U-shaped palatal defect in the Robin anomalad: developmental and clinical relevance

The palatal defect in patients with the Robin anomalad was found to be U shaped. This finding is compatible with the hypothesis that the underlying dysmorphic event is usually early mandibular hypoplasia with secondary extrinsic obstruction of palatal closure by a posteriorly displaced tongue. The more common V-shaped defects of palate closure arise by a different mechanism. Unfortunately, available recurrence risk data for cleft palate do not allow for this distinction. Furthermore, physicians should be alert for instances in which the Robin anomalad is but one feature of a broader pattern of malformation. In the current study, 25% of the 28 patients ascertained as having the Robin anomalad had a recognizable syndrome for which specific, but varying, genetic counsel was indicated.

Genotype-phenotype correlation of Coffin-Siris syndrome caused by mutations in SMARCB1, SMARCA4, SMARCE1, and ARID1A

Coffin-Siris syndrome (CSS) is a rare congenital malformation syndrome, recently found to be caused by mutations in several genes encoding components of the BAF complex. To date, 109 patients have been reported with their mutations: SMARCB1 (12%), SMARCA4 (11%), SMARCE1 (2%), ARID1A (7%), ARID1B (65%), and PHF6 (2%). We review genotype-phenotype correlation of all previously reported patients with mutations in SMARCB1, SMARCA4, SMARCE1, and ARID1A through reassessment of their clinical and molecular findings. Cardinal features of CSS included variable degrees of intellectual disability (ID) predominantly affecting speech, sucking/feeding difficulty, and craniofacial (thick eyebrows, long eyelashes), digital (hypoplastic 5th fingers or toes, hypoplastic 5th fingernails or toenails), and other characteristics (hypertrichosis). In addition, patients with SMARCB1 mutations had severe neurodevelopmental deficits including severe ID, seizures, CNS structural abnormalities, and no expressive words as well as scoliosis. Especially, those with a recurrent mutation "p.Lys364del" represented strikingly similar phenotypes including characteristic facial coarseness. Patients with SMARCA4 mutations had less coarse craniofacial appearances and behavioral abnormalities. Patients with SMARCE1 mutations had a wide spectrum of manifestations from severe to moderate ID. Patients with ARID1A also had a wide spectrum of manifestations from severe ID and serous internal complications that could result in early death to mild ID. Mutations in SMARCB1, SMARCA4, and SMARCE1 are expected to exert dominant-negative or gain-of-function effects, whereas those in ARID1A are expected to exert loss-of-function effects.

Swallowing disorders in Pierre Robin sequence: its correction by distraction

Pierre Robin sequence is characterized by micro-gnathia, glossoptosis, feeding difficulties, and upper respiratory obstruction, which are frequently complicated by bronchial aspiration and pulmonary infection. Gastroesophageal reflux is also common in these patients. To assess the results of mandibular distraction, a study was performed in 18 patients to detect swallowing disorders associated with apnea episodes and gastroesophageal reflux. Polysomnography, barium pharyngoscopy, determination of blood gases, and esophageal pH measurements were undertaken before and 4 months after distraction osteogenesis. Bilateral corticotomies, followed by distraction with external devices, were performed, achieving 7 to 19 mm of elongation (mean = 12 mm). Gastroesophageal reflux was found in 83% of cases associated with apnea episodes, but it disappeared after distraction osteogenesis. Mean preoperative oxygen saturation was 72%, and it was 93% afterward. The preoperative apnea index was 18.3, and the preoperative 8.5 hypopnea index was 8.5; both disappeared. Pharyngeal transit time became less than 1 second after treatment. Abnormal tongue movements and barium stasis in the pharyngeal recess and in the trachea were eliminated in all the patients.

Coffin-Siris syndrome and related disorders involving components of the BAF (mSWI/SNF) complex: historical review and recent advances using next generation sequencing

This issue of Seminars in Medical Genetics, American Journal of Medical Genetics Part C investigates the human diseases caused by mutations in the BAF complex (also known as the mammalian SWI/SNF complex) genes, particularly focusing on Coffin-Siris syndrome (CSS). CSS is a rare congenital malformation syndrome characterized by developmental delay or intellectual disability (ID), coarse facial appearance, feeding difficulties, frequent infections, and hypoplasia/aplasia of the fifth fingernails and fifth distal phalanges. In 2012, 42 years after the first description of CSS in 1970, five causative genes (SMARCB1, SMARCE1, SMARCA4, ARID1A, ARID1B), all encoding components of the BAF complex, were identified as being responsible for CSS through whole exome sequencing and pathway-based genetic screening. The identification of two additional causative genes (PHF6, SOX11) followed. Mutations in another BAF complex gene (SMARCA2) and (TBC1D24) were found to cause clinically similar conditions with ID, Nicolaides-Baraitser syndrome and DOORS syndrome, respectively. Also, ADNP was found to be mutated in an autism/ID syndrome. Furthermore, there is growing evidences for germline or somatic mutations in the BAF complex genes to be causal for cancer/cancer predisposition syndromes. These discoveries have highlighted the role of the BAF complex in the human development and cancer formation. The biology of BAF is very complicated and much remains unknown. Ongoing research is required to reveal the whole picture of the BAF complex in human development, and will lead to the development of new targeted therapies for related disorders in the future.

Reduced mandibular dimensions and asymmetry in juvenile rheumatoid arthritis. Pathogenetic factors

The pathogenesis of reduced mandibular dimensions and asymmetry was studied in 103 patients with juvenile rheumatoid arthritis. Abnormalities of the temporomandibular joint were intimately related to mandibular growth disturbances. Unilateral joint abnormality resulted in jaw asymmetry and underdevelopment on the affected side. Duration of disease and of corticosteroid therapy, age at disease onset, and age when the data were recorded were correlated with the size of the mandible. Our findings did not support a hypothesis of cervical spine involvement as an etiologic factor of reduced mandibular size.

The ARID1B phenotype: what we have learned so far

Evidence is now accumulating from a number of sequencing studies that ARID1B not only appears to be one of the most frequently mutated intellectual disability (ID) genes, but that the range of phenotypes caused by ARID1B mutations seems to be extremely wide. Thus, it is one of the most interesting ID genes identified so far in the exome sequencing era. In this article, we review the literature surrounding ARID1B and attempt to delineate the ARID1B phenotype. The vast majority of published ARID1B patients have been ascertained through studies of Coffin-Siris syndrome (CSS), which leads to bias when documenting the frequencies of phenotypic features. Additional observations of those individuals ascertained through exome sequencing studies helps in delineation of the broader clinical phenotype. We are currently establishing an ARID1B consortium, aimed at collecting ARID1B patients identified through genome-wide sequencing strategies. We hope that this endeavor will eventually lead to a more comprehensive view of the ARID1B phenotype.

Watershed infarcts in the fetal and neonatal brainstem. An aetiology of central hypoventilation, dysphagia, Möibius syndrome and micrognathia

Watershed zone infarcts of the human cerebral cortex at the overlapping junctions of the anterior and middle cerebral arterial territories are well known. Another watershed zone exists in the brainstem tegmentum, between the terminal perfusion zones of the paramedian penetrating and long circumferential arteries, which are paired segmental vessels arising from the basilar artery. The vertebrobasilar circulation achieves its mature configuration and caudorostral flow by 9 weeks gestation. Systemic hypotension and other conditions of reduced basilar perfusion in the fetus, either early or late in gestation, may result in symmetrical longitudinal columns of infarction in the midbrain and tegmentum of the pons and medulla oblongata and laminar necrosis of the midbrain tectum. Within this zone are cranial nerve nuclei III-XII, the nucleus and tractus solitarius or central pneumotaxic center, as well as the nucleus ambiguus and other somatic motor nuclei that subserve muscles of swallowing, mastication and tongue movement. Watershed infarcts in the human fetal and neonatal brainstem are clinically expressed as multiple cranial neuropathies, failure of central respiratory drive and apnea, dysphagia and aspiration, Möbius syndrome and Pierre Robin sequence. MRI is sometimes helpful, but most of the involved neuroanatomical structures are beneath the resolution of present imaging techniques, and the diagnosis during life depends upon clinical neurological examination of the neonate, sometimes supported by evoked potential studies. Postmortem examination confirms the diagnosis and dates the lesions, but also contributes to better understand transient or persistent vascular insufficiencies in the fetal and neonatal brainstem.

Teratogenic effects of biotin deficiency in mice

Teratogenic effects of maternal biotin deficiency produced by a diet containing egg white were studied in mice. More than 90% of the fetuses from biotin-deficient females showed external or skeletal congenital abnormalities. The predominant malformations were micrognathia (91%), cleft palate (82%) and micromelia (41%). Simultaneous supplementation of biotin at the level of 10 mg/kg in the diet thoroughly prevented these malformations. Thus congenital malformations observed in this study were apparently due to the maternal dietary deficiency of biotin during pregnancy. Even though so many fetuses were malformed and many were also stunted, their dams did not exhibit any overt signs of biotin deficiency such as alopecia, dermatitis or nervous irritability.

Deficiency in origin licensing proteins impairs cilia formation: implications for the aetiology of Meier-Gorlin syndrome

Mutations in ORC1, ORC4, ORC6, CDT1, and CDC6, which encode proteins required for DNA replication origin licensing, cause Meier-Gorlin syndrome (MGS), a disorder conferring microcephaly, primordial dwarfism, underdeveloped ears, and skeletal abnormalities. Mutations in ATR, which also functions during replication, can cause Seckel syndrome, a clinically related disorder. These findings suggest that impaired DNA replication could underlie the developmental defects characteristic of these disorders. Here, we show that although origin licensing capacity is impaired in all patient cells with mutations in origin licensing component proteins, this does not correlate with the rate of progression through S phase. Thus, the replicative capacity in MGS patient cells does not correlate with clinical manifestation. However, ORC1-deficient cells from MGS patients and siRNA-mediated depletion of origin licensing proteins also have impaired centrosome and centriole copy number. As a novel and unexpected finding, we show that they also display a striking defect in the rate of formation of primary cilia. We demonstrate that this impacts sonic hedgehog signalling in ORC1-deficient primary fibroblasts. Additionally, reduced growth factor-dependent signaling via primary cilia affects the kinetics of cell cycle progression following cell cycle exit and re-entry, highlighting an unexpected mechanism whereby origin licensing components can influence cell cycle progression. Finally, using a cell-based model, we show that defects in cilia function impair chondroinduction. Our findings raise the possibility that a reduced efficiency in forming cilia could contribute to the clinical features of MGS, particularly the bone development abnormalities, and could provide a new dimension for considering developmental impacts of licensing deficiency.

Impaired mandibular growth and micrognathic development in children with juvenile rheumatoid arthritis. A longitudinal study of lateral cephalographs

The present report is a longitudinal study of the craniofacial growth, based on lateral cephalographs of a group of 26 patients with juvenile rheumatoid arthritis (JRA), and a matched English control group. In the 26 matched pairs, the mean age at baseline was 8.4 years and at 6-year follow-up 14.7 years, female/male ratio was 3.3/1, and all patients had temporomandibular joint (TMJ) abnormalities. The study revealed obvious growth disturbances in the facial skeleton in the children with JRA. Compared with the controls, the patients showed a smaller mandible with an altered morphology and position. The mandible became more retruded by rotating posteriorly, around a centre in the molar region, and was characterized by appositional growth in the gonion area, vertical growth in the anterior part and proclination of the lower incisors. During the observation period the growth disturbances became more pronounced, reflecting the progressive nature of the abnormal development. Based on these findings, a future aspect of research in this field could be TMJ surgery and orthognathic surgery in an early stage, trying to avoid this unfavourable facial development.

Mandibular growth, temporomandibular joint changes and dental occlusion in juvenile rheumatoid arthritis. A 17-year follow-up study

To evaluate the mandibular growth and temporomandibular joint (TMJ) changes in juvenile rheumatoid arthritis, a clinical and radiographic 17-year re-examination of 9 of 19 patients has been carried out. A varying degree of micrognathia (mandibular retrognathia, 'bird face') was observed by means of radiographic cephalometric analysis, at both the base-line and follow-up examination of 6 of the patients. No facial asymmetry was found. Rotation of the mandible in relation to the anterior cranial base during the follow-up period, observed in 5 of the 6 patients, indicated a further disturbance of mandibular growth. In 3 patients with mandibular rotation, a dental occlusion anomaly was observed. The TMJ revealed radiographic changes in 6 patients at the base-line examination and in all patients at the re-examination. Micrognathia and the dental occlusion anomaly were associated with radiographic TMJ changes.

Teratogenicity of vitamin B6 deficiency: omphalocele, skeletal and neural defects, and splenic hypoplasia

Vitamin B(6) deficiency was induced in pregnant rats with a deficient diet and with 4-deoxypyridoxine, a B(6) antagonist. Treated animals developed typical skin changes of B(6) deficiency. Fetuses were small and appeared anemic. Major fetal malformations were omphalocele, exencephaly, cleft palate, micrognathia, digital defects, and splenic hypoplasia. This teratologic system was developed as a model for human syndromes that exhibit combined immunologic and neurologic or skeletal defects.

Hypersomnia with periodic apneas in acquired micrognathia. A bird-like face syndrome

We describe a syndrome characterized by acquired micrognathia, hypersomnia, and periodic apneas during sleep. Six patients affected with the syndrome underwent nocturnal and diurnal polygraphic recordings that demonstrated that during sleep there is an uninterrupted succession of apneas, primarily the obstructive type, analogous to those observed in Pickwickian syndrome. Simultaneous recording of pulmonary and systemic arterial pressure during sleep and repeated blood gas analyses have shown that as soon as the apneas appear there is a decisive increase in pulmonary and systemic pressure and serious alveolar hypoventilation. The hemodynamic and ventilatory changes are even more intense during rapid eye movement sleep. Tracheostomy, performed on five of our patients, is the only treatment producing complete clinical remission of the syndrome.

A new Le Fort I internal distraction device in the treatment of severe maxillary hypoplasia

PURPOSE

The purpose of this pilot study was to test a new Le Fort I internal distraction device.

PATIENTS AND METHODS

A new internal Le Fort I distraction device designed by 1 of the authors was used in 3 patients with cleft lip and palate and severe maxillary hypoplasia who needed maxillary advancements in excess of 12 mm. Presurgical planning used CASSOS (SoftEnable Technology, Ltd, Hong Kong SAR, China) prediction tracing software and a stereolithographic model to calculate the distraction vector. The distractors were pre-bent and installed on the stereolithographic model and activated to advance the maxilla. Surgery was performed in a conventional manner, and distraction was started after a 7-day latency phase at the rate of 1 mm/day and continued until the presurgical plan was achieved. The distractor was removed after a 3-month consolidation phase. Cephalometric radiographs were taken at the completion of each phase.

RESULTS

This new Le Fort I internal distraction device successfully distracted the maxillae as planned in all 3 patients. At the end of the distraction phase, the maxillary advancement was measured at 15.8 mm, 15.8 mm, and 13.5 mm, respectively. In each patient, a clockwise rotation of the maxilla was observed with a tendency to a posterior open bite. Postoperative radiographs also showed that the actual distraction vectors differed from the planned vectors. After the consolidation phase, radiographs showed a relapse of 2.6 mm, 0 mm, and 5.0 mm, respectively. There was no further relapse on 3-month follow-up radiographs. Each case showed radiographic evidence of excellent new bone formation at the osteotomy sites.

CONCLUSION

The new Le Fort I internal distraction device produced the necessary advancement in all 3 patients. The study also showed that the actual distraction vector differed from the planned vector. This discrepancy was caused by a clockwise rotation of the maxilla during the distraction. Finally, the study showed a variable relapse rate not previously reported in maxillary distraction.

The role of simultaneous gap arthroplasty and distraction osteogenesis in the management of temporo-mandibular joint ankylosis with mandibular deformity in children

INTRODUCTION

Temporo-mandibular joint ankylosis is a common cause of acquired deformity in children.

PURPOSE

Surgical correction of the ankylosis only leaves the patient with an uncorrected mandibular deformity. This study was to evaluate the use of distraction osteogenesis for simultaneous correction of the mandibular deformity.

MATERIAL

This study was done on six children with temporo-mandibular joint ankylosis and mandibular deformity. Uniaxial double pin distractors with Schanz pins were used in this study.

METHODS

The patients underwent simultaneous gap arthroplasty and mandibular osteotomy (retromolar) with distractor insertion. Distraction was started on the fifth post-operative day. The patients were put on dynamic temporo-mandibular joint exercises on the first post-operative day.

RESULTS

All patients had a satisfactory mouth opening on follow-up. Satisfactory cosmetic correction of the mandibular deformity was also achieved in all these patients. Some degree of malocclusion resulted from treatment due to which the patients were placed on orthodontic treatment.

CONCLUSIONS

Distraction osteogenesis can be used simultaneously with gap arthroplasty in patients with temporo-mandibular ankylosis, for the correction of the mandibular deformity.

Bilateral bifid mandibular condyle

The bifid condyle is a rather uncommon condition that is diagnosed radiographically. Its etiology is unknown, although the most tenable theory is that it is of traumatic origin. The purpose of this article is to report a new case of a bilateral bifid condyle (the left one manifested a trifid appearance) and to review the relevant literature.

Intraoral distraction osteogenesis for the correction of facial deformities following temporomandibular joint ankylosis: a modified technique

The aim of this study was to evaluate the feasibility of transoral bimaxillary distraction osteogenesis before releasing temporomandibular joint (TMJ) ankylosis using intraoral mandibular distractors. Nine patients (5 males, 4 females) aged 14-35 (mean 19) years were included. A bilateral Le Fort I osteotomy was performed together with a mandibular osteotomy on the affected side(s). An intraoral distractor(s) was inserted in the lower jaw, followed by an intermaxillary fixation (IMF) to maintain preoperative dental occlusion. The distractor was activated, after a latency period of 5-7 days, 2 times daily by 0.5 mm. There followed a consolidation period of 6-8 weeks. TMJ ankylosis was then released via a peri-auricular incision, a gap arthroplasty was performed, and mandibular movement was established after removal of the IMF and distractor. Optimal results were achieved clinically and radiologically with minimal relapse and complications. Apart from minor complaints, the distraction process was smooth and tolerable in all cases. Total mandibular elongation ranged from 17 to 25 mm (20.7 mm). Occlusal canting decreased to 0 degrees in 7 patients and to 1 degree in 2 patients (mean 0.2 degrees). After a mean follow-up period of 17 months, a mean postoperative mouth opening of 34.7 mm was achieved (0.6 mm preoperatively) and no re-ankylosis was detected. Intraoral distraction of a deformed mandible and maxilla before releasing TMJ ankylosis is a feasible and perhaps advantageous technique.

Mandibular morphology and growth with and without hypodontia in subjects with Pierre Robin sequence

INTRODUCTION

Mandibular micrognathia is the hallmark of Pierre Robin sequence (PRS). A high prevalence of mandibular hypodontia has been reported in subjects with PRS. The hypothesis of this study is that the morphology of the mandible in subjects with PRS and mandibular hypodontia is different from that in subjects with PRS but without mandibular hypodontia.

METHODS

The study was conducted at the craniofacial center of The Hospital for Sick Children in Toronto. The study sample comprised 16 caucasian children with nonsyndromic PRS (7 boys, 9 girls) with mandibular hypodontia and 18 white children with nonsyndromic PRS (6 boys, 12 girls) without hypodontia. Longitudinal lateral cephalograms were available before orthodontic treatment (T1; mean age, 11.7 years) and after orthodontic treatment but before orthognathic surgery (T2; mean age, 16.6 years). A new, customized cephalometric analysis with additional landmarks and measurements to study mandibular morphology was performed. Differences in measurements were studied by using analysis of variance adjusted for age and sex.

RESULTS

Cephalometric measurements were smaller in the group with mandibular hypodontia at T1: mandibular length (3.36 mm, P = .04), ramal length (2.78 mm, P = .04), posterior facial height (3.97 mm, P = .03), and mandibular molar eruption (1.96 mm, P = .02). At T2, the differences increased: mandibular length (4.56 mm, P = .02), ramal length (4.04 mm, P = .002), posterior facial height (5.98 mm, P = .001), and mandibular molar eruption (2.08 mm, P = .04). Comparison of growth increments between the 2 groups from T1 to T2 showed a greater cranial base deflection increment in the group with mandibular hypodontia (0.88 degrees, P = .02) and a larger posterior facial height increment in the group without mandibular hypodontia (2.02 mm, P = .04).

CONCLUSIONS

Children with nonsyndromic PRS with mandibular hypodontia had smaller mandibles than children with nonsyndromic PRS and normal complements of mandibular teeth. Their patterns of growth did not improve during adolescence, and the magnitude of differences increased.

Teratogenic effects of avidin-induced biotin deficiency in mice

Teratogenic effects of maternal biotin deficiency were examined at different levels of severity by adding three levels of avidin (10, 20, or 40 mg/kg) in the basal diet. There was a considerable increase of fetuses with multiple congenital malformations (micrognathia, cleft palate, and micromelia) with increasing amounts of avidin. The dose-response relationship was observable in the incidence of each malformation as well. The body weight of live fetuses was also significantly reduced. However, the dams did not exhibit any typical signs of biotin deficiency, such as loss of hair, dermatitis, or nervous irritability. These results suggest that biotin is important for early embryonic development in the mouse.

Morphological Evaluation of Changes in Velopharyngeal Function following Maxillary Distraction in Patients with Repaired Cleft Palate during Mixed Dentition

Objective

To describe the morphological changes of nasopharyngeal components after maxillary distraction and clarify whether the morphological characteristics are related to velopharyngeal function (VPF).

Design

Perceptual judgments of hypernasality and nasendoscopy were performed before and after treatment. Lateral cephalograms were obtained to describe the morphological changes.

Setting

Department of Oral and Maxillofacial Surgery, Miyazaki Medical College, Miyazaki, Japan.

Participants

Nine patients with repaired cleft palate in the mixed dentition stage underwent maxillary distraction using a face mask and an intraoral fixed appliance system.

Outcome Measures

The severity of hypernasality, velopharyngeal insufficiency, and measurements such as pharyngeal depth, velar length, and the rotation of the palatal plane were evaluated.

Results

Increase in pharyngeal depth was not always proportional to the amount of advancement. It depended on the posture of the posterior pharyngeal wall and the rotation of palatal plane.

Conclusion

Cephalometric measurements of the nasopharynx before and after surgery confirmed subsequent changes in VPF. These were suggested to be useful in predicting future VPF. When performing maxillary distraction in patients with cleft palate in the mixed dentition stage, and when velopharyngeal closure is found to occur by velar contact against the hypertrophied adenoid, patients should be counseled about risks of subsequent deterioration in their speech before surgery.

Clinical features, diagnostic criteria, and management of Coffin-Siris syndrome

Coffin-Siris syndrome (OMIM#135900) is a multiple congenital anomaly syndrome classically characterized by hypo- or aplasia of the fifth digit nails or phalanges, as well as coarse facial features, sparse scalp hair, and moderate to severe cognitive and/or developmental delay. The recent identification of molecular etiologies has served to effectively characterize a large set of patients who have been described with Coffin-Siris between the time of its initial description and the present. However, despite recent advances, a number of patients who traditionally fit the diagnosis have yet to have identified causes. This could be due to patients who lie outside the defined phenotype, or alternatively, to additional as yet unidentified genes which may play roles. Here we outline the range of clinical features described in the broader diagnostic category, review the continuing phenotypic challenges and note those subsets of patients for whom molecular causes have yet to be clarified. Finally, we discuss recommendations for clinical management of these individuals.

New internal Le Fort I distractor for the treatment of midface hypoplasia

A new Le Fort I internal distraction device was developed by one of the authors (J. G.) and successfully used on a patient with cleft lip and palate and severe maxillary hypoplasia. The device consisted of an upper plate and a lower plate, which were installed above and below the Le Fort I osteotomy. The upper plate was shaped like a "U," and the lower plate was shaped like an inverted "U." The design of the device was unique in that the distraction screws were placed in the maxillary sinus and orientated parallel to the sagittal plane. Presurgical planning used a stereolithographic (STL) model and the CASSOS software to calculate the distraction vector. The distractors were prebent and installed on the STL model and activated to advance the maxilla 15.5 mm. Surgery was performed in a conventional manner, and distraction was started on the seventh day after surgery. At the completion of distraction, a total of 15.5 mm of distraction was achieved. The distractors were removed 3 months after surgery. Results showed that the patient's severe maxillary hypoplasia was corrected as predicted and there was excellent new bone formation between the edges of the osteotomy.