Ocular adnexal phenotype and management of a patient with mosaic expression of a mutation in TWIST2.

Ablepharon-macrostomia syndrome (AMS) and Barber-Say syndrome (BSS) are congenital ectodermal dysplasias associated with mutations in the TWIST2 gene. Among the ophthalmic anomalies that occur in these syndromes, underdevelopment of the anterior lamella of the eyelid is a defining feature. Reports of mosaic expression of TWIST2 mutations are extremely rare, with only five confirmed or suspected cases described to date. Mosaic expression of TWIST2 variants is correlated with a less severe phenotype than that reported for the typical expression of TWIST2 variants associated with BSS or AMS. Abnormal development of the anterior lamella appears to be a common feature in all cases of AMS with mosaic expression. Here, we describe the phenotype of a patient with mosaic expression of a TWIST2 mutation that is typically associated with AMS. We additionally describe the surgical approach employed in the treatment of this patient.

An optimized base editor with efficient C-to-T base editing in zebrafish.

BACKGROUND: Zebrafish is a model organism widely used for the understanding of gene function, including the fundamental basis of human disease, enabled by the presence in its genome of a high number of orthologs to human genes. CRISPR/Cas9 and next-generation gene-editing techniques using cytidine deaminase fused with Cas9 nickase provide fast and efficient tools able to induce sequence-specific single base mutations in various organisms and have also been used to generate genetically modified zebrafish for modeling pathogenic mutations. However, the editing efficiency in zebrafish of currently available base editors is lower than other model organisms, frequently inducing indel formation, which limits the applicability of these tools and calls for the search of more accurate and efficient editors. RESULTS: Here, we generated a new base editor (zAncBE4max) with a length of 5560 bp following a strategy based on the optimization of codon preference in zebrafish. Our new editor effectively created C-to-T base substitution while maintaining a high product purity at multiple target sites. Moreover, zAncBE4max successfully generated the Twist2 p.E78K mutation in zebrafish, recapitulating pathological features of human ablepharon macrostomia syndrome (AMS). CONCLUSIONS: Overall, the zAncBE4max system provides a promising tool to perform efficient base editing in zebrafish and enhances its capacity to precisely model human diseases.

Programmable base editing in zebrafish using a modified CRISPR-Cas9 system.

The use of CRISPR/Cas9 to knockout genes in zebrafish has been well established. However, to better model many human diseases that are caused by point mutations, a robust methodology for generating desirable DNA base changes is still needed. Recently, Cas9-linked cytidine deaminases (base editors) evolved as a strategy to introduce single base mutations in model organisms. They have been used to convert cytidine to thymine at specific genomic loci. Here we describe a protocol for using the base editing system in zebrafish and its application to reproduce a single base mutation observed in human Ablepharon-Macrostomia Syndrome.

Clinical Description, Molecular Analysis of TWIST2 Gene, and Surgical Treatment in a Patient With Barber-Say Syndrome.

Barber-Say syndrome is a rare autosomal dominant disease characterized by dysmorphic features, mainly of the eyelids and skin. It is caused by heterozygous mutations in gene TWIST2, localized in chromosome 2q37.3. The authors present the case of a pediatric patient with a clinical diagnosis of Barber-Say syndrome with ocular symptoms related to exposure keratitis. Molecular analysis of her DNA revealed a mutation on TWIST2 gene confirming the diagnosis of Barber-Say syndrome. Surgical treatment of the patient's eyelids resolved her signs and symptoms.

Barber-Say syndrome and Ablepharon-Macrostomia syndrome: An overview.

Barber-Say syndrome (BSS) and Ablepharon-Macrostomia syndrome (AMS) are congenital malformation syndromes caused by heterozygous mutations in TWIST2. Here we provide a critical review of all patients published with these syndromes. We excluded several earlier reports due to misdiagnosis or insufficient data for reliable confirmation of the diagnosis. There remain 16 reliably diagnosed individuals with BSS and 16 with AMS. Major facial characteristics present in both entities, albeit often in differing frequencies, are excessive facial creases, hypertelorism, underdevelopment of the anterior part of the eyelids (anterior lamella), ectropion, broad nasal ridge and tip, thick and flaring alae nasi, protruding maxilla, wide mouth, thin upper vermillion, and attached ear lobes. In BSS a remarkable extension of the columella on the philtrum can be seen, and in both the medial parts of the cheeks bulge towards the corners of the mouth (cheek pads). Scalp hair is sparse in AMS only, but sparse eyebrows and eyelashes occur in both entities, and general hypertrichosis occurs in BSS. We compare these characteristics with those in Setleis syndrome which can also be caused by TWIST2 mutations. The resemblance between the three syndromes is considerable, and likely differences seem larger than they actually are due to insufficiently complete evaluation for all characteristics of the three entities in the past. It is likely that with time it can be concluded that BSS. AMS and Setleis syndrome form a continuum. © 2016 Wiley Periodicals, Inc.

Recurrent Mutations in the Basic Domain of TWIST2 Cause Ablepharon Macrostomia and Barber-Say Syndromes.

Ablepharon macrostomia syndrome (AMS) and Barber-Say syndrome (BSS) are rare congenital ectodermal dysplasias characterized by similar clinical features. To establish the genetic basis of AMS and BSS, we performed extensive clinical phenotyping, whole exome and candidate gene sequencing, and functional validations. We identified a recurrent de novo mutation in TWIST2 in seven independent AMS-affected families, as well as another recurrent de novo mutation affecting the same amino acid in ten independent BSS-affected families. Moreover, a genotype-phenotype correlation was observed, because the two syndromes differed based solely upon the nature of the substituting amino acid: a lysine at TWIST2 residue 75 resulted in AMS, whereas a glutamine or alanine yielded BSS. TWIST2 encodes a basic helix-loop-helix transcription factor that regulates the development of mesenchymal tissues. All identified mutations fell in the basic domain of TWIST2 and altered the DNA-binding pattern of Flag-TWIST2 in HeLa cells. Comparison of wild-type and mutant TWIST2 expressed in zebrafish identified abnormal developmental phenotypes and widespread transcriptome changes. Our results suggest that autosomal-dominant TWIST2 mutations cause AMS or BSS by inducing protean effects on the transcription factor's DNA binding.

Ablepharon macrostomia syndrome: A distinct genetic entity clinically related to the group of FRAS-FREM complex disorders.

Ablepharon macrostomia syndrome (AMS; OMIM 200110) is an extremely rare congenital malformation syndrome. It overlaps clinically with Fraser syndrome (FS; OMIM 219000), which is known to be caused by mutations in either FRAS1, FREM2, or GRIP1, encoding components of a protein complex that plays a role in epidermal-dermal interactions during morphogenetic processes. We explored the hypothesis that AMS might be either allelic to FS or caused by mutations in other genes encoding known FRAS1 interacting partners. No mutation in either of these genes was found in a cohort of 11 patients with AMS from 10 unrelated families. These findings demonstrate that AMS is genetically distinct from FS. It is proposed that it constitutes a separate entity within the group of FRAS-FREM complex disorders.

A de novo 1.38 Mb duplication of 1q31.1 in a boy with hemifacial microsomia, anophthalmia, anotia, macrostomia, and cleft lip and palate.

We reported a 2-year-old boy with developmental delay, mild mental retardation, and severe craniofacial malformation, including facial asymmetry with hypoplasia of the left zygoma, maxilla, and mandible, and left anophthalmia and anotia. A genome-wide screen revealed a 1.38 Mb duplication on chromosome 1q31.1, which was absent in his parents and 27 healthy controls. The duplication region contains two Refseq genes, PLA2G4A and C1orf99, which have not been reported to be implicated in craniofacial malformation. Functional studies of these genes and additional clinical analysis are necessary to elucidate the pathogenesis of craniofacial malformation.

Evidence for autosomal dominant inheritance of ablepharon-macrostomia syndrome.

Ablepharon-macrostomia syndrome (AMS) is characterized by absent or short eyelids, macrostomia, ear anomalies, absent lanugo and hair, redundant skin, abnormal genitalia, and developmental delay in two-thirds of the reported patients. Additional anomalies include dry skin, growth retardation, hearing loss, camptodactyly, hypertelorism, absent zygomatic arches, and umbilical abnormalities. We present the second familial case of ablepharon-macrostomia syndrome in a newborn female and her 22-year-old father making autosomal dominant inheritance more likely than the previously proposed autosomal recessive transmission for this disorder. These cases likely represent the 16th and 17th reported cases of AMS and the first case suspected on prenatal ultrasound. Additionally, the child shows more prominent features of the disorder when compared to her father documenting variable expression and possible anticipation.

Oral and dental abnormalities in Barber-Say syndrome.

A previously unreported case of Barber-Say syndrome is described with special attention to dental manifestations. A 7-year-old female with multiple congenital anomalies such mammary gland hypoplasia, hypertrichosis, ectropion, and redundant skin was seen at the School of Dentistry of the University of São Paulo. Oral examination revealed macrostomia, broad alveolar ridges, gingival fibromatosis, taurodontism, delayed tooth eruption, and malocclusion. Dental treatment included gingivoplasty and orthodontic treatment.

Barber-Say syndrome in a father and daughter.

We report on a father to daughter transmission of Barber-Say syndrome (BSS), a rare, congenital disorder characterized by severe generalized hypertrichosis, macrostomia, ocular telecanthus, bulbous nose and atrophic skin. These two cases further support the autosomal dominant inheritance. Both presented with the typical BSS symptoms but the phenotypic expression in the father was milder. Treatment is challenging for both patients and doctors, requiring a multidisciplinary approach.

Macrostomía bilateral aislada congénita / Congenital isolated bilateral macrostomia

Introducción. Dentro de las malformaciones craneofaciales, la macrostomía bilateral aislada es una de las malformaciones más inhabituales, con una frecuencia del 0,3% de los niños con fisuras faciales. Consiste en una hendidura orofacial entre el maxilar superior y el inferior derivada de una alteración del primer arco branquial. Su etiología es desconocida, pero una de las teorías más establecidas es el error de fusión entre el maxilar superior y el inferior durante el desarrollo embrionario. Suele aparecer de manera aislada, sin estar asociada a otros defectos, en contraposición a la macrostomía unilateral, que normalmente forma parte de un síndrome específico. Observación clínica. Exponemos el caso de un recién nacido de sexo femenino que presenta a la exploración un alargamiento bilateral de la comisura bucal de un centímetro de longitud mostrando una apertura amplia, sin otra malformación externa asociada. Todas las exploraciones complementarias que se realizaron para detectar malformaciones asociadas fueron normales. La evolución el periodo neonatal fue correcta, salvo una succión débil en las primeras horas de vida que desapareció progresivamente. Comentarios. Es importante realizar una minuciosa exploración física y diferentes exploraciones complementarias, como ecografía transfontanelar y abdominal, serie ósea y ecocardiograma para encontrar otras anormalidades, en especial si es de presentación unilateral. El tratamiento es quirúrgico con una evolución favorable y donde el proceso de deglución y fonación está conservado(AU)

Introduction. Isolated bilateral macrostomia is one of the rarest malformations within the craniofacial defects, with a frequency of 0.3% of children with facial clefts. It is defined by the presence of an orofacial cleft between the upper and lower jawbone caused by an alteration of the first branchial arch. Its etiology is unknown but one of the most established theories is the error of fusion between upper and lower jaw during embryonic development. Usually it appears isolated, without being associated with other defects, in contrast to unilateral macrostomia, which most often presents in the context of a specific syndrome. Case report. We describe the case of a female newborn that presented a bilateral one-centimeter elongation of the mouth, showing a large opening without other associated external malformations. Imaging studies excluded internal malformations. The evolution was optimal in the neonatal period except for a weak suction in the first hours of life that gradually improved. Comments. In the presence of macrostomia, it is important to perform a thorough evaluation, including physical examination and imaging studies such as transfontanellar and abdominal ultrasound, echocardiography and skeletal series to evaluate for other abnormalities, especially in cases of unilateral presentation. Surgical treatment usually results in successful outcome with preservation of swallowing and phonation(AU)

[vrk1 gene mutation test in two Chinese pedigrees of the first and second branchial arch syndrome].

OBJECTIVE: To explore the role of vrk1 gene in two Chinese pedigrees of the first and second branchial arch syndrome. METHOD: Sixty members in 2 Chinese pedigrees were recruited. The exon 2 -13 were analyzed by polymerase chain reaction and direct sequencing. RESULT: We found a new SNP in proband of Shandong pedigree. CONCLUSION: vrk1 gene mutation can be excluded in 2 Chinese pedigrees of the first and second branchial arch syndrome.

Fraser and Ablepharon macrostomia phenotypes: concurrence in one family and association with mutated FRAS1.

To date, Fraser syndrome (FS) and Ablepharon macrostomia syndrome (AMS) have been considered distinct disorders, but they share strikingly similar patterns of congenital abnormalities, specifically craniofacial anomalies. While recent research has led to the identification of the genes FRAS1 and FREM2 as the cause of FS, the genetic basis of AMS continues to be enigmatic. We report on the concurrence of AMS-like and Fraser phenotypes in a Brazilian family. Both affected sibs were homozygous for a novel splice site mutation in the FRAS1 gene. Extensive studies on mRNA expression indicated that this mutation most likely leads to loss of function as most previously reported FRAS1 mutations associated with FS. We conclude that a phenotype resembling AMS is a rare clinical expression of FS with no obvious genotype-phenotype correlation. However, the molecular basis of "true" AMS which has been reported as a sporadic disorder in all cases but one, and so far with no relation to FS, is probably different and still needs to be further investigated.

Ablepharon-macrostomia syndrome in a 46-year-old woman.

Ablepharon-macrostomia syndrome (AMS) is a rare condition reported to date in 13 patients worldwide. AMS is characterized by absent or short eyelids, absent eyebrows and eyelashes, macrostomia, and external ear abnormalities. Additional features include alopecia or sparse hair, hypoplastic malar region, redundant skin, rudimentary nipples, abnormal genitalia. While the AMS phenotype is well delineated in infants and children, clinical manifestations are rather poorly characterized in adulthood. Here, we report on an Italian woman who received a diagnosis of AMS at the age of 46 years after several surgical treatments. A clinical comparison between our patient and previously reported AMS cases aids in delineating the adult phenotype of AMS and further broadens the clinical spectrum of this condition.

Lateral facial clefts: a case report.

A female new-born with bilateral lateral facial clefts, resulting in macrostomia, is reported. In addition she had a diminished palpebral fissure length. She died suddenly at the age of 6 months, presumably due to respiratory insufficiency. The unique combination of facial anomalies, present in this patient, has not been reported before. We discuss the differential diagnosis and the classification of facial clefts.

Frontonasal dysplasia, macroblepharon, eyelid colobomas, ear anomalies, macrostomia, mental retardation and CNS structural anomalies: defining the phenotype.

We report a Brazilian boy, born to normal and nonconsanguineous parents showing, among other signs, brachycephaly, a wide forehead, a widow's peak, hypertelorism, wide palpebral fissures with multiple eyelid colobomas, a broad nasal root, a long philtrum, macrostomia, prominent lips, a high arched palate, a midline alveolar cleft, a small and grooved chin, ear anomalies, structural anomaly of the corpus callosum, and mental retardation. To our knowledge this additional patient defines a particular clinical condition previously reported [Guion-Almeida M.L. Richieri-Costa A. (1999) Clinical Dysmorphol 8;1-4; Masuno M. et al. (2000) Clin Dysmorphol 9:59-60].