Clinically diverse phenotypes and genotypes of patients with branchio-oto-renal syndrome

Practical Approach to Congenital Anomalies of the Kidneys: Focus on Anomalies With Insufficient or Abnormal Nephron Development: Renal Dysplasia, Renal Hypoplasia, and Renal Tubular Dysgenesis

Congenital anomalies of the kidney and urinary tract (CAKUT) accounts for up to 30% of antenatal congenital anomalies and is the main cause of kidney failure in children worldwide. This review focuses on practical approaches to CAKUT, particularly those with insufficient or abnormal nephron development, such as renal dysplasia, renal hypoplasia, and renal tubular dysgenesis. The review provides insights into the histological features, pathogenesis, mechanisms, etiologies, antenatal and postnatal presentation, management, and prognosis of these anomalies. Differential diagnoses are discussed as several syndromes may include CAKUT as a phenotypic component and renal dysplasia may occur in some ciliopathies, tumor predisposition syndromes, and inborn errors of metabolism. Diagnosis and genetic counseling for CAKUT are challenging, due to the extensive variability in presentation, genetic and phenotypic heterogeneity, and difficulties to assess postnatal lung and renal function on prenatal imaging. The review highlights the importance of perinatal autopsy and pathological findings in surgical specimens to establish the diagnosis and prognosis of CAKUT. The indications and the type of genetic testing are discussed. The aim is to provide essential insights into the practical approaches, diagnostic processes, and genetic considerations offering valuable guidance for pediatric and perinatal pathologists.

Genomic Landscape of Branchio-Oto-Renal Syndrome through Whole-Genome Sequencing: A Single Rare Disease Center Experience in South Korea

Branchio-oto-renal (BOR) and branchio-otic (BO) syndromes are characterized by anomalies affecting the ears, often accompanied by hearing loss, as well as abnormalities in the branchial arches and renal system. These syndromes exhibit a broad spectrum of phenotypes and a complex genomic landscape, with significant contributions from the EYA1 gene and the SIX gene family, including SIX1 and SIX5. Due to their diverse phenotypic presentations, which can overlap with other genetic syndromes, molecular genetic confirmation is essential. As sequencing technologies advance, whole-genome sequencing (WGS) is increasingly used in rare disease diagnostics. We explored the genomic landscape of 23 unrelated Korean families with typical or atypical BOR/BO syndrome using a stepwise approach: targeted panel sequencing and exome sequencing (Step 1), multiplex ligation-dependent probe amplification (MLPA) with copy number variation screening (Step 2), and WGS (Step 3). Integrating WGS into our diagnostic pipeline detected structure variations, including cryptic inversion and complex genomic rearrangement, eventually enhancing the diagnostic yield to 91%. Our findings expand the genomic architecture of BOR/BO syndrome and highlight the need for WGS to address the genetic diagnosis of clinically heterogeneous rare diseases.

Novel likely pathogenic variant in the EYA1 gene causing Branchio oto renal syndrome and the exploration of pathogenic mechanisms

OBJECTIVE

Branchio-oto-renal syndrome (BOR, OMIM#113,650) is a rare autosomal dominant disorder that presents with a variety of symptoms, including hearing loss (sensorineural, conductive, or mixed), structural abnormalities affecting the outer, middle, and inner ear, branchial fistulas or cysts, as well as renal abnormalities.This study aims to identify the pathogenic variants by performing genetic testing on a family with Branchio-oto-renal /Branchio-otic (BO, OMIM#602,588) syndrome using whole-exome sequencing, and to explore possible pathogenic mechanisms.

METHODS

The family spans 4 generations and consists of 9 individuals, including 4 affected by the BOR/BO syndrome. Phenotypic information, including ear malformation and branchial cleft, was collected from family members. Audiological, temporal bone imaging, and renal ultrasound examinations were also performed. Whole-exome sequencing was conducted to identify candidate pathogenic variants and explore the underlying molecular etiology of BOR/BO syndrome by minigene experiments.

RESULTS

Intra-familial variability was observed in the clinical phenotypes of BOR/BO syndrome in this family. The severity and nature of hearing loss varied in family members, with mixed or sensorineural hearing loss. The proband, in particular, had profound sensorineural hearing loss on the left and moderate conductive hearing loss on the right. Additionally, the proband exhibited developmental delay, and her mother experienced renal failure during pregnancy and terminated the pregnancy prematurely. Genetic testing revealed a novel heterozygous variant NM_000503.6: c.639 + 3 A > C in the EYA1 gene in affected family members. In vitro minigene experiments demonstrated its effect on splicing. According to the American College of Medical Genetics (ACMG) guidelines, this variant was classified as likely pathogenic.

CONCLUSION

This study highlights the phenotypic heterogeneity within the same family, reports the occurrence of renal failure and adverse pregnancy outcomes in a female patient at reproductive age with BOR syndrome, and enriches the mutational spectrum of pathogenic variants in the EYA1 gene.

Case report: A novel mutation in the EYA1 gene in a child with branchiootic syndrome with secretory otitis media and bilateral vestibular hypofunction

Branchiootic syndrome (BOS) is a rare, autosomal dominant syndrome characterized by malformations of the ear associated with hearing loss, second branchial arch anomalies, and the absence of renal anomalies. Herein, we report the case of an 8-year-old male patient with BOS. The proband also experiences mixed conductive and sensorineural hearing loss in the right ear, and severe-to-profound sensorineural hearing loss in the left ear. Preauricular pits, branchial fistulae, and cochlear hypoplasia were present bilaterally. Type III cup-shaped ear, and external auditory canal stenosis were detected in the right ear. Lateral semicircular canal-vestibule dysplasia was detected in the left ear. Moreover, the patient had unilateral secretory otitis media (SOM) in the right ear and bilateral vestibular hypofunction (VH), which has not been reported in previous studies. The patient's hearing on the right side was restored to nearly normal after myringotomy. Whole exome sequencing identified a novel frameshift mutation in EYA1 (NM_000503.6): c.1697_1698delinT [p.(Lys566IlefsTer73)] in the proband, which was defined a "pathogenic" mutation according to American College of Medical Genetics and Genomics guidelines. This is the first report of a child presenting with BOS, SOM and VH, which expands the known clinical manifestations of this syndrome. We also observed a novel EYA1 gene mutation in this patient with BOS, which enriches the mutation map and provides a reference for genetic diagnosis of this syndrome.

A Novel EYA1 Mutation Causing Alternative RNA Splicing in a Chinese Family With Branchio-Oto Syndrome: Implications for Molecular Diagnosis and Clinical Application

OBJECTIVES

Branchio-oto syndrome (BOS) primarily manifests as hearing loss, preauricular pits, and branchial defects. EYA1 is the most common pathogenic gene, and splicing mutations account for a substantial proportion of cases. However, few studies have addressed the structural changes in the protein caused by splicing mutations and potential pathogenic factors, and several studies have shown that middle-ear surgery has limited effectiveness in improving hearing in these patients. BOS has also been relatively infrequently reported in the Chinese population. This study explored the genetic etiology in the family of a proband with BOS and provided clinical treatment to improve the patient's hearing.

METHODS

We collected detailed clinical features and peripheral blood samples from the patients and unaffected individuals within the family. Pathogenic mutations were identified by whole-exome sequencing and cosegregation analysis and classified according to the American College of Medical Genetics and Genomics guidelines. Alternative splicing was verified through a minigene assay. The predicted three-dimensional protein structure and biochemical experiments were used to investigate the pathogenicity of the mutation. The proband underwent middle-ear surgery and was followed up at 1 month and 6 months postoperatively to monitor auditory improvement.

RESULTS

A novel heterozygous EYA1 splicing variant (c.1050+4 A>C) was identified and classified as pathogenic (PVS1(RNA), PM2, PP1). Skipping of exon 11 of the EYA1 pre-mRNA was confirmed using a minigene assay. This mutation may impair EYA1-SIX1 interactions, as shown by an immunoprecipitation assay. The EYA1-Mut protein exhibited cellular mislocalization and decreased protein expression in cytological experiments. Middle-ear surgery significantly improved hearing loss caused by bone-conduction abnormalities in the proband.

CONCLUSION

We reported a novel splicing variant of EYA1 in a Chinese family with BOS and revealed the potential molecular pathogenic mechanism. The significant hearing improvement observed in the proband after middle-ear surgery provides a reference for auditory rehabilitation in similar patients.

Syndromic Hearing Loss in Children

Pattern recognition of specific temporal bone radiological phenotypes, in association with abnormalities in other organ systems, is critical in the diagnosis and management of syndromic causes of hearing loss. Several recent publications have demonstrated the presence of specific radiological appearances, allowing precise genetic and/or syndromic diagnosis, in the right clinical context. This review article aims to provide an extensive but practical guide to the radiologist dealing with syndromic causes of hearing loss.

Misdiagnosed Branchio-Oto-Renal syndrome presenting as proteinuria and renal insufficiency with insidious signs since early childhood: a report of three cases

BACKGROUND

Branchio-oto-renal (BOR) syndrome is an inherited multi-systemic disorder. Auricular and branchial signs are highly suggestive of BOR syndrome but often develop insidiously, leading to a remarkable misdiagnosis rate. Unlike severe morphological abnormalities of kidneys, knowledge of glomerular involvement in BOR syndrome were limited.

CASE PRESENTATION

Three cases, aged 8 ~ 9 years, visited pediatric nephrology department mainly for proteinuria and renal insufficiency, with 24-h proteinuria of 23.8 ~ 68.9 mg/kg and estimated glomerular filtration rate of 8.9 ~ 36.0 mL/min/1.73m2. Moderate-to-severe albuminuria was detected in case 1, while mixed proteinuria was detected in case 2 and 3. Insidious auricular and branchial fistulas were noticed, all developing since early childhood but being neglected previously. EYA1 variants were confirmed by genetic testing in all cases. Delay in diagnosis was 8 ~ 9 years since extra-renal appearances, and 0 ~ 6 years since renal abnormalities. In case 1, therapy of glucocorticoid and immunosuppressive agents to accompanying immune-complex mediated glomerulonephritis was unsatisfying.

CONCLUSIONS

BOR syndrome is a rare cause of proteinuria and abnormal kidney function and easily missed, thus requiring more awareness. Careful medical history taking and physical examination are essential to early diagnosis. Massive proteinuria was occasionally seen in BOR syndrome, which might be related to immune complex deposits. A novel pathogenic variant (NM_000503.6 (EYA1): c.1171delT p.Ser391fs*9) was firstly reported.

[Hereditary hearing loss]

Understanding the genetic basis of hearing loss is becoming increasingly relevant, as 50-70% of congenital hearing loss is hereditary and postlingual hearing loss is also often of hereditary origin. To date, more than 220 genes for hearing loss have been identified and more than 600 syndromes with hearing loss described. This review article explains the classification of genetic hearing loss into syndromic versus non-syndromic forms and the modes of inheritance involved. Some of the most common syndromes (Usher, Pendred, Jervell-Lange-Nielsen, Waardenburg, branchiootorenal, and Alport syndrome) are introductorily described. New sequencing technologies have significantly expanded the diagnostic options for genetic hearing loss and made them more accessible. This text aims to encourage initiation of genetic diagnosis in hearing-impaired patients with suspected hereditary genesis in order to provide the best possible counseling for affected individuals and their families.

The Cochlea in Branchio-Oto-Renal Syndrome: An Objective Method for the Diagnosis of Offset Cochlear Turns

BACKGROUND AND PURPOSE

An "unwound" or "offset" cochlea has been described as a characteristic imaging feature in patients with branchio-oto-renal syndrome, and recently recognized to be associated in particular to those with EYA1 gene mutations. Determination of this feature has traditionally relied on subjective visual assessment. Our aim was to establish an objective assessment method for cochlear offset (the cochlear turn alignment ratio) and determine an optimal cutoff turn alignment ratio value that separates individuals with EYA1-branchio-oto-renal syndrome from those with SIX1-branchio-oto-renal syndrome and healthy controls.

MATERIALS AND METHODS

Temporal bone CT or MR imaging from 40 individuals with branchio-oto-renal syndrome and 40 controls was retrospectively reviewed. Cochlear offset was determined visually by 2 independent blinded readers and then quantitatively via a standardized technique yielding the cochlear turn alignment ratio. The turn alignment ratio values were compared between cochleae qualitatively assessed as "not offset" and "offset." Receiver operating characteristic analysis was used to determine the ability of the turn alignment ratio to differentiate between these populations and an optimal cutoff turn alignment ratio value. Cochlear offset and turn alignment ratio values were analyzed for each branchio-oto-renal syndrome genotype subpopulation and for controls.

RESULTS

The turn alignment ratio can accurately differentiate between cochleae with and without an offset (P < .001). The optimal cutoff value separating these populations was 0.476 (sensitivity = 1, specificity = 0.986, J = 0.986). All except 1 cochlea among the EYA1-branchio-oto-renal syndrome subset and all with unknown genotype branchio-oto-renal syndrome had a cochlear offset and a turn alignment ratio of <0.476. All except 1 cochlea among the SIX1-branchio-oto-renal syndrome subset and all controls had no offset and a turn alignment ratio of >0.476.

CONCLUSIONS

There is a statistically significant difference in turn alignment ratios between offset and nonoffset cochleae, with an optimal cutoff of 0.476. This cutoff value allows excellent separation of EYA1-branchio-oto-renal syndrome from SIX1-branchio-oto-renal syndrome and from individuals without branchio-oto-renal syndrome or sensorineural hearing loss. The turn alignment ratio is a reliable and objective metric that can aid in the imaging evaluation of branchio-oto-renal syndrome.

The genetic basis of congenital anomalies of the kidney and urinary tract

During the past decades, remarkable progress has been made in our understanding of the molecular basis of kidney diseases, as well as in the ability to pinpoint disease-causing genetic changes. Congenital anomalies of the kidney and urinary tract (CAKUT) are remarkably diverse, and may be either isolated to the kidney or involve other systems, and are notorious in their variable genotype-phenotype correlations. Genetic conditions underlying CAKUT are individually rare, but collectively contribute to disease etiology in ~ 16% of children with CAKUT. In this review, we will discuss basic concepts of kidney development and genetics, common causes of monogenic CAKUT, and the approach to diagnosing and managing a patient with suspected monogenic CAKUT. Altogether, the concepts presented herein represent an introduction to the emergence of nephrogenetics, a fast-growing multi-disciplinary field that is focused on deciphering the causes and manifestations of genetic kidney diseases as well as providing the framework for managing patients with genetic forms of CAKUT.

Review of genetic testing in kidney disease patients: Diagnostic yield of single nucleotide variants and copy number variations evaluated across and within kidney phenotype groups

Genetic kidney disease comprises a diverse group of disorders. These can roughly be divided in the phenotype groups congenital anomalies of the kidney and urinary tract, ciliopathies, glomerulopathies, stone disorders, tubulointerstitial kidney disease, and tubulopathies. Many etiologies can lead to chronic kidney disease that can progress to end-stage kidney disease. Despite each individual disease being rare, together these genetic disorders account for a large proportion of kidney disease cases. With the introduction of massively parallel sequencing, genetic testing has become more accessible, but a comprehensive analysis of the diagnostic yield is lacking. This review gives an overview of the diagnostic yield of genetic testing across and within the full range of kidney disease phenotypes through a systematic literature search that resulted in 115 included articles. Patient, test, and cohort characteristics that can influence the diagnostic yield are highlighted. Detection of copy number variations and their contribution to the diagnostic yield is described for all phenotype groups. Also, the impact of a genetic diagnosis for a patient and family members, which can be diagnostic, therapeutic, and prognostic, is shown through the included articles. This review will allow clinicians to estimate an a priori probability of finding a genetic cause for the kidney disease in their patients.

A Perihilar Variant of Focal Segmental Glomerulosclerosis Due to De novo Branchio-oto-renal Syndrome

Branchio-oto-renal syndrome is an autosomal dominant disorder characterized by branchial anomalies, hearing loss, and renal urinary tract malformations. We herein report a 32-year-old Japanese man with a right preauricular pit, bilateral mixed hearing loss, and malposition of the right kidney who presented with proteinuria. The findings of a left kidney biopsy were compatible with a perihilar variant of secondary focal segmental glomerular sclerosis. A trio exome analysis conducted among the patient and his parents failed to identify the causal gene variant, despite a sporadic pattern. His kidney function remained stable for 11 years with an angiotensin II receptor blocker.

Anatomical and audiological considerations in branchiootorenal syndrome: A systematic review

Objective

Establish anatomical considerations, audiological outcomes, and optimal management in patients with branchiootic/branchiootorenal syndrome (BO/BOR).

Methods

Databases reviewed: Medline, Pubmed, Embase, Web of Science, Cochrane Collection, and ClinicalTrials.gov. Clinical or radiological studies of patients with BOR syndrome describing either the audiological profile or anatomical changes were included. Articles in which BOR syndrome was associated with other syndromes, and those that were focused only on general and genetic aspects of BOR syndrome were excluded. Articles were assessed using Oxford Centre for Evidence‐Based Medicine (OCEBM) grading system and the Brazzelli risk of bias tool for nonrandomized studies.

Results

Searches identified 379 articles. Of these, 64 studies met the inclusion criteria, reporting outcomes in 482 patients from at least 95 families. In 308 patients, hearing loss was categorized as sensorineural (29%), conductive (20%), and mixed (51%). Hearing outcomes were variable in terms of onset, pattern, and severity; ranging from mild to profound deafness. One hundred sixty‐nine patients presented with inner ear anomalies, 145 had middle, and 151 had external ear abnormalities. In 44 studies, 58 ear operations were described. Mixed outcomes were reported in patients managed with hearing aids or middle ear surgery; however, successful cochlear implantation was described in all five cases.

Conclusion

The anatomical and audiological profiles of patients with BO/BOR are variable. A range of surgical procedures were described, however lacked objective outcome measures. Given the range of anatomical variants, management decisions should be made on an individual basis including full audiological and radiological assessment.

Level of evidence

NA.

Re-Examining the Cochlea in Branchio-Oto-Renal Syndrome: Genotype-Phenotype Correlation

BACKGROUND AND PURPOSE

Temporal bone imaging plays an important role in the work-up of branchio-oto-renal syndrome. Previous reports have suggested that the unwound or offset cochlea is a highly characteristic marker for branchio-oto-renal syndrome. Our goals were to examine the prevalence of this finding in a branchio-oto-renal syndrome cohort and analyze genetic-phenotypic associations not previously established.

MATERIALS AND METHODS

This multicenter retrospective study included 38 ears in 19 unrelated individuals with clinically diagnosed branchio-oto-renal syndrome and confirmed mutations in the EYA1 or SIX1 genes. Two blinded neuroradiologists independently reviewed and documented temporal bone imaging findings in 13 categories for each ear. Imaging phenotypes were correlated with genotypes.

RESULTS

There was excellent interrater agreement for all 13 phenotypic categories (κ ≥ 0.80). Of these, 9 categories showed statistically significant differences between patients with EYA1-branchio-oto-renal syndrome and SIX1-branchio-oto-renal syndrome. Cochlear offset was present in 100% of patients with EYA1-branchio-oto-renal syndrome, but in only 1 ear (12.5%) among patients with SIX1-branchio-oto-renal syndrome. A short thorny appearance of the cochlear apical turn was observed in most patients with SIX1-branchio-oto-renal syndrome.

CONCLUSIONS

An offset cochlea is associated with the EYA1-branchio-oto-renal syndrome genotype. The SIX1-branchio-oto-renal syndrome genotype is associated with a different cochlear phenotype that almost always is without offset and has a short thorny tip as the apical turn. Therefore, cochlear offset is not a characteristic marker for all patients with branchio-oto-renal syndrome. The lack of a cochlear offset in a patient with clinically suspected branchio-oto-renal syndrome does not exclude the diagnosis and, in fact, may be predictive of the SIX1 genotype.

Phenotype-genotype correlation in patients with typical and atypical branchio-oto-renal syndrome

Some patients have an atypical form of branchio-oto-renal (BOR) syndrome, which does not satisfy the diagnostic criteria, despite carrying a pathogenic variant (P variant) or a likely pathogenic variant (LP variant) of a causative gene. P/LP variants phenotypic indices have yet to be determined in patients with typical and atypical BOR syndrome. We hypothesized that determining phenotypic and genetic differences between patients with typical and atypical BOR syndrome could inform such indices. Subjects were selected from among patients who underwent genetic testing to identify the cause of hearing loss. Patients were considered atypical when they had two major BOR diagnostic criteria, or two major criteria and one minor criterion; 22 typical and 16 atypical patients from 35 families were included. Genetic analysis of EYA1, SIX1, and SIX5 was conducted by direct sequencing and multiplex ligation-dependent probe amplification. EYA1 P/LP variants were detected in 25% and 86% of atypical and typical patients, respectively. Four EYA1 P/LP variants were novel. Branchial anomaly, inner ear anomaly, and mixed hearing loss were correlated with P/LP variants. Development of refined diagnostic criteria and phenotypic indices for atypical BOR syndrome will assist in effective detection of patients with P/LP variants among those with suspected BOR syndrome.

Genetic and Phenotypic Variability in Chinese Patients With Branchio-Oto-Renal or Branchio-Oto Syndrome

Background: Branchio-oto-renal syndrome (BOR) and branchio-oto syndrome (BOS) are rare autosomal dominant disorders defined by varying combinations of branchial, otic, and renal anomalies. Here, we characterized the clinical features and genetic etiology of BOR/BOS in several Chinese families and then explored the genotypes and phenotypes of BOR/BOS-related genes, as well as the outcomes of auditory rehabilitation in different modalities.

Materials and Methods: Probands and all affected family members underwent detailed clinical examinations. Their DNA was subjected to whole-exome sequencing to explore the underlying molecular etiology of BOR/BOS; candidate variants were validated using Sanger sequencing and interpreted in accordance with the American College of Medical Genetics guidelines. In addition, a literature review concerning EYA1 and SIX1 alterations was performed to explore the genotypes and phenotypes of BOR/BOS-related genes.

Results: Genetic testing identified the novel deletion (c.1425delC, p(Asp476Thrfs*4); NM_000,503.6), a nonsense variant (c.889C > T, p(Arg297*)), and two splicing variants in the EYA1 gene (c.1050+1G > T and c.1140+1G > A); it also identified one novel missense variant in the SIX1 gene (c.316G > A, p(Val106Met); NM_005,982.4). All cases exhibited a degree of phenotypic variability between or within families. Middle ear surgeries for improving bone-conduction component hearing loss had unsuccessful outcomes; cochlear implantation (CI) contributed to hearing gains.

Conclusion: This is the first report of BOR/BOS caused by the SIX1 variant in China. Our findings increase the numbers of known EYA1 and SIX1 variants. They also emphasize the usefulness of genetic testing in the diagnosis and prevention of BOR/BOS while demonstrating that CI for auditory rehabilitation is a feasible option in some BOR/BOS patients.

The Eyes Absent proteins in development and in developmental disorders

The Eyes Absent (EYA) transactivator-phosphatase proteins are important contributors to cell-fate determination processes and to the development of multiple organs. The transcriptional regulatory activity as well as the protein tyrosine phosphatase activities of the EYA proteins can independently contribute to proliferation, differentiation, morphogenesis and tissue homeostasis in different contexts. Aberrant EYA levels or activity are associated with numerous syndromic and non-syndromic developmental disorders, as well as cancers. Commensurate with the multiplicity of biochemical activities carried out by the EYA proteins, they impact upon a range of cellular signaling pathways. Here, we provide a broad overview of the roles played by EYA proteins in development, and highlight the molecular signaling pathways known to be linked with EYA-associated organ development and developmental disorders.

Otological manifestations in branchiootorenal spectrum disorder: A systematic review and meta-analysis

Branchiootorenal spectrum disorder (BORSD) is a group of rare autosomal dominant entities characterized by branchiogenic malformations, hearing loss (HL) and renal anomalies. It comprises branchiootorenal syndrome and branchiootic syndrome, distinguished by the presence or absence of renal abnormalities. Pathogenic variants have been discovered in the following genes: EYA1, SIX5, SIX1 and SALL1. As the otological phenotype in BORSD is inconsistently reported, we performed a systematic review to provide an up-to-date overview, correlated with the genotype. Forty publications were included, describing 295 individual patients. HL was diagnosed in 95%, usually bilateral and mixed-type, and differed among the different genes involved. Mixed moderate-to-severe HL was the predominant finding in patients with EYA1 involvement, regardless of the presence of renal abnormalities. The sensorineural HL of profound severity was more prevalent in patients with SIX1 mutations. No significant differences among different mutation types or location within the genes could be observed. Structural otological manifestations, ranging from periauricular to inner ear anomalies, were common in both genes. Especially periauricular anomalies were more common and more severe in EYA1. In summary, otological differences among the different genes involved in BORSD are observed, so the molecular analysis is strongly advised.

Targeted next-generation sequencing identifies a novel frameshift EYA1 variant causing branchio-otic syndrome in a Chinese family

OBJECTIVE

To evaluate the genotype-phenotype correlation of branchio-otic syndrome (BOS) in a Chinese family.

METHODS

The proband in this study was an 18-month-old boy with hearing loss, preauricular pit, and branchial fistula without a renal anomaly. We collected blood samples from 6 family members, including 4 who were affected by the syndrome. Targeted next-generation sequencing and Sanger sequencing were performed to identify pathogenic mutations in this family.

RESULTS

Pedigree analysis indicated that the mode of inheritance in the family was consistent with the autosomal dominant pattern. Hearing loss was the most common manifestation, occurring in 4 patients. Other findings included preauricular pits (n=2), cervical fistulas (n=3) and abnormal pinnae (n=4). None of the patients had renal anomalies. Evaluation by pure-tone audiometry and temporal bone imaging demonstrated bilateral mixed hearing loss, as well as middle ear and inner ear deformities, in two patients. Mutational analysis of candidate genes in the selected patients led to the identification of a novel frameshift variant NM_000503.4: c.1075_1077delinsAT (p.Gly359Ilefs*7) in the EYA1 gene.

CONCLUSIONS

The EYA1 c.1075_1077delinsAT mutation is the causative variant in the Chinese family with BOS, although the penetrance is variable within patients.

Growth hormone deficiency in a child with branchio-oto-renal spectrum disorder: Clinical evidence of EYA1 in pituitary development and a recommendation for pituitary function surveillance

Branchio-oto-renal spectrum disorder (BORSD) is a rare autosomal dominant condition characterized by ear abnormalities with hard of hearing/deafness, second branchial arch malformations and renal anomalies. Pathogenic variations in EYA1 gene are found in the majority of clinically diagnosed individuals with BORSD. We describe an infant with BORSD related to a paternally inherited heterozygous pathogenic variation in EYA1 gene presenting with poor growth and hypoglycemia due to growth hormone deficiency. Magnetic resonance imaging revealed a diminutive pituitary gland and morphologically abnormal sella. Upon initiation of growth hormone therapy, the hypoglycemia resolved and catch up growth ensued. Pituitary abnormalities have not been reported previously in patients with BORSD. The zebrafish ortholog of eya1 is important for the development of adenohypophysis, suggesting that this patient's growth hormone deficiency and pituitary abnormality are part of BORSD. Inclusion of screening for pituitary hormone deficiency and pituitary imaging should be considered as a part of surveillance in patients with BORSD.

Branchial cleft fistula to branchio-oto-renal syndrome: A case report and literature review

Branchial cleft abnormality is a common congenital neck malformation in children, which is caused by the abnormal development of the gill sac or gill groove. It is mainly manifested as a cyst in the sinus tract and fistula in the neck, as well as branchio-oto-renal syndrome (BORS). As a rare autosomal dominant genetic disease, the typical manifestations of BORS are hearing loss, abnormal branchial cleft development and renal dysplasia. In this paper, a patient was admitted to the hospital for bilateral branchial cleft fistulas combined with bilateral anterior auricular fistulas, auricular appendix, auricle dysplasia, external auditory canal stenosis, and hearing loss. The patient was diagnosed with BORS, and underwent fistulectomy of the neck and anterior ear, external auditory canal formation, and tympanoplasty. The aim of this report is to strengthen clinicians' understanding of BORS and reduce the rate of clinical missed diagnosis through our case report and literature review.

Clinical and genetic variability of PAX2-related disorder in the Japanese population

Pathogenic variants of paired box gene 2 (PAX2) cause autosomal-dominant PAX2-related disorder, which includes renal coloboma syndrome (RCS). Patients with PAX2-related disorder present with renal and ophthalmological pathologies, as well as with other abnormalities, including developmental problems and hearing loss. We sequenced PAX2 in 457 patients with congenital anomalies of the kidney and urinary tract or with renal dysfunction of unknown cause and identified 19 different pathogenic variants in 38 patients from 30 families (6.5%). Thirty-four patients had renal hypodysplasia or chronic kidney disease of unknown cause, and three had focal segmental glomerulosclerosis. Although no obvious genotype-phenotype correlation was observed, six of the seven patients who developed end-stage renal disease in childhood had truncating variants. Twenty-three patients had ocular disabilities, mostly optic disc coloboma. Non-renal and non-ophthalmological manifestations included developmental disorder, electrolyte abnormality, and gonadal abnormalities. Two unrelated patients had congenital cystic adenomatoid malformations in their lungs. Six of ten probands with PAX2 mutation identified by next-generation sequencing did not show typical RCS manifestations. We conclude that PAX2-related disorder has a variable clinical presentation and can be diagnosed by next-generation sequencing even in the absence of typical RCS manifestations.

Temporal bone and intracranial abnormalities in syndromic causes of hearing loss: an updated guide

PURPOSE

To describe in detail the temporal bone and brain findings in both common and rare syndromic causes of hearing loss, with the purpose of broadening among radiologists and enhance the current understanding of distinct imaging features in paediatric patients with syndromic hearing loss.

METHODS

A detailed search of electronic databases has been conducted, including PubMed, Ovid Medline, Scopus, Cochrane Library, Google Scholar, National Institute for Health and Care Excellence (NICE), Embase, and PsycINFO.

RESULTS

Syndromic causes of hearing loss are characterised by different and sometimes specific abnormalities in the temporal bone.

CONCLUSION

A complete knowledge of the image findings in the temporal bones, brain, skull and other body regions is critical for the optimal assessment and management of these patients.

A de novo SIX1 variant in a patient with a rare nonsyndromic cochleovestibular nerve abnormality, cochlear hypoplasia, and bilateral sensorineural hearing loss

Background

Childhood hearing impairment affects language and cognitive development. Profound congenital sensorineural hearing impairment can be due to an abnormal cochleovestibular nerve (CVN) and cochleovestibular malformations, however, the etiology of these conditions remains unclear.

Methods

We used a trio‐based exome sequencing approach to unravel the underlying molecular etiology of a child with a rare nonsyndromic CVN abnormality and cochlear hypoplasia. Clinical and imaging data were also reviewed.

Results

We identified a de novo missense variant [p(Asn174Tyr)] in the DNA‐binding Homeodomain of SIX1, a gene which previously has been associated with autosomal dominant hearing loss (ADHL) and branchio‐oto‐renal or Branchio‐otic syndrome, a condition not seen in this patient.

Conclusions

SIX1 has an important function in otic vesicle patterning during embryogenesis, and mice show several abnormalities to their inner ear including loss of inner ear innervation. Previous reports on patients with SIX1 variants lack imaging data and nonsyndromic AD cases were reported to have no inner ear malformations. In conclusion, we show that a de novo variant in SIX1 in a patient with sensorineural hearing loss leads to cochleovestibular malformations and abnormalities of the CVN, without any other abnormalities. Without proper interventions, severe to profound hearing loss is devastating to both education and social integration. Choosing the correct intervention can be challenging and a molecular diagnosis may adjust intervention and improve outcomes, especially for rare cases.

Comprehensive analysis of syndromic hearing loss patients in Japan

More than 400 syndromes associated with hearing loss and other symptoms have been described, corresponding to 30% of cases of hereditary hearing loss. In this study we aimed to clarify the mutation spectrum of syndromic hearing loss patients in Japan by using next-generation sequencing analysis with a multiple syndromic targeted resequencing panel (36 target genes). We analyzed single nucleotide variants, small insertions, deletions and copy number variations in the target genes. We enrolled 140 patients with any of 14 syndromes (BOR syndrome, Waardenburg syndrome, osteogenesis imperfecta, spondyloepiphyseal dysplasia congenita, Stickler syndrome, CHARGE syndrome, Jervell and Lange-Nielsen syndrome, Pendred syndrome, Klippel-Feil syndrome, Alport syndrome, Norrie disease, Treacher-Collins syndrome, Perrault syndrome and auditory neuropathy with optic atrophy) and identified the causative variants in 56% of the patients. This analysis could identify the causative variants in syndromic hearing loss patients in a short time with a high diagnostic rate. In addition, it was useful for the analysis of the cases who only partially fulfilled the diagnostic criteria.

EYA1 mutations leads to Branchio-Oto syndrome in two Chinese Han deaf families

OBJECTIVES

Branchio-Oto (BO) syndrome is one of the common syndromic forms of hearing loss. In this study, we aimed to characterize the clinical and genetic features of BO syndrome in two Chinese Han deaf families.

METHODS

The auditory and other BO-related clinical features of Family 1809 and Family 1974 were summarized. Targeted next-generation sequencing in 144 known deafness genes was performed in the probands. Co-segregation of the pathogenic mutations and the phenotype was confirmed by Sanger sequencing in the family members.

RESULTS

Interfamilial and intrafamilial variations can be observed in the clinical phenotypes of BO syndrome in Family 1809 and 1974. A novel c.1493_1494insAT (p.Ile498PhefsTer*3) mutation and a previous reported c.967-2A>G mutation in EYA1 were identified as the pathogenic cause in Family 1974 and 1809, respectively.

CONCLUSION

Our results supported the heterogeneity of the genetic and phenotypic spectrum of BO syndrome. The recurrent c.967-2A>G in different ethnical groups suggested that it is a hot-spot mutation.

Association between the clinical presentation of congenital anomalies of the kidney and urinary tract (CAKUT) and gene mutations: an analysis of 66 patients at a single institution

BACKGROUND

The association between the clinical presentation of congenital anomalies of the kidney and urinary tract (CAKUT) and gene mutations has yet to be fully explored.

METHODS

In this retrospective cohort study, we examined patients with CAKUT who underwent gene analysis. The analysis was performed in patients with bilateral renal lesions, extrarenal complications, or a family history of renal disease. The data from the diagnosis, gene mutations, and other complications were analyzed.

RESULTS

In total, 66 patients with CAKUT were included. Of these, gene mutations were detected in 14 patients. Bilateral renal lesions were significantly related to the identification of gene mutations (p = 0.02), and no gene mutations were observed in patients with lower urinary tract obstruction (six patients). There was no significant difference in the rate of gene mutations between those with or without extrarenal complications (p = 0.76). The HNF1β gene mutation was identified in most of the patients with hypodysplastic kidney with multicystic dysplastic kidney (six of seven patients). There was no significant difference in the presence or absence of gene mutations with respect to the renal survival rate (log-rank test p = 0.53). The renal prognosis varied, but the differences were not statistically significant for any of the gene mutations.

CONCLUSIONS

CAKUT with bilateral renal lesions were significantly related to gene mutations. We recommend that CAKUT-related gene analysis be considered in cases of bilateral renal lesions. No gene mutations were observed in patients with lower urinary tract obstruction. The renal prognosis varied for each gene mutation.