International Journal of Pediatric Otorhinolaryngology (2005) 69, 1123—1128

www.elsevier.com/locate/ijporl

CASE REPORT

Identification of a novel mutation in the EYA1gene in a Korean family with branchio-oto-renal(BOR) syndrome

Sung Hee Kim a, Jong-Hun Shin a, Chang-Ki Yeo a, Soon Hee Chang b,Su-Yon Park c, Eun Hae Cho c, Chang-Seok Ki c,*, Jong-Won Kim c

aDepartment of Otolaryngology, Daegu Fatima Hospital, Daegu, Republic of KoreabDepartment of Laboratory Medicine, Daegu Fatima Hospital, Daegu, Republic of KoreacDepartment of LaboratoryMedicine, SamsungMedical Center, Sungkyunkwan University School ofMedicine,50 Irwon-Dong, Gangnam-Gu, Seoul 135-710, Republic of Korea

Received 27 December 2004; accepted 1 March 2005

KEYWORDSBranchio-oto-renal

syndrome;BOR;EYA1;Mutation;Korean

Summary The branchio-oto-renal (BOR) syndrome is an autosomal dominant dis-order characterized by the association of branchial cysts or fistulae, external earmalformation and/or preauricular pits, hearing loss, and renal anomalies. Mutationsin the EYA1 gene on the chromosome band 8q13.3, the human homologue of theDrosophila eyes absent (eya) gene, have been identified to be the underlying geneticdefects of the syndrome. We found a Korean family with BOR syndrome and identifieda novel insertion mutation (c.1474_1475insC; R492PfsX40) in the EYA1 gene. To thebest of our knowledge, this is the first report of genetically confirmed case of BORsyndrome in Korea.# 2005 Elsevier Ireland Ltd. All rights reserved.

1. Introduction

The branchio-oto-renal (BOR) syndrome (MIM113650), first described by Melnick et al. [1], ischaracterized by the association of branchialanomalies (i.e. preauricular pits and branchial fis-tulae or cysts), otic anomalies affecting the outer,middle, and/or inner ear that frequently lead tohearing loss (sensorineural, conductive, or mixed),and a wide spectrum of renal anomalies ranging

* Corresponding author. Tel.: +82 2 3410 2709;fax: +82 2 3410 2719.

E-mail address: cs.ki@samsung.com (C.-S. Ki).

0165-5876/$ — see front matter # 2005 Elsevier Ireland Ltd. All rigdoi:10.1016/j.ijporl.2005.03.003

from mild hypoplasia to lethal bilateral renal apla-sia. The clinical features of BOR syndrome are indi-cative of an early developmental defect. Thesyndrome is transmitted as an autosomal dominantdisorder with high but incomplete penetrance andvariable expressivity [2—4]. The incidence of BORsyndrome is approximately 1:40,000, accounting for2% of profoundly deaf children. Hearing loss is themost constant feature of BOR syndrome, detected inmore than 90% of affected individuals [5].

The gene responsible for BOR syndrome wasmapped to the chromosome band 8q13.3 [6,7].The causative gene, EYA1, the human homologueof the Drosophila eye absent (eya) gene, was iden-

hts reserved.

1124 S.H. Kim et al.

tified by positional cloning, and mutations thereofhave been reported [8]. Although a list of mutationshas been identified in the EYA1 gene in patients withBOR syndrome with different ethnic backgroundsworldwide, there has been no report of geneticallyconfirmed case in Korea [8—20]. Recently, we founda Korean family with BOR syndrome and identified amutation in the EYA1 gene, which has not beenreported previously.

Fig. 1 Pedigree of the family with BOR syndrome. Crosssymbols indicate family members who underwent genetictesting.

2. Case report

2.1. Proband

The proband, a 3-year-old girl (Fig. 1, III:1), wasreferred to the Department of Otolaryngology,Daegu Fatima Hospital, because of delayed devel-opment of speech and language. The patient did notrespond to familiar voices or sounds but was startledby loud noises. Her perinatal course was uneventful.She had no history of otorrhea or otitis media buthad a history of operation for bilateral branchialarch fistulae when she was 6 months old due tofrequent infections.

Physical examination revealed bilateral cup-shaped anteverted microtia, preauricular tag onthe right side, and operation scars for bilateralsecond branchial arch fistulae (Fig. 2). Neither pre-auricular fistulae nor sinuses were observed. Otolo-gic examination revealed narrowed externalauditory canals, but normal-appearing and mobile

Fig. 2 The auricles of the proband. The operation scars

tympanic membranes. Otherwise, no remarkablefindings were observed on physical examination.

A sedated auditory brain-stem response revealedno identifiable wave V peak at 100 dB in the left earand a reproducible wave V at 60 dB in the right ear.Auditory steady state response (ASSR) was obtainedfor further frequency-specific information and to fitthe hearing aid properly (Fig. 3).

Temporal bone computed tomography (CT) wasperformed to detect any middle and inner earanomalies and showed scarcely pneumatized mas-toids with soft tissue density in the mastoid andtympanic cavity and an abnormal configuration ofthe ossicular chain (Fig. 4). In addition to the hypo-

(arrow) for bilateral branchial fistulae are observed.

Novel EYA1 gene mutation in a Korean BOR family 1125

Fig. 3 ASSR in the proband showing the estimated hearing threshold.

plastic cochlea, a widened vestibule with smalllateral semicircular canals, and enlarged vestibularaqueduct were observed on both ears. She had beendiagnosed with acute otitis media a few days before

Fig. 4 Axial computed tomographic image of the rightear in the proband showing: (A) widened vestibule withsmall semicircular canals (arrow) and enlarged vestibularaqueduct (*); and (B) scarcely pneumatized mastoid withan abnormal configuration of the ossicular chain (arrow-head), high jugular bulb (x), and soft tissue density in themiddle ear cavity (*), as well as hypoplastic cochlea(arrow).

taking the temporal bone CT. Based on the findingsof audiologic study, she was recommended to wear ahearing aid on the right side, and currently she is onthe course of auditory rehabilitation. Ultrasonogra-phy of her abdomen revealed agenesis of kidney onthe right side.

2.2. Mother

The proband’s mother (Fig. 1, II:5) was a healthy 30-year-old woman. She had cup-shaped antevertedears and bilateral second branchial arch fistulaewithout preauricular fistulae or sinuses. Her eldersister denied that she had delayed development ofspeech and language. Otologic examinationrevealed normal-appearing and mobile tympanicmembranes. Other findings of physical examinationwere unremarkable. She was not cooperative toundergo any audiologic studies.

Morphological and functional abnormalities ofthe kidney were evaluated by ultrasonographyand serum BUN/Cr levels, which showed normalfindings. Temporal bone CT revealed relativelywell-pneumatized mastoid and hypoplastic cochleaand vestibule with enlarged vestibular aqueduct. Ofnote, her temporal bone anomalies were milderthan those of her daughter.

The proband’s grandfather (Fig. 1, I:1) wasreported to have second branchial arch fistulaeand microtia, with a similar morphology as in theproband and her mother. He died of laryngeal can-cer, however, the family members reported of hishearing difficulty. There was a strong family historyof hearing impairment, microtia, and branchialanomalies, but no report of renal disease.

1126 S.H. Kim et al.

Fig. 5 Direct sequencing of the EYA1 gene shows overlapping peaks from the nucleotide c.1475G (open arrow) due to aheterozygous 1 bp insertion of cytosine (c.1474_1475insC; R492PfsX40) in the proband and her mother.

3. Genetic analysis

After we had obtained informed consent, bloodsamples were collected from the proband and herfamily members. Genomic DNA was isolated fromperipheral blood leukocytes using a Wizard genomicDNA purification kit following the manufacturer’sinstructions (Promega, Madison, WI, USA). All 16coding exons of the EYA1 gene were amplified bypolymerase chain reaction (PCR) using the primersdesigned by the authors (available upon request).Cycle sequencing was performed with a BigDyeTerminator Cycle Sequencing Ready Reaction kit(Applied Biosystems, Foster City, CA) on the ABI3100 Genetic Analyzer (Applied Biosystems, FosterCity, CA). Mutation nomenclature was based on theEYA1 cDNA sequence of NM_000503.

Bi-directional sequencing analysis demonstratedthat the proband had a novel insertion mutation(c.1474_1475insC; R492PfsX40) in exon 15 of theEYA1 gene (Fig. 5). Further analysis of family mem-bers revealed that her mother had the same muta-tion but other family members, including thematernal grandmother, maternal aunt, and mater-nal uncle, did not have the mutation.

4. Discussion

BOR syndrome is a clinically and genetically hetero-geneous disease entity involving multiorgans/systems that manifests predominantly duringorganogenesis [21]. Previous studies have shown awide variation of clinical phenotypes between andwithin the families, making the establishment ofcorrelationcomplex.Andno single commonmutation

has been reported, with most of the mutations beingunique to each family [8—20]. Branchio-otic (BO)syndrome (MIM 602588), a related disorder withoutrenal anomalies, is known to be allelic to BOR syn-drome [11,22]. However, a genetic heterogeneity hasbeen reported; twoadditional loci havebeenmappedfor BOR/BO syndrome, and a second causative gene(SIX1) has recently been identified [23—26].

Stinckens et al. reviewed 184 cases of BOR syn-drome from the literature and reported the fre-quencies of the main features of BOR syndrome asfollows: malformed auricles (86.8%), second bran-chial arch fistula/cyst (86.5%), preauricular sinus(87.0%), renal anomalies (58.3%), stenosis of naso-lacrimal duct (47%), and hearing impairment (95.4%)[6]. Molecular testing can confirm the diagnosisof BOR syndrome and can provide information forgenetic counseling of the families. However,it should be reminded that prediction of thephenotype in an individual with a mutation is prac-tically not feasible due to expression variability[3,4,14,21].

In this case, the finding of kidney agenesis in theproband prompted genetic study for a hereditarysyndrome. The observation that her mother, whohad the same mutation as in the proband, did nothave renal abnormalities underscores the variablerenal manifestations in BOR syndrome

Rarely, the hearing loss in BOR syndrome has beenreported to be progressive. While long-term audio-metric follow-up data are limited, Kempermanet al. [27] reported a correlation between progres-sive fluctuant sensorineural hearing loss with calorichypofunction and the presence of enlarged vestib-ular aqueduct in BOR syndrome. It is important toperform imaging studies to evaluate inner ear

Novel EYA1 gene mutation in a Korean BOR family 1127

anomalies and to predict the risk of progressive and/or fluctuant hearing loss. The proband reportedherein had several anomalies in the ossicular chainand inner ear including enlarged vestibular aque-duct, which may portend the possibility of progres-sive hearing loss. In addition, she had middle eareffusion when she took the temporal bone CT. Closefollow-up of the middle ear effusion and evaluationfor progressive sensorineural hearing loss are impor-tant in this patient.

Suspicion of BOR syndrome and search for familyhistory and renal involvement in patients with bran-chial and otologic anomalies will allow earlierdetection of patients and molecular diagnosis, thekey to timely genetic counseling and treatment, andpossibly prevention of serious sequelae.

Acknowledgements

The authors thank the patients and family membersfor their participation. This work was supported bythe Samsung Biomedical Research Institute grant,#SBRI C-A4-102-1.

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