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Journal of Pediatric Genetics Dec 2016Genetic etiologies for congenital anomalies of the facial skeleton, namely, the maxilla and mandible, are important to understand and recognize. Malocclusions occur when... (Review)
Review
Genetic etiologies for congenital anomalies of the facial skeleton, namely, the maxilla and mandible, are important to understand and recognize. Malocclusions occur when there exist any significant deviation from what is considered a normal relationship between the upper jaw (maxilla) and the lower jaw (mandible). They may be the result of anomalies of the teeth alone, the bones alone, or both. A number of genes play a role in the facial skeletal development and are regulated by a host of additional regulatory molecules. As such, numerous craniofacial syndromes specifically affect the development of the jaws. The following review discusses several genetic anomalies that specifically affect the bones of the craniofacial skeleton and lead to malocclusion.
PubMed: 27895973
DOI: 10.1055/s-0036-1593505 -
Lin Chuang Er Bi Yan Hou Tou Jing Wai... Jan 2022To explore the clinical diagnosis, otological treatment and molecular etiology in a rare syndromic hearing loss case characterized by mandibulofacial dysostosis with... (Review)
Review
To explore the clinical diagnosis, otological treatment and molecular etiology in a rare syndromic hearing loss case characterized by mandibulofacial dysostosis with microcephaly(MFDM). The proband underwent detailed history collection, systematic physical examination and phenotypic analysis, as well as audiological examination, chest X-ray, temporal bone CT and brain MRI and other imaging examinations. The blood DNA of the proband and his parents was extracted and tested by the whole exom sequencing. The EFTUD2-related-MFDM literatures published by the end of 2020 were searched and sifted in PubMed and CNKI databases,the clinical characteristics of MFDM were summarized. In this study, the patient presented with hypoplasia of auricle, micrognathia, microcephaly, developmental retardation, severe sensorineural hearing loss in both ears, and developmental malformation of middle and inner ear. Genetic analysis revealed a de novo deletion c.623_624delAT in EFTUD2 gene. According to the clinical features and genetic test results, the patient was diagnosed as MFDM. In order to solve the problem of hearing loss, the patient was further performed bilateral cochlear implantation, and part of the electrodes responded well during and after operation. This is the first domestic reported case of MFDM caused by EFTUD2 gene mutation. The key problem of cochlear implantation for this kind of patient is to avoid damaging the malformed facial nerve during the operation.The effect of speech rehabilitation after cochlear implant operation is related to many factors such as intelligence development of the patients.
Topics: Cochlear Implantation; Humans; Mandibulofacial Dysostosis; Microcephaly; Peptide Elongation Factors; Ribonucleoprotein, U5 Small Nuclear; Syndrome
PubMed: 34979617
DOI: 10.13201/j.issn.2096-7993.2022.01.008 -
American Journal of Medical Genetics.... Feb 2021Mandibulofacial dysostosis with microcephaly (MFDM) is due to haploinsufficiency of spliceosomal GTPase EFTUD2. Features include microcephaly, craniofacial...
Mandibulofacial dysostosis with microcephaly (MFDM) is due to haploinsufficiency of spliceosomal GTPase EFTUD2. Features include microcephaly, craniofacial dysmorphology, developmental disability, and other anomalies. We surveyed parents of individuals with MFDM to expand knowledge about health, development, and parental concerns. Participants included attendees of the inaugural MFDM family conference in June 2019 and members of the MFDM online group. To explore MFDM variable expressivity, we offered targeted Sanger sequencing for untested parents. Forty-seven parents participated in the survey. 59% of individuals with MFDM were male, with mean age 6.4 years (range 8 months to 49 years). Similar to the literature (n = 123), common features include microcephaly, cleft palate, choanal stenosis, tracheoesophageal fistula, heart problems, and seizures. New information includes airway intervention details, age-based developmental outcomes, rate of vision refractive errors, and lower incidences of prematurity and IUGR. Family concerns focused on development, communication, and increased support. Targeted Sanger sequencing for families of seven individuals demonstrated de novo variants, for a total of 91.9% de novo EFTUD2 variants (n = 34/37). This study reports the largest single cohort of individuals with MFDM, expands phenotypic spectrum and inheritance patterns, improves understanding of developmental outcomes and care needs, and identifies development as the biggest concern for parents.
Topics: Abnormalities, Multiple; Adolescent; Adult; Child; Child, Preschool; Cohort Studies; Female; GTP Phosphohydrolases; Genetic Predisposition to Disease; Haploinsufficiency; Humans; Infant; Male; Mandibulofacial Dysostosis; Microcephaly; Middle Aged; Mutation; Peptide Elongation Factors; Phenotype; Ribonucleoprotein, U5 Small Nuclear; Spliceosomes; Young Adult
PubMed: 33247512
DOI: 10.1002/ajmg.a.61977 -
Frontiers in Bioscience (Landmark... Jan 2017Mammalian mitochondrial DNA (mtDNA) exists in structures called nucleoids, which correspond to the configuration of nuclear DNA. Mitochondrial transcription factor A... (Review)
Review
Mammalian mitochondrial DNA (mtDNA) exists in structures called nucleoids, which correspond to the configuration of nuclear DNA. Mitochondrial transcription factor A (TFAM), first cloned as an mtDNA transcription factor, is critical for packaging and maintaining mtDNA. To investigate functional aspects of TFAM, we identified many RNA-binding proteins as candidate TFAM interactors, including ERAL1 and p32. In this review, we first describe the functions of TFAM, replication proteins such as polymerase gamma and Twinkle, and mitochondrial RNA binding proteins. We describe the role of mitochondrial nucleic acid binding proteins within the mitochondrial matrix and two oxidative phosphorylation-related proteins within the mitochondrial intermembrane space. We then discuss how mitochondrial dysfunction is related to several diseases, including mitochondrial respiratory disease, Miller syndrome and cancer. We also describe p32 knockout mice, which are embryonic lethal and exhibit respiratory chain defects. Miller syndrome is a recessive disorder characterized by postaxial acrofacial dysostosis and caused by a mutation in . Finally, we explain that p32 and mitochondrial creatine kinase may be novel markers for the progression of prostate cancer.
Topics: Abnormalities, Multiple; Animals; Carrier Proteins; DNA Helicases; DNA Polymerase gamma; DNA, Mitochondrial; DNA-Binding Proteins; GTP-Binding Proteins; Humans; Limb Deformities, Congenital; Mandibulofacial Dysostosis; Mice; Micrognathism; Mitochondrial Diseases; Mitochondrial Proteins; Mutation; Neoplasm Proteins; Neoplasms; RNA-Binding Proteins; Ribonuclease P; Transcription Factors
PubMed: 27814609
DOI: 10.2741/4479 -
American Journal of Human Genetics May 2023Heterozygous pathogenic variants in POLR1A, which encodes the largest subunit of RNA Polymerase I, were previously identified as the cause of acrofacial dysostosis,...
Heterozygous pathogenic variants in POLR1A, which encodes the largest subunit of RNA Polymerase I, were previously identified as the cause of acrofacial dysostosis, Cincinnati-type. The predominant phenotypes observed in the cohort of 3 individuals were craniofacial anomalies reminiscent of Treacher Collins syndrome. We subsequently identified 17 additional individuals with 12 unique heterozygous variants in POLR1A and observed numerous additional phenotypes including neurodevelopmental abnormalities and structural cardiac defects, in combination with highly prevalent craniofacial anomalies and variable limb defects. To understand the pathogenesis of this pleiotropy, we modeled an allelic series of POLR1A variants in vitro and in vivo. In vitro assessments demonstrate variable effects of individual pathogenic variants on ribosomal RNA synthesis and nucleolar morphology, which supports the possibility of variant-specific phenotypic effects in affected individuals. To further explore variant-specific effects in vivo, we used CRISPR-Cas9 gene editing to recapitulate two human variants in mice. Additionally, spatiotemporal requirements for Polr1a in developmental lineages contributing to congenital anomalies in affected individuals were examined via conditional mutagenesis in neural crest cells (face and heart), the second heart field (cardiac outflow tract and right ventricle), and forebrain precursors in mice. Consistent with its ubiquitous role in the essential function of ribosome biogenesis, we observed that loss of Polr1a in any of these lineages causes cell-autonomous apoptosis resulting in embryonic malformations. Altogether, our work greatly expands the phenotype of human POLR1A-related disorders and demonstrates variant-specific effects that provide insights into the underlying pathogenesis of ribosomopathies.
Topics: Humans; Mice; Animals; Mandibulofacial Dysostosis; Apoptosis; Mutagenesis; Ribosomes; Phenotype; Neural Crest; Craniofacial Abnormalities
PubMed: 37075751
DOI: 10.1016/j.ajhg.2023.03.014 -
Frontiers in Pediatrics 2023Mandibulo-Facial Dysostosis with Microcephaly (MFDM) is a rare disease with a broad spectrum of symptoms, characterized by zygomatic and mandibular hypoplasia,...
INTRODUCTION
Mandibulo-Facial Dysostosis with Microcephaly (MFDM) is a rare disease with a broad spectrum of symptoms, characterized by zygomatic and mandibular hypoplasia, microcephaly, and ear abnormalities. Here, we aimed at describing the external ear phenotype of MFDM patients, and train an Artificial Intelligence (AI)-based model to differentiate MFDM ears from non-syndromic control ears (binary classification), and from ears of the main differential diagnoses of this condition (multi-class classification): Treacher Collins (TC), Nager (NAFD) and CHARGE syndromes.
METHODS
The training set contained 1,592 ear photographs, corresponding to 550 patients. We extracted 48 patients completely independent of the training set, with only one photograph per ear per patient. After a CNN-(Convolutional Neural Network) based ear detection, the images were automatically landmarked. Generalized Procrustes Analysis was then performed, along with a dimension reduction using PCA (Principal Component Analysis). The principal components were used as inputs in an eXtreme Gradient Boosting (XGBoost) model, optimized using a 5-fold cross-validation. Finally, the model was tested on an independent validation set.
RESULTS
We trained the model on 1,592 ear photographs, corresponding to 1,296 control ears, 105 MFDM, 33 NAFD, 70 TC and 88 CHARGE syndrome ears. The model detected MFDM with an accuracy of 0.969 [0.838-0.999] ( < 0.001) and an AUC (Area Under the Curve) of 0.975 within controls (binary classification). Balanced accuracies were 0.811 [0.648-0.920] ( = 0.002) in a first multiclass design (MFDM vs. controls and differential diagnoses) and 0.813 [0.544-0.960] ( = 0.003) in a second multiclass design (MFDM vs. differential diagnoses).
CONCLUSION
This is the first AI-based syndrome detection model in dysmorphology based on the external ear, opening promising clinical applications both for local care and referral, and for expert centers.
PubMed: 37664547
DOI: 10.3389/fped.2023.1171277 -
Frontiers in Genetics 2021Pre-mRNA splicing is performed by the spliceosome, a dynamic macromolecular complex consisting of five small uridine-rich ribonucleoprotein complexes (the U1, U2, U4,... (Review)
Review
Pre-mRNA splicing is performed by the spliceosome, a dynamic macromolecular complex consisting of five small uridine-rich ribonucleoprotein complexes (the U1, U2, U4, U5, and U6 snRNPs) and numerous auxiliary splicing factors. A plethora of human disorders are caused by genetic variants affecting the function and/or expression of splicing factors, including the core snRNP proteins. Variants in the genes encoding proteins of the U5 snRNP cause two distinct and tissue-specific human disease phenotypes - variants in , , and are associated with retinitis pigmentosa (RP), while variants in and cause the craniofacial disorders mandibulofacial dysostosis Guion-Almeida type (MFDGA) and Burn-McKeown syndrome (BMKS), respectively. Furthermore, recurrent somatic mutations or changes in the expression levels of a number of U5 snRNP proteins (, , , , and ) have been associated with human cancers. How and why variants in ubiquitously expressed spliceosome proteins required for pre-mRNA splicing in all human cells result in tissue-restricted disease phenotypes is not clear. Additionally, why variants in different, yet interacting, proteins making up the same core spliceosome snRNP result in completely distinct disease outcomes - RP, craniofacial defects or cancer - is unclear. In this review, we define the roles of different U5 snRNP proteins in RP, craniofacial disorders and cancer, including how disease-associated genetic variants affect pre-mRNA splicing and the proposed disease mechanisms. We then propose potential hypotheses for how U5 snRNP variants cause tissue specificity resulting in the restricted and distinct human disorders.
PubMed: 33584830
DOI: 10.3389/fgene.2021.636620 -
European Journal of Paediatric Dentistry Dec 2023Mandibulofacial dysostosis Guion-Almeida Type (MFDGA; OMIM#610536) is a rare autosomal dominant genetic disorder caused by heterozygous pathogenic variants in the EFTUD2...
Mandibulofacial dysostosis Guion-Almeida Type (MFDGA; OMIM#610536) is a rare autosomal dominant genetic disorder caused by heterozygous pathogenic variants in the EFTUD2 gene. Mandibulofacial dysostoses are characterised by the core triad malar hypoplasia, maxillary hypoplasia and dysplastic ears, all derived by the impaired development of the first and second branchial arches. Differential diagnosis is often challenging. The early genetic diagnosis is extremely useful, not only for the correct management of cranial malformations, but also for the early diagnosis and treatment of the comorbidities associated to the disease, which greatly benefit from early treatment.
Topics: Humans; Branchial Region; Mandibulofacial Dysostosis; Diagnosis, Differential; Zygoma; Peptide Elongation Factors; Ribonucleoprotein, U5 Small Nuclear
PubMed: 38015115
DOI: 10.23804/ejpd.2023.24.04.03 -
Genetics in Medicine : Official Journal... Jan 2023Craniofacial microsomia (CFM) represents a spectrum of craniofacial malformations, ranging from isolated microtia with or without aural atresia to underdevelopment of...
PURPOSE
Craniofacial microsomia (CFM) represents a spectrum of craniofacial malformations, ranging from isolated microtia with or without aural atresia to underdevelopment of the mandible, maxilla, orbit, facial soft tissue, and/or facial nerve. The genetic causes of CFM remain largely unknown.
METHODS
We performed genome sequencing and linkage analysis in patients and families with microtia and CFM of unknown genetic etiology. The functional consequences of damaging missense variants were evaluated through expression of wild-type and mutant proteins in vitro.
RESULTS
We studied a 5-generation kindred with microtia, identifying a missense variant in FOXI3 (p.Arg236Trp) as the cause of disease (logarithm of the odds = 3.33). We subsequently identified 6 individuals from 3 additional kindreds with microtia-CFM spectrum phenotypes harboring damaging variants in FOXI3, a regulator of ectodermal and neural crest development. Missense variants in the nuclear localization sequence were identified in cases with isolated microtia with aural atresia and found to affect subcellular localization of FOXI3. Loss of function variants were found in patients with microtia and mandibular hypoplasia (CFM), suggesting dosage sensitivity of FOXI3.
CONCLUSION
Damaging variants in FOXI3 are the second most frequent genetic cause of CFM, causing 1% of all cases, including 13% of familial cases in our cohort.
Topics: Humans; Goldenhar Syndrome; Congenital Microtia; Ear; Face; Micrognathism
PubMed: 36260083
DOI: 10.1016/j.gim.2022.09.005 -
Nature Communications Aug 2021Craniofacial microsomia (CFM) is the second most common congenital facial anomaly, yet its genetic etiology remains unknown. We perform whole-exome or genome sequencing...
Craniofacial microsomia (CFM) is the second most common congenital facial anomaly, yet its genetic etiology remains unknown. We perform whole-exome or genome sequencing of 146 kindreds with sporadic (n = 138) or familial (n = 8) CFM, identifying a highly significant burden of loss of function variants in SF3B2 (P = 3.8 × 10), a component of the U2 small nuclear ribonucleoprotein complex, in probands. We describe twenty individuals from seven kindreds harboring de novo or transmitted haploinsufficient variants in SF3B2. Probands display mandibular hypoplasia, microtia, facial and preauricular tags, epibulbar dermoids, lateral oral clefts in addition to skeletal and cardiac abnormalities. Targeted morpholino knockdown of SF3B2 in Xenopus results in disruption of cranial neural crest precursor formation and subsequent craniofacial cartilage defects, supporting a link between spliceosome mutations and impaired neural crest development in congenital craniofacial disease. The results establish haploinsufficient variants in SF3B2 as the most prevalent genetic cause of CFM, explaining ~3% of sporadic and ~25% of familial cases.
Topics: Adolescent; Adult; Animals; Child; Exome; Female; Genetic Association Studies; Goldenhar Syndrome; Haploinsufficiency; Humans; Infant; Male; Mutation; Neural Crest; Pedigree; RNA Splicing Factors; Spliceosomes; Xenopus laevis
PubMed: 34344887
DOI: 10.1038/s41467-021-24852-9