Branchio-oculo-facial Syndrome Research Articles

Genetic analysis of a Chinese pedigree affected with Branchio-oculo-facial syndrome and a literature review

To explore the genetic etiology of a Chinese pedigree affected with Branchio-oculo-facial syndrome (BOFS) and summarize the prenatal phenotype of BOFS patients. A pedigree with BOFS which had presented at the Genetics and Prenatal Diagnosis Center of the First Affiliated Hospital of Zhengzhou University in December 2021 was selected as the study subject. Clinical data of the pedigree was collected. The fetus was subjected to routine prenatal ultrasound scan. Trio-whole exome sequencing (trio-WES) was carried out for the fetus and its parents, and candidate variant was verified by Sanger sequencing. Relevant literature was searched from the database to summarize the prenatal phenotype of BOFS patients. Ultrasound exam suggested the fetus had cleft lip and palate. Its father had presented with high palatal arch, prematurely grayed hair, occult cleft lip, congenital preauricular fistula, red-green color blindness and unilateral renal agenesis. Its grandfather also had high palatal arch, prematurely gray hair, protruding ears, congenital preauricular fistula and hearing disorders. Trio-WES revealed that the fetus and its father had both harbored a heterozygous c.890-1G>A variant of the TFAP2A gene. The same variant was not found in its mother. Sanger sequencing confirmed that its grandfather had also harbored the same variant. Based on the guidelines from the American College of Medical Genetics and Genomics (ACMG), the variant was rated as likely pathogenic (PVS1+PM2_Supporting). Combined with 36 similar cases retrieved from the literature, the prenatal phenotypes of BOFS patients had included growth restriction (25/37), renal abnormalities (10/37), cleft lip and palate (5/37) and oligohydramnios (5/37). The c.890-1G>A variant of the TFAP2A gene probably underlay the pathogenesis of BOFS in this pedigree. Discovery of the novel variant has enriched the mutational spectrum of the TFAP2A gene. The common prenatal phenotypes of BOFS have included growth restriction, renal abnormalities, cleft lip and palate and oligohydramnios. Delineation of the intrauterine phenotype of BOFS may facilitate its prenatal diagnosis, clinical diagnosis, treatment and genetic counseling.

EP415 - Expanding the mutational spectrum for branchiooculofacial syndrome: a novel nonsense variant

eP415 - Expanding the mutational spectrum for branchiooculofacial syndrome: a novel nonsense variant

Alterações funcionais e estruturais do complexo craniofacial na síndrome branquio-óculo-facial: relato de caso

Introdução: A Síndrome Branquio-Óculo-Facial é uma doença autossômica rara com expressão variável, dependente das mutações genéticas, cujo fenótipo caracteriza-se por alterações oculares, auriculares e craniofaciais. Objetivo: Descrever características clínicas, alterações funcionais e estruturais do complexo craniofacial de sujeito com síndrome branquio-óculo-facial. Método: Paciente de 13 anos e 3 meses, respiradora oral com perda auditiva condutiva de grau moderadamente severo em ambas as orelhas, diagnosticada com síndrome branquio-óculo-facial, apresentou: fissura labiopalatina transforame bilateral completa corrigida por labioplastia e palatoplastia primárias, assimetria facial, fístula em região anterior de palato duro, atresia maxilar transversa, dentinogênese imperfeita, trespasse horizontal negativo, oclusão Classe I de Angle e mordida aberta anterior e lateral bilateralmente, desvio severo da linha média superior para a esquerda, incisivo lateral superior permanente semi-erupcionado por vestibular do canino superior decíduo do lado esquerdo, retenção prolongada do segundo molar inferior decíduo direito, apinhamento dentário inferior, hipotonia e posicionamento inadequado de língua, ausência de vedamento labial em repouso, deglutição adaptada, alteração na mobilidade de lábios, bochechas e palato mole com escape de ar nasal na fala, caracterizando disfunção velofaríngea. Sujeitos com fissura lábiopalatina podem apresentar grande variedade de alterações na produção dos fones. Paciente apresenta crescimento deficiente da maxila que, como relatado na literatura, pode alterar o desenvolvimento do terço médio da face com repercussão na oclusão dentária, fala e formato do nariz. Conclusão: As alterações clínicas funcionais e estruturais relatadas são na maioria do complexo craniofacial, demonstrando a importância da otorrinolaringologia, fonoaudiologia e odontologia na terapêutica interdisciplinar dos pacientes com a síndrome.

Branchio–oculo–facial syndrome

Branchio-oculo-facial syndrome (BOFS) is a rare autosomal dominant condition with variable expressivity, caused by mutations in the TFAP2A gene. We report a three generational family with four affected individuals. The consultand has typical features of BOFS including infra-auricular skin nodules, coloboma, lacrimal duct atresia, cleft lip, conductive hearing loss and typical facial appearance. She also exhibited a rare feature of preaxial polydactyly. Her brother had a lethal phenotype with multiorgan failure. We also report a novel variant in TFAP2A gene. This family highlights the variable severity of BOFS and, therefore, the importance of informed genetic counselling in families with BOFS.

Analysis of TFAP2A mutations in Branchio-Oculo-Facial Syndrome indicates functional complexity within the AP-2α DNA-binding domain

Multiple lines of evidence indicate that the AP-2 transcription factor family has an important regulatory function in human craniofacial development. Notably, mutations in TFAP2A, the gene encoding AP-2α, have been identified in patients with Branchio-Oculo-Facial Syndrome (BOFS). BOFS is an autosomal-dominant trait that commonly presents with facial clefting, eye defects and branchial skin anomalies. Examination of multiple cases has suggested either simple haploinsufficiency or more complex genetic causes for BOFS, especially as the clinical manifestations are variable, with no clear genotype-phenotype correlation. Mutations occur throughout TFAP2A, but mostly within conserved sequences within the DNA contact domain of AP-2α. However, the consequences of the various mutations for AP-2α protein function have not been evaluated. Therefore, it remains unclear if all BOFS mutations result in similar changes to the AP-2α protein or if they each produce specific alterations that underlie the spectrum of phenotypes. Here, we have investigated the molecular consequences of the mutations that localize to the DNA-binding region. We show that although individual mutations have different effects on DNA binding, they all demonstrate significantly reduced transcriptional activities. Moreover, all mutant derivatives have an altered nuclear:cytoplasmic distribution compared with the predominantly nuclear localization of wild-type AP-2α and several can exert a dominant-negative activity on the wild-type AP-2α protein. Overall, our data suggest that the individual TFAP2A BOFS mutations can generate null, hypomorphic or antimorphic alleles and that these differences in activity, combined with a role for AP-2α in epigenetic events, may influence the resultant pathology and the phenotypic variability.

Mutations in KCTD1 Cause Scalp-Ear-Nipple Syndrome

Scalp-ear-nipple (SEN) syndrome is a rare, autosomal-dominant disorder characterized by cutis aplasia of the scalp; minor anomalies of the external ears, digits, and nails; and malformations of the breast. We used linkage analysis and exome sequencing of a multiplex family affected by SEN syndrome to identify potassium-channel tetramerization-domain-containing 1 (KCTD1) mutations that cause SEN syndrome. Evaluation of a total of ten families affected by SEN syndrome revealed KCTD1 missense mutations in each family tested. All of the mutations occurred in a KCTD1 region encoding a highly conserved bric-a-brac, tram track, and broad complex (BTB) domain that is required for transcriptional repressor activity. KCTD1 inhibits the transactivation of the transcription factor AP-2α (TFAP2A) via its BTB domain, and mutations in TFAP2A cause cutis aplasia in individuals with branchiooculofacial syndrome (BOFS), suggesting a potential overlap in the pathogenesis of SEN syndrome and BOFS. The identification of KCTD1 mutations in SEN syndrome reveals a role for this BTB-domain-containing transcriptional repressor during ectodermal development.

A family with a complex clinical presentation characterized by arrhythmogenic right ventricular dysplasia/cardiomyopathy and features of branchio‐oculo‐facial syndrome

Arrhythmogenic right ventricular dysplasia/cardiomyopathy (ARVD/C) is a familial form of cardiomyopathy typically caused by mutations in genes that encode an element of the cardiac desmosome. Branchio-oculo-facial syndrome (BOFS) is a craniofacial disorder caused by TFAP2A mutations. In a family segregating ARVD/C, some members also had features of BOFS. Genetic testing for ARVD/C identified a mutation in PKP2, encoding plakophilin-2, a component of the cardiac desmosome. Evaluation of dysmorphology by chromosome microarray (CMA) identified a 4.4 Mb deletion at chromosome 6p24 that included both TFAP2A and DSP, encoding desmoplakin, an additional component of the cardiac desmosome implicated in ARVD/C. A family member with both the 6p24 deletion and PKP2 mutation had more severe cardiac dysfunction. These findings suggest that this contiguous gene deletion contributes to both ARVD/C and BOFS, and that DSP haploinsufficiency may contribute to cardiomyopathy. This family provides a clinical example that underscores the need for careful evaluation in clinical scenarios where genetic heterogeneity is known to exist. Finally, it suggests that individuals with unexplained cardiomyopathy and dysmorphic facial features may benefit from CMA analysis.

Branchiooculofacial Syndrome and Bilateral Ectopic Thymus: Report of a Family

Branchiooculofacial syndrome (BOFS) is a rare autosomal-dominant condition characterized by branchial cleft sinus and ophthalmologic and craniofacial abnormalities that can range from mild to severe forms. Ectopic thymus, an uncommon condition with just over 100 cases reported in the literature, is seen in BOFS. We report a family with BOFS affecting the mother and two daughters, showing the dominant inheritance and variable phenotypical expression of BOFS.

Épidémiologie des fentes labio-palatines : expérience du Registre de malformations congénitales d’Alsace entre 1995 et 2006

To review clinical and epidemiologic data of orofacial clefts and to evaluate the efficacy and the impact of prenatal diagnosis. A population-based retrospective study was carried out on data from the Congenital Malformations of Alsace Registry (France) between 1995 and 2006. A total of 321 orofacial clefts were recorded (overall prevalence, 2.1 per 1000), divided into cleft lip (CL) or cleft lip palate (CLP) (204 cases) and cleft palate (117 cases). The cleft lip and cleft lip palate CL±P sex-ratio was 1.87, whereas the CP sex-ratio was 1. CLs were more often unilateral than CLPs (79% versus 59%). CLs were unilateral in 79% of the cases (60/76), bilateral in 20% of the cases (15/76), and median in 1% (1/76); 55% of the unilateral CLs were right and 45% were left. CLPs were unilateral in 59% of the cases (76/128), bilateral in 39% of the cases (50/128), and median in 2% (2/128); 45% of the unilateral CLPs were right and 55% were left. The 117 CPs were divided into 50 clefts of the total palate (43%) and 67 clefts of the posterior palate (57%); 25 cases (21%) of Pierre Robin sequence were collected. Sixty-six percent of CL±P (134/204) were associated with other congenital anomalies, including chromosome abnormality in 31 cases and identified monogenic syndrome or association in 12 cases. The most frequent chromosome abnormalities were 16 cases of trisomy 13 and 7 cases of trisomy 18. No cases of 22q11.2 microdeletion or duplication were detected among CL±P. Monogenic syndromes were identified in 6% (12/204) of CL±P cases: Van der Woude syndrome (2 cases); CHARGE syndrome (2 cases); ectrodactyly, ectodermal dysplasia, and cleft/lip palate (EEC) syndrome (2 cases); branchiooculofacial (BOF) syndrome (1 case); Treacher-Collins syndrome (1 case); Nager syndrome (1 case); Goldenhar syndrome (1 case); holoprosencephaly spectrum (1 case); and Meckel syndrome (1 case). Forty-two percent of CPs (49/117) were associated with other congenital anomalies; chromosome abnormality was identified in 12 cases and monogenic syndrome was diagnosed in 14 cases. The most frequent chromosome abnormality was 22q11 microdeletion (5 cases). Monogenic syndromes were recognized in 12% of the CP cases (14/117): fragile X syndrome (2 cases), Meckel syndrome (2 cases), Orofaciodigital syndrome type I (OFD1) (1 case), Stickler syndrome (1 case), Larsen syndrome (1 case), Kniest syndrome (1 case), Cornelia de Lange syndrome (1 case), thanatophoric dysplasia (1 case), other unknown bone chondrodysplasia (1 case), Fryns syndrome (1 case), fetal akinesia sequence (1 case), and Silver-Russel syndrome (1 case). Fifty-two percent of CL cases (106/204) were prenatally diagnosed. An increasing tendency was observed between the 1995-2000 and 2001-2006 periods with a detection rate increasing from 47% to 56%. During the whole period, only 1 case of CP was prenatally diagnosed. Eighty-two percent of all cases (263/321) were livebirths; 8 stillbirths were reported (2%); 50 syndromic or associated cases (16%) led to medical abortion (no termination of pregnancy was performed for isolated cleft). Orofacial clefts are a frequent malformation with a total prevalence of 2.1 per 1000 total births. Sonbographic prenatal diagnosis of orofacial clefts remains difficult with a mean detection rate about 50% for CL±P and is extremely rare for CP. Associated malformations and genetic syndromes are frequent and require a systematic survey. This study also highlights the different pathogenic background of CL±P compared to CP, regarding the sex-ratio and the proportion and type of associated malformations.

Middle and inner ear malformations in mutation‐proven branchio‐oculo‐facial (BOF) syndrome: Case series and review of the literature

Hearing impairment is common in individuals with branchio-oculo-facial (BOF) syndrome. The majority of described individuals have conductive hearing impairment due to malformed ossicles and/or external canal stenosis or atresia, although a sensorineural component to the hearing impairment in BOF syndrome is increasingly being reported. Sophisticated computed tomography (CT) of the temporal bone has revealed middle and inner ear malformations in three previous reports. We present middle and inner ear abnormalities in three additional individuals with mutation-proven BOF syndrome. We suggest that temporal bone CT imaging be included in the medical workup of a child with BOF syndrome, in order to guide management.

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.

Branchio-oculo-facial Syndrome Presenting with Concomitant Thyroglossal Duct Cyst

Branchial cleft anomalies are rare developmental defects of the neck, with an estimated 2% to 3% being bilateral. Although most are isolated findings, some are associated with syndromes. We report a 2-month-old boy with bilateral branchial cleft anomalies, low-set ears, and hydronephrosis who tested positive for a mutation in the TFAP2A gene (A256V) implicated in branchio-oculo-facial (BOF) syndrome. Magnetic resonance imaging (MRI) revealed a thyroglossal duct cyst at the base of the tongue. To our knowledge, this is the first reported case of BOF syndrome presenting concomitantly with a thyroglossal duct cyst.

Evidence of an Involvement of TFAP2A Gene in Nonsyndromic Cleft LIP with or without Cleft Palate: An Italian Study

Unraveling of factors involved in multifactorial diseases is a great challenge. Different approaches can be contemplate and applied to a variety of congenital malformations. In the present investigation TFAP2A has been considered a good candidate gene for nonsyndromic cleft lip with or without cleft palate (NSCLP) aetiology, basing on a sum of considerations. TFAP2A has been seen involved in orofacial development in mice; it is located in the NSCLP candidate region 6p24; it codes for a transcription factor which regulates expression of IRF6, a gene implied in NSCLP; finally, it is embroiled in the branchiooculofacial syndrome, that includes clefting as feature. A family based association analysis was performed with a sample study of 405 NSCLP triads. Evidence of association was obtained with both single marker and haplotype analyses, thus providing a support for TFAP2A in NSCLP aetiology.

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.

Additional clinical and molecular analyses of TFAP2A in patients with the branchio‐oculo‐facial syndrome

The branchio-oculo-facial syndrome (BOFS) is a rare disorder with approximately 50 sporadic and familial cases in the literature. We report on the clinical and molecular analyses of five additional patients with BOFS (two familial and three sporadic). DNA analysis of the TFAP2A gene associated with BOFS using DNA sequencing detected a mutation [c.763A>G (p.Arg255Gly)] in two unrelated patients. This mutation had been reported in another patient and indicates a probable mutational hotspot in the TFAP2A gene. We also detected three new mutations which are restricted to exons 4-6. These gene regions are almost free of any single nucleotide polymorphisms. An evolutionary sequence comparison showed a high degree of sequence conservation from humans to the honey bee (Apis mellifera) in exon 6 showing that this part of the protein is probably essential. Our study represents the second group of BOFS patients with molecular confirmation, expanding the phenotype and spectrum of mutations and limiting it to a restricted part of the gene.

Confirmation of TFAP2A gene involvement in branchio‐oculo‐facial syndrome (BOFS) and report of temporal bone anomalies

Branchio-oculo-facial syndrome (BOFS) is an autosomal-dominant condition characterized by three main features, respectively: branchial defects, ocular anomalies, and craniofacial defects including cleft lip and/or palate (CL/P). We report on one family with three affected, and two sporadic cases that have been found to carry missense mutations in the newly reported BOFS gene: TFAP2A. This report confirms the involvement of this transcription factor in this developmental syndrome with clinical variability. Moreover, we present CT scan temporal bone anomalies in the familial cases, related to branchial arch defects, highlighting the importance of radiological investigations for differential diagnosis.

Reduced TFAP2A function causes variable optic fissure closure and retinal defects and sensitizes eye development to mutations in other morphogenetic regulators.

Mutations in the transcription factor encoding TFAP2A gene underlie branchio-oculo-facial syndrome (BOFS), a rare dominant disorder characterized by distinctive craniofacial, ocular, ectodermal and renal anomalies. To elucidate the range of ocular phenotypes caused by mutations in TFAP2A, we took three approaches. First, we screened a cohort of 37 highly selected individuals with severe ocular anomalies plus variable defects associated with BOFS for mutations or deletions in TFAP2A. We identified one individual with a de novo TFAP2A four amino acid deletion, a second individual with two non-synonymous variations in an alternative splice isoform TFAP2A2, and a sibling-pair with a paternally inherited whole gene deletion with variable phenotypic expression. Second, we determined that TFAP2A is expressed in the lens, neural retina, nasal process, and epithelial lining of the oral cavity and palatal shelves of human and mouse embryos--sites consistent with the phenotype observed in patients with BOFS. Third, we used zebrafish to examine how partial abrogation of the fish ortholog of TFAP2A affects the penetrance and expressivity of ocular phenotypes due to mutations in genes encoding bmp4 or tcf7l1a. In both cases, we observed synthetic, enhanced ocular phenotypes including coloboma and anophthalmia when tfap2a is knocked down in embryos with bmp4 or tcf7l1a mutations. These results reveal that mutations in TFAP2A are associated with a wide range of eye phenotypes and that hypomorphic tfap2a mutations can increase the risk of developmental defects arising from mutations at other loci.

Lesser Forms of Cleft Lip Associated With the Branchio-Oculo-Facial Syndrome

Lesser forms of incomplete cleft lip (CL) have been called microform, occult, forme fruste, and congenitally healed. The association of a minimal bilateral CL in branchio-oculo-facial syndrome (BOFS) is well described and commonly referred to as a "pseudocleft." We conducted a systematic analysis of CL types in BOFS, including a retrospective cross-sectional chart and photographic review with variable longitudinal follow-up of our patients and those described in the literature. We compared data on the type of CL and palate (CL/P) and craniofacial and extracranial anomalies in patients with BOFS and classified the lesser forms CL as either minor-form, microform, or mini-microform as defined by the extent of disruption at the vermilion-cutaneous junction. The study comprised 62 patients with BOFS (1 new and 61 in literature, 4 treated by J.B.M). Forty-four patients (71%) had CL only; 16 (26%) had CL/P; and 2 patients had neither CL nor isolated CP. Thirty-five patients with CL had adequate information for analysis (defined as either seen by J.B.M., having a published photograph, or having a detailed description). The most common type was bilateral symmetrical, lesser form CL (n = 20): minor-form (n = 2), microform (n = 6), or mini-microform (n = 12). Among 17 asymmetrical forms, the left side was more severely affected side than the right (12 vs 5). Of 9 patients with CL/P and adequate clinical description, 4 were bilaterally symmetrically complete. Other anomalies, in addition to the familiar cardinal features of BOFS, included facial nerve weakness (n = 6), chin dimple or cleft of the lower lip (n = 4), upper labial pits (n = 6), minor digital anomalies (n = 12), renal anomalies (n = 14), and ectopic thymus (n = 18). This analysis reaffirms the high frequency of CL or CL/P in BOFS and the rarity of isolated cleft palate and underscores that the term "pseudocleft" lip is incorrect. The more precise lesser form designations used in this study may prove useful for future clinical studies because the causative gene, TFAP2A, is known. Lesser forms of CL may be the most subtle expression of BOFS and assist in identifying patients. Unlike major forms of CL/P, either, syndromic or non syndromic, lesser forms suggest that the developmental insult occurs later in labial formation when fusion of the medial nasal process and maxillary process is nearly complete. The deficient vermilion-mucosa and hypoplastic orbicularis oris may be the result of incomplete or deficient mesodermal penetration of the ectodermal envelope. Another possible pathogenic explanation is that failure of labial closure occurs earlier than in a major cleft when the primitive cells of ectoderm and mesoderm retain the capacity to "heal" the defect.

A complexTFAP2Aallele is associated with branchio‐oculo‐facial syndrome and inner ear malformation in a deaf child

We present a 4-year-old girl with congenital profound sensorineural deafness associated with inner ear malformation (incomplete partition type II, enlarged vestibule, and enlarged vestibular aqueduct). The proposita also had pseudocleft lips, skin defects, auricle abnormalities, and unilateral multicystic dysplastic kidney, leading to the diagnosis of branchio-oculo-facial (BOF) syndrome. Mutation analysis of the TFAP2A gene showed a de novo deletion of 18 and insertion of 6 nucleotides, resulting in deletion of amino acids LPGARR and insertion of RI between amino acids 276 and 281. Altered amino acids are located within the basic DNA binding and dimerization domains of TFAP2A. Previously reported amino acid substitutions in TFAP2A involved only DNA binding domain in four patients with BOF syndrome who were not reported to have profound sensorineural deafness. Our report implies that the localization of mutations in TFAP2A might be responsible with the phenotypic findings in BOF syndrome.

Síndrome brânquio-óculo-facial (BOFS) e cardiopatias congênitas

We report the case of a 43-day-old boy with branchio-oculo-facial syndrome (BOFS) and congenital heart defect. On clinical examination, he presented growth retardation, epicanthal folds, small palpebral fissures, telecanthus, broadened nasal bridge, lip pseudocleft, micrognathia, dysplastic and posteriorly-rotated ears, branchial clefts, short and webbed neck, supernumerary nipple, hypotonia and decreased deep tendon reflexes. Echocardiography showed the presence of a type-A complete atrioventricular septal defect and patent ductus arteriosus. This description strengthens the possibility of congenital heart defects being part of the spectrum of anomalies seen in BOFS.