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Researchers at the University of Michigan Medical School recently accomplished the first permanent correction of a deafness-related genetic mutation. The experiment was performed with shaker-2 mice -- a strain of mice born that is born deaf due to genetic defects.
Scientists used a Genetic Engineering technology to first locate the gene responsible for the deafness and then injected short sections of normal cloned DNA into fertilized mouse eggs. On June 23, 1997 the first shaker-2 mouse without the genetic defects was born. The results were reported in the May 29, 1998 issue of Science.
The discovery of the defective gene in mice quickly led researchers to find a nearly identical gene in human beings that may be responsible for some cases of congenital deafness in human beings.
"Interaction between scientists working with the mouse genome and the human genome made it possible to locate these genes so quickly," said Sally A. Camper, associate professor of human genetics at the U-M Medical School. "It’s a perfect example of how transgenic technology in mice can contribute to research with the potential to help people."
Camper noted that there are 12 other related forms of deafness-related mutations in which the responsible gene remains unknown and that "finding the defective gene is the first step toward developing new treatments which someday could restore hearing in children and adults."
The UM scientist now hope to find a way to deliver the normal gene into the cells of adult animals. "The next step is to develop delivery vehicles to introduce the normal gene into inner ear cells of individuals who carry these deafness genes," said Yehoash Raphael, assistant professor of otolaryngology at the UM Medical school. "Once adequate vectors are available, gene therapy for genetic-based deafness will become a reality."
Source:
"DNA cure of genetic deafness in mice helps human research," UniSci Science and Research News, May 29, 1998.