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Objective: Hearing impairment is the most common sensorineural disease in humans. About 1-3 per 1 000 neonates suffers at birth or in the first years from high-grade to severe hearing impairment. About half of the cases are due to genetic alterations. Most commonly, the GJB2 gene (connexin-26) is concerned with the mutation c.35delG. MATERIAL AND METHODES: All patients showed a severe to profound hearing impairment to the course. DNA isolation, amplification and sequencing was performed using standard techniques., Results: In the studied patient population we have 142 pa-tients with a homozygous deletion mutation in GJB2 gene (c.35delG) and 29 patients who are heterozygous for this mutation on one allele and heterozygous for another loss-of-function mutation in GJB2 gene. Of these 171 patients were 16 (9.3%) on an inconspicuous newborn hearing screening using Otoacoustic Emissions (OAE). Total was observed a progression of hearing impairment in 31 of these patients (18.1%)., Conclusions: This fact suggests that homozygous deletion mutation c.35delG does not always contribute to an congenital hearing impairment, but to a progressive hearing loss that might develop over the first months and years of life. Additionally, we have to re-evaluate the value of OAE for newborn hearing screening, keeping in mind that one positive result is no warranty for a normal development of hearing function, but a result that should be checked in the course. We recommend annual hearing tests to the paediatrician and with a known familial hearing loss and other risk factors pedaudiological controls., (© Georg Thieme Verlag KG Stuttgart · New York.)

Hearing impairment is the most common sensorineural disorder in humans. Approximately one of thousand new-borns is affected by severe to profound deafness at birth or during early childhood. Genetic causes account for around half of these cases of prelingual hearing impairment and the remainder are attributed to environmental factors. Genetic causes of hearing impairment in combination with a syndrome as Usher, Pendred are distinguished from non-syndromic hearing impairment. In the last years a tremendous growth in the localisation and identification of genes for non-syndromic hereditary hearing impairment has evolved. It has become clear that these conditions are genetically extremely heterogeneous. Approximately 120 different gene loci associated with non syndromic hearing impairment have been identified. Presently 54 gene loci associated with autosomal dominant mode of inheritance and 67 gene loci with autosomal recessive mode of inheritance have been identified; 7 are X-chromosome linked and 4 mitochondrial. Of these, 19 genes have been characterised for autosomal dominant (DFNA), 20 for autosomal recessive (DFNB), and 2 for X-linked (DFN) disorders. These genes encode proteins of diverse functions, including transcription factors, cytoskeletal and extracellular matrix components, and ion channels. Despite this heterogeneity, up to 50 % of prelingual recessive non-syndromic deafness can be attributed to mutations in the GJB2 gene (Connexin-26, gap-junction protein). However, the diversity of genes and genetic loci implicated in hearing loss illustrates the complexity of the genetic basis of hearing. Knowing the gene and the function of its products helps understanding the mechanisms of hearing.

Background: Both LAV- (large or enlarged vestibular aqueduct) and Pendred-syndrome are autosomal recessive diseases. In contrast to Pendred-syndrome, LAV-syndrome is characterised only by an enlarged vestibular aqueduct. Pendred-syndrome is a more complex disease. Classically it is characterised by sensorineural hearing loss and enlargement of the thyroid gland. Up to now, only mutations in SLC26A4 gene are known as being responsible for both syndromes. The gene for Pendred-syndrome (SLC26A4) has been localised by linkage analysis of chromosome 7q31. This protein is expressed in the inner ear, thyroid gland, kidney, and placenta. Functional analysis of the gene product (pendrin) in Xenopus laevis oocytes revealed that pendrin acts as an iodide/chloride and chloride/formate exchanger., Method: Each of the exons and flanking splice regions of the SLC26A4 gene were analysed by direct sequencing. Haplotype analysis was undertaken with microsatellite markers spanning a 5 Mbp area around the localisation of the SLC26A4 gene., Results: In sequence analysis of 42 patients with bilateral enlargement of the vestibular aqueduct, no mutation could be identified in 30 % of cases. In some of these cases, a linkage to the gene localisation on chromosome 7q31 could not be detected., Conclusion: Our results indicate evidence for a second gene involved in the development of LAV-syndrome.

Background: Hitherto more than hundred genes and gene loci for non-syndromic or syndromic deafness have been identified. Mutations in the connexin 26 gene (GJB2) account for up to 50 % of the cases of autosomal recessive hearing loss. The genes GJB2 (Connexin 26), GJB3 (connexin 31) and GJB6 (connexin 31) are located on chromosome 13q11-12. In the inner ear up to four different connexins are expressed. Connexins appertain to a group of gap junction proteins. These proteins can oligomerize to form single-membrane channels called connexons. Each connexon is composed of six subunits, that allow communication between adjacent cells by providing a channel for diffusion of ions, metabolites and second messengers., Method: Each of the exons and flanking splice regions of the connexin 26, 30, and 31 genes (GJB2, GJB3, and GJB6) have been analysed by direct sequencing., Results: In the involved families three heterozygous mutations could be detected in the connexin 26 (GJB2) and connexin 30 (GJB6) genes. If a combination of two of those mutations occurs, 35DeltaG with 146/147DeltaC and 35DeltaG with GJB6-D13S1830 it results in hearing loss and deafness., Conclusion: By evidences of a familial background of hearing loss it is reasonable to analyse the connexin genes (GJB2, GJB3 and GJB6) for mutations, additionally to a specific hearing diagnostic, in order to enhance linguistic development through hearing aid or CI-implantation at an early stage.

Background: Lipoma of the retropharyngeal space is a rare benign tumour often showing unspecific clinical symtoms. It can grow to an enormous extent causing total obstruction of the upper respiratory tract. Until now its etiology is unknown. With a variety of differential diagnoses, a diagnostic concept is necessary., Case Report: A 41 year old male patient complained about a nondolent swelling of the neck. The radiological diagnostics showed a huge lipoma of the para- and retropharyngeal space with subtotal obstruction of the pharynx. The lipoma was removed completely via transcervical approach., Conclusion: Lipoma as differential diagnosis of retropharyngeal tumours always has to be considered. Surgical intervention is recommended. To prevent functional complications resulting from tumour and surgery and to get information about the extent of the lipoma, accurate radiological imaging is mandatory.

Background: Pendred-syndrome is an autosomal recessive disease that is classically characterised by sensorineural hearing loss and enlargement of the thyroid gland. The gene SLC26A4/PDS for the pendred-syndrome has been localised by linkage analysis on chromosome 7q31. This protein is expressed in the inner ear, thyroid gland, kidney and placenta. Functional analysis in Xenopus laevis oocytes revealed that it acts as an iodide/chloride and chloride/formate exchanger., Method: Each of the exons and flanking splice regions of the SLC26A4/PDS gene was analysed by direct sequencing., Results: In the involved family two heterozygous mutations could be detected which results by combination in hearing loss and deafness., Conclusion: By evidences of familial background in hearing loss and thyroid disorder it is reasonable to analyse the PDS gene for mutation to have early the possibility for medical care of linguistic development through hearing aid or CI-implantation.