Treacher Collins Syndrome

Mandibular Dysmorphology and Clinical Presentation in Treacher Collins Syndrome

INTRODUCTION

Treacher Collins syndrome is a rare congenital disease characterized by the multiple craniofacial malformations. Although the deformities affecting patients with Treacher Collins syndrome have been well characterized, the effects of these malformations to clinical severity of the syndrome are not well understood.

OBJECTIVE

To determine the association of specific Treacher Collins mandibular malformations with clinical severity.

DESIGN

A retrospective radiographic observational study.

SETTING

Study conducted at a single institution, a quaternary craniofacial care center.

PATIENTS

54 patients with Treacher Collins syndrome.

INTERVENTIONS

Computed tomography (CT), clinical photographs and medical history were included in this analysis. Mandibles were isolated from CT data and reconstructed in three dimensions using Mimics software. Cephalometric measurements were performed on CT data. Clinical severity was determined by Teber and Vincent scores. Association of craniofacial dysmorphology to clinical severity was determined by Spearman rank coefficient.

MAIN OUTCOME MEASURES

The main results obtained were the measurements of the mandibles and the quantification of the malformations of the evaluated patients.

RESULTS

Among the most frequent findings in the sample are hypoplasia of the zygomatic complex, descending palpebral cleft and mandibular hypoplasia. Patients with a lower ramus/corpus ratio had a higher (more severe) Teber and Vincent classification.

CONCLUSION

Patients with the most compromised mandible are also the patients with the highest number of malformations, thus, the most severe patients.

Electrocardiographic abnormalities in patients with microtia

The main objective of this study was to investigate the incidence and characteristics of electrocardiographic abnormalities in patients with microtia, and to explore cardiac maldevelopment associated with microtia. This retrospective study analyzed a large cohort of microtia patients admitted to Plastic Surgery Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, from September 2017 to August 2022. The routine electrocardiographic reports of these patients were reviewed to assess the incidence and characteristics of abnormalities. The study included a total of 10,151 patients (5598 in the microtia group and 4553 in the control group) who were admitted to the Plastic Surgery Hospital of Peking Union Medical College. The microtia group had a significantly higher incidence of abnormal electrocardiographies compared to the control group (18.3% vs. 13.6%, P < 0.01), even when excluding sinus irregularity (6.1% vs. 4.4%, P < 0.01). Among the 1025 cases of abnormal electrocardiographies in the microtia group, 686 cases were reported with simple sinus irregularity. After excluding sinus irregularity as abnormal, the most prevalent abnormalities was right bundle branch block (37.5%), followed by sinus bradycardia (17.4%), ST-T wave abnormalities (13.3%), atrial rhythm (9.1%), sinus tachycardia (8.3%), and ventricular high voltage (4.7%). Less common ECG abnormalities included atrial tachycardia (2.1%), ventricular premature contraction (2.4%), and ectopic atrial rhythm (1.8%). atrioventricular block and junctional rhythm were present in 1.2% and 0.9% of the cases, respectively. Wolff Parkinson White syndrome and dextrocardia had a lower prevalence, at 0.6% and 0.9%, respectively. The occurrence of electrocardiographic abnormalities in microtia patients was found to be higher compared to the control group. These findings highlight the potential congenital defect in cardiac electrophysiology beyond the presence of congenital heart defect that coincide with microtia.

Epidemiology of congenital malformations of the external ear in Hunan Province, China, from 2016 to 2020

To describe the epidemiology of congenital malformations of the external ear (CMEE). Data were obtained from the Birth Defects Surveillance System in Hunan Province, China, 2016 to 2020. The prevalence of CMEEs is defined as the number of cases per 1000 fetuses (births and deaths at 28 weeks of gestation and beyond) (unit: ‰). Prevalence and 95% confidence intervals (CI) were calculated by the log-binomial method. Chi-square trend tests (χ2trend) were used to determine trends in prevalence by year. P < .05 was considered statistically significant. Crude odds ratios (ORs) were calculated to examine the association of sex, residence, and maternal age with CMEEs. Our study included 847,755 fetuses, and 14,459 birth defects were identified, including 1227 CMEEs (accounted for 8.49% of birth defects). The prevalences of birth defects and CMEEs were 17.06‰ (95%CI: 16.78-17.33) and 1.45‰ (95%CI: 1.37-1.53), respectively. A total of 185 microtia-anotias were identified, accounting for 15.08% of CMEEs, with a prevalence of 0.22‰ (95%CI: 0.19-0.25). And 1042 other CMEEs were identified, accounting for 84.92% of CMEEs. From 2016 to 2020, the prevalences of birth defects were 18.20‰, 18.00‰, 16.31‰, 16.03‰, and 16.47‰, respectively, showing a downward trend (χ2trend =8.45, P < .01); the prevalences of CMEEs were 1.19‰, 1.62‰, 1.80‰, 1.21‰, and 1.35‰, respectively, with no significant trend (χ2trend =0.09, P = .77). CMEEs were more common in males than females (1.60‰ vs 1.27‰, OR = 1.26, 95%CI: 1.12-1.41), in urban areas than in rural areas (1.77‰ vs 1.23‰, OR = 1.45, 95%CI: 1.29-1.62). The prevalences of CMEEs for maternal age < 20, 20-24, 25-29, 30-34, and ≥ 35 were 1.75‰, 1.27‰, 1.44‰, 1.47‰, and 1.58‰, respectively, with no significant difference (P > .05, reference: 25-29). Most CMEEs were diagnosed by clinical examinations (92.34%), and most CMEEs were diagnosed postpartum (within 7 days) (96.25%). In summary, we have presented the epidemiology of CMEEs in Hunan Province, China. CMEEs were more common in males than females, in urban areas than rural areas, whereas there was no significant difference in prevalence of CMEEs by maternal age. We inferred that CMEEs may be mainly related to genetics, and the mechanism needs to be examined in the future.

Possible germline mosaicism in a pedigree with Treacher Collins syndrome: A case report and brief review

Treacher Collins syndrome (TCS) is a rare congenital craniofacial disorder, typically inherited as an autosomal dominant condition. Here, we report on a family in which germline mosaicism for TCS was likely present. The proband was diagnosed with TCS based on the typical clinical features and a pathogenic variant TCOF1 (c.4369_4373delAAGAA, p.K1457Efs*12). The mutation was not detected in his parents' peripheral blood DNA samples, suggesting a de novo mutation had occurred in the proband. However, a year later, the proband's mother became pregnant, and the amniotic fluid puncture revealed that the fetus carried the same mutation as the proband. Prenatal ultrasound also indicated a maxillofacial dysplasia with unilateral microtia. The mother then disclosed a previous birth history in which a baby had died of respiratory distress shortly after birth, displaying a TCS-like phenotype. Around the same time, the proband's father was diagnosed with mild bilateral conductive hearing loss. Based on array data, we concluded that the father may have had germline mosaicism for TCOF1 mutation. Our findings highlight the importance of considering germline mosaicism in sporadic de novo TCOF1 mutations when providing genetic consulting, and prenatal diagnosis is important when the proband's parents become pregnant again.

The application of three-dimensional printing in the management of a difficult airway due to Treacher Collins syndrome

We describe the use of three-dimensional printing to create precise airway models for a patient with Treacher Collins syndrome who presented for bimaxillary temporomandibular joint prostheses, and for whom airway management was predicted to be difficult. The model was based on pre-operative cone beam computed tomography images and printed in the 3D Lab of Hospital Universitario La Paz. Transparent models allowed clear visualisation for simulation and iterative refinement of airway management techniques and aided in risk assessment and instrument sizing. This case report emphasises the utility of this approach in complex airway scenarios.

Molecular etiology of defective nuclear and mitochondrial ribosome biogenesis: Clinical phenotypes and therapy

Ribosomopathies are rare congenital disorders associated with defective ribosome biogenesis due to pathogenic variations in genes that encode proteins related to ribosome function and biogenesis. Defects in ribosome biogenesis result in a nucleolar stress response involving the TP53 tumor suppressor protein and impaired protein synthesis leading to a deregulated translational output. Despite the accepted notion that ribosomes are omnipresent and essential for all cells, most ribosomopathies show tissue-specific phenotypes affecting blood cells, hair, spleen, or skin. On the other hand, defects in mitochondrial ribosome biogenesis are associated with a range of clinical manifestations affecting more than one organ. Intriguingly, the deregulated ribosomal function is also a feature in several human malignancies with a selective upregulation or downregulation of specific ribosome components. Here, we highlight the clinical conditions associated with defective ribosome biogenesis in the nucleus and mitochondria with a description of the affected genes and the implicated pathways, along with a note on the treatment strategies currently available for these disorders.

Comprehensive Serial Treatment of Treacher Collins Syndrome

OBJECTIVE

To discuss and summarize the comprehensive serial surgical treatment of Treacher Collins syndrome.

MATERIALS AND METHODS

From September 2012 to January 2020, 12 patients with Treacher Collins syndrome were treated by autologous fat graft, mandibular distraction osteogenesis, orbitozygomatic reconstruction with calvarial external lamina, orthognathic surgery combined with postoperative orthodontics, transplantation of upper eyelid orbicularis myocutaneous flap, lateral canthal ligament reduction, and other methods. The authors evaluated the postoperative improvement, summarized experiences, and reviewed literatures about the comprehensive serial treatment of Treacher Collins syndrome.

RESULTS

All patients showed significant improvement in appearance and function, and no complications were found during the follow-up period of 5 months to 3 years.

CONCLUSIONS

The deformities of Treacher Collins syndrome involves multiple craniofacial region, and only by formulating comprehensive serial treatment strategies according to the malformation characteristics of different patients can the best effect be achieved.

Congenital Mandibular Hypoplasia: Patient-Specific Total Joint Replacement as a Line Extension in the Treatment of Complex Craniofacial Anomalies

Introduction

Congenital mandibular hypoplasia (CMH) remains challenging because of the underlying combined hard and soft tissue deficiency. Treatment options include craniofacial distraction, orthognathic surgery, and autologous grafts, although the latter produces inadequate results after distraction and autologous grafting. Unsatisfactory long-term stability may cause relapse, necessitating reoperation.

Material and Methods

We investigated the feasibility of using alloplastic total joint replacement (TJR) in growing and young adult CMH patients. The primary outcome was long-term reconstruction stability, without implant failure. Secondary outcomes were TMJ function and pain, and jaw movements achieved during surgery.

Results

Three patients (age: 9–22 years) were treated by the same surgeon at one institution during 2018–2021. Anamnesis and clinical parameters were obtained from patient records. Preoperative 3D-scans were superimposed with postoperative 3D-scans and preoperative plans, including TJR-implant STL files, to measure jaw movement. All patients underwent prior reconstructive surgery. Mandibular movement of 16.4–20.1 mm in the sagittal direction was achieved. Post-TJR follow-up ranged from 24 to 42 months. No long-term complications occurred. At the latest follow-up, the maximal interincisal opening was between 21 and 40 mm, and all implants were functioning, without failure.

Conclusion

In selected CMH cases, alloplastic TJR can deliver satisfactory medium-term results with predictable and stable outcomes, even in growing patients.

Intrafamilial Phenotypic Heterogeneity in a Chinese Family with a POLR1D p.Q31Rfs*10 Variant: A Challenge in Prenatal Diagnosis

Introduction

Treacher Collins syndrome (TCS), also known as mandibulofacial dysostosis, is an inherited craniofacial defect. Here, we report a TCS family in which the members carry the same POLR1D variant but present with phenotypic variability.

Case Presentation

A 19-year-old healthy primigravida was revealed by ultrasound at 12 weeks of gestation to have a fetus with micrognathia. Prenatal genetic testing detected a heterozygous single-nucleotide deletion (NM_015972:c.91del, p.Q31Rfs*10) in the POLR1D gene, inherited from the healthy mother. Variants of POLR1D have been reported to be associated with TCS. Family studies found that a paternal healthy cousin of the mother had a similar pregnancy outcome, with a fetus of TCS and the same POLR1D variant.

Discussion

Our study results pose a great challenge to prenatal diagnosis of TCS. The prenatal diagnosis cannot only rely on genetic testing. Instead, an early detailed sonographic survey will be helpful for the identification of TCS.

Neonatal Airway Abnormalities

Neonatal airway abnormalities are commonly encountered by the neonatologist, general pediatrician, maternal fetal medicine specialist, and otolaryngologist. This review article discusses common and rare anomalies that may be encountered, along with discussion of embryology, workup, and treatment. This article aims to provide a broad overview of neonatal airway anomalies to arm those caring for these children with a broad differential diagnosis and basic knowledge of how to manage basic and complex presentations.

[Genetic characteristics of microtia-associated syndromes in neonates]

Microtia is the second most common maxillofacial birth defect in neonates and has an prevalence rate of 3.06/10 000 in China, and 20%-60% of microtia cases is associated with a certain type of syndrome. This article elaborates on the clinical phenotypes and genetic characteristics of three microtia-associated syndromes (MASs) with high prevalence, high incidence rate of ear deformity, and definite genetic etiology, i.e., oculo-auriculo-vertebral spectrum, branchio-oto-renal spectrum disorder, and Treacher-Collins syndrome, and summarizes another three common MASs, so as to provide a reference for the genetic diagnosis of neonatal MAS.

The important role of RPS14, RPL5 and MDM2 in TP53-associated ribosome stress in mycophenolic acid-induced microtia

OBJECTIVE

Mycophenolate embryopathy (ME) is a congenital malformation induced by mycophenolic acid (MA). Microtia is the most common ME phenotype. This study aimed to identify the key genes in the pathological process of microtia caused by mycophenolate mofetil (MM) through bioinformatics methods, to explore the potential pathogenesis, and to provide a direction for future genetic research on aetiology.

METHODS

Genes related to MM and microtia were obtained from the GeneCards database for bioinformatics. Metacore was used to identify and visualize the upstream and downstream gene relationships in the protein-protein interaction (PPI) results of these genes. The clusterProfiler R software package was used to simulate and visualize the enrichment results based on data from Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) analyses.

RESULTS

Fifty-nine genes were associated with microtia and MM/MA. The hub genes with the most significant effects on MM/MA-induced microtia pathogenesis included tumour protein P53 (p53), MDM2 proto-oncogene (MDM2), ribosomal protein L5 (RPL5) and ribosomal protein S14 (RBS14). The GO term with the most enriched genes was peptidyl-tyrosine phosphorylation. For the KEGG terms, there was significant enrichment regarding the haematopoietic cell lineage, apoptosis, p53 signalling, proteasome and necroptosis.

CONCLUSIONS

We propose that an axis composed of MA, microtia, TP53 and related genes is involved in ME pathogenesis. The important role of TP53-associated ribosome stress in ME pathogenesis is consistent with our previous findings from MA-induced cleft lip and palate. Deregulation of genes protective against TP53 overexpression, such as MDM2, could be a strategy for constructing a microtia animal model.

Anesthetic Management of Treacher Collins Syndrome in an Outpatient Surgical Center

Patient: Male, 15-year-old

Final Diagnosis: Treacher Collins syndrome

Symptoms: Difficult airway management

Medication:—

Clinical Procedure: —

Specialty: Anesthesiology

Description of Total Population Hospital Admissions for Treacher Collins Syndrome in Australia

OBJECTIVE

To describe patterns and demographic characteristics of total-population hospital admissions with a diagnosis of Treacher Collins syndrome (TCS) in Australia.

DATA SOURCE

Population summary data for inpatient hospitals admissions (public and private) with a principal diagnosis of TCS (ICD10-AM-Q87.04) were obtained from the Australian Institute of Health and Welfare National Hospital Morbidity Database for a 11-year period (2002-2013).

MAIN OUTCOME MEASURES

The primary outcome was hospital separation rate (HSR), calculated by dividing the number of hospital separations by estimated resident population per year. Trends in HSR s adjusted for age and sex were investigated by negative binomial regression presented as annual percent change and the association of rates with age and sex was expressed as incidence rate ratio.

RESULTS

In 244 admissions identified, we observed an increase of 4.55% (95% confidence interval [CI] -1.78, 11.29) in HSR's over the 11-year period. Rates were higher during infancy (1.87 [95% CI 1.42, 2.42]), declining markedly with increasing age. The average length of hospital stay was 6.09 days (95% CI 5.78, 6.40) per episode, but longer for females and infants.

CONCLUSIONS

Findings indicate an increase in hospitalization rates, especially among infants and females which potentially relates to early airway intervention procedures possibly influenced by sex specific-disease severity and phenotypic variability of TCS. Awareness of the TCS phenotype and improved access to genetic testing may support more personalized and efficient care. Total-population administrative data offers a potential to better understand the health burden of rare craniofacial diseases.

Neural crest metabolism: At the crossroads of development and disease

The neural crest is a migratory stem cell population that contributes to various tissues and organs during vertebrate embryonic development. These cells possess remarkable developmental plasticity and give rise to many different cell types, including chondrocytes, osteocytes, peripheral neurons, glia, melanocytes, and smooth muscle cells. Although the genetic mechanisms underlying neural crest development have been extensively studied, many facets of this process remain unexplored. One key aspect of cellular physiology that has gained prominence in the context of embryonic development is metabolic regulation. Recent discoveries in neural crest biology suggest that metabolic regulation may play a central role in the formation, migration, and differentiation of these cells. This possibility is further supported by clinical studies that have demonstrated a high prevalence of neural crest anomalies in babies with congenital metabolic disorders. Here, we examine why neural crest development is prone to metabolic disruption and discuss how carbon metabolism regulates developmental processes like epithelial-to-mesenchymal transition (EMT) and cell migration. Finally, we explore how understanding neural crest metabolism may inform upon the etiology of several congenital birth defects.

The important role of MDM2, RPL5, and TP53 in mycophenolic acid-induced cleft lip and palate

Mycophenolate embryopathy (MPE) is a mycophenolic acid (MPA)-induced congenital malformation with distinctive symptoms. Cleft lip/palate (CLP) is one of the most common symptoms of MPE. The aim of this study was to screen and verify hub genes involved in MPA-induced CLP and to explore the potential molecular mechanisms underlying MPE.Overlapping genes related to MPA and CLP were obtained from the GeneCards database. These genes were further analyzed via bioinformatics. The Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analysis results were visualized with the Cytoscape ClueGO plug-in. Gene protein-protein interaction (PPI) networks were constructed based on data obtained from the Search Tool for the Retrieval of Interacting Genes/Proteins (STRING) database.Overall, 58 genes related to MPA and CLP were identified. The genes most relevant to MPA-induced CLP included ABCB1, COL1A1, Rac1, TGFβ1, EDN1, and TP53, as well as the TP53-associated genes MDM2 and RPL5. GO analysis demonstrated gene enrichment regarding such terms as ear, mesenchymal, striated muscle, and ureteric development. KEGG analysis demonstrated gene enrichment in such pathways as the HIF-1 signaling pathway, glycosylphosphatidylinositol-anchor biosynthesis, the TNF signaling pathway, and hematopoietic stem cell development.Bioinformatic analysis was performed on the genes currently known to be associated with MPA-induced CLP pathogenesis. MPA-induced CLP is mediated by multiple ribosome stress related genes and pathways. MDM2, RPL5 and TP53 could be the main contributor in this pathogenesis, along with several other genes. ABCB1 polymorphism could be related to the probability of MPA-induced CLP.

A novel nonsense mutation in the TCOF1 gene in one Chinese newborn with Treacher Collins syndrome

OBJECTIVE

The purpose of this study is that analyze the clinical characters of Treacher Collins syndrome (TCS) with the de nove TCOF1 mutation and emphasize the genetic research result.

METHODS

Genomic DNA from the proband and his parents were extracted from 200 to 400 μl of peripheral blood samples. A 4000 pathgenic genes diagnostic screening panel developed by our laboratory group was used for gene mutation screening. The panel covered the TCOF1 (NM_001135243.1), POLR1C (NM_203,290) and POLR1D (NM_015,972) genes associating with TCS.

RESULTS

We reported a case of typical, complete syndrome with a nonsense mutation c.1622G > A (p.W541*) in exon 11 of TCOF1, who presents bilateral external ears abnormalities, atresia of external auditory canals, antimongoloid slant of the eyes, bilateral partial coloboma of the lateral part of the lower lids, a large and protruding nose, macrostomia, cleft palate and hair displacement anterior to the auricle.

CONCLUSIONS

Our report expands the spectrum of known pathogenic TCOF1 variants associated with TCS in humans.TCOF1 deficiency may cause a severe neonatal presentation with birth defects.

Skeletal Stem Cells-A Paradigm Shift in the Field of Craniofacial Bone Tissue Engineering

Defects of the craniofacial skeleton arise as a direct result of trauma, diseases, oncological resection, or congenital anomalies. Current treatment options are limited, highlighting the importance for developing new strategies to restore form, function, and aesthetics of missing or damaged bone in the face and the cranium. For optimal reconstruction, the goal is to replace "like with like." With the inherent challenges of existing options, there is a clear need to develop alternative strategies to reconstruct the craniofacial skeleton. The success of mesenchymal stem cell-based approaches has been hampered by high heterogeneity of transplanted cell populations with inconsistent preclinical and clinical trial outcomes. Here, we discuss the novel characterization and isolation of mouse skeletal stem cell (SSC) populations and their response to injury, systemic disease, and how their re-activation in vivo can contribute to tissue regeneration. These studies led to the characterization of human SSCs which are able to self-renew, give rise to increasingly fate restricted progenitors, and differentiate into bone, cartilage, and bone marrow stroma, all on the clonal level in vivo without prior in vitro culture. SSCs hold great potential for implementation in craniofacial bone tissue engineering and regenerative medicine. As we begin to better understand the diversity and the nature of skeletal stem and progenitor cells, there is a tangible future whereby a subset of human adult SSCs can be readily purified from bone or activated in situ with broad potential applications in craniofacial tissue engineering.

Mutation analysis of TCOF1 gene in Chinese Treacher Collins syndrome patients

Background

Treacher Collins syndrome (TCS) is a rare autosomal dominant or recessive disorder, that involves unique bilateral craniofacial malformations. The phenotypes of TCS are extremely diverse. Interventional surgery can improve hearing loss and facial deformity in TCS patients.

Method

We recruited seven TCS families. Variant screening in probands was performed by targeted next‐generation sequencing (NGS). The variants identified were confirmed by Sanger sequencing. The pathogenicity of all the mutations was evaluated using the guidelines of the American College of Medical Genetics and Genomics (ACMG) and InterVar software.

Results

Three frameshift variants, two nonsense variants, one missense variant, and one splicing variant of TCOF1 were identified in the seven TCS probands. Five variants including c.1393C > T, c.4111 + 5G>C, c.1142delC, c.2285_2286delCT, and c.1719delG had not been previously reported. Furthermore, we report the c.149A > G variant for the first time in a Chinese TCS patient. We provided prenatal diagnosis for family 4. Proband 7 chose interventional surgery.

Conclusion

We identified five novel variants in TCOF1 in Chinese patients with TCS, which expands the mutation spectrum of TCOF1 in TCS. Bone conduction hearing rehabilitation can improve hearing for TCS patients and prenatal diagnosis can provide fertility guidance for TCS families.

Cranial Neural Crest Cells and Their Role in the Pathogenesis of Craniofacial Anomalies and Coronal Craniosynostosis

Craniofacial anomalies are among the most common of birth defects. The pathogenesis of craniofacial anomalies frequently involves defects in the migration, proliferation, and fate of neural crest cells destined for the craniofacial skeleton. Genetic mutations causing deficient cranial neural crest migration and proliferation can result in Treacher Collins syndrome, Pierre Robin sequence, and cleft palate. Defects in post-migratory neural crest cells can result in pre- or post-ossification defects in the developing craniofacial skeleton and craniosynostosis (premature fusion of cranial bones/cranial sutures). The coronal suture is the most frequently fused suture in craniosynostosis syndromes. It exists as a biological boundary between the neural crest-derived frontal bone and paraxial mesoderm-derived parietal bone. The objective of this review is to frame our current understanding of neural crest cells in craniofacial development, craniofacial anomalies, and the pathogenesis of coronal craniosynostosis. We will also discuss novel approaches for advancing our knowledge and developing prevention and/or treatment strategies for craniofacial tissue regeneration and craniosynostosis.

Broad-spectrum next-generation sequencing-based diagnosis of a case of Nager syndrome

BACKGROUND

Nager syndrome is a rare genetic syndrome characterized by craniofacial and preaxial limb anomalies. Haploinsufficiency of the SF3B4 gene has been identified as a significant reason for Nager syndrome. Treacher Collins syndrome (TCS) has similar facial features; however, the TCOF1, POLR1D, and POLR1C genes have been reported as the critical disease-causing genes. Similar phenotypes make it easy to misdiagnose.

CASE REPORT

In this report, we have presented a case of one newborn with acrofacial dysostosis, who was first diagnosed with TCS. Expanded next-generation sequencing eventually detected a (c.1A>G) heterozygous mutation in the SF3B4 gene at chr1:149899651 that was confirmed by Sanger sequencing. Combined with his preaxial limb anomalies discovered after his death, a diagnosis of Nager syndrome was made.

CONCLUSIONS

This report presents one patient with Nager syndrome who was initially misdiagnosed with TCS. Correct genetic testing will be beneficial to future prenatal diagnosis.

TCOF1 pathogenic variants identified by Whole-exome sequencing in Chinese Treacher Collins syndrome families and hearing rehabilitation effect

Background

Treacher Collins syndrome (TCS, OMIM 154500) is an autosomal disorder of craniofacial development with an incidence rate of 1/50,000 live births. Although TCOF1, POLR1D, and POLR1C, have been identified as the pathogenic genes for about 90% TCS patients, the pathogenic variants of about 8–11% cases remain unknown. The object of this study is to describe the molecular basis of 14 clinically diagnosed TCS patients from four families using Whole-exome sequencing (WES) followed by Sanger sequencing confirmation, and to analyze the effect of bone conduction hearing rehabilitation in TCS patients with bilateral conductive hearing loss.

Results

Four previously unreported heterozygous pathogenic variants (c.3047-2A > G, c.2478 + 5G > A, c.489delC, c.648delC) were identified in the TCOF1 gene, one in each of the four families. Sanger sequencing in family members confirmed co-segregation of the identified TCOF1 variants with the phenotype. The mean pure-tone threshold improvements measured 3 months after hearing intervention were 28.8 dB for soft-band BAHA, 36.6 ± 2.0 dB for Ponto implantation, and 27.5 dB SPL for Bonebridge implantation. The mean speech discrimination improvements measured 3 months after hearing intervention in a sound field with a presentation level of 65 dB SPL were 44%, 51.25 ± 5.06, and 58%, respectively. All six patients undergoing hearing rehabilitation in this study got a satisfied hearing improvement.

Conclusions

WES combined with Sanger sequencing enables the molecular diagnosis of TCS and may detect other unknown causative genes. Bone conduction hearing rehabilitation may be an optimal option for TCS patients with bilateral conductive hearing loss.