title: Toward diagnostic and phenotype markers for genetically transmitted speech delay.
abstract: Converging evidence supports the hypothesis that the most common subtype of childhood speech sound disorder (SSD) of currently unknown origin is genetically transmitted. We report the first findings toward a set of diagnostic markers to differentiate this proposed etiological subtype (provisionally termed speech delay-genetic) from other proposed subtypes of SSD of unknown origin. Conversational speech samples from 72 preschool children with speech delay of unknown origin from 3 research centers were selected from an audio archive. Participants differed on the number of biological, nuclear family members (0 or 2+) classified as positive for current and/or prior speech-language disorder. Although participants in the 2 groups were found to have similar speech competence, as indexed by their Percentage of Consonants Correct scores, their speech error patterns differed significantly in 3 ways. Compared with children who may have reduced genetic load for speech delay (no affected nuclear family members), children with possibly higher genetic load (2+ affected members) had (a) a significantly higher proportion of relative omission errors on the Late-8 consonants; (b) a significantly lower proportion of relative distortion errors on these consonants, particularly on the sibilant fricatives /s/, /z/, and //; and (c) a significantly lower proportion of backed /s/ distortions, as assessed by both perceptual and acoustic methods. Machine learning routines identified a 3-part classification rule that included differential weightings of these variables. The classification rule had diagnostic accuracy value of 0.83 (95% confidence limits = 0.74-0.92), with positive and negative likelihood ratios of 9.6 (95% confidence limits = 3.1-29.9) and 0.40 (95% confidence limits = 0.24-0.68), respectively. The diagnostic accuracy findings are viewed as promising. The error pattern for this proposed subtype of SSD is viewed as consistent with the cognitive-linguistic processing deficits that have been reported for genetically transmitted verbal disorders.
authors.affiliation: Phonology Project, Waisman Center, University of Wisconsin-Madison, WI 53705, USA. shriberg@waisman.wisc.edu
authors.forename: Lawrence D
authors.initials: LD
authors.lastname: Shriberg
authors.forename: Barbara A
authors.initials: BA
authors.lastname: Lewis
authors.forename: J Bruce
authors.initials: JB
authors.lastname: Tomblin
authors.forename: Jane L
authors.initials: JL
authors.lastname: McSweeny
authors.forename: Heather B
authors.initials: HB
authors.lastname: Karlsson
authors.forename: Alison R
authors.initials: AR
authors.lastname: Scheer
mesh_terms: D002675:Child, Preschool; D005260:Female; D006801:Humans; D008297:Male; D010641:Phenotype; D010700:Phonetics; D013061:Speech Acoustics; D013064:Speech Disorders / Q000175:diagnosis* / Q000235:genetics*; D013068:Speech Production Measurement