Connatal hearing disorders in children. Part II: Genetic hearing loss

Molecular genetic tests enable a differentiated view of patho-physio log ica I correlation of sensori-neural hearing impairment. On the basis of 4791 records of the German Central Registry on Childhood Hearing Loss (Deutsches Zentralregister fur kindliche Horstorungen (DZH)) it was shown that 35% of all permanent hearing impairment in Germany is caused genetically and 20% are acquired. The proportion of indistinct etiology remains at 45%. The number of children who have a hearing impairment by birth is also vague. It has to be expected that approximately 5% of these children develop a hearing impairment afterwards albeit its genetic determination. In 4791 cases a syndromal phenotype was assumed in 8.9%. Practical advice is given for clinical routine diagnostics with pragmatic suggestions and some distinct syndromes are described. Hitherto identified deafness genes reveal their role in pathological auditory function. Future diagnostic and therapeutic strategies are outlined on the basis of molecular genetic methods.