DEAFNESS GENE

MicroRNA mir-96 mutation leads to loss of hearing if it is present in a single copy and deafness if it is present in two copies.

The results of a search conducted under the projects "Sirocco" and "Eurohear" which was funded by the European Union was posted in nature genetics journal.The association between a new type of gene and progressive loss of hearing is concerned in this discovery.The mir-96 gene is a small piece of RNA that affect the process of generation of other molecules in sensory hair cells of the inner ear .

The results came from the collaboration of two research groups, one Spanish and one English.

Karen Steel who was one of the coordinators of the team of British Sanger Institute, said "We were able to demonstrate relatively quickly if the mice that were carriers of one copy of the variant of this gene suffer from progressive loss of hearing, and if they were carrying both genes, they were suffering from severe hearing loss. The main principal questions to be answered concerning the possibility to determine which variant was involved and how influences on hearing ".

Chromosome 7 which was identified recently is the possible location of the gene altered the two groups of researchers have sequenced the gene in each "homologous genomic regions in man and mouse that are associated with hearing loss" and it has showed the presence of a mutation in the gene mir - 96.

Miguel Angel Moreno-Pelayois is the author of the study and researcher at the Hospital Ramon y Cajal in Spain.He said "We know a number of genes associated with deafness in humans and mice, but we discovered with surprise that this belongs to a new class of MicroRNA genes defined. No one had observed a mutation that can cause disease in a couple of MicroRNA sequence. This is the first MicroRNA gene associated with hearing loss and e 'is significant that the first to be associated with a hereditary condition. "

Experts recognized that the MicroRNA may bind to the active messengers in the generation of cell protein, effectively stopping the process and now have discovered that it is possible to analyze the role of mutation in mice. It also seems that the sensory hair cells in the mutant mice are affected by mir-96 gene, while mice carrying two copies of the gene mutant hair cells are deformed from birth and cells subjected to a degeneration in the early stages of life.

Morag Lewis of the Sanger Institute who discovered the mutation had commented that "The mutation, or variation of a single letter of genetic code from A to T in this tiny extension, is sufficient to cause a serious loss in mice".

This mechanism may also occur in human beings.But, according to analysis of the two families used as a sample, the mutation does not happen ever in the same regions where the mouse, although affect neighboring regions, and always very important for the proper functioning of mir-96 .