Around ten to twenty per cent of older adults suffer from hearing problems caused by neurological processing disorders. The neurogenetics working group has tackled the problem - and discovered genetic backgrounds.
Around two to three per cent of all children and ten to twenty per cent of older adults suffer from hearing problems caused by neurological processing disorders. Although their inner ear is fully functional, their brain interprets the acoustic signals incorrectly. According to recent findings, such a hearing disorder is often associated with dyslexia (reading and understanding words and texts) and autism.
The Neurogenetics working group at the University of Oldenburg, led by Prof Dr Hans Gerd Nothwang, has now identified new key molecules for the error-free interpretation of acoustic signals together with scientists from the University of Tel Aviv (Israel). The experts recently presented their research findings in the internationally renowned online journal of the Public Library of Science PLOS ONE 2012.
Auditory processing disorders are twice as common in boys as in girls. "This points to a genetic background," emphasises Nothwang. In order to identify the genetic causes of developmental disorders of the auditory pathway, he and his team are trying to track down the factors that are significantly involved in the development of the auditory pathway.
"We have only known about microRNAs - small nucleic acids - that play an important role in gene regulation for a few years. The enzyme Dicer is required for their production in the cell," explains the neurobiologist. The scientists from Oldenburg and Tel Aviv used a special procedure to switch off this enzyme locally in mice, thereby preventing cellular microRNAs from being produced in the auditory pathway.
Switching off Dicer in the embryonic stage had drastic consequences: Part of the auditory pathway did not develop at all, while another area was significantly impaired. "These findings allowed us to conclude for the first time that the class of small regulatory nucleic acids are the key molecules responsible for the correct development of the auditory pathway," says Nothwang. Through further genetic analyses, it was also possible to narrow down the critical time window for the action of Dicer and thus of microRNAs to early embryonic development. The experts recently presented their research results in the internationally renowned online journal of the Public Library of Science PLOS ONE 2012.
In future, the scientists want to go one step further and identify the crucial microRNAs and their exact functions. "Genetic disorders such as mutations in the microRNAs very probably lead to abnormal developments in the auditory pathway. They could therefore contribute to auditory processing disorders," says the neurobiologist. The successful co-operation with the Israeli working group will also be continued for these investigations. The project is also supported by the "Hearing4all" cluster of excellence. The University of Oldenburg is leading the consortium on the topic of hearing.
Elena Rosengauer, Heiner Hartwich, Anna Maria Hartmann, Anya Rudnicki, Somisetty Venkata Satheesh, Karen B. Avraham, Hans Gerd Nothwang: "Egr2::cre mediated conditional ablation of dicer disrupts histogenesis of mammalian central auditory nuclei." PLoS ONE 2012