Genetic Factors in Selected Complex Congenital Malformations with Cleft Defect

A screen of mutants generated and imaged by the International Mouse Phenotyping Consortium identifies 39 novel genes regulating the development of the secondary palate

The International Mouse Phenotyping Consortium (IMPC) has generated thousands of knockout mouse lines, of which a large proportion is embryonic or early neonatal lethal. The IMPC has generated and imaged embryos from lethal lines and made the three-dimensional image data sets publicly available. In this study, we used this resource to screen homozygous null mutants for defects in the development of the secondary palate. Altogether, we analyzed optical sections from 3216 embryos isolated at embryonic day (E) 15.5 and E18.5 from 478 homozygous mutant lines. Through this analysis, we discovered 39 novel genes important for palatal development. These studies provide new insights into the molecular regulation of palatogenesis and craniofacial disease and offer a useful resource for future exploration.

Rare and Multiple Hypodontia in Van der Woude Syndrome: Case Report

Van der Woude syndrome (VWS) is a rare syndrome of genetic etiology, commonly occasioned by mutations in the IRF6 gene and that causes disorders in craniofacial development. VWS is characterized by the presence of paramedian fistulas in the lower lip and cleft lip and / or cleft palate. Although some dental phenotypes have been reported in this syndrome, multiple and rare hypodontias were not described. Through this case report, we present a case of Van der Woude Syndrome (VWS) with rare and multiple hypodontia in which clinical data and radiographic exams were evaluated. The patient presented hypodontia of eight permanent teeth (lateral incisors, second premolars and second molars). So, when the dentist recognizes multiple and/or rare hypodontias, for an accurate diagnosis, detailed examination of the lower lip is indicated, as well as a survey of the family history and referral for genetic counseling, since the syndrome presents high penetrance. The patient is expected to be rehabilitated to have a good quality of life. Rehabilitation in these cases requires alveolar bone graft, orthodontics and prosthesis to replace missing teeth.

[The Pierre Robin sequence from an anesthesiologic perspective : Presentation of the procedure based on a retrospective analysis at a university hospital]

INTRODUCTION

As part of surgical interventions in pediatric patients, children with craniofacial malformations and syndromes are presented in the field of oral and maxillofacial surgery, anesthesia and also in all other clinical disciplines. In particular, the Pierre Robin sequence in the clinical context leads to a situation albeit a rare one, which should be given high attention in preoperative, intraoperative and postoperative care.

MATERIAL AND METHODS

In a retrospective analysis from 1993 to 2020 in the Department of Oral and Maxillofacial Surgery at the University Hospital Halle (Saale), a total of 54 patients were identified with syndromic changes and a need for surgical treatment. During this period, 12 patients with a Pierre Robin sequence were genetically confirmed, who received a total of 20 surgical interventions under general anesthesia at different times. Statistical analysis was performed using SPSS 17.0.

RESULTS

In 12 patients with a Pierre Robin sequence, 20 surgical procedures were performed with the patient under general anesthesia. The youngest patients had an average age of 6 months, the oldest 16 years at the time of the operation. The average age was 5.7 years. In addition to the genetic component, all children were assigned to the ASA I classification. The surgical indication was initially an isolated cleft palate in all patients, followed by further interventions such as dental restorations, corrective surgery in the area of the palate or ear nose throat (ENT) examinations. Drug induction of general anesthesia was weight-adapted using propofol 1%, fentanyl or remifentanil and rocuronium. In our study, out of 18 orotracheal intubations, only 2 patients had to be intubated by video laryngoscopy. One patient required nasal intubation and another was fitted with a laryngeal mask. The success rate of conventional intubation was 89.5%. Postoperatively, one infant had recurrent drops in saturation, so that reintubation was necessary.

The genetic factors contributing to the risk of cleft lip-cleft palate and their clinical utility

Cleft lip and cleft palate (CL/P) are among the most common congenital malformations in neonates and have syndromic or nonsyndromic forms. Nonsyndromic forms of malformation are being reported to be associated with chromosomal DNA modification by teratogenic exposure and to complex genetic contributions of multiple genes. Syndromic forms are shown to be related to chromosomal aberrations or monogenic diseases. There is a growing body of data illustrating the association of several genes with risk of developing this malformation, including genetic defects in T-box transcription factor-22 (TBX22), interferon regulatory factor-6 (IRF6), and poliovirus receptor-like-1 (PVRL1), responsible for X-linked cleft palate, cleft lip/palate-ectodermal dysplasia syndrome, and Van der Woude and popliteal pterygium syndromes, respectively. Genetic variants in MTR, PCYT1A, ASS1, SLC 25A13, GSTM1, GSTT1, SUMO1 BHMT1, and BHMT2 are being reported to be linked with CL/P risk. The etiology of nonsyndromic CLP is still remained to be unknown, although mutations in candidate genes have been found. Here, we provide an overview about the potential variants to be associated with CL/P for identification of the relative risk of CLP with respect to the basis of genetic background and environmental factors (e.g., dietary factors, alcohol use).

Isolated Cleft Lip and Palate: Maxillary Gap Sign and Palatino-Maxillary Diameter at 11-13 Weeks

OBJECTIVE

To evaluate the maxillary gap sign and describe markers for the first-trimester diagnosis of isolated cleft lip and palate (CLP) at 11-13 weeks.

METHODS

Firstly, this was a prospective assessment of 1,087 fetuses including 5 cases of isolated CLP in 2 centers which were referred for the 11-13 weeks scan. Secondly, intra- and interobserver variability of the maxillary gap sign was evaluated for observers R.L. and A.B. in 2 sessions (affected cases vs. 50 normal fetuses in each session) to reduce the bias of different ultrasound manufacturer visualizations (Philips, GE). Thirdly, the palatino-maxillary diameter (PMD) was examined in stored images, DICOM loops and volumes of the midsagittal and parasagittal view of the fetal head and brain at 11+0-13+6 weeks of gestation from 5 fetuses with isolated CLP and 302 consecutively assessed normal controls. The PMD values in fetuses with isolated CLP and normal controls were compared.

RESULTS

Firstly, 5 out of 6 referred pregnancies with isolated CLP were detected prospectively using the midsagittal view for measurement of nuchal translucency due to an abnormal appearance. One out of 6 patients with isolated CLP declined the 11-13 weeks scan. Secondly, intra- and interobserver variability showed no false positive cases; all cases with isolated CLP were identified by both sonographers; however, in 2 cases the maxillary gap sign was doubtful. Therefore, thirdly, we developed the PMD measurement which increased significantly with crown-rump length (CRL) from respective mean values at CRL of 45 mm to 4.66 mm and to 8.95 mm at CRL of 84 mm. In the CLP group, the PMD was below the 5th percentile of the control group in 4 out of 5 (80%) cases.

CONCLUSIONS

The midsagittal view for measurement of nuchal translucency shows a high reproducibility regarding abnormal views for maxillary gap sign. In the midsagittal view of the fetal head, face, and brain at 11-13 weeks, the majority of fetuses with isolated CLP have a measurable abnormality in addition, the PMD.

Pathogenesis of Cleft Palate in Robin Sequence: Observations From Prenatal Magnetic Resonance Imaging

PURPOSE

The etiology of the palatal cleft in Robin sequence (RS) is unknown. The purpose of this study was to assess the position of the fetal tongue at prenatal magnetic resonance imaging (MRI) and to suggest a potential relation between tongue position and development of the cleft palate seen in most patients with RS.

MATERIALS AND METHODS

This is a retrospective case-and-control study including fetuses with prenatal MRIs performed in the authors' center from 2002 to 2017. Inclusion criteria were 1) prenatal MRI of adequate quality, 2) liveborn infant, and 3) postnatal diagnosis of RS (Robin group) or cleft lip and palate (CLP group). Patients with postnatal RS without a palatal cleft were excluded. A control group with normal facial morphology was matched by gestational age. The outcome variable was tongue position at fetal MRI, described as within the cleft, along the floor of the mouth (normal), other, or indeterminate.

RESULTS

One hundred twenty-two patients with mean gestational age at MRI of 25.8 ± 4.9 weeks were included (Robin, n = 21 [17%]; CLP, n = 47 [39%]; control, n = 54 [44%]). The tongue was visualized within the palatal cleft in 76.2% of the Robin group and 4.3% of the CLP group. The tongue was found along the floor of the mouth (normal) in the remainder of the Robin and CLP groups and in 100% of the control group.

CONCLUSION

These findings suggest a relation between in utero tongue position and the development of cleft palate in RS.