Richieri-Costa-Pereira syndrome is an autosomal-recessive acrofacial dysostosis characterized by mandibular median cleft associated with other craniofacial anomalies and severe limb defects. Learning ...and language disabilities are also prevalent. We mapped the mutated gene to a 122 kb region at 17q25.3 through identity-by-descent analysis in 17 genealogies. Sequencing strategies identified an expansion of a region with several repeats of 18- or 20-nucleotide motifs in the 5′ untranslated region (5′ UTR) of EIF4A3, which contained from 14 to 16 repeats in the affected individuals and from 3 to 12 repeats in 520 healthy individuals. A missense substitution of a highly conserved residue likely to affect the interaction of eIF4AIII with the UPF3B subunit of the exon junction complex in trans with an expanded allele was found in an unrelated individual with an atypical presentation, thus expanding mutational mechanisms and phenotypic diversity of RCPS. EIF4A3 transcript abundance was reduced in both white blood cells and mesenchymal cells of RCPS-affected individuals as compared to controls. Notably, targeting the orthologous eif4a3 in zebrafish led to underdevelopment of several craniofacial cartilage and bone structures, in agreement with the craniofacial alterations seen in RCPS. Our data thus suggest that RCPS is caused by mutations in EIF4A3 and show that EIF4A3, a gene involved in RNA metabolism, plays a role in mandible, laryngeal, and limb morphogenesis.
Abstract Low‐pass whole genome sequencing (LP‐WGS) has been applied as alternative method to detect copy number variants (CNVs) in the clinical setting. Compared with chromosomal microarray analysis ...(CMA), the sequencing‐based approach provides a similar resolution of CNV detection at a lower cost. In this study, we assessed the efficiency and reliability of LP‐WGS as a more affordable alternative to CMA. A total of 1363 patients with unexplained neurodevelopmental delay/intellectual disability, autism spectrum disorders, and/or multiple congenital anomalies were enrolled. Those patients were referred from 15 nonprofit organizations and university centers located in different states in Brazil. The analysis of LP‐WGS at 1x coverage (>50kb) revealed a positive testing result in 22% of the cases (304/1363), in which 219 and 85 correspond to pathogenic/likely pathogenic (P/LP) CNVs and variants of uncertain significance (VUS), respectively. The 16% (219/1363) diagnostic yield observed in our cohort is comparable to the 15%–20% reported for CMA in the literature. The use of commercial software, as demonstrated in this study, simplifies the implementation of the test in clinical settings. Particularly for countries like Brazil, where the cost of CMA presents a substantial barrier to most of the population, LP‐WGS emerges as a cost‐effective alternative for investigating copy number changes in cytogenetics.
Here we report on a Brazilian child who presented semilobar holoprosencephaly, frontonasal encephaloceles and bilateral cleft lip and palate. Malformations also included agenesis of the corpus ...callosum, abnormal cortical gyres, dilation of the aqueduct, bilateral endolymphatic sac, bilateral cystic cocci‐vestibular malformation, and a cribriform defect. The 3D TC craniofacial images showed abnormal frontonasal transition region, with a bone bifurcation, and partial agenesis of nasal bone. The trunk and upper and lower limbs were normal. To our knowledge, this rare association of holoprocensephaly with frontonaso‐orbital encephaloceles without limb anomalies has never been reported before. Karyotype was normal. SNP‐array showed no copy‐number alterations but revealed 25% of regions of homozygosity (ROH) with normal copy number, indicating a high coefficient of inbreeding, which significantly increases the risk for an autosomal recessive disorder. Whole exome sequencing analysis did not reveal any pathogenic or likely pathogenic variants. We discuss the possible influence of two variants of uncertain significance found within the patient's ROHs. First, a missense p.(Gly394Ser) in PCSK9, a gene involved in the regulation of plasma low‐density lipoprotein cholesterol. Second, an inframe duplication p.(Ala75_Ala81dup) in SP8, a zinc‐finger transcription factor that regulates signaling centers during craniofacial development. Further studies and/or the identification of other patients with a similar phenotype will help elucidate the genetic etiology of this complex case.
Acrofrontofacionasal dysostosis type 1 (AFFND1) is an extremely rare disorder characterized by several dysmorphic features, skeletal abnormalities and intellectual disability, and described only in ...seven patients in the literature. A biallelic variant in the Neuroblastoma Amplified Sequence (NBAS) gene was recently identified in two Indian patients with AFFND1. Here we report genetic investigation of AFFND1 in the originally described Brazilian families and the identification of an extremely rare, recessively-inherited, intronic variant in the Phosphatidylinositol Glycan class B (PIGB) gene NC_000015.10 (NM_004855.4): c.795-19T > G) in the affected individuals. The PIGB gene encodes an enzyme involved in the biosynthesis of the glycosylphosphatidylinositol (GPI) anchor, which is required for the post-translational modification of a large variety of proteins, enabling their correct cellular localization and function. Recessive variants in PIGB have previously been reported in individuals with a neurodevelopmental syndrome having partial overlap with AFFND1. In vitro assays demonstrated that the intronic variant leads to exon skipping, suggesting the Brazilian AFFND1 patients may be null for PIGB, in agreement with their severe clinical phenotype. These data increase the number of pathogenic variants in the PIGB gene, place AFFND1 among GPI deficiencies and extend the spectrum of phenotypes associated with GPI biosynthesis defects.
•AFFND1 is an ultra-rare disease with skeletal and developmental defects and intellectual disability.•The GPI anchor biosynthesis is a key molecular pathway in developmental processes.•The ER membrane protein PIGB is involved in late steps of GPI anchor biosynthesis.•A novel homozygous intronic variant in the PIGB gene cause AFFND1 in two Brazilian patients.•These data extend the phenotypic spectrum of PIGB variants and of inherited GPI deficiencies.
Biallelic loss-of-function mutations in the RNA-binding protein EIF4A3 cause Richieri-Costa-Pereira syndrome (RCPS), an autosomal recessive condition mainly characterized by craniofacial and limb ...malformations. However, the pathogenic cellular mechanisms responsible for this syndrome are entirely unknown. Here, we used two complementary approaches, patient-derived induced pluripotent stem cells (iPSCs) and conditional Eif4a3 mouse models, to demonstrate that defective neural crest cell (NCC) development explains RCPS craniofacial abnormalities. RCPS iNCCs have decreased migratory capacity, a distinct phenotype relative to other craniofacial disorders. Eif4a3 haploinsufficient embryos presented altered mandibular process fusion and micrognathia, thus recapitulating the most penetrant phenotypes of the syndrome. These defects were evident in either ubiquitous or NCC-specific Eif4a3 haploinsufficient animals, demonstrating an autonomous requirement of Eif4a3 in NCCs. Notably, RCPS NCC-derived mesenchymal stem-like cells (nMSCs) showed premature bone differentiation, a phenotype paralleled by premature clavicle ossification in Eif4a3 haploinsufficient embryos. Likewise, nMSCs presented compromised in vitro chondrogenesis, and Meckel's cartilage was underdeveloped in vivo. These findings indicate novel and essential requirements of EIF4A3 for NCC migration and osteochondrogenic differentiation during craniofacial development. Altogether, complementary use of iPSCs and mouse models pinpoint unique cellular mechanisms by which EIF4A3 mutation causes RCPS, and provide a paradigm to study craniofacial disorders.
Abstract
Context
The reproductive axis is controlled by a network of gonadotropin-releasing hormone (GnRH) neurons born in the primitive nose that migrate to the hypothalamus alongside axons of the ...olfactory system. The observation that congenital anosmia (inability to smell) is often associated with GnRH deficiency in humans led to the prevailing view that GnRH neurons depend on olfactory structures to reach the brain, but this hypothesis has not been confirmed.
Objective
The objective of this work is to determine the potential for normal reproductive function in the setting of completely absent internal and external olfactory structures.
Methods
We conducted comprehensive phenotyping studies in 11 patients with congenital arhinia. These studies were augmented by review of medical records and study questionnaires in another 40 international patients.
Results
All male patients demonstrated clinical and/or biochemical signs of GnRH deficiency, and the 5 men studied in person had no luteinizing hormone (LH) pulses, suggesting absent GnRH activity. The 6 women studied in person also had apulsatile LH profiles, yet 3 had spontaneous breast development and 2 women (studied from afar) had normal breast development and menstrual cycles, suggesting a fully intact reproductive axis. Administration of pulsatile GnRH to 2 GnRH-deficient patients revealed normal pituitary responsiveness but gonadal failure in the male patient.
Conclusions
Patients with arhinia teach us that the GnRH neuron, a key gatekeeper of the reproductive axis, is associated with but may not depend on olfactory structures for normal migration and function, and more broadly, illustrate the power of extreme human phenotypes in answering fundamental questions about human embryology.
Mandibulofacial dysostosis Bauru type: Refining the phenotype Moura, Priscila P.; Kokitsu‐Nakata, Nancy M.; Yatabe, Marília S. ...
American journal of medical genetics. Part A,
July 2017, 2017-Jul, 2017-07-00, 20170701, Letnik:
173, Številka:
7
Journal Article
Recenzirano
Mandibulofacial dysostosis (MFD) Bauru type (OMIM 604830) is a rare genetic condition characterized mainly by malar hypoplasia, orofacial cleft, and micrognathia. Here, we describe the clinical and ...radiographic sings of 13 individuals (12 female and 1 male) from eight unrelated kindreds with MFD Bauru type, including four previously reported cases, treated at the Hospital for Rehabilitation of Craniofacial Anomalies. The clinical phenotype was characterized by severe underdevelopment of mandible, midface hypoplasia, orofacial cleft, bitemporal narrowing, mild upper eyelid down slanting, high nasal bridge, thick and everted lower lip, minor ears abnormalities, and hearing loss. Radiographic aspects included downslanting of zygomatic arch, maxillary hypoplasia, microretrognathia, hypoplastic mandibular condyles, and ectopic external auditory canal. Recurrence was observed in two of eight families and the affected distribution pattern was compatible with autosomal dominant inheritance in one and autosomal recessive in another, indicating possible genetic heterogeneity for this condition. Clinical and radiographic findings in this report contribute to the delineation of this rare MFD.
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