FY2005 President's Budget Request for the NIDCD
DEPARTMENT OF HEALTH AND HUMAN SERVICES
Fiscal Year 2005 President's Budget Request
for the National Institute on Deafness and Other
Communication Disorders
Statement by
Dr. James F. Battey, Jr., M.D., Ph.D.
Director, National Institute on Deafness and Other Communication
Disorders
Mr. Chairman and Members of the Committee, I am pleased to present
the President's budget request for the National Institute on Deafness
and Other Communication Disorders (NIDCD). The fiscal year (FY)
2005 budget includes $393,507,000 which reflects an increase of
$11,561,000 and a 3% increase over the FY 2004 final conference
level. Disorders of human communication exact a significant economic,
social, and personal cost for many individuals. The NIDCD supports
research and research training in the normal and disordered processes
of hearing, balance, smell, taste, voice, speech, and language.
NIDCD's mission includes the support of research to create assistive
devices which substitute for lost and impaired sensory and communication
function. Equally important to the NIDCD mission has been the discovery
of genetic mutations that affect communication disorders. This work
would not have been possible without the completion of the Human
Genome project, supported in part by the National Institutes of
Health. Enabled by this landmark accomplishment, scientists supported
by the NIDCD have been studying the genes responsible for non syndromic
(not associated with any other problem) hereditary hearing impairment.
Within the last 8 years, 54 genes have been identified, largely
due to the contributions of NIDCD. Scientists are now focusing their
efforts on identifying more genes, learning what role the genes
have in deafness, and determining which genes affect certain populations
of individuals. For example, recent studies have demonstrated that
particular ethnic groups carry specific genetic mutations. Studying
the genes that cause non syndromic hereditary deafness will also
permit early and more accurate genetic testing and foster the development
of innovative intervention and prevention strategies, and more effective
treatment methods for individuals with deafness and other communication
disorders. My testimony today will primarily focus on the many genetic
discoveries that have allowed NIDCD-supported scientists to learn
more about the causes of communication disorders, a first step in
prevention and treatment.
New Way to Identify Usher Syndrome in Children
Usher syndrome Type 1 is an inherited disorder. Children born with
this disorder are deaf, suffer balance problems, and gradually lose
their vision. Although Usher syndrome affects individuals of other
racial and ethnic backgrounds, scientists have recently identified
a clear pattern of its inheritance in Ashkenazi Jews, who are descendants
of Jews from Germany, Austria and Eastern Europe. In 2003, a NIDCD-supported
scientist identified a mutation within the gene known to be responsible
for Usher syndrome. The particular mutation seems to be responsible
for most of the Usher syndrome seen in Ashkenazi Jews. Because scientists
now know which mutation is responsible for this type of Usher syndrome,
they can develop genetic tests to detect the mutation in Ashkenazi
Jewish children who are born deaf. By identifying children destined
to lose their sight, parents and doctors can help them learn to
communicate and prepare them for blindness. Some of these children
will be appropriate candidates to receive a cochlear implant. Cochlear
implants are small electronic devices that enable individuals who
are deaf or have severe hearing loss to detect sound. This research
will now enable doctors to provide important quality of life improvements
for children with Usher syndrome.
Gene Replacement Therapy Can Generate New Hair Cells
The sensory hair cells of the inner ear play an important role in
detecting sound. People who lose hair cells due to excess noise,
infections, or accidents often lose some or all of their ability
to hear. Scientists have determined that many forms of inherited
deafness are also due to problems with hair cells. The hair cells
of the inner ear act like miniature amplifiers. Sound waves that
enter the inner ear are converted into a series of chemical and
electrical signals within the cells. These signals are ultimately
transmitted to the brain via the auditory nerve and interpreted
as sound. In the past, only birds or reptiles were thought to be
capable of generating new hair cells. Now, NIDCD supported scientists
have discovered a way to use gene therapy to generate new hair cells
in the ears of adult mammals. Scientists used a virus to transfer
a gene called Math1 into the ears of guinea pigs. Math1 is expressed
in developing hair cells, and its expression is thought to cause
the cells to become hair cells, rather than becoming another cell
type within the ear. The virus infects cells of the ear and causes
them to produce the Math1 protein. Early experiments suggest that
when the virus infects cells that do not normally express Math1,
some of these cells become hair cells. In addition, the new hair
cells also attract fibers of the auditory nerve, suggesting that
the new cells may also be able to establish a link to the part of
the brain that interprets sound - the auditory cortex. If this work
can be duplicated in human beings, it may be the first step towards
enabling scientists to use gene therapy to restore hearing to those
who have lost it, or to enable deaf individuals to hear.
New Short Electrode Will Allow Greater Benefit from Cochlear
Implants
Cochlear implants are commercially available miniature hearing prostheses
capable of assisting those who are profoundly deaf or severely hearing
impaired. Approximately 60,000 individuals all over the world have
received cochlear implants. The implant bypasses damaged or missing
hair cells to send electrical signals through an array of electrodes
within the cochlea (inner ear). Current cochlear implants send sound
information that covers the entire frequency range. In order to
send both high and low frequency information, the electrodes of
the cochlear implant are inserted as far into the cochlea as possible.
Unfortunately, inserting the electrodes into the cochlea compromises
any residual (remaining) hearing the individual may have had prior
to implantation. Consequently, scientists developed a new shorter
electrode to help an additional population of individuals with hearing
loss. These individuals have a considerable amount of residual hearing
and their primary hearing loss is in sounds in the high frequency
range. They are also experienced, yet unsuccessful, adult hearing
aid users with severe to profound hearing impairment who would not
have been conventional cochlear implant candidates. The short electrode
is inserted into the base (or bottom) of the cochlea to restore
hearing at high frequencies, while preserving low frequency hearing,
or residual hearing, in the apex (or top) of the implanted ear.
The preliminary data demonstrates residual hearing can be preserved
with this short electrode, and provides evidence that this is most
beneficial for understanding speech in a noisy background. Furthermore,
the innovative short electrode may be an ideal treatment for those
with presbycusis, which is the loss of hearing that gradually occurs
in most individuals as they grow older. This new electrode design
allows many more people with some degree of hearing loss to benefit
from cochlear implant technology.
Identifying Genes Important for the Sense of Taste
The worldwide obesity epidemic is causing health professionals to
focus their attention on how people choose which foods to eat. Because
taste plays an important role in food choice, scientists are interested
in figuring out how taste buds tell the brain that they have tasted
something, and which taste genes are responsible for sensing different
food flavors. Vegetables such as broccoli, cauliflower, cabbage,
and brussels sprouts contain compounds related to phenylthiocarbamide
(PTC). For more than 50 years, scientists thought that the ability
to taste PTC and similar compounds was determined by a single gene.
If an individual inherited the PTC-tasting version of the gene,
then they detected its bitter taste. If the tasting version of the
gene was not inherited, the compound had no taste to that individual.
Now NIDCD scientists, in collaboration with scientists in California
and Utah, have identified a gene that regulates a person's sensitivity
to the bitter taste of PTC. This explains why people seem to demonstrate
a range of sensitivity to PTC's taste and may even influence whether
or not an individual likes to eat broccoli and other vegetables
containing PTC-like compounds. Because they determine an individual's
sensitivity to a particular taste, inherited genes probably influence
food choices. In the future, doctors may now be able to use this
knowledge as part of a strategy to prevent and treat obesity and
to overcome poor nutrition due to poor food choices. Increased knowledge
about how taste cells tell the brain that they have detected a particular
flavor may also help doctors restore the sense of taste to those
who have lost it due to injury, disease or aging.
Vocal Fold Paralysis
Vocal fold paralysis is a genetic disorder that can be inherited.
The vocal folds are two bands of smooth muscle tissue that lie opposite
each other and are located in the larynx or voice box. When at rest,
the vocal folds are open to allow an individual to breathe. Voice
is produced by vibration of the vocal folds. To produce voice, air
from the lungs passes through the folds, causing vibration and thus
making sound. The sound from this vibration then travels through
the throat, nose, and mouth (resonating cavities). The size and
shape of these cavities, along with the size and shape of the vocal
folds, help to determine voice quality. Paralysis of the vocal folds
impacts voice quality and inhibits an individual's ability to communicate.
This disorder can also cause life-threatening breathing difficulties
in affected newborn infants.
Intramural scientists at the NIDCD and the National Institute
of Neurological Disorders and Stroke are studying a family in which
this disorder occurs and have found that vocal fold paralysis is
due to degeneration of the nerves involved in movement. Weakness
in the muscles of the arms and legs can also accompany this disorder.
In the study, genetic analyses were used to locate the site of the
causative gene to a section on chromosome 2. Further studies revealed
that mutations in the dynactin gene, which resides at this location,
are responsible for this disorder. Dynactin is a molecule that helps
transport materials within nerve cells, and this research finding
suggests that dynactin transport is essential for health and maintenance
of at least some motor nerve cells.
This finding allows for a genetic tool for diagnosing vocal fold
paralysis, which can aid in the clinical and neonatal management
of this disorder. In addition, these findings provide better understanding
of motor nerve cells and the molecular mechanisms that cause motor
nerve degeneration.
NIH Roadmap
The NIH Roadmap initiative to support interdisciplinary research
and research training will advance the NIDCD mission because it
encourages collaboration of scientists from seemingly unrelated
disciplines. Interdisciplinary collaborations from a variety of
scientific disciplines are necessary for developing assistive communications
devices such as hearing aids and cochlear implants. The success
of the development of the cochlear implant is a good example of
successful interdisciplinary research as it involved the effort
of physicists, chemists, material scientists, psychologists otolaryngologists,
audiologists, speech-language pathologists, electrical engineers,
and biomedical engineers. We look forward to expanding upon that
type of research in the coming years.
Finally Mr. Chairman, I would like to thank you and Members of this
Committee for giving me the opportunity today to speak to you about
the exciting recent discoveries from the NIDCD. I am pleased to
answer any questions that you have.
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