Cleft palate morphology, genetic etiology, and risk of mortality in infants with Robin sequence.

Robin sequence (RS) has many genetic and nongenetic causes, including isolated Robin sequence (iRS), Stickler syndrome (SS), and other syndromes (SyndRS). The purpose of this study was to determine if the presence and type of cleft palate varies between etiologic groups. A secondary endpoint was to determine the relationship of etiologic group, cleft type, and mortality. Retrospective chart review of patients with RS at two high-volume craniofacial centers. 295 patients with RS identified. CP was identified in 97% with iRS, 95% with SS, and 70% of those with SyndRS (p < .0001). U-shaped CP was seen in 86% of iRS, 82% with SS, but only 27% with SyndRS (p < .0001). At one institution, 12 children (6%) with RS died, all from the SyndRS group (p < .0001). All died due to medical comorbidities related to their syndrome. Only 25% of children who died had a U-shaped CP. The most common palatal morphology among those who died was an intact palate. U-shaped CP was most strongly associated with iRS and SS, and with a lower risk of mortality. RS with submucous CP, cleft lip and palate or intact palate was strongly suggestive of an underlying genetic syndrome and higher risk of mortality.

A Homozygous Deletion of Exon 5 of KYNU Resulting from a Maternal Chromosome 2 Isodisomy (UPD2) Causes Catel-Manzke-Syndrome/VCRL Syndrome.

Vertebral, Cardiac, Renal and Limb Defect Syndrome (VCRL), is a very rare congenital malformation syndrome. Pathogenic variants in HAAO (3-Hydroxyanthranilate 3,4-dioxygenase), NADSYN1 (NAD+ Synthetase-1) and KYNU (Kynureninase) have been identified in a handful of affected individuals. All three genes encode for enzymes essential for the NAD+ de novo synthesis pathway. Using Trio-Exome analysis and CGH array analysis in combination with long range PCR, we have identified a novel homozygous copy number variant (CNV) encompassing exon 5 of KYNU in an individual presenting with overlapping features of VCRL and Catel-Manzke Syndrome. Interestingly, only the mother, not the father carried the small deletion in a heterozygous state. High-resolution SNP array analysis subsequently delineated a maternal isodisomy of chromosome 2 (UPD2). Increased xanthurenic acid excretion in the urine confirmed the genetic diagnosis. Our findings confirm the clinical, genetic and metabolic phenotype of VCRL1, adding a novel functionally tested disease allele. We also describe the first patient with NAD+ deficiency disorder resulting from a UPD. Furthermore, we provide a comprehensive review of the current literature covering the genetic basis and pathomechanisms for VCRL and Catel-Manzke Syndrome, including possible phenotype/genotype correlations as well as genetic causes of hypoplastic left heart syndrome.

Predictors of Respiratory Dysfunction at Diagnosis of Robin Sequence.

OBJECTIVES/HYPOTHESIS: Robin sequence (RS) consists of associated micrognathia, glossoptosis, and respiratory dysfunction, with or without cleft palate. Studies on how different patient characteristics impact the severity of respiratory dysfunction are scarce and contradictory; this study investigates how different features affect respiratory obstruction severity at diagnosis of RS in controlled analysis. STUDY DESIGN: Retrospective cohort study that enrolled 71 RS patients under 90 days old who received care in our institution from 2009 to 2020. METHODS: The primary outcome, respiratory dysfunction, was categorized into four severity groups and analyzed using a multinomial logistic regression model that considered age, sex, mandible length, cleft palate, syndromic diagnosis, other airway anomalies, and degree of glossoptosis. RESULTS: Mandible length, syndromic diagnosis, and Yellon grade 3 glossoptosis were related to poorer respiratory outcomes (need for respiratory support). In univariate analysis, for each additional 1 mm of mandible length at diagnosis, a mean reduction of 28% in the risk of needing respiratory support was observed (OR = 0.72; 0.58-0.89); syndromic diagnosis and grade 3 glossoptosis also raised the risk (OR = 6.50; 1.59-26.51 and OR = 12.75; 1.03-157.14, respectively). In multivariate analysis, only mandible length significantly maintained its effects (OR = 0.73; 0.56-0.96), a 27% reduction. CONCLUSIONS: Mandible length was an independent predictor for more severe respiratory dysfunction in RS patients, with larger mandibles showing protective effects. Syndromic diagnosis and Yellon grade 3 glossoptosis are also likely to be associated with poorer respiratory outcomes, although this was not demonstrated in multivariate analysis. LEVEL OF EVIDENCE: 4 Laryngoscope, 131:2811-2816, 2021.

A novel missense variant in RBM10 can cause a mild form of TARP syndrome with developmental delay and dysmorphic features.

RBM10, is an RNA binding protein that is important for development by regulating the expression of multiple genes. RBM10 is on the X chromosome, and nonsense and frameshift RBM10 variants cause TARP syndrome in males. In a 4-year-old male, we identified a novel maternally inherited missense RBM10 variant in the RRM2 RNA binding domain, c.965C>T, p.Pro322Leu. His clinical features included intellectual disability, developmental delay, growth restriction, hypotonia, and craniofacial malformations. These features were much milder than those described in previously reported cases of TARP syndrome. By in vitro assays, we found that the mutant p.Pro322Leu RBM10 protein retained its specific RNA binding capacity, while gaining a low-affinity nonspecific RNA binding. It was normally localized to the nucleus, but its expression level was significantly reduced with a significantly short half-life. These results indicated that the p.Pro322Leu missense variant causes a developmental disorder in humans through a unique loss-of-function mechanism.

Variable pulmonary manifestations in Chitayat syndrome: Six additional affected individuals.

Hand hyperphalangism leading to shortened index fingers with ulnar deviation, hallux valgus, mild facial dysmorphism and respiratory compromise requiring assisted ventilation are the key features of Chitayat syndrome. This condition results from the recurrent heterozygous missense variant NM_006494.2:c.266A>G; p.(Tyr89Cys) in ERF on chromosome 19q13.2, encoding the ETS2 repressor factor (ERF) protein. The pathomechanism of Chitayat syndrome is unknown. To date, seven individuals with Chitayat syndrome and the recurrent pathogenic ERF variant have been reported in the literature. Here, we describe six additional individuals, among them only one presenting with a history of assisted ventilation, and the remaining presenting with variable pulmonary phenotypes, including one individual without any obvious pulmonary manifestations. Our findings widen the phenotype spectrum caused by the recurrent pathogenic variant in ERF, underline Chitayat syndrome as a cause of isolated skeletal malformations and therefore contribute to the improvement of diagnostic strategies in individuals with hand hyperphalangism.

Carey-Fineman-Ziter Syndrome: A MYMK-Related Myopathy Mimicking Brainstem Dysgenesis.

Carey-Fineman-Ziter syndrome is a congenital myopathy associated with mutations in the MYMK gene. It is clinically defined by the combination of hypotonia, Moebius-Robin sequence, facial anomalies and motor delay. Historically it was considered a brainstem dysgenesis syndrome. We provide detailed information of a Spanish boy with compound heterozygous variants in MYMK gene. A muscle biopsy performed as a toddler only disclosed minimal changes, but muscle MRI showed severe fatty infiltration of gluteus muscles and to a lesser extent in adductors magnus, sartorius and soleus muscles. Clinical course is fairly static, but the identification of new well characterized genetic cases will help to delineate the complete phenotype.

Catel-Manzke syndrome without Manzke dysostosis.

Catel-Manzke syndrome is characterized by hand anomalies, Robin sequence, cardiac defects, joint hyperextensibility, and characteristic facial features. Approximately 40 patients with Catel-Manzke have been reported, all with the pathognomonic bilateral or unilateral hyperphalangy caused by an accessory bone between the second metacarpal and proximal phalanx known as Manzke dysostosis. Here we present the first case of molecularly confirmed Catel-Manzke syndrome with Robin sequence but without Manzke dysostosis.

TARP syndrome: Long-term survival, anatomic patterns of congenital heart defects, differential diagnosis and pathogenetic considerations.

TARP syndrome (TARPS) is an X-linked syndromic condition including Robin sequence, congenital heart defects, developmental delay, feeding difficulties and talipes equinovarus, as major features. The disease is caused by inactivating mutations in RBM10 which encodes for a RNA binding motif protein involved in transcript processing. We herein report a male born from healthy and non-consanguineous parents, presenting prenatal record of intrauterine fetal growth retardation, and postnatal features including growth and developmental delays, CNS abnormalities, facial dysmorphisms, bilateral syndactyly at the hands, talipes equinovarus and congenital heart defects. By using trio-based Whole Exome Sequencing approach, a maternally inherited RBM10 frameshift variant causing decay of the RBM10 transcript was identified. Despite the syndrome is considered lethal in affected males, our subject with molecularly confirmed TARPS is still alive at 11 years of age supporting the chance of surviving. Long-term surviving in TARPS is extremely rare and should be considered in genetic counselling and clinical follow up of the syndrome. We provide the natural history of the syndrome, reviewing the major clinical characteristics. Congenital heart defects are confirmed as specific diagnostic markers for the syndrome. In addition, cardiac anatomical details are defining a possible clinical overlap with syndromic conditions related to the hedgehog pathway and/or primary cilium anomalies as Oral-Facial-Digital or Smith-Lemli-Opitz syndromes.

Conditional deletion of Bmp2 in cranial neural crest cells recapitulates Pierre Robin sequence in mice.

Bone morphogenetic protein (BMP) signaling plays a crucial role in the development of craniofacial organs. Mutations in numerous members of the BMP signaling pathway lead to several severe human syndromes, including Pierre Robin sequence (PRS) caused by heterozygous loss of BMP2. In this study, we generate mice carrying Bmp2-specific deletion in cranial neural crest cells using floxed Bmp2 and Wnt1-Cre alleles to mimic PRS in humans. Mutant mice exhibit severe PRS with a significantly reduced size of craniofacial bones, cleft palate, malformed tongue and micrognathia. Palate clefting is caused by the undescended tongue that prevents palatal shelf elevation. However, the tongue in Wnt1-Cre;Bmp2f/f mice does not exhibit altered rates of cell proliferation and apoptosis, suggesting contribution of extrinsic defects to the failure of tongue descent. Further studies revealed obvious reduction in cell proliferation and differentiation of osteogenic progenitors in the mandible of the mutants, attributing to the micrognathia phenotype. Our study illustrates the pathogenesis of PRS caused by Bmp2 mutation, highlights the crucial role of BMP2 in the development of craniofacial bones and emphasizes precise coordination in the morphogenesis of palate, tongue and mandible during embryonic development.

The effect of mandibular distraction osteogenesis on airway obstruction and polysomnographic parameters in children with Robin sequence.

INTRODUCTION: The optimal surgical technique for the management of patients with Robin Sequence (RS) has not been established. One of the most commonly used surgical techniques, mandibular distraction osteogenesis (MDO), is still controversial because of its potential risks and the lack of clear evidence of its efficacy. OBJECTIVES: To assess variations in airway patency, clinical symptoms, and polysomnographic parameters in children with RS who underwent MDO. METHODS: In this prospective cohort study, 38 patients with RS were evaluated before and after MDO. Symptom severity was classified using a grading scale for RS clinical manifestations. Patients underwent flexible fiberoptic laryngoscopy, and the images were classified by a blinded examiner using two validated grading scales for airway obstruction. Patients not requiring ventilatory support underwent a polysomnography. RESULTS: Patients' symptoms significantly improved after MDO, as shown by a decreased score in the grading scale for RS clinical manifestations (preoperative score of 2.20 vs. postoperative score of 0.81; P < 0.001). The two endoscopic grading scales also showed a statistically significant postoperative improvement in airway obstruction (first scale: preoperative score of 1.56 vs. postoperative score of 0.92; second scale: preoperative score of 2.19 vs. postoperative score of 1.16; P < 0.001 for both). Moreover, there was a statistically significant variation in the following polysomnographic parameters evaluated pre- and postoperatively: apnea-hypopnea index, total sleep time, oxygen desaturation nadir, and oxygen desaturation index (P < 0.05). CONCLUSIONS: MDO seems to be an effective surgical option for children, as shown by postoperative improvements in clinical symptoms, endoscopic grading scales, and polysomnographic parameters.

Cephalometric Findings in Nine Individuals With Richieri-Costa-Pereira Syndrome.

The Richieri-Costa-Pereira syndrome (RCPS) is an autosomal-recessive acrofacial dysostosis caused by mutations in EIF4A3, characterized by mandibular cleft comprising other craniofacial anomalies and limb defects such as cleft palate/Robin Sequence, microstomia, absence of mandibular central incisors, minor ear anomalies, clubfeet and first and 5 ray defects. The findings from this study are useful for better understanding the morphological consequences of disorders of EIF4A3, and having a better picture of the anatomic characteristics of the syndrome for a better therapeutic planning. Twenty-four angular and linear variables were measured to assess anteroposterior and vertical (superior-inferior) position of the cranial base, maxilla, mandible, and facial profile. The cephalometric radiographic analysis was performed on 9 individuals with RCPS, obtained at a mean age of 10.3 years, and compared with randomly selected age-matched 9 controls, without clefts and with well-balanced faces, with mean age of 10.6 years (both groups range 8.1 to 13.7 years). t test was used for analysis of means and Levene test for equality of variances. The syndrome group presented severe mandibular hypoplasia and retrognathism (P = 0.009, P = 0.001), greater facial convexity (N'PnPog and N'SnPog, P < 0.05) in syndrome group compared with the control group (P = 0.003, P = 0.004). In conclusion, in the RCPS group, most craniofacial defects affect the lower facial third, considering the severely affected mandible.

Pierre Robin Sequence: An Evidence-Based Treatment Proposal.

BACKGROUND: The Pierre Robin sequence (PRS) has been defined as the presence of micrognathia, glossoptosis, and respiratory obstruction in the neonatal period. Since its original description, different therapeutic approaches have been proposed obtaining different success rates, but there is no consensus about its management. METHODS: A literature review was conducted in PubMed, Embase, and Cochrane databases, for the period of January,1985 to November, 2016. A number of 23 articles resulting from clinical studies, discussing diagnostic tests or therapeutic approaches, and directly or indirectly comparing diagnostic or treatment modalities were selected and assessed using the GRADE methodology. RESULTS: After reviewing and analyzing the selected articles, an evidence-based algorithm for diagnosis and integral management of PRS patients was designed. CONCLUSION: Based on the anatomical principles and natural evolution of PRS, the clinical scenario must be evaluated thoroughly as a dynamic event to develop a management sequence that minimizes morbidity and mortality and accelerates patients' reinsertion to normal life.

Airway Volume Simulation in Virtual Mandibular Distraction: A Cohort Study.

BACKGROUND: The authors investigated the accuracy of virtual surgical planning in predicting airway volume changes after mandibular distraction in patients with Pierre Robin sequence and associated tongue-based airway obstruction. METHODS: The authors completed a single-institution retrospective review of patients for whom virtual surgical planning was used during mandibular distraction osteogenesis for treatment of tongue-based airway obstruction. Preoperative airway volume, virtual surgical planning-predicted airway volume, and postoperative airway volume were calculated from three-dimensional computed tomographic scans using industry software. A blinded institutional radiologist also calculated pre- and post-operative airway volumes. Pre- and post-operative polysomnography was used to titrate the endpoint of mandibular lengthening. RESULTS: Eleven patients were included in the study. Mean apnea-hypopnea index (5.42 ± 4.53 versus 44.96 ± 20.57; p < 0.001) and mean nadir oxygen saturation (70.3 ± 9.72 percent versus 82.9 ± 9.62 percent; p = 0.003) improved with mandibular distraction. There was moderate correlation between predicted and actual mandibular distraction lengths (R = 0.65; p = 0.003). There was a strong correlation between predicted and industry-calculated actual post-distraction airway volume (R = 0.99; p < 0.001). There was no significant correlation between actual mandibular distraction length and industry-calculated actual post-distraction airway volume for the entire cohort (R = 0.05; p = 0.49), but correlation approached significance by institutional calculations. No significant correlation existed between industry and institutional-calculated percentage change in post-distraction airway volume (R = 0.06; p = 0.57). CONCLUSIONS: Predictive airway volume calculation may be an effective adjunct to determine anatomic endpoint of mandibular distraction but small sample size, operator and software variability, and patient airway morphology may confound firm conclusions. Further studies are warranted.

Identification of STAC3 variants in non-Native American families with overlapping features of Carey-Fineman-Ziter syndrome and Moebius syndrome.

Horstick et al. (2013) previously reported a homozygous p.Trp284Ser variant in STAC3 as the cause of Native American myopathy (NAM) in 5 Lumbee Native American families with congenital hypotonia and weakness, cleft palate, short stature, ptosis, kyphoscoliosis, talipes deformities, and susceptibility to malignant hyperthermia (MH). Here we present two non-Native American families, who were found to have STAC3 pathogenic variants. The first proband and her affected older sister are from a consanguineous Qatari family with a suspected clinical diagnosis of Carey-Fineman-Ziter syndrome (CFZS) based on features of hypotonia, myopathic facies with generalized weakness, ptosis, normal extraocular movements, cleft palate, growth delay, and kyphoscoliosis. We identified the homozygous c.851G>C;p.Trp284Ser variant in STAC3 in both sisters. The second proband and his affected sister are from a non-consanguineous, Puerto Rican family who was evaluated for a possible diagnosis of Moebius syndrome (MBS). His features included facial and generalized weakness, minimal limitation of horizontal gaze, cleft palate, and hypotonia, and he has a history of MH. The siblings were identified to be compound heterozygous for STAC3 variants c.851G>C;p.Trp284Ser and c.763_766delCTCT;p.Leu255IlefsX58. Given the phenotypic overlap of individuals with CFZS, MBS, and NAM, we screened STAC3 in 12 individuals diagnosed with CFZS and in 50 individuals diagnosed with MBS or a congenital facial weakness disorder. We did not identify any rare coding variants in STAC3. NAM should be considered in patients presenting with facial and generalized weakness, normal or mildly abnormal extraocular movement, hypotonia, cleft palate, and scoliosis, particularly if there is a history of MH.

A defect in myoblast fusion underlies Carey-Fineman-Ziter syndrome.

Multinucleate cellular syncytial formation is a hallmark of skeletal muscle differentiation. Myomaker, encoded by Mymk (Tmem8c), is a well-conserved plasma membrane protein required for myoblast fusion to form multinucleated myotubes in mouse, chick, and zebrafish. Here, we report that autosomal recessive mutations in MYMK (OMIM 615345) cause Carey-Fineman-Ziter syndrome in humans (CFZS; OMIM 254940) by reducing but not eliminating MYMK function. We characterize MYMK-CFZS as a congenital myopathy with marked facial weakness and additional clinical and pathologic features that distinguish it from other congenital neuromuscular syndromes. We show that a heterologous cell fusion assay in vitro and allelic complementation experiments in mymk knockdown and mymkinsT/insT zebrafish in vivo can differentiate between MYMK wild type, hypomorphic and null alleles. Collectively, these data establish that MYMK activity is necessary for normal muscle development and maintenance in humans, and expand the spectrum of congenital myopathies to include cell-cell fusion deficits.

[Cleft lip and palate]. / Lippen-Kiefer-Gaumen-Spalten.

BACKGROUND: Cleft lip and palate (CLP) represents a group of malformations of unknown etiology but similar phenotypes. This implies consequences for the diagnostics, therapy, prevention, prognosis and risk estimation. OBJECTIVE: Definition of CLP subtypes and the embryonic development, clarification of correlations and differences between entities using epidemiological data, overview of the present state of genetic analyses, correlation to syndromes, sequences and associations and resulting consequences for clinical practice. MATERIAL AND METHODS: Update on embryological development of the face, summary of epidemiological and genetic studies and considerations on pedopathological and forensic aspects. RESULTS: Syndromic and non-syndromic CLP exhibit different and highly variable etiologies, therapeutic needs and prognosis. A thorough understanding is mandatory to distinguish between the different subgroups. In addition to specific aspects of CLP for the pediatric (forensic) pathologist this article provides an overall view of the topic which aims to help understand these malformations.

Secuencia malformativa de Pierre Robin: informe de un caso y revisión de la literatura / Pierre Robin sequence: case report and literature review

Durante la infancia es muy frecuente encontrar alteraciones del desarrollo,las cuales derivan de una defi ciente formación de las estructurasanatómicas durante la embriogénesis. Puede encontrarse un sinnúmerode alteraciones del desarrollo que afectan la región bucal y maxilofacial.La gran mayoría de estas alteraciones han sido catalogadas como síndromes de orden genético; sin embargo, no todas pueden describirse como tales, pues existen anomalías del desarrollo que aparecen como consecuencia de una deficiente embriogénesis de la región facial, provocando alteraciones anatómicas y funcionales, pero que se apartan de componentes genéticos y cromosómicos específi cos. La secuencia malformativa de Pierre Robin es una de ellas, ya que esta condición es producida por una afección inicial, de la cual derivarán otras afeccionesadicionales a nivel del paladar y de la mandíbula que ocasionarán en elpaciente dificultad para la alimentación y respiración. Debido a que las alteraciones de esta condición afectan directamente la cavidad bucal,es crucial que el odontólogo se encuentre familiarizado con esta anomalía. El objetivo del presente artículo es describir las característicasque configuran esta entidad nosológica mediante la exposición de un caso clínico y revisión de la literatura.

During childhood, it is frequent to find development disorders whichare linked to the weak formation of anatomic structures duringembryogenesis. It is possible to find a plethora of developmentdisorders that aff ect the oral and maxillofacial region. The majorityof these disorders has been classifi ed as genetic malformations butnot all can be described as such. That is because some developmentdisorders appear as a result of a defi cient embryogenesis of the face,producing thus anatomic and functional malformations but that standapart from genetic and chromosomic specifi c components. The Pierre Robin sequence is one of them, given that this condition is producedby an initial disorder, followed by other disorders in the palate andjaw; provoking alimentary and breathing disabilities in the patient.Due to these disorders and their impact on the mouth, it is crucial thatdentists be familiarized with such anomalies. The aim of this article isto describe the key characteristics that defi ne this disease through thepresentation of a clinical case and a literature review.

Targeted molecular investigation in patients within the clinical spectrum of Auriculocondylar syndrome.

Auriculocondylar syndrome, mainly characterized by micrognathia, small mandibular condyle, and question mark ears, is a rare disease segregating in an autosomal dominant pattern in the majority of the families reported in the literature. So far, pathogenic variants in PLCB4, GNAI3, and EDN1 have been associated with this syndrome. It is caused by a developmental abnormality of the first and second pharyngeal arches and it is associated with great inter- and intra-familial clinical variability, with some patients not presenting the typical phenotype of the syndrome. Moreover, only a few patients of each molecular subtype of Auriculocondylar syndrome have been reported and sequenced. Therefore, the spectrum of clinical and genetic variability is still not defined. In order to address these questions, we searched for alterations in PLCB4, GNAI3, and EDN1 in patients with typical Auriculocondylar syndrome (n = 3), Pierre Robin sequence-plus (n = 3), micrognathia with additional craniofacial malformations (n = 4), or non-specific auricular dysplasia (n = 1), which could represent subtypes of Auriculocondylar syndrome. We found novel pathogenic variants in PLCB4 only in two of three index patients with typical Auriculocondylar syndrome. We also performed a detailed comparative analysis of the patients presented in this study with those previously published, which showed that the pattern of auricular abnormality and full cheeks were associated with molecularly characterized individuals with Auriculocondylar syndrome. Finally, our data contribute to a better definition of a set of parameters for clinical classification that may be used as a guidance for geneticists ordering molecular testing for Auriculocondylar syndrome. © 2017 Wiley Periodicals, Inc.