Integrative analysis of Lunatic Fringe variants associated with spondylocostal dysostosis type-III.

Lunatic Fringe (LFNG) is required for spinal development. Biallelic pathogenic variants cause spondylocostal dysostosis type-III (SCD3), a rare disease generally characterized by malformed, asymmetrical, and attenuated development of the vertebral column and ribs. However, a variety of SCD3 cases reported have presented with additional features such as auditory alterations and digit abnormalities. There has yet to be a single, comprehensive, functional evaluation of causative LFNG variants and such analyses could unveil molecular mechanisms for phenotypic variability in SCD3. Therefore, nine LFNG missense variants associated with SCD3, c.564C>A, c.583T>C, c.842C>A, c.467T>G, c.856C>T, c.601G>A, c.446C>T, c.521G>A, and c.766G>A, were assessed in vitro for subcellular localization and protein processing. Glycosyltransferase activity was quantified for the first time in the c.583T>C, c.842C>A, and c.446C>T variants. Primarily, our results are the first to satisfy American College of Medical Genetics and Genomics PS3 criteria (functional evidence via well-established assay) for the pathogenicity of c.583T>C, c.842C>A, and c.446C>T, and replicate this evidence for the remaining six variants. Secondly, this work indicates that all variants that prevent Golgi localization also lead to impaired protein processing. It appears that the FRINGE domain is responsible for this phenomenon. Thirdly, our data suggests that variant proximity to the catalytic residue may influence whether LFNG is improperly trafficked and/or enzymatically dysfunctional. Finally, the phenotype of the axial skeleton, but not elsewhere, may be modulated in a variant-specific fashion. More reports are needed to continue testing this hypothesis. We anticipate our data will be used as a basis for discussion of genotype-phenotype correlations in SCD3.

Clinical trials in skeletal dysplasia: a paradigm for treating rare diseases.

BACKGROUND: Genetic skeletal dysplasia conditions (GSDs) account for 5% of all birth defects. Until recently, targeted treatments were only available for select few conditions; 1 however, opportunities arising from developments in molecular diagnostic technologies are now leading to unparalleled therapeutic advances. This review explores current GSD clinical trials, their challenges and the hopes for the future. SOURCES OF DATA: A systematic literature search of relevant original articles, reviews and meta-analyses restricted to English was conducted using PubMed up to February 2020 regarding emerging GSD therapies. AREAS OF AGREEMENT: We discuss current clinical trials for in achondroplasia, osteopetrosis, osteogenesis imperfecta, hypophosphataemic rickets, hypophosphatasia and fibrous ossificans progressiva. AREAS OF CONTROVERSY: We explore challenges in GSD drug development from clinician input, cost-effectiveness and evidenced-based practice. GROWING POINTS: We explore opportunities brought by earlier diagnosis, its treatment impact and the challenges of gene editing. AREAS TIMELY FOR DEVELOPING RESEARCH: We horizon scan for future clinical trials.

Nosology and classification of genetic skeletal disorders: 2019 revision.

The application of massively parallel sequencing technology to the field of skeletal disorders has boosted the discovery of the underlying genetic defect for many of these diseases. It has also resulted in the delineation of new clinical entities and the identification of genes and pathways that had not previously been associated with skeletal disorders. These rapid advances have prompted the Nosology Committee of the International Skeletal Dysplasia Society to revise and update the last (2015) version of the Nosology and Classification of Genetic Skeletal Disorders. This newest and tenth version of the Nosology comprises 461 different diseases that are classified into 42 groups based on their clinical, radiographic, and/or molecular phenotypes. Remarkably, pathogenic variants affecting 437 different genes have been found in 425/461 (92%) of these disorders. By providing a reference list of recognized entities and their causal genes, the Nosology should help clinicians achieve accurate diagnoses for their patients and help scientists advance research in skeletal biology.

Paleodysmorphology and paleoteratology: Diagnosing and interpreting congenital conditions of the skeleton in anthropological contexts.

Most congenital conditions have low prevalence, but collectively they occur in a few percent of all live births. Congenital conditions are rarely encountered in anthropological studies, not least because many of them have no obvious effect on the skeleton. Here, we discuss two groups of congenital conditions that specifically affect the skeleton, either qualitatively or quantitatively. Skeletal dysplasias (osteochondrodysplasias) interfere with the histological formation, growth and maturation of skeletal tissues leading to diminished postural length, but the building plan of the body is unaffected. Well- known skeletal dysplasias represented in the archeological record include osteogenesis imperfecta and achondroplasia. Dysostoses, in contrast, interfere with the building plan of the body, leading to e.g. missing or extraskeletal elements, but the histology of the skeletal tissues is unaffected. Dysostoses can concern the extremities (e.g., oligodactyly and polydactyly), the vertebral column (e.g., homeotic and meristic anomalies), or the craniofacial region. Conditions pertaining to the cranial sutures, i.e., craniosynostoses, can be either skeletal dysplasias or dysostoses. Congenital conditions that are not harmful to the individual are known as anatomical variations, several of which have a high and population-specific prevalence that could potentially make them useful for determining ethnic origins. In individual cases, specific congenital conditions could be determinative in establishing identity, provided that ante-mortem registration of those conditions was ensured. Clin. Anat. 29:878-891, 2016. © 2016 The Authors Clinical Anatomy published by Wiley Periodicals, Inc. on behalf of American Association of Clinical Anatomists.

Experience of a skeletal dysplasia registry in Turkey: a five-years retrospective analysis.

This study shares data on 417 patients with genetic disorders of skeleton including 10 fetal autopsies encountered in a 5-year period at a tertiary university hospital in Ankara, Turkey. We included patients with osteochondrodysplasias, excluding overgrowth syndromes, dysostoses, and craniofacial syndromes. When grouped according to the "International Skeletal Dysplasia Society 2010 classification" the most frequent group is "FGFR3 group" (achondroplasia). "Decreased bone density group" takes the second place, consistent with the literature. We also demonstrated, a relatively higher frequency of recessively inherited skeletal dysplasias when the diagnosis is an entity other than achondroplasia or osteogenesis imperfecta. The literature on the incidence of genetic disorders of skeleton from the Middle East and Eastern Mediterranean is limited to fetal and neonatal autopsies or birth prevelance reports. The higher rate of consanguineous marriages which increases the frequency of autosomal recessive entities makes it difficult to apply data from other parts of the world. Total consanguinity rate among parents in our study was 53% and there were regional differences. The highest (79%) was among parents from South-east Anatolia. This study is the first broad retrospective analysis of genetic disorders of skeleton from our region. We aim to provide a descriptive source for future studies and discuss our findings in comparison to reports from other parts of the world.

Practical Considerations in Computerized Surgical Planning for Frontofacial Surgery.

The field of frontofacial surgery has advanced considerably, building on the pioneering techniques of Paul Tessier, with computerized surgical planning (CSP) emerging as a critical component. CSP has enhanced the precision and efficiency of surgeries for craniofacial dysostoses and hypertelorism, resulting in improved outcomes. This review delves into the importance of understanding orbital anatomy and the crucial bony and soft tissue landmarks essential to the application of CSP in frontofacial procedures, encompassing Le Fort III and monobloc advancements, as well as the correction of hypertelorism.

Children with Rare Nager Syndrome-Literature Review, Clinical and Physiotherapeutic Management.

Nager syndrome is a rare human developmental disorder characterized by craniofacial defects including the downward slanting of the palpebral fissures, cleft palate, limb deformities, mandibular hypoplasia, hypoplasia or absence of thumbs, microretrognathia, and ankylosis of the temporomandibular joint. The prevalence is very rare and the literature describes only about a hundred cases of Nager syndrome. There is evidence of autosomal dominant and autosomal recessive inheritance for Nager syndrome, suggesting genetic heterogeneity. The majority of the described causes of Nager syndrome include pathogenic variants in the SF3B4 gene, which encodes a component of the spliceosome; therefore, the syndrome belongs to the spliceosomopathy group of diseases. The diagnosis is made on the basis of physical and radiological examination and detection of mutations in the SF3B4 gene. Due to the diversity of defects associated with Nager syndrome, patients require multidisciplinary, complex, and long-lasting treatment. Usually, it starts from birth until the age of twenty years. The surgical procedures vary over a patient's lifetime and are related to the needed function. First, breathing and feeding must be facilitated; then, oral and facial clefts should be addressed, followed by correcting eyelid deformities and cheekbone reconstruction. In later age, a surgery of the nose and external ear is performed. Speech and hearing disorders require specialized logopedic treatment. A defect of the thumb is treated by transplanting a tendon and muscle or transferring the position of the index finger. In addition to surgery, in order to maximize a patient's benefit and to reduce functional insufficiency, complementary treatments such as rehabilitation and physiotherapy are recommended. In our study, we describe eight patients of different ages with various cases of Nager syndrome. The aim of our work was to present the actual genetic knowledge on this disease and its treatment procedures.

Management of Sagittal and Lambdoid Craniosynostosis: Open Cranial Vault Expansion and Remodeling.

The prevalence of sagittal and lambdoid suture craniosynostosis differs considerably, as they are notably the most and least prevalent sutures involved in isolated suture craniosynostosis, respectively. The goals of reconstructing the cranial vault in both entities is the same: to release the fused suture, expand cranial volume, restore normal head shape and morphology, and allow for normal growth of the cranial vault. With regards to sagittal suture synostosis, opinions vary on whether reconstruction should focus on either the anterior or poster cranial vault. In contrast, the poster cranial vault is always targeted in lambdoid suture craniosynostosis.

Possible autosomal recessive inheritance in a neonate with Nager syndrome: Case report.

INTRODUCTION AND IMPORTANCE: Nager syndrome is a rare inherited disorder characterized by craniofacial malformations occurring in association with abnormalities of the thumb and radial parts of the forearm. CASE PRESENTATION: We presented a 18-day-old boy with Nager syndrome. The diagnosis based on his clinical presentation. He was born to non-consanguineous healthy parents. He had three deceased siblings who had similar clinical features. This family gave further evidence for autosomal recessive inheritance. Nager syndrome can be detected using prenatal screening ultrasound. CLINICAL DISCUSSION: The etiology of Nager Syndrome is poorly described. Most cases arise spontaneously, although autosomal recessive and autosomal dominant modes of inheritance have been reported. Nager syndrome is suspected to have an autosomal recessive inheritance pattern, when unaffected parents have more than one affected child. CONCLUSION: Treatment required the coordinated efforts of a team of specialists. Many manifestations of the disease can be improved by surgery and other supportive treatments.

Targeted Next-Generation Sequencing in the Diagnosis of Facial Dysostoses.

BACKGROUND: Defects in the development of the first and second pharyngeal arches and their derivatives result in abnormal formation of the craniofacial complex, consequently giving rise to facial dysostoses (FDs). FDs represent a group of rare and highly heterogeneous disease entities that encompass mandibulofacial dysostoses (MFDs) with normal extremities and acrofacial dysostoses (AFDs) with limb anomalies in addition to craniofacial defects. METHODS: We examined 11 families with variable clinical symptoms of FDs, in most of which only one member was affected. We applied two custom gene panels-first comprising 37 genes related to the genetic disorders of craniofacial development such as FDs (On-Demand AmpliSeq Thermo Fisher Scientific gene panel with two primer pools) and second composed of 61 genes and 11 single nucleotide variants (SNVs) known to be involved in the development of skull malformations, mainly in the form of craniosynostoses (SureSelect Agilent Technologies). Targeted next-generation sequencing (NGS) was performed using the Ion Torrent S5 platform. To confirm the presence of each detected variant, we have analyzed a genomic region of interest using Sanger sequencing. RESULTS: In this paper, we summarized the results of custom targeted gene panel sequencing in the cohort of sixteen patients from 11 consecutive families affected by distinct forms of FDs. We have found three novel pathogenic variants in the TCOF1 gene-c.2145_2148dupAAAG p.(Ser717Lysfs ∗42), c.4370delA p.(Lys1457Argfs ∗118), c.83G>C p.(Arg28Pro) causing Treacher Collins syndrome type 1, two novel missense variants in the EFTUD2 gene-c.491A>G p.(Asp164Gly) and c.779T>A p.(Ile260Asn) in two female patients affected by acrofacial dysostosis Guion-Almeida type, one previously reported-c.403C>T (p.Arg135Cys), as well as one novel missense variant-c.128C>T p.(Pro43Leu) in the DHODH gene in the male patient with Miller syndrome and finally one known pathogenic variant c.574G>T p.(Glu192∗) in the SF3B4 gene in the patient with Nager syndrome. CONCLUSION: Our study confirms the efficiency and clinical utility of the targeted gene panel sequencing and shows that this strategy is suitable and efficient in the molecular screening of variable forms of FDs.

Pyknodysostosis: report of a rare case with review of literature.

Pyknodysostosis is a rare autosomal recessive disorder characterized by the post natal onset of short limbs, short stature, and generalized hyperostosis along with acro-osteolysis with sclerosis of the terminal phalanges, a feature that is considered essentially pathognomonic. Other features include persistence of fontanelles, delayed closure of sutures, wormian bones, absence of frontal sinuses, and obtuse mandibular gonial angle with relative mandibular prognathism. We report a case of 17-year-old girl who presented with a chief complaint of retention of deciduous teeth. General physical examination demonstrated short stature, frontal and parietal bossing, depressed nasal bridge, beaked nose, hypoplastic midface, wrinkled skin over the finger tips, and nail abnormalities. Radiographs showed multiple impacted permanent and supernumerary teeth, hypoplastic paranasal sinuses with acro-osteolysis of terminal phalanges, and open fontanelles, and sutures along with wormian bones in the lambdoidal region.