The winter 2004 edition of the American Annals of the Deaf carried an article by Trevor Johnston titled "W(h)ither the Deaf Community? Population, Genetics, and the Future of Australian Sign Language." In his analysis of trends involving school enrollment, neonatal screening, and census data in Australia, Johnston concluded that the incidence of severe and profound childhood deafness has been less than traditionally assumed and currently is declining to even lower levels. Many of the issues Johnston raised have been discussed by other authors, but this is the first case to my knowledge where they have been discussed succinctly in a brief article.
Starting with a generally accepted assumption in many countries that early childhood deafness occurs in approximately 1 child per 1,000, Johnston reported that most studies have included children with losses ranging from mild to profound, with the majority of cases falling into the mild and moderate categories. For example, he cited the Colorado screening program, which reported that 2.5 children per 1,000 were identified as having a hearing loss, but that only 10% of these children, or 0.25 per 1,000, had a profound loss. Research from Great Britain has reported similar results and Johnston concluded from data in New South Wales that an upper limit of 0.7 per 1,000 would not be surprising for Australia.
Johnston attributed the apparent decline to a number of factors, chief of which has been improvements in medical cafe, with the most striking example being the development of a vaccine to control rubella. The last worldwide rubella epidemic occurred in the mid-1960s. Since then there has been a decline in early childhood deafness caused by nongenetic factors.
Other contributors to the decline include cochlear implantation, improved hearing aids, and, looming on the horizon, genetic screening and gene therapy. Since the completion of the Human Genome Project, a number of possibilities have arisen, along with serious moral issues. Most readers probably are familiar with the connexin 26 gene, which apparently accounts for roughly 50% of all heritable deafness. As Johnston reported, the gene can be identified through screening and so parents-to-be can make reproductive decisions based on that information. In fact, in vitro fertilization has been performed so that only a fertilized egg not carrying the connexin 26 gene would be selected and implanted. Johnston concluded that these developments have serious implications for education and for the Australian Deaf community as well as for Australian sign language (Auslan). …