Melnick-Needles syndrome (MNS; MIM 309350) is an X-linked skeletal dysplasia caused by mutations in FLNA. Females with the condition present with characteristic facial features, short stature, skeletal anomalies, including poorly modeled and sclerotic bones, and structural abnormalities such as cardiac and urological defects. Previously males were thought to present with either a mild phenotype compatible with life or a severe lethal presentation depending on the maternal phenotype. The discovery of a limited number of mutations in FLNA as the cause of the condition has clarified the molecular basis of the disorder, but only a very small number of severely affected males have been reported with MNS. Furthermore, no mildly affected males have been described with a molecular confirmation of the condition. In this report, we describe the clinical and molecular findings of a mildly affected mother with MNS and her severely affected son. They shared a well-documented disease-causing variant in FLNA, p.(Ala1188Thr), one of two highly recurrent mutations leading to the disorder. This is only the fourth report of a male with perinatal lethal MNS and a molecular confirmation; it is the first description of this specific mutation in a male.

Profilin 1 Negatively Regulates Osteoclast Migration in Postnatal Skeletal Growth, Remodeling, and Homeostasis in Mice

Profilin 1 (Pfn1), a regulator of actin polymerization, controls cell movement in a context-dependent manner. Pfn1 supports the locomotion of most adherent cells by assisting actin-filament elongation, as has been shown in skeletal progenitor cells in our previous study. However, because Pfn1 has also been known to inhibit migration of certain cells, including T cells, by suppressing branched-end elongation of actin filaments, we hypothesized that its roles in osteoclasts may be different from that of osteoblasts. By investigating the osteoclasts in culture, we first verified that Pfn1-knockdown (KD) enhances bone resorption in preosteoclastic RAW264.7 cells, despite having a comparable number and size of osteoclasts. Pfn1-KD in bone marrow cells showed similar results. Mechanistically, Pfn1-KD osteoclasts appeared more mobile than in controls. In vivo, the osteoclast-specific conditional Pfn1-deficient mice (Pfn1-cKO) by CathepsinK-Cre driver demonstrated postnatal skeletal phenotype, including dwarfism, craniofacial deformities, and long-bone metaphyseal osteolytic expansion, by 8 weeks of age. Metaphyseal and diaphyseal femurs were drastically expanded with suppressed trabecular bone mass as indicated by μCT analysis. Histologically, TRAP-positive osteoclasts were increased at endosteal metaphysis to diaphysis of Pfn1-cKO mice. The enhanced movement of Pfn1-cKO osteoclasts in culture was associated with a slight increase in cell size and podosome belt length, as well as an increase in bone-resorbing activity. Our study, for the first time, demonstrated that Pfn1 has critical roles in inhibiting osteoclast motility and bone resorption, thereby contributing to essential roles in postnatal skeletal homeostasis. Our study also provides novel insight into understanding skeletal deformities in human disorders.

Structural basis of the filamin A actin-binding domain interaction with F-actin

Actin-cross-linking proteins assemble actin filaments into higher-order structures essential for orchestrating cell shape, adhesion, and motility. Missense mutations in the tandem calponin homology domains of their actin-binding domains (ABDs) underlie numerous genetic diseases, but a molecular understanding of these pathologies is hampered by the lack of high-resolution structures of any actin-cross-linking protein bound to F-actin. Here, taking advantage of a high-affinity, disease-associated mutant of the human filamin A (FLNa) ABD, we combine cryo-electron microscopy and functional studies to reveal at near-atomic resolution how the first calponin homology domain (CH1) and residues immediately N-terminal to it engage actin. We further show that reorientation of CH2 relative to CH1 is required to avoid clashes with actin and to expose F-actin-binding residues on CH1. Our data explain localization of disease-associated loss-of-function mutations to FLNaCH1 and gain-of-function mutations to the regulatory FLNaCH2. Sequence conservation argues that this provides a general model for ABD-F-actin binding.

The ontogeny of Robin sequence

The triad of micrognathia, glossoptosis, and concomitant airway obstruction defined as "Robin sequence" (RS) is caused by oropharyngeal developmental events constrained by a reduced stomadeal space. This sequence of abnormal embryonic development also results in an anatomical configuration that might predispose the fetus to a cleft palate. RS is heterogeneous and many different etiologies have been described including syndromic, RS-plus, and isolated forms. For an optimal diagnosis, subsequent treatment and prognosis, a thorough understanding of the embryology and pathogenesis is necessary. This manuscript provides an update about our current understanding of the development of the mandible, tongue, and palate and possible mechanisms involved in the development of RS. Additionally, we provide the reader with an up-to-date summary of the different etiologies of this phenotype and link this to the embryologic, developmental, and genetic mechanisms.

Skeletal Dysplasia Mutations Effect on Human Filamins' Structure and Mechanosensing

Cells' ability to sense mechanical cues in their environment is crucial for fundamental cellular processes, leading defects in mechanosensing to be linked to many diseases. The actin cross-linking protein Filamin has an important role in the conversion of mechanical forces into biochemical signals. Here, we reveal how mutations in Filamin genes known to cause Larsen syndrome and Frontometaphyseal dysplasia can affect the structure and therefore function of Filamin domains 16 and 17. Employing X-ray crystallography, the structure of these domains was first solved for the human Filamin B. The interaction seen between domains 16 and 17 is broken by shear force as revealed by steered molecular dynamics simulations. The effects of skeletal dysplasia associated mutations of the structure and mechanosensing properties of Filamin were studied by combining various experimental and theoretical techniques. The results showed that Larsen syndrome associated mutations destabilize or even unfold domain 17. Interestingly, those Filamin functions that are mediated via domain 17 interactions with other proteins are not necessarily affected as strongly interacting peptide binding to mutated domain 17 induces at least partial domain folding. Mutation associated to Frontometaphyseal dysplasia, in turn, transforms 16-17 fragment from compact to an elongated form destroying the force-regulated domain pair.

Neuroimaging Findings in Pediatric Genetic Skeletal Disorders: A Review

Genetic skeletal disorders (GSDs) are a heterogeneous group characterized by an intrinsic abnormality in growth and (re-)modeling of cartilage and bone. A large subgroup of GSDs has additional involvement of other structures/organs beside the skeleton, such as the central nervous system (CNS). CNS abnormalities have an important role in long-term prognosis of children with GSDs and should consequently not be missed. Sensitive and specific identification of CNS lesions while evaluating a child with a GSD requires a detailed knowledge of the possible associated CNS abnormalities. Here, we provide a pattern-recognition approach for neuroimaging findings in GSDs guided by the obvious skeletal manifestations of GSD. In particular, we summarize which CNS findings should be ruled out with each GSD. The diseases (n = 180) are classified based on the skeletal involvement (1. abnormal metaphysis or epiphysis, 2. abnormal size/number of bones, 3. abnormal shape of bones and joints, and 4. abnormal dynamic or structural changes). For each disease, skeletal involvement was defined in accordance with Online Mendelian Inheritance in Man. Morphological CNS involvement has been described based on extensive literature search. Selected examples will be shown based on prevalence of the diseases and significance of the CNS involvement. CNS involvement is common in GSDs. A wide spectrum of morphological abnormalities is associated with GSDs. Early diagnosis of CNS involvement is important in the management of children with GSDs. This pattern-recognition approach aims to assist and guide physicians in the diagnostic work-up of CNS involvement in children with GSDs and their management.

Mutations in MAP3K7 that Alter the Activity of the TAK1 Signaling Complex Cause Frontometaphyseal Dysplasia

Frontometaphyseal dysplasia (FMD) is a progressive sclerosing skeletal dysplasia affecting the long bones and skull. The cause of FMD in some individuals is gain-of-function mutations in FLNA, although how these mutations result in a hyperostotic phenotype remains unknown. Approximately one half of individuals with FMD have no identified mutation in FLNA and are phenotypically very similar to individuals with FLNA mutations, except for an increased tendency to form keloid scars. Using whole-exome sequencing and targeted Sanger sequencing in 19 FMD-affected individuals with no identifiable FLNA mutation, we identified mutations in two genes-MAP3K7, encoding transforming growth factor β (TGF-β)-activated kinase (TAK1), and TAB2, encoding TAK1-associated binding protein 2 (TAB2). Four mutations were found in MAP3K7, including one highly recurrent (n = 15) de novo mutation (c.1454C>T [ p.Pro485Leu]) proximal to the coiled-coil domain of TAK1 and three missense mutations affecting the kinase domain (c.208G>C [p.Glu70Gln], c.299T>A [p.Val100Glu], and c.502G>C [p.Gly168Arg]). Notably, the subjects with the latter three mutations had a milder FMD phenotype. An additional de novo mutation was found in TAB2 (c.1705G>A, p.Glu569Lys). The recurrent mutation does not destabilize TAK1, or impair its ability to homodimerize or bind TAB2, but it does increase TAK1 autophosphorylation and alter the activity of more than one signaling pathway regulated by the TAK1 kinase complex. These findings show that dysregulation of the TAK1 complex produces a close phenocopy of FMD caused by FLNA mutations. Furthermore, they suggest that the pathogenesis of some of the filaminopathies caused by FLNA mutations might be mediated by misregulation of signaling coordinated through the TAK1 signaling complex.

Maxillofacial Changes in Melnick-Needles Syndrome

Background. Melnick-Needles Syndrome is rare congenital hereditary skeletal dysplasia caused by mutations in the FLNA gene, which codifies the protein filamin A. This condition leads to serious skeletal abnormalities, including the stomatognathic region. Case Presentation. This paper describes the case of a 13-year-old girl diagnosed with Melnick-Needles Syndrome presenting with different forms of skeletal dysplasia, such as cranial hyperostosis, short upper limbs, bowed long bones, metaphyseal thickening, genu valgum (knock-knee), shortened distal phalanges, narrow pelvis and shoulders, rib tapering and irregularities, elongation of the vertebrae, kyphoscoliosis, micrognathia, hypoplastic coronoid processes of the mandible, left stylohyoid ligament suggesting ossification, and dental development anomalies. Conclusion. Knowledge of this rare syndrome on the part of dentists is important due to the fact that this condition involves severe abnormalities of the stomatognathic system that cause an impact on the development of the entire face as well as functional and esthetic impairments.

Otopalatodigital spectrum disorders: refinement of the phenotypic and mutational spectrum

Otopalatodigital spectrum disorders (OPDSD) constitute a group of dominant X-linked osteochondrodysplasias including four syndromes: otopalatodigital syndromes type 1 and type 2 (OPD1 and OPD2), frontometaphyseal dysplasia, and Melnick-Needles syndrome. These syndromes variably associate specific facial and extremities features, hearing loss, cleft palate, skeletal dysplasia and several malformations, and show important clinical overlap over the different entities. FLNA gain-of-function mutations were identified in these conditions. FLNA encodes filamin A, a scaffolding actin-binding protein. Here, we report phenotypic descriptions and molecular results of FLNA analysis in a large series of 27 probands hypothesized to be affected by OPDSD. We identified 11 different missense mutations in 15 unrelated probands (n=15/27, 56%), of which seven were novel, including one of unknown significance. Segregation analyses within families made possible investigating 20 additional relatives carrying a mutation. This series allows refining the phenotypic and mutational spectrum of FLNA mutations causing OPDSD, and providing suggestions to avoid the overdiagnosis of OPD1.

Low Density Lipoprotein Receptor Related Proteins as Regulators of Neural Stem and Progenitor Cell Function

The central nervous system (CNS) is a highly organised structure. Many signalling systems work in concert to ensure that neural stem cells are appropriately directed to generate progenitor cells, which in turn mature into functional cell types including projection neurons, interneurons, astrocytes, and oligodendrocytes. Herein we explore the role of the low density lipoprotein (LDL) receptor family, in particular family members LRP1 and LRP2, in regulating the behaviour of neural stem and progenitor cells during development and adulthood. The ability of LRP1 and LRP2 to bind a diverse and extensive range of ligands, regulate ligand endocytosis, recruit nonreceptor tyrosine kinases for direct signal transduction and signal in conjunction with other receptors, enables them to modulate many crucial neural cell functions.

When Closure Fails: What the Radiologist Needs to Know About the Embryology, Anatomy, and Prenatal Imaging of Ventral Body Wall Defects

Ventral body wall defects (VBWDs) are one of the main categories of human congenital malformations, representing a wide and heterogeneous group of defects sharing a common feature, that is, herniation of one or more viscera through a defect in the anterior body wall. Gastroschisis and omphalocele are the 2 most common congenital VBWDs. Other uncommon anomalies include ectopia cordis and pentalogy of Cantrell, limb-body wall complex, and bladder and cloacal exstrophy. Although VBWDs are associated with multiple abnormalities with distinct embryological origins and that may affect virtually any system organs, at least in relation to anterior body wall defects, they are thought (except for omphalocele) to share a common embryologic mechanism, that is, a failure involving the lateral body wall folds responsible for closing the thoracic, abdominal, and pelvic portions of the ventral body wall during the fourth week of development. Additionally, many of the principles of diagnosis and management are similar for these conditions. Fetal ultrasound (US) in prenatal care allows the diagnosis of most of such defects with subsequent opportunities for parental counseling and optimal perinatal management. Fetal magnetic resonance imaging may be an adjunct to US, providing global and detailed anatomical information, assessing the extent of defects, and also helping to confirm the diagnosis in equivocal cases. Prenatal imaging features of VBWDs may be complex and challenging, often requiring from the radiologist a high level of suspicion and familiarity with the imaging patterns. Because an appropriate management is dependent on an accurate diagnosis and assessment of defects, radiologists should be able to recognize and distinguish between the different VBWDs and their associated anomalies. In this article, we review the relevant embryology of VBWDs to facilitate understanding of the pathologic anatomy and diagnostic imaging approach. Features will be illustrated with prenatal US and magnetic resonance imaging and correlated with postnatal and clinical imaging.

Grb7 and Filamin-a associate and are colocalized to cell membrane ruffles upon EGF stimulation

Grb7 is an adaptor molecule mediating signal transduction from multiple cell surface receptors to diverse downstream pathways. Grb7, along with Grb10 and Grb14, make up the Grb7 protein family. This protein family has been shown to be overexpressed in certain cancers and cancer cell lines. Grb7 and a receptor tyrosine kinase, ErbB2, are overexpressed in 20-30% of breast cancers. Grb7 overexpression has been linked to enhanced cell migration and metastasis, although the participants in these pathways have not been fully determined. In this study, we report the Grb7 protein interacts with Filamin-a, an actin-crosslinking component of the cell cytoskeleton. Additionally, we have demonstrated the interaction between Grb7 and Flna is specific to the RA-PH domains of Grb7, and the immunoglobulin-like repeat 16-19 domains of Flna. We demonstrate that full-length Grb7 and Flna interact in the mammalian cellular environment, as well as in vitro. Immunofluorescent microscopy shows potential co-localization of Grb7 and Flna in membrane ruffles upon epidermal growth factor stimulation. These studies are amongst the first to establish a clear connection between Grb7 signaling and cytoskeletal remodeling.

Airway management of a child with frontometaphyseal dysplasia (Gorlin Cohen syndrome)

Frontometaphyseal dysplasia (FMD), also called Gorlin-Cohen syndrome, is a rare hereditary X-linked dominant craniotubular bone disorder. The presentation describes the airway management of a 2-year-old child suffering from FMD with significant retrognathia, posted for major long bone corrective osteotomy. Induction with a combination of dexmedetomidine and ketamine preceded a successful endotracheal intubation under spontaneous ventilation.

A syndrome of facial dysmorphism, cubital pterygium, short distal phalanges, swan neck deformity of fingers, and scoliosis

We report on an adolescent girl with sparse scalp hair, wide columella extending below alae nasi, webbing at elbows, broad finger tips, short distal phalanx of fingers, swan neck deformity of fingers, scoliosis, tall vertebrae, short fibulae, short fourth metatarsal bone, abnormal distal humeri, and unilateral clubfoot at birth. The combination of these features represents a novel phenotype. We sequenced the protein-coding regions of the FLNA and FLNB genes and did not observe any pathogenic sequence variation. Chromosomal microarray revealed a de novo copy number variation of uncertain clinical significance on 7p22.3.

Correction of spine deformity in patients with Melnick-needles syndrome: report of 2 cases and literature review

BACKGROUND

Melnick-Needles syndrome (MNS) is a rare X-linked dominant disorder affecting the skeletal system and connective tissue. To date, < 70 cases with MNS have been documented. Although few reports in the literature have shown that these patients might develop kyphoscoliosis, there is no report regarding long-term follow-up of patients with MNS undergo spine surgery. The aim of this study is to describe 2 unique cases of MNS with long-term follow-up after instrumented posterior spinal fusion, multiple-level Ponte osteotomies, and pedicle subtraction osteotomies.

METHODS

A 17-year-old female patient (patient 1) was evaluated for the first time at our institution. She was diagnosed with MNS, severe kyphoscoliosis, and restrictive lung disease. After pulmonary function improvement, she underwent posterior spinal fusion. Halo-femoral traction with gradual weight increase was used a week before spinal surgery. Surgical correction of her spinal deformity was achieved through a hooks-and-wires construct. The second patient was an 18-year-old female (patient 2) who carried the diagnosis of MNS when she was first seen at our institution. She had a significant thoracolumbar junction kyphosis and gibbous. She also suffered from significant pulmonary disease with a stent in her right main stem bronchus. A posterior procedure consisting of multiple-level Ponte osteotomies and pedicle subtraction osteotomy at L2 was carried out.

RESULTS

Eight- and 5-year follow-up of patients 1 and 2, respectively, demonstrated solid fusion, a well-maintained correction, and no evidence of implant breakage.

CONCLUSIONS

The reported cases add to the literature of excellent long-term results of spinal deformity correction with instrumented posterior spinal fusion in patients with MNS. Patients with this condition should be closely monitored from early childhood for the development of spine deformity so that early referral to a spine surgeon can be made followed by appropriate treatment, if necessary.

Growth retardation, intellectual disability, facial anomalies, cataract, thoracic hypoplasia, and skeletal abnormalities: a novel phenotype

We report on a 14-year-old girl with growth deficiency, microcephaly, intellectual disability, distinctive dysmorphic features (bulbous nose with wide nasal base, hypotelorism, deeply set eyes, protruding cupped ears, and thick lower lip), cataract, pigmentary retinopathy, hypoplastic thorax, kyphoscoliosis, and unusual skeletal changes but without chromosomal imbalances detected by array-CGH who probably represents a novel phenotype.

Abnormal facial appearance, body asymmetry, limb deformities, and internal malformations

We describe a newborn girl with multiple congenital anomalies and abnormal phenotype comprising underdeveloped corpus callosum with ventriculomegaly, chorioretinal atrophy, pulmonary arterial hypertension, annular pancreas, horseshoe kidney, asymmetric limb and chest anomalies, spinal segmentation defects, hypertrichosis, and unusual face with large anterior fontanel, high anterior hairline, broad forehead, mildly underdeveloped midface, hypertelorism, depressed nasal bridge, short and upturned nose, large mouth, retrognathia, and large and malformed ears. Work-up included cytogenetic studies of lymphocytes and skin fibroblasts, subtelomere Multiplex Ligation-dependent Probe Amplification (MLPA), whole-genome oligo-array, and molecular analysis of SETBP1 and NSDHL: no abnormalities were found. Mucopolysaccharide urinary excretion was elevated. Results of metabolic studies for sterol and peroxisomal abnormalities in fibroblasts were normal. Additional electronic microscopy studies in skin fibroblasts did not show evidence for storage in fibroblasts or lysosomal changes. Nosologic considerations allowed exclusion of Schinzel-Giedion and Urioste syndrome. This condition seems not to have been described before; a segregating Mendelian mutation is assumed.

Structure of filamin A immunoglobulin-like repeat 10 from Homo sapiens

Filamin A (FlnA) plays a critical role in cytoskeletal organization, cell motility and cellular signaling. FlnA utilizes different binding sites on a series of 24 immunoglobulin-like domains (Ig repeats) to interact with diverse cytosolic proteins and with cytoplasmic portions of membrane proteins. Mutations in a specific domain, Ig10 (FlnA-Ig10), are correlated with two severe forms of the otopalatodigital syndrome spectrum disorders Melnick-Needles syndrome and frontometaphyseal dysplasia. The crystal structure of FlnA-Ig10 determined at 2.44 Å resolution provides insight into the perturbations caused by these mutations.

In-frame deletion in FLNA causing familial periventricular heterotopia with skeletal dysplasia in males

Periventricular heterotopia (PH) is an etiologically heterogeneous disorder characterized by nodules of neurons ectopically placed along the lateral ventricles. Truncating and missense mutations of the FLNA gene have been identified in almost 100% of families and 26% of sporadic patients with PH. The otopalatodigital syndrome spectrum is caused by distinct FLNA missense mutations or in-frame deletions disrupting the development of craniofacial and long bones. We report on a clinical, neuroimaging, X-ray, and molecular study of a family in which classical bilateral PH appeared as an isolated anatomic feature in the mother and was associated with skeletal abnormalities and facial dysmorphisms in her two sons. Both boys exhibited PH associated with flat face and spatulate finger tips, short broad phalanx and metacarpus, and bowed radius with dislocated wrist joints. All three patients harbored the c.7865_7870del in-frame deletion (p.2622_2623delDK) in the carboxyl-terminal domain (repeat 24) of FLNA. The X-inactivation observed in the mother was skewed towards the mutant allele, resulting in the preferential expression of the wild-type allele. The in-frame deletion in the carboxyl-terminal domain of FLNA caused a phenotype in which PH was associated with skeletal features suggestive of the otopalatodigital syndrome spectrum in boys. There appears to be a continuum among allelic disorders due to FLNA mutations.

Podosomal proteins as causes of human syndromes: a role in craniofacial development?

Podosomes and invadopodia are actin-rich protrusions of the plasma membrane important for matrix degradation and cell migration. Most of the information in this field has been obtained in cancer cells, where the presence of invadopodia has been related to increased invasiveness and metastatic potential. The importance of the related podosome structure in other pathological or physiological processes that require cell invasion is relatively unexplored. Recent evidence indicates that essential components of podosomes are responsible for several human syndromes, some of which are characterized by serious developmental defects involving the craniofacial area, skeleton and heart, and very poor prognosis. Here we will review them and discuss the possible role of podosomes as a player in correct embryo development.

Terminal osseous dysplasia is caused by a single recurrent mutation in the FLNA gene

Terminal osseous dysplasia (TOD) is an X-linked dominant male-lethal disease characterized by skeletal dysplasia of the limbs, pigmentary defects of the skin, and recurrent digital fibroma with onset in female infancy. After performing X-exome capture and sequencing, we identified a mutation at the last nucleotide of exon 31 of the FLNA gene as the most likely cause of the disease. The variant c.5217G>A was found in six unrelated cases (three families and three sporadic cases) and was not found in 400 control X chromosomes, pilot data from the 1000 Genomes Project, or the FLNA gene variant database. In the families, the variant segregated with the disease, and it was transmitted four times from a mildly affected mother to a more seriously affected daughter. We show that, because of nonrandom X chromosome inactivation, the mutant allele was not expressed in patient fibroblasts. RNA expression of the mutant allele was detected only in cultured fibroma cells obtained from 15-year-old surgically removed material. The variant activates a cryptic splice site, removing the last 48 nucleotides from exon 31. At the protein level, this results in a loss of 16 amino acids (p.Val1724_Thr1739del), predicted to remove a sequence at the surface of filamin repeat 15. Our data show that TOD is caused by this single recurrent mutation in the FLNA gene.

Mutational analysis of two boys with the severe perinatally lethal Melnick-Needles syndrome

Melnick-Needles syndrome (MNS) (OMIM 309350) is a rare, X-linked dominant condition, caused by mutations in the filamin A gene (FLNA, on Xq28). In females, the syndrome presents with bone dysplasia and characteristic facial changes. Affected males may show two different phenotypes. One is similar to the female phenotype and is seen in children born to unaffected mothers and suggesting new mutations. Alternatively, males born to affected mothers have an embryonic or perinatally lethal disorder. It has been claimed that MNS constitutes part of a spectrum including frontometaphyseal dysplasia, otopalatodigital syndrome type 1 (OPD1) and otopalatodigital syndrome type 2 (OPD2). These conditions are produced by different mutations in the filamin A gene (FLNA). MNS is caused by three different mutations in FLNA exon 22, to date detected only in females. We describe the clinical manifestations and present the results of FLNA exon 22 mutations screening in two boys with the perinatally lethal form of MNS and their affected mothers. In order to obtain DNA amplification from paraffin-embedded tissues, we designed a new method based on hemi-nested PCR. One of the children (and his mother) had a previously undescribed mutation produced by a double SNP in the positions 3776 and 3777 of the gene and leading to an amino acid substitution (NP_001447:p.[Gly1176Asp]). The second child (and his mother) had an already known mutation (NP_001447.2:p[.Ser1199Leu]). This is the first report confirming the presence FLNA mutations in boys with the perinatally lethal phenotype of MNS. (

The Erlenmeyer flask bone deformity in the skeletal dysplasias

Erlenmeyer flask bone deformity (EFD) is a long-standing term used to describe a specific abnormality of the distal femora. The deformity consists of lack of modeling of the di-metaphysis with abnormal cortical thinning and lack of the concave di-metaphyseal curve resulting in an Erlenmeyer flask-like appearance. Utilizing a literature review and cohort study of 12 disorders we found 20 distinct disorders were associated with EFD. We interrogated the International Skeletal Dysplasia Registry (ISDR) radiographic database (1988-2007) to determine which skeletal dysplasias or syndromes were highly associated with EFD, whether it was a uniform finding in these disorders, and if forms of EFD could be differentiated. EFD was classified into three groups. The first catogory was the typical EFD shaped bone (EFD-T) resultant from absent normal di-metaphyseal modeling with relatively normal appearing radiographic trabecular bone. EFD-T was identified in: frontometaphyseal dysplasia, craniometaphyseal dysplasia, craniodiaphyseal dysplasia, diaphyseal dysplasia-Engelmann type, metaphyseal dysplasia-Pyle type, Melnick-Needles osteodysplasty, and otopalatodigital syndrome type I. The second group was the atypical type (EFD-A) due to absence of normal di-metaphyseal modeling with abnormal radiographic appearance of trabecular bone and was seen in dysosteosclerosis and osteopetrosis. The third group was EFD-marrow expansion type (EFD-ME) in which bone marrow hyperplasia or infiltration leads to abnormal modeling (e.g., Gaucher disease). Further, radiographic review determined that it was not always a consistent finding and that there was variability in both appearance and location within the skeleton. This analysis and classification aided in differentiating disorders with the finding of EFD.

Angeborene Hirnfehlbildungen und geistige Behinderung

Hirnfehlbildungen sind klinisch und genetisch bedeutsame Ursachen für psychomotorische Entwicklungsstörungen und Epilepsien. Die diagnostische Einordnung erfolgt durch bildgebende Verfahren und ist die Grundlage für eine individuelle genetische Abklärung und für zuverlässige prognostische Aussagen. Für einen beträchtlichen Teil der Hirnfehlbildungen sind die molekularen Ursachen bereits bekannt. Mutationen in diesen Genen können mit milden Verlaufsformen assoziiert sein, bis hin zur geistigen Behinderung ohne strukturelle Hirnfehlbildungen. Die Aufklärung der molekulargenetischen Ursachen von Hirnfehlbildungen trägt zum besseren Verständnis der Gehirnentwicklung bei und eröffnet gleichzeitig neue Einsichten in die Pathophysiologie von geistiger Behinderung und Epilepsie. Darüber hinaus ermöglicht sie die Erkennung und individuelle genetische Beratung von Anlageträgern und ist eine Voraussetzung für die pränatale molekulargenetische Diagnostik in Risikofamilien.

Syndromes and Disorders Associated with Omphalocele (III): Single Gene Disorders, Neural Tube Defects, Diaphragmatic Defects and Others

Omphalocele can be associated with single gene disorders, neural tube defects, diaphragmatic defects, fetal valproate syndrome, and syndromes of unknown etiology. This article provides a comprehensive review of omphalocele-related disorders: otopalatodigital syndrome type II; Melnick-Needles syndrome; Rieger syndrome; neural tube defects; Meckel syndrome; Shprintzen-Goldberg omphalocele syndrome; lethal omphalocele-cleft palate syndrome; cerebro-costo-mandibular syndrome; fetal valproate syndrome; Marshall-Smith syndrome; fibrochondrogenesis; hydrolethalus syndrome; Fryns syndrome; omphalocele, diaphragmatic defects, radial anomalies and various internal malformations; diaphragmatic defects, limb deficiencies and ossification defects of skull; Donnai-Barrow syndrome; CHARGE syndrome; Goltz syndrome; Carpenter syndrome; Toriello-Carey syndrome; familial omphalocele; Cornelia de Lange syndrome; C syndrome; Elejalde syndrome; Malpuech syndrome; cervical ribs, Sprengel anomaly, anal atresia and urethral obstruction; hydrocephalus with associated malformations; Kennerknecht syndrome; lymphedema, atrial septal defect and facial changes; and craniosynostosismental retardation syndrome of Lin and Gettig. Perinatal identification of omphalocele should alert one to the possibility of omphalocele-related disorders and familial inheritance and prompt a thorough genetic counseling for these disorders.