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© Newswise.
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Stuttering Is Highly Influenced by Genes
Release Date: Immediate EVIDENCE MOUNTS THAT STUTTERING IS HIGHLY INFLUENCED BY GENETIC FACTORS Researchers from the United States and Australia have joined forces to complete a new study that examines the hypothesis that stuttering may be a largely inherited condition. These findings, as well as a summary of NIH work on the genetics of stuttering, will be presented before 11,000 audiologists and speech pathologists attending the 74th Annual Meeting of the American Speech-Language-Hearing Association (ASHA), November 18-21, 1999 at the Moscone Center, San Francisco, CA. ASHA is the nation's professional scientific and credentialing organization for professionals involved in the diagnosis and treatment of disorders of hearing and speech. ROCKVILLE, MD- Are people genetically predisposed to stutter? Researchers from both sides of the Pacific have joined together to examine whether this puzzling speech disorder may have a significant genetic component. To test this, twins in Australia who stuttered were examined, and significant differences in concordance rates for stuttering were found between identical and fraternal twin pairs. New and powerful mathematical models were used to analyze these concordance rates, and these results strongly supported a large role for genetic factors. Stuttering is a disorder that prevents speakers from engaging in smooth, effortless speech. It usually begins in childhood, and can result in feelings of anxiety and speech-avoidance behaviors. Despite nearly a century of work, the cause of this disorder remains unknown. Highlights of this study, Genetic Findings of Stuttering in Adult Twins, include: -- Genetic models were fitted to two samples: a screening sample of 3,768 Australian twins who answered a questionnaire that included items about stuttering, and a subsample of these twins for whom an interview-based diagnosis was reached (457 cases). -- Results suggested that genetic factors were much more likely to explain the pattern of results than were environmental factors (Aheritability@ of .70, which is considered very high for a complex disorder such as this). -- Non-genetic (environmental) factors also play a role in determining who will stutter, but these factors are still unknown. -- Certain specific characteristics of stuttering, such as who will recover and how much emotional (anxiety) involvement is present, also appears to be under some genetic influence. -- Study also confirms an observation that stuttering often co-occurs with other speech-related problems, particularly problems with speech sound development during childhood (articulation disorder). 58% of twins who stuttered reported having had articulation disorders as children, in comparison to fewer than 20% of the unaffected (non-stuttering) cases. The authors of this study are Susan Felsenfeld, Ph.D., from Duquesne University, Pittsburgh, PA; M.C. Neale, from the Virginia Institute for Psychiatric and Behavior Genetics, Richmond, VA; Katherine Kirk, Gu Zhu, Dixie Statham, and Nick Martin, all at the Queensland Institute of Medical Research, Queensland Australia. This research was supported by a grant from the National Institutes of Health (National Institute of Deafness and Other Communication Disorders (NIDCD). Dr. Felsenfeld has also joined with Dennis Drayna, Ph.D. at this conference to discuss the professional (treatment and counseling) and psychosocial implications of molecular genetics work (the Ahuman side@ of the genetics revolution). Dr. Drayna will present an overview of the technical process of genetic linkage and gene finding, and will also discuss the ongoing NIH genetic linkage study of stuttering that he coordinates. Conclusion: Genetic research methods hold the promise of identifying genes responsible for stuttering in at least some families. -end- For author interviews and press releases for presentation, where available, contact Donna Krupa (703.527.7357) or Mona Thomas (301.897.0156). Or contact the ASHA Newsroom in San Francisco (415.905.1727 or 1728).
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