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.