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FY2002 President's Budget Request for the NIDCD

DEPARTMENT OF HEALTH AND HUMAN SERVICES

Fiscal Year 2002 President's Budget Request
for the National Institute on Deafness and Other Communication Disorders

Statement by
Dr. James F. Battey, Jr.
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) for FY 2002, a sum of $336,757,000, which reflects an increase of $35,631,000 over the comparable FY 2001 appropriation. The NIH budget request includes the performance information required by the Government Performance and Results Act (GPRA) of 1993. Prominent in the performance data is NIH's second annual performance report, which compares our FY 2000 results to the goals in our FY 2000 performance plan. As performance trends on research outcomes emerge, the GPRA data will help NIH to identify strategies and objectives to continuously improve its programs.

The United States recently celebrated the 10th anniversary of the signing of the Americans with Disabilities Act, a law enacted in 1990 to promote integration, equal opportunity, and inclusion of millions of Americans with a disability. Even with this legislation, individuals affected by a communication disability may still find it difficult to enter the labor force and live a productive life because of the daily challenges they face. It is often impossible for them to perform the simple acts of speaking, listening, or otherwise making their wants and needs understood. Disorders of hearing, balance, smell, taste, voice, speech, and language exact a significant economic, social, and personal cost for many individuals. The NIDCD supports and conducts research and research training in the normal processes and the disorders of human communication that affect approximately 46 million Americans. Human communication research now has more potential for productive exploration than at any time in history. With substantive investigations conducted over the past decades, the advent of exciting new research tools and new highly trained scientists, the NIDCD is pursuing a more complete understanding of the scientific mechanisms underlying normal communication and the etiology of human communication disorders. Examples of this research are highlighted in this statement for the record.

The Speed of Sound: Rapid Motor Protein of Inner Ear Identified

Millions of Americans, especially middle-aged and older individuals, suffer from mild to moderate hearing loss. It is likely that a defect in the most sensitive cell types in the inner ear, the hair cells, causes this type of hearing deficit. The hair cells of the inner ear are sensory receptor cells that give humans and other mammals the remarkable ability to hear. As sound travels to the ears, down the ear canal, through the bones of the middle ear and into the inner ear, the outer hair cells amplify the mechanical vibrations produced by the sound through a process known as electromotility. These electrical changes in the cell allow it to rapidly change its length and stiffness. The length changes amplify the vibrations, which are sensed by the other hair cells (inner hair cells) that send auditory information to the brain. NIDCD-supported scientists have recently identified the gene that codes for the motor protein responsible for outer hair cell electromotility as well. Prestin (from the musical term presto, indicating a rapid tempo) was selected as the name of the gene to emphasize one of the most interesting features in the cellular motor process, its speed in changing the length of outer hair cells. Outer hair cells can elongate and contract at rates close to 100,000 times a second! Future research on Prestin should lead to significant advances in understanding the auditory system, and may lead to the development of new therapeutic measures for hearing impairment.

Genes Responsible for Hereditary Hearing Impairment

NIDCD-supported scientists continue to make impressive scientific progress in mapping and cloning genes responsible for hereditary hearing impairment. Over the past few years, the chromosomal location of over 60 genes whose mutation results in hereditary hearing impairment have been identified. In the past three years, nearly 20 genes have been identified whose mutations cause hereditary hearing impairment. The identification of these genes enables scientists or clinicians to rapidly identify individuals carrying the defective gene even if the hearing loss has a delayed onset and is not yet evident. In addition, the identification and isolation of genes responsible for hereditary hearing impairment immediately provide a powerful tool to determine how the mutation results in deafness by targeted gene mutations or deletions in an animal model. The animal model can provide information on which structures of the ear are affected, as well as the molecular and physiological defects that result in hearing impairment, and provide a system to test potential new therapies.

Gene Cloned for Syndrome That Causes Deafness and Blindness

Usher syndrome type 1 is an inherited sensory defect involving profound deafness, balance disorders, and eventual progression to blindness. It is the most common genetic cause of a syndrome leading to blindness and deafness in Americans. Studies of affected families in the United States and abroad indicate that there are more than six distinct genes whose mutations result in this devastating inherited disease. NIDCD-supported scientists are collaborating with researchers from France, Germany, Lebanon, and Japan to identify the defective gene responsible for one form of this disorder, USHER1C. They identified the defective USHER1C gene in unrelated families in the United States, Lebanon, and Europe. The finding will allow for genetic-based diagnosis of Usher syndrome before a deaf individual begins to lose sight. Early diagnosis will permit the study of the complete progression of retinal degeneration and provide opportunities in the future for possible treatment before the retinal degeneration begins.

An Animal Model for Pendred Syndrome

Individuals with Pendred syndrome have sensorineural deafness and goiter (enlargement of the thyroid gland). In a collaboration between National Human Genome Research Institute and NIDCD intramural scientists, genetic analysis revealed that mutations in the Pendrin gene occur in deaf individuals without thyroid disease, indicating that the gene is responsible for a much broader spectrum of deafness than only those individuals with Pendred syndrome. To determine the cause of this disorder, the Pendrin gene was deleted in mice and analysis of this mouse model was conducted. The mutant mice were found to be deaf and have a variable spectrum of balance problems similar to symptoms of individuals with the syndrome. The scientists observed swelling in parts of the developing inner ear in the mutant mouse embryos. The resulting fluid imbalance within the inner ear subsequently leads to the destruction of the sensory hair cells necessary for hearing. This mutant mouse model provides important clues about inner ear pathology associated with the human syndrome.

Otitis Media Is Linked to a Strong Genetic Component

Otitis media (OM), or middle ear infection, is the most common reason why a sick child visits a physician and is the most common reason that children receive antibiotics or undergo surgery. Previous anatomical, physiological, and epidemiological studies have raised the question of whether the likelihood of having multiple bouts of this common disease has a hereditary component. Studying twins and triplets to determine the extent to which this common disease might be due to genetic factors, NIDCD-supported scientists have determined that there is a strong genetic component to the rate of occurrence of otitis media in children. The implications of these findings are numerous for both immediate and future improvements in treatment of OM. For example, primary care physicians can follow siblings and offspring of affected children as potentially high-risk cases. These children could be monitored more closely for early detection and treatment of disease, reducing the risk of hearing loss. In addition, identification of the genetic factors that cause this disease could eventually result in genetic diagnostic tests to identify individuals with enhanced risk. Finally, studies of the molecular basis for the increased risk and frequency of otitis media could lead to new approaches for intervention and treatment of this disease.

Molecular Biology of Taste Signal Transduction

A long history of NIDCD-supported research has shown that taste perception involves four basic taste qualities: sweet, sour, salty, and bitter. In a recent study, a fifth taste has been recognized and its taste receptor identified--umami--the taste of monosodium glutamate or the taste associated with protein-rich foods. From this finding, scientists have determined that each taste quality appears to be mediated by a distinct biochemical pathway. Salty and sour substances activate specialized ion channels in the membrane of the taste receptor cells in the taste buds in the tongue. In contrast, umami-, sweet-, and bitter-tasting substances activate another pathway involving G-protein-coupled receptors. Scientists recently characterized the diverse structure, function, and expression of a large family of mammalian G-protein-coupled receptors, called T2Rs, which are selectively expressed in a subset of taste receptor cells of the tongue and palate. T2R receptors were shown to mediate bitter taste perception in humans and mice.

The Genetics of Stuttering

Stuttering is a speech disorder in which the normal flow of speech is disrupted by frequent repetitions or prolongations of speech sounds, syllables, or words. Currently, there is no cure for the 3 million Americans who stutter. The precise causes of stuttering have not been identified but there is evidence that it is genetically determined. NIDCD intramural scientists have been conducting a large study that involves individuals who stutter and their families. From this group, the scientists have recently identified a single region of the genome that may contain one or more genes involved in stuttering. Understanding the genetic causes of stuttering will eventually lead to treatment for this age-old disorder.

Language Impairment in Autism

NIDCD-supported scientists were the first to investigate the language profiles on a large sample of children with autism. One cardinal feature of autism is the delay or absence of spoken language. In the study, the researchers found significant differences in language skills, although articulation skills (or how the sounds of the language are produced) remained normal in all the children. Different subgroups of children with autism were identified on the basis of their performance on the language measures. Some children with autism have normal language skills, while others have language skills significantly below their age expectations. The scientists also observed that the performance profile across the standardized measures for the language-impaired children with autism was similar to the profile of children with specific language impairment (SLI). These findings suggest that there may be overlapping or shared characteristics among families with SLI and autism. Future studies will need to investigate the mechanisms underlying language processing in children with SLI, autism, and perhaps other disorders, in order to advance the understanding of language disorders in children.

Expanding Efforts to Identify Hearing Impairment in Newborns

As efforts increase in many states to screen all newborn infants for hearing impairment before discharge from the hospital, more infants will be identified with hearing impairment at an early age when appropriate intervention can be started that will optimize their long-term speech and language skills. NIDCD-supported scientists have examined the importance of age at enrollment in intervention programs and subsequent language outcomes for a group of deaf and hard-of-hearing children. Significantly better language scores were associated with early enrollment, and high levels of family involvement correlated with positive language outcomes. These results provide further evidence that children will benefit when early identification of hearing loss is combined with an early intervention strategy that actively involves family participation.

Advances in the genetics of hereditary hearing impairment and in the early identification of hearing impairment have now converged, leading some clinicians to suggest genetic testing/evaluation be performed on all infants who are identified with a hearing loss at birth. In consideration of these developments, the NIDCD is planning a study to address the clinical relationship between genetic and audiologic/otologic information, as well as to assess the clinical validity, value, and utility of genetic testing in the diagnosis, treatment, and management of hearing impairment.

Cochlear Implants Are Cost Effective

Over 20,000 Americans with profound hearing impairment have received cochlear implants, with approximately one-half of the recipients being children. This device converts sound into electrical impulses on an array of electrodes surgically inserted into the inner ear, bypassing the hair cells and stimulating the auditory nerve directly. NIDCD-supported studies have shown that children with cochlear implants exhibit improvements in speech perception, speech production, and better language and reading performance. In addition, a recent analysis showed that cochlear implants improve the children's quality of life, and result in a net saving to society. The cost benefit is in the form of fewer demands on special education and greater wage-earning opportunities for implant recipients.

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