Biology Reference
In-Depth Information
gies for identifying new genes for deafness. With the successful completion
of the mapping of the human genome, assigning functions to the genes that
have been mapped has emerged as a major goal of research in human gen-
etics. It may no longer be necessary to engage in the laborious collection
and genotyping of samples from large pedigrees, consanguineous families
or even sib pairs. By implementing a sequential screening strategy, begin-
ning with the forms of deafness that are most common and easiest to test
for, it may prove feasible to simply screen large repositories of DNA
samples from probands in multiplex sibships for mutations in plausible can-
didate genes and/or murine orthologs by direct sequencing or other tech-
niques. In this way, it may ultimately be possible to determine the
frequencies of genes for deafness in different racial and ethnic groups, as
well as the distribution of mutations in these genes.
Lastly, progress will undoubtedly be made in specific therapies to treat
or prevent hearing loss. Biotinidase deficiency and streptomycin ototoxic-
ity are perhaps the only forms of genetic hearing loss for which preventive
pharmacologic treatment is already available, by providing supplemental
biotin in the first instance, and avoiding aminoglycosides in the second. Dra-
matic though the results of cochlear implants have been, this therapy may
some day be supplanted by the use of genetically corrected autologous stem
cells to replace defective hair cells, or regenerate other specific cellular com-
ponents of the cochlea. If one or more of these therapeutic approaches are
successful, the 20
th
century may well have been the last in which deafness
was a familiar part of the human experience.
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