C o m m o n wisdom has long h e l d tha t the optimal welfare of the hearing-impaired is served by identification of the loss as early as possible and by immediate application of therapeut ic intervention. In the past, ha rd d a t a s u p p o r t i n g t h i s a s s u m p t i o n w e r e notably absent. But new economic , educational, and basic research findings are now confirming the fact that concer ted efforts should be m a d e to identify a n d habil i tate h e a r i n g loss at the earl iest possible t ime, which, in our present state of knowledge, is at birth.

Reprint requests: Ms. Downs, Department of Otolaryngology, University of Colorado Health Sciences Center, Denver, CO 80262. Genetic inheritance is thought to be responsible for 35 to 50 percent of the hearing losses that are present at birth or that become manifest in early life. The prevention of such hearing losses has only recently entered the realm of possibility, with the advent of genetic mapping and the prospective gene therapy that is the probable strategy for prevention. A new government program called the Human Genome Project gives hope for the fulfillment of that prospect. The Human Genome Project aims at mapping and decoding all of the estimated 100,000 human genes—a detailed construction manual for the genome, the entirety of genetic material that defines us as a species. It will assign genes to specific chromosomal locations that may allow detection of the carriers of genetic conditions. More than 600 of the genes that cause human diseases have been mapped, including such disorders as cystic fibrosis, Duchenne muscular dystrophy, neurofibromatosis (tupe 2), X-linked conductive hearing impairment with congenital fixation of the stapes, and a possible form of Alport syndrome. Some 20 other entities that involve deafness have been mapped to specific chromosomes, with a degree of confidence. The new technology in gene mapping will lead to some progress in understanding genetic types of hearing impairment. Prenatal testing or carrier screening eventually will be available, although still in the exploratory stage. Among other benefits, genetic screening could help identify couples at risk of having children with genetic disorders. The couple could then conceive several embryos in vitro (outside the womb), test for one that is defect-free, and reimplant it in the womb. The possibilities of manipulating an embryo to fix a defective gene, thereby preventing a birth defect, are another consequence of the gene mapping project. Such prevention is highly desired, so long as the technique is not used for selection of particular traits rather than against—an ethical dilemma that may have to be dealt with. But doctors now envision a time when they will practice "gene therapy"— actually entering cells to repair their ge168

Reprint requests: Ms. Downs, Department of Otolaryngology, University of Colorado Health Sciences Center, Denver, CO 80262. Pediatric audiology came quietly into being in the early 1940s, spurred by dedicated educators of the deaf who studied the auditory behaviors of normal children. These educators were Alexander and Irene Ewing in England. They combined the use of gross noisemakers with their own sophisticated skills of observation, developing those simple techniques into an art. And what an art! A case can still be made that the highest form of pediatric audiology is a known sound stimulus in the hand of a zealous, practiced observer pointed at an infant's ear. Many thousands of hearingimpaired individuals are getting on with more successful lives as a result of having been identified early in life by such techniques. But there are not enough of those fortunate ones. In this issue of Seminars we find the full 20th century response to the need for a pediatric audiology that utilizes a state-of-the-art technology to ensure that all children will have available to them the identification of their problems at the earliest possible moment. For the goal is all. Not just the children with parents who can afford testing and monitoring; not just those who happen to fall into a category that places them at risk for deafness; not just the ones that happen to be in the right place at the right time to be screened, but all children. They are all entitled to be touched by the screening hand of modern technology. Hearing losses varying in degree, type, and configuration must be identified early enough to allow interventions that will lessen their symptoms. Not only those severe and profound losses so devastating to speech and language, but even the mildest losses with their sequelae in delayed expressive language. The development of cochlear implants will make it even more critical that losses be identified early. We can now envision a world where a deaf baby can be implanted at birth and, with the plasticity of the young brain, use the implant code to become a functional hearing person. How far have we gone to achieve this best of all worlds?