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Biomedical subjects

F Apaydin

Publications and source records attributed to F Apaydin.

9 recordsLinked to original sources
PubMed2004

[Waardenburg syndrome. A heterogenic disorder with variable penetrance].

BACKGROUND: Waardenburg syndrome (WS) is an autosomal dominant disorder characterised by pigmentary anomalies of the skin, hairs, eyes and various defects of other neural crest derived tissues. It accounts for over 2% of congenital hearing impairment. At least four types are recognized on the basis of clinical and genetic criteria. PATIENTS AND METHODS: Based on a screening of congenitally hearing impaired children, 12 families with WS type II were detected. Of special interest was the phenotype of these families, in particular the reduced penetrance of hearing impairment within the families. RESULTS AND CONCLUSION: In all cases a high variability of the disease phenotype was detected and the penetrance of the clinical traits varied accordingly. Therefore, it is not possible to predict the clinical phenotype even in a single family. Based on these studies, we plan to identify the pathogenetic cause of the disease in order to perform a detailed genotype/phenotype analysis.

Genetic Heterogeneity↗
PubMed2002

Substitutions in the conserved C2C domain of otoferlin cause DFNB9, a form of nonsyndromic autosomal recessive deafness.

DFNB, the nonsyndromic hearing loss with an autosomal recessive mode of inheritance constitutes the majority of severe to profound prelingual forms of hearing impairment, usually leading to inability of speech acquisition. We analyzed a consanguineous family with autosomal recessive deafness which has been shown to segregate within chromosomal region 2p23.1 (DFNB9; MIM 601071). By SSCP analysis and DNA sequencing of the 48 exons of the DFNB9 gene, coding for otoferlin, previously reported mutations in OTOF were excluded. Next to a frequent T > C single nucleotide polymorphism in exon 8, two novel mutations linked in exon 15 of the OTOF long splice form were identified comprising substitutions at positions 490 (Pro > Gln) and 515 (Ile > Thr), both located in the conserved Ca(2+) binding C2C domain of this peptide. Comparisons of homology using human and mice otoferlins and closely related peptides and computer simulation analyses suggest that changes in the mutated segment's secondary structure affect the Ca(2+) binding capacity of the C2C domain in otoferlin.

Alternative Splicing↗
PubMed1999

Clinical evidence for dystrophin dysfunction as a cause of hearing loss in locus DFN4.

OBJECTIVE: Locus DFN4 is an X-linked nonsyndromic hearing loss locus originally mapped to Xp21.2. Recently, we have mapped deafness in a second family from Turkey to the same region, refining the location to within the Duchenne muscular dystrophy (DMD) locus. The objective of this study was to characterize the clinical phenotype of the Turkish family with comprehensive audiovestibular testing and high-resolution temporal bone computerized tomography. METHODS: Fourteen members of a three-generation family were studied in detail including two deaf affected males. Members of the family underwent general physical and otologic examination, vestibular testing, pure-tone audiometry, otoacoustic emissions, and immitance testing. An affected male underwent high-resolution computerized tomography of the temporal bone, electroretinogram (ERG), electromyography, electroneurography, and determination of serum creatinine phosphokinase level. RESULTS: Affected males were congenitally deaf with normal vestibular function. Carrier females showed a mild sensorineural hearing loss affecting all frequencies and absent otoacoustic emissions. Otoacoustic emissions in a younger, 3-year-old carrier girl were normal. In an affected male, ERG demonstrated subnormal scotopic b-wave typically seen in DMD. Computerized tomography of the temporal bone was normal. With the exception of the ERG finding, there was no clinical or laboratory evidence of DMD or Becker muscular dystrophy (BMD). CONCLUSION: The abnormal ERG in the Turkish family in conjunction with mapping of the DFN4 locus to within DMD strongly suggests that a defect in dystrophin is responsible for the hearing loss in this family. Patients with DMD and BMD should be screened systematically for sensorineural hearing loss. This family provides additional evidence for the critical role of cytoskeletal proteins in normal hearing.

Dystrophin↗
PubMed1998

A second family with nonsyndromic sensorineural hearing loss linked to Xp21.2: refinement of the DFN4 locus within DMD.

X-linked inherited hearing impairment is a group of heterogeneous disorders accounting for less than 2% of hereditary hearing loss. DFN4, a sex-linked hearing impairment associated with profound sensorineural hearing loss, has been previously mapped to Xp21.2, a region containing the DMD locus. We have identified a family from Turkey with deafness in which the disease maps to and refines the DFN4 locus. In contrast to the previous family, the crossover points are entirely within the DMD locus. Two-point lod score analysis for the markers DXS 997, DXS 1214, and DXS 1219 showed a lod score of 2. 59. 5' and 3' crossovers were between DMD 44 and DXS 1219 and between DXS 1214 and DXS 985, respectively, suggesting that DFN4 is either an allele of DMD or a mutation in a DMD nested gene. The restriction of the DFN4 locus to DMD suggests that dystrophin may play an important role in hearing.

Chromosome Mapping↗
PubMed1998

[Hereditary deafness in Turkey. Initial results].

The authors describe a study in progress to identify Turkish families with hereditary hearing loss and isolate possible responsible disease genes. Due to extreme genetic heterogeneity and limited audiological differentiation of hereditary hearing loss, it is necessary to identify large or small families from genetic isolates to locate loci responsible for hearing loss on a chromosome. To accomplish this goal, the medical records of 3800 children were examined at the ENT Clinic of Ege University between 1975 and 1994. All were suspected of having various hearing impairments. Additionally, students from two schools for the hearing impaired in Izmir and Eskisehir, Turkey were examined. To date, 16 families with syndromal deafness and 55 families with non-syndromal hereditary hearing loss involving two or more affected individuals have been identified and categorized according to the mode of inheritance. The majority (66%) of the non-syndromal families showed an autosomal recessive pattern, 29% an autosomal dominant inheritance and 5% an X-linked mode of inheritance. In the study presented there has been a predominance of affected males versus females and the consanguinity rate was 22%.

Child↗
PubMed1996

[A computer-assisted patient databank for the ENT field].

In this study, a patient database program was prepared for patients admitted to the ENT Department of Ege University Hospital, Izmir. The algorithm of the program was created by using dBASE IV. In order to develop a patient database, a careful preparation and running stage had to be accomplished. However, the most important factor was proper maintenance. The greatest problem during the maintenance stage was compliance of the doctors or secretaries using the program. This was overcome by choosing or making a user-friendly, flexible, practical and beneficial patient database program. The study also showed that doctors could make their own patient databases and use them efficiently if they are interested in computers.

Algorithms↗
PubMed1992

The evaluation of the changes of voice registers in trainee singers by using the two-channel signal processing method.

This study was done at the ENT Department of the Ege University Medical Faculty on twenty trainee singers. Using the two-channel signal processing method, the electroglottographic (EGG) signals and the voice signals were digitized with an analog-digital converting card during an ascending and descending glissando exercised by the trainee singer. These signals were recorded on the computer's hard disk and the obtained data was analysed. It has been determined that the EGG signals were more irregular the singing formant of the voice signal was very weak or absent and the change of register was more significant in less trained singers. This method can be used to evaluate objectively the change of voice registers in the training of the singers and be easily performed by adding an analog-digital converting card to a PC computer, without the need of expensive modern devices.

Adolescent↗
PubMedDate not supplied

A second middle eastern kindred with autosomal recessive non-syndromic hearing loss segregates DFNB9.

A second kindred has been identified which supports the previously reported location of DFNB9. Linkage has been established to markers closely linked to DFNB9 which is located on 2p22-p23. The hearing impaired individuals in this highly consanguineous kindred from Eastern Turkey have prelingual profound hearing loss which affects all frequencies. A genetic map of the 2p22-p23 region where DFNB9 resides was generated using marker genotypes available from the CEPH database. All markers were placed on this genetic map using a likelihood ratio criterion of 1000:1. This map suggests that the region for DFNB9 is less than 1.08 cM, 95% confidence interval (0-2.59 cM).

Chromosome Mapping↗