Biology Reference
In-Depth Information
developed recently (Oberholtzer et al. 1994; Heller et al. 1998), as well as
a mouse cochlear cDNA library constructed from 400 mouse cochleae
(Crozet et al. 1997).
4. Summary
Thus far, cytogenetic analysis has been used in only a small number of
studies of patients with hearing loss. This reflects the fact that chromoso-
mal studies are costly, and karyotypic anomalies are likely to account for a
low percentage of cases. In addition, only a relatively small proportion of
molecular biologists have any expertise with cytogenetic techniques.
Appropriately, cytogenetics is not the first technique to be considered when
evaluating a child with nonsyndromic deafness. However, cytogenetic
testing could be valuable in cases of deafness of unknown etiology, partic-
ulary if there were accompanying congenital anomalies, or a family history
of multiple spontaneous abortions. When all other causes of deafness, either
genetic or acquired, are eliminated, cytogenetics could be used to determine
if the hearing loss may be due to a chromosome rearrangement, such as a
balanced translocation. The advantage would be that, if such a chromosome
rearrangement were found, it would immediately suggest the location of
the deafness gene.
The cochlear ESTs and libraries that exist have been extremely helpful
in understanding different aspects of the molecular biology of the inner ear.
Many of the deafness genes that have been cloned thus far have originated
from one of these libraries, or been shown to be expressed in the inner ear
by virtue of being found in one of the cochlear libraries. The current
cochlear EST collection will be augmented in the near future by the pro-
duction of additional cochlear ESTs, providing an enriched biological
resource for investigating gene expression in the inner ear.
Acknowledgments.
The writing of this manuscript was supported by NIH
grants R01 DC-03402 to C. C .M. and DC-01076 to M. C. King.
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