The branchio-oculo-facial syndrome

A New Case and Comprehensive Review of the Ophthalmic Manifestations of 172 Individuals With Branchio-Oculo-Facial Syndrome

PURPOSE

To review the literature on branchio-oculo-facial syndrome and describe a new case.

METHODS

A girl presented with a de novo pathogenic mutation in the TFAP2A gene consistent with branchiooculo-facial syndrome. A systematic review was also performed to characterize the eye manifestations associated with the syndrome.

RESULTS

A total of 172 total patients were identified from the literature. Among these, 102 patients received molecular confirmation. The most common pathogenic variants reported were p.R255G, p.A256V, p.R254W, and p.G251E. Common eye abnormalities associated with the syndrome in total combined cases (represents individuals with a clinical diagnosis only of branchiooculo-facial syndrome plus those who additionally had molecular confirmation of the syndrome from genetic testing) were nasolacrimal duct stenosis (n = 98, 57%), coloboma (n = 76, 46%), anophthalmia/microphthalmia (n = 64, 37%), and cataracts (n = 27, 16%).

CONCLUSIONS

This analysis provides a comprehensive review of genetic variants and ophthalmic findings to characterize the most common eye manifestations associated with branchio-oculo-facial syndrome. The report provides incentive to further investigate TFAP2A variants and identify genotype-phenotype correlations. [J Pediatr Ophthalmol Strabismus. 20XX;XX(X):XX-XX.].

A Heterozygous Novel Mutation in TFAP2A Gene Causes Atypical Branchio-Oculo-Facial Syndrome With Isolated Coloboma of Choroid: A Case Report

Background: Branchio-oculo-facial syndrome (BOFS) is a rare congenital developmental disorder with highly variable clinical phenotypes in autosomal dominant inheritance. The aim of this study is to identify disease-causing mutations in a Chinese family with predominant coloboma of choroid. Case report: We described a family (a mother and her daughter) with unclear clinical diagnosis. The mother (proband) presented with bilateral coloboma of choroid, whereas her daughter had a relatively severe phenotype and presented with larger bilateral choroid coloboma and high-vaulted arch. We applied the next generation sequencing (NGS) panel and analyzed 776 genes related to inherited ocular disorders on the proband. Four candidate heterozygous variants in four genes, respectively, were detected in the proband. Validation of these variants were subsequently performed in the family using Sanger sequencing. Among these variants, a novel nonsense mutation c.912C>A, p.(Cys304^*) (NM_001042425.2) which in exon 6 of the conserved helix-span-helix domain in TFAP2A results in a premature termination codon. It may trigger nonsense-mediated mRNA decay (NMD). Both the affected mother and daughter had this variant, whereas it was absent in the asymptomatic father. Together with the silicon tools and clinical features, we concluded that the variant c.912C>A, p.(Cys304^*), was the second reported nonsense mutation in TFAP2A gene, which was the disease-causing mutation of the family. Conclusion: There are many hereditary diseases accompanied by ocular anomalies. For instance, BOFS, patients with atypical features are always at risk of being under-diagnosed. NGS is a powerful method to identify the genetic cause and improve genetic counseling for less clarified hereditary ocular diseases.

Branchi-oculo-facial syndrome: a case report to highlight recent genetic considerations

Branchio-oculo-facial syndrome (BOFS) is a rare entity described during the last century which has been recently linked to mutations of the gene encoding for the transcription factor named 'TFAPA2'. We report here a sporadic case of BOFS with a partial phenotype caused by a de novo mutation of this gene and discuss recent genetic findings.

Clinical presentation and the presence of hearing impairment in branchio-oculo-facial syndrome: a new mutation in the TFAP2A gene

We report on the clinical presentation of branchio-oculo-facial (BOF) syndrome in 2 patients with mutations in the TFAP2A gene (OMIM 107580). This TFAP2A gene was recently shown to be involved in the causation of BOF syndrome. An overview of the literature on BOF syndrome is given based on clinical reports written in the period during which mutation analysis was not yet available for BOF syndrome. We also give descriptions of the mutations in the TFAP2A gene in our 2 new patients with BOF syndrome. Congenital conductive hearing impairments are described, including hearing rehabilitation and the results of ear surgery.

AP-2alpha knockout mice exhibit optic cup patterning defects and failure of optic stalk morphogenesis

Appropriate development of the retina and optic nerve requires that the forebrain-derived optic neuroepithelium undergoes a precisely coordinated sequence of patterning and morphogenetic events, processes which are highly influenced by signals from adjacent tissues. Our previous work has suggested that transcription factor activating protein-2 alpha (AP-2alpha; Tcfap2a) has a non-cell autonomous role in optic cup (OC) development; however, it remained unclear how OC abnormalities in AP-2alpha knockout (KO) mice arise at the morphological and molecular level. In this study, we show that patterning and morphogenetic defects in the AP-2alpha KO optic neuroepithelium begin at the optic vesicle stage. During subsequent OC formation, ectopic neural retina and optic stalk-like tissue replaced regions of retinal pigment epithelium. AP-2alpha KO eyes also displayed coloboma in the ventral retina, and a rare phenotype in which the optic stalk completely failed to extend, causing the OCs to be drawn inward to the midline. We detected evidence of increased sonic hedgehog signaling in the AP-2alpha KO forebrain neuroepithelium, which likely contributed to multiple aspects of the ocular phenotype, including expansion of PAX2-positive optic stalk-like tissue into the OC. Our data suggest that loss of AP-2alpha in multiple tissues in the craniofacial region leads to severe OC and optic stalk abnormalities by disturbing the tissue-tissue interactions required for ocular development. In view of recent data showing that mutations in human TFAP2A result in similar eye defects, the current findings demonstrate that AP-2alpha KO mice provide a valuable model for human ocular disease.

TFAP2A mutations result in branchio-oculo-facial syndrome

Branchio-oculo-facial syndrome (BOFS) is a rare autosomal-dominant cleft palate-craniofacial disorder with variable expressivity. The major features include cutaneous anomalies (cervical, infra- and/or supra-auricular defects, often with dermal thymus), ocular anomalies, characteristic facial appearance (malformed pinnae, oral clefts), and, less commonly, renal and ectodermal (dental and hair) anomalies. The molecular basis for this disorder is heretofore unknown. We detected a 3.2 Mb deletion by 500K SNP microarray in an affected mother and son with BOFS at chromosome 6p24.3. Candidate genes in this region were selected for sequencing on the basis of their expression patterns and involvement in developmental pathways associated with the clinical findings of BOFS. Four additional BOFS patients were found to have de novo missense mutations in the highly conserved exons 4 and 5 (basic region of the DNA binding domain) of the TFAP2A gene in the candidate deleted region. We conclude BOFS is caused by mutations involving TFAP2A. More patients need to be studied to determine possible genetic heterogeneity and to establish whether there are genotype-phenotype correlations.

Branchio-oculo-facial syndrome

Branchio-oculo-facial syndrome (BOFS) is a very rare autosomal dominant disorder with incomplete penetrance and variable expression; with phenotypic variation ranging from mild to severe forms, involving eye, ear, oral and craniofacial structure. We report three members of one family, showing great variability in its phenotypic expression and review the recent literature.

Branchio-oculo-facial syndrome with cleft lip and bilateral dermal thymus

OBJECTIVE

The objective of this study was to demonstrate that the branchiooculo-facial (BOF) syndrome is a cervicocephalic neural crest maldevelopment.

RESULTS

Using an embryologic study, we linked the clinical features and the level of the neural crest deficiency. We report here two cases of BOF syndrome with a particular branchial cleft presenting as bilateral supernumerary thymus glands on the surface of the skin; one of the cases was associated with tetralogy of Fallot. One patient underwent lip reconstruction at 4 months, combined with excision of bilateral auricular pits and superior labial fistula. The other patient had a surgical correction of the tetralogy of Fallot, and at 2 months, the two stages of the lip reconstruction were performed, combined with bilateral auricular pit excision. Both patients have shown normal developmental patterns to date.

CONCLUSION

The BOF syndrome must be considered as a neurocristopathy at different levels, with a tiny mesencephalo-prosencephalic lesion and a severe rhombencephalic lesion that includes seven consecutive hindbrain segments, from rhombomere 2 to rhombomere 8.

Bilateral clinical anophthalmos

We report on the risk factors, associations and outcome of 5 children with bilateral clinical anophthalmos. Our study showed no gestational, environmental or hereditary association but confirmed strong association with multiple systemic abnormalities.

Further delineation of the branchio-oculo-facial syndrome

We review 43 patients (15 new, 28 literature) with the branchio-oculo-facial (BOF) syndrome, which has a distinctive phenotype ranging from mild to severe forms, consisting of eye, ear, oral, and craniofacial anomalies. Virtually ubiquitous and possibly pathognomonic are the cervical/infra-auricular skin defects. Much less common are supra-auricular defects occurring as isolated anomalies or with cervical defects. Regardless of location, these lesions may have aplastic, "hemangiomatous," or otherwise abnormal overlying skin, and draining sinus fistulae. Renal malformations are frequent, but congenital heart and central nervous system defects are rare. Psychomotor performance is usually normal, but development delays, hypotonia, and visual, hearing, and speech problems are common. Autosomal dominant inheritance seems likely. Overlap between the BOF and branchio-otorenal syndromes has been observed, but elucidation of its molecular basis is not yet available. This article also discusses 5 patients with atypical manifestations considered to be possibly affected or probably unaffected, who are sufficiently unusual to be excluded from the final data analysis.

Branchio-oculo-facial syndrome: broadening the spectrum

We present 3 individuals, a mother, her son, and an unrelated child, with a number of manifestations reported in the branchio-oculo-facial syndrome (BOFS). The former 2 individuals lacked the ocular and branchial abnormalities normally encountered in this syndrome. However, unilateral renal agenesis was present in the first child, a defect infrequently found in the BOF syndrome. Both the mother and her son also had bilateral supra-auricular sinuses. These defects may represent persistence of the otic vesicle sinus tract. The second child has a mild expression of this condition, among the mildest reported in the literature. The BOFS appears to represent a spectrum involving the development of the optic vesicles, branchial arches, eyes, face, lips, and kidneys. The variations seen in this disorder and the overlap between this condition and the branchio-oto-renal syndrome may represent different mutations within a single gene or may be a contiguous gene deletion syndrome.