Genetic Factors Related to Stuttering

Genetic studies in developmental stuttering are important for their potential in ultimately determining pathophysiological basis of this disorder. This study will combine two approaches to examine genetic aspects of stuttering, linkage in families, and candidate gene analysis. Linkage studies will be completed using adult individuals who are diagnosed as persons who stutter and those who can be judged as never having stuttered from one or more families with large numbers of affected individuals within several generations. Candidate gene analyses will also be carried out in adults who stutter to determine if the frequency of polymorphisms for certain neurotransmitter receptors and enzymes differ from control populations. In addition, given the heterogeneity of the population of adults who stutter, other phenotypic probes such as motor skills, language skills, neuropsychological abilities and psychological responses to stuttering will also be assessed in order to identify subgroups in which the phenotype expression of the gene may differ.

Inclusion criteria

Subjects must be over the age of 5 and under the age of 90.

Subjects must be in general good health, without evidence of chronic medical illness.

Onset of stuttering in affected individuals must have occurred in childhood (between 3 and 10 years of age), unrelated to psychological or neurological trauma.

Subjects will not be tested for the presence of HIV antibodies. Persons with positive HIV antibodies will not be excluded, unless they are taking medication which may change their performance on tasks used for phenotypic assignment.

Subjects will be screened for history of psychiatric illness, such as depression, anxiety or obsessive-compulsive disorders according to DSM-IV criteria. A history of these disorders will not disqualify any subject from participation, but will be noted as a variable in phenotypic assignment.