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
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.
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.