The genetic basis of persistence and recovery in stuttering

Abstract

The purpose of this study was to elaborate on genetic perspectives of stuttering with reference to recovery and chronicity in children. Past research has provided evidence of a genetic factor in the transmission of susceptibility to stuttering, but factors governing persistence and recovery have not been as yet identified.Immediate and extended families of 66 stuttering probands were investigated to determine frequencies of persistent and recovered stuttering. Pedigree analysis and segregation analysis were utilized to examine patterns of heritability.The following questions were investigated: (1) Is there a sex effect in recovery from stuttering? This hypothesis examined the notion that females have a greater chance of recovery than do males, leading to the changing sex ratio from approximately 2:1 males to females close to onset of the disorder, to 4 or 5:1 in adulthood. A significant chi square indicated that recovery among females is significantly more frequent than among males, as shown by the sharply different sex ratios of persistent vs. recovered stutterers. (2) Is persistence or recovery from stuttering heritable? If recovery appears to be heritable, (a) are recovered and persistent stuttering a unitary disorder where recovered stuttering is a genetically milder form of persistent stuttering; (b) is recovery transmitted independent of stuttering; or (c) are recovered and persistent stuttering independent disorders? Results indicated that persistence or recovery are indeed heritable, and further, that recovery is not a milder form, nor do the two types of stuttering appear to be unrelated, independent disorders. Data are most consistent with the hypothesis that persistence is in part due to an additional genetic factor.Segregation analyses supported these conclusions and provided statistical evidence for both a single major locus and polygenic component for persistent and recovered stuttering.This study was supported by grant #R01-DC00459 from the National Institute of Deafness and Other Communication Disorders, National Institutes of Health, Principal Investigator: Ehud Yairi.U of I OnlyETDs are only available to UIUC Users without author permissio