I recently attended a public seminar at the renown Karolinska Institute in Stockholm: “Hereditary Hearing Impairment and Therapeutic Strategies”.
The subject of hearing, and not hearing well, is important to me. I have worn a hearing aid in each ear for around ten years, and have lived around hearing-impaired relatives.
Click on Image (vanderbilt.edu)
The seminar was presented by four clinical researchers, some of whom are practicing physicians, all conducting research into the causes of, and treatment for Syndromic Sensorineural Hearing Loss and deafblind syndromes. It was held in the new Nobel Forum, conveniently located at the entrance to the large campus of the Institute. The speakers were:
- William J. Kimberling, University of Iowa, USA
- Claes Möller, Örebro University, Örebro, Sweden
- Richard J. Smith, University of Iowa, USA
- Lisbeth Tranebjærg, University of Copenhagen, Denmark
The speakers communicated clearly and used prepared slides. The presenters were obviously aware of the problems hearing-impaired people have in understanding words that are not precisely and too rapidly spoken.
After the conference I formulated this analogy: what the speakers and their colleagues are finding and accomplishing through their research is much like the moon landing program of the 1960s and 1970s. The important goal of the landing on the moon required a focused effort to develop new paradigms and technologies, with valuable spin-offs into other fields, such as information technology and communications.
Similarly, in pursuing the goal of understanding the causes of hearing and related impairments, researchers in this field are building ever accelerating bodies of knowledge that are leading to treatments and technologies only dreamed of 25 years ago. The one most visible and dramatic result is the cochlear implant.
On the horizon is a paradigm-changing method of addressing hearing deficiencies: genetic engineering. A little more about this after some of the key points I recorded from the four-hour presentation, which included a break for coffee, tea and the inevitable and vital kanelbulle—cinnamon bun—found everywhere in Sweden.
- Many children who have varying degrees of deafness or deafblindness are incorrectly diagnosed. Depending on the severity of the hearing problems (between 50-70% of which are inherited through the genes of both parents) children who are misdiagnosed will be treated improperly, insufficiently, not at all, or too late to for them to form important parts of the brain. The earlier the correct diagnosis, even in the first weeks of life outside the womb, the better the chance of helping the child to communicate and otherwise function to the limit of his or her inherited capabilities.
Tools for early successful detection of deafness, whether inherited or acquired (often occurring during the birth process, or from diseases or conditions of the mother during pregnancy, such as cytomegalovirus) include: neonatal screening within the first 2-5 days; evoked otoacoustic emissions (OAE); auditory brainstem response (ABR); auditory steady state responses (ASSR); and, observations of other deficiency symptoms in the body. The new tool of DNA analysis can obviate these tedious and time-consuming tests.
Children who are still in the developmental stage need to learn a language for proper brain development, including sign language.
Non-syndromic hearing impairments affect around 4% of people by age 45. (The BMJ Journal states that more than 60% of people aged over 70 suffer sufficient hearing loss to benefit from a hearing aid).
Much attention was given to Usher Syndrome, a condition that occurs approximately as often as Lou Gehrig’s Disease, Muscular Dystrophy and Huntington’s Disease, but is not nearly as well known. About 10 genes have been identified that contribute to Usher Syndrome. In addition, there are a large number of genes that contribute to non-syndromic deafness (that is, deafness in the absence of any other medical finding) including:
- 27 nonsyndromic recessive genes
- 22 nonsyndromic dominant genes
- 1 x-linked gene
- 13 mitochondrial mutations
Researchers are continuing to find genes that can cause deafness when they are mutated. The goal is to detect these genetic changes through early DNA analysis to help clinicians diagnose the precise cause of deafness. This knowledge can help the doctor explain the likely prognosis and best available treatment. Both clinicians and parents also gain a realistic understanding of the outcomes for the life of the child.
Of great interest was the presentation on advances in gene therapy, the new paradigm for the earliest possible treatment of humans. Ultimately, gene therapy will be personalized to the specific type of hearing loss.
Dr. Smith took us through the stages of the gene therapy process which is now employed, successfully, using laboratory mice. The next stage will to be to employ the process in primates. The last stage will be to undertake clinical trials with consenting human subjects. Dr. Smith said that “we can now tell you the genetic cause, if any, in your deafness, but we can’t yet offer you gene therapy.” But, given the aforementioned rapid advances in the relevant scientific fields, it seems probable we will have this therapy available within the foreseeable future.
The capstone of the presentation was the final discussion stimulated by the conference host, Professor Mats Ulfendahl, who asked the four panelists to tell us what they thought the greatest advances have been in the last number of years. Here are some responses:
- The ability to test the genetics of families to rule out incorrect diagnoses of infants and children who are preliminarily diagnosed with neurological deficiencies
- The mapping of the human genome which exponentially expands the pool of useful knowledge applicable in the medical and physiological realms
- Information and other technologies available to deaf and deafblind people to improve the quality of their lives
- Cochlear implants for small children to help them grow their brain and language capabilities, and for older children merely to hear sounds which also benefits the brain
- The ability to make earlier and more accurate diagnoses
Finally, for the future, research discovery time is ever shortening.
I came away from the conference filled with admiration, even affection, for the four scientists in their consistent reference to the ultimate object of their research: the human being who will benefit from their work.