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Apraxia Research Articles and Citations

2005 - 2006

(Note: If you are aware that we’ve missed important professional citation related to research or practice related to childhood apraxia of speech and/or speech motor control in children, please inform us! We’d be grateful! Correspond to

Betz SK, Stoel-Gammon C.
Measuring articulatory error consistency in children with developmental apraxia of speech.
Clin Linguist Phon. 2005 Jan-Feb;19(1):53-66.
Error inconsistency is often cited as a characteristic of children with speech disorders, particularly developmental apraxia of speech (DAS); however, few researchers operationally define error inconsistency and the definitions that do exist are not standardized across studies. This study proposes three formulas for measuring various aspects of articulatory error consistency: proportion of errors, consistency of error types, and consistency of the most frequently used error type. Each formula is explained using examples of productions from children with DAS and phonological delay. Clinical implications for the use of error consistency to differentially diagnosis DAS and phonological delay are discussed.

Feuk L, Kalervo A, Lipsanen-Nyman M, Skaug J, Nakabayashi K, Finucane B, Hartung D, Innes M, Kerem B, Nowaczyk MJ, Rivlin J, Roberts W, Senman L, Summers A, Szatmari P, Wong V, Vincent JB, Zeesman S, Osborne LR, Cardy JO, Kere J, Scherer SW, Hannula-Jouppi K.
Absence of a paternally inherited FOXP2 gene in developmental verbal dyspraxia.
Am J Hum Genet. 2006 Nov;79(5):965-72.
Mutations in FOXP2 cause developmental verbal dyspraxia (DVD), but only a few cases have been described. We characterize 13 patients with DVD–5 with hemizygous paternal deletions spanning the FOXP2 gene, 1 with a translocation interrupting FOXP2, and the remaining 7 with maternal uniparental disomy of chromosome 7 (UPD7), who were also given a diagnosis of Silver-Russell Syndrome (SRS). Of these individuals with DVD, all 12 for whom parental DNA was available showed absence of a paternal copy of FOXP2. Five other individuals with deletions of paternally inherited FOXP2 but with incomplete clinical information or phenotypes too complex to properly assess are also described. Four of the patients with DVD also meet criteria for autism spectrum disorder. Individuals with paternal UPD7 or with partial maternal UPD7 or deletion starting downstream of FOXP2 do not have DVD. Using quantitative real-time polymerase chain reaction, we show the maternally inherited FOXP2 to be comparatively underexpressed. Our results indicate that absence of paternal FOXP2 is the cause of DVD in patients with SRS with maternal UPD7. The data also point to a role for differential parent-of-origin expression of FOXP2 in human speech development.

Jacks A, Marquardt TP, Davis BL.
Consonant and syllable structure patterns in childhood apraxia of speech: developmental change in three children.
J Commun Disord. 2006 Nov-Dec;39(6):424-41.
Changes in consonant and syllable-level error patterns of three children diagnosed with childhood apraxia of speech (CAS) were investigated in a 3-year longitudinal study. Spontaneous speech samples were analyzed to assess the accuracy of consonants and syllables. Consonant accuracy was low overall, with most frequent errors on middle- and late-developing sounds. Omissions and substitutions were the dominant error types. Analysis of syllables revealed higher frequencies of error on complex mono- and polysyllables. Multiple regression analyses revealed that consonant accuracy is predicted by syllable shape accuracy and polysyllable frequency. Improvement was noted over time, although irregular patterns of consonant and syllable-level errors persisted across the period studied. Findings suggest that consonant errors in CAS are related to syllable-level deficits, namely difficulty constructing syllabic frames for speech production targets. Learning outcomes: On the basis of this article, the reader will be able to (1) describe the deficits in consonant production demonstrated by the participants, (2) analyze the relationship between consonant production and syllable-level patterns of error and (3) consider the value of addressing syllable construction as a therapeutic goal.

Kumin L.
Speech intelligibility and childhood verbal apraxia in children with Down syndrome.
Downs Syndr Res Pract. 2006 Jul;10(1):10-22.
Many children with Down syndrome have difficulty with speech intelligibility. The present study used a parent survey to learn more about a specific factor that affects speech intelligibility, i.e. childhood verbal apraxia. One of the factors that affects speech intelligibility for children with Down syndrome is difficulty with voluntarily programming, combining, organising, and sequencing the movements necessary for speech. Historically, this difficulty, childhood verbal apraxia, has not been identified or treated in children with Down syndrome but recent research has documented that symptoms of childhood verbal apraxia can be found in children with Down syndrome. The survey examined whether and to what extent childhood verbal apraxia is currently being identified and treated in children with Down syndrome. The survey then asked parents to identify certain speech characteristics that occur always, frequently, sometimes or never in their child’s everyday speech. There were 1620 surveys received. Survey results indicated that approximately 15% of the parents responding to the survey had been told that their child has childhood verbal apraxia. Examination of the everyday speech characteristics identified by the parents indicated that many more children are showing clinical symptoms of childhood verbal apraxia although they have not been given that diagnosis. The most common characteristics displayed by the subjects included decreased intelligibility with increased length of utterance, inconsistency of speech errors, difficulty sequencing oral movements and sounds, and a pattern of receptive language superior to expressive language. The survey also examined the impact of childhood verbal apraxia on speech intelligibility. Results indicated that children with Down syndrome who have clinical symptoms of childhood verbal apraxia have more difficulty with speech intelligibility, i.e. there was a significant correlation between childhood verbal apraxia and parental intelligibility ratings. Children with apraxia often do not begin to speak until after age 5. There was a significant correlation between speech intelligibility and age at which the child began to speak, i.e. children who began to speak after age 5 had lower parental intelligibility ratings. A diagnosis of difficulty with oral motor skills is more frequently given than a diagnosis of apraxia; 60.2% of parents had been given this diagnosis. According to survey results, it is rare (2%) for a diagnosis of childhood verbal apraxia to be made without a diagnosis of difficulty with oral motor skills.

Macdermot KD, Bonora E, Sykes N, Coupe AM, Lai CS, Vernes SC, Vargha-Khadem F, McKenzie F, Smith RL, Monaco AP, Fisher SE.
Identification of FOXP2 truncation as a novel cause of developmental speech and language deficits.
Am J Hum Genet. 2005 Jun;76(6):1074-80
FOXP2, the first gene to have been implicated in a developmental communication disorder, offers a unique entry point into neuromolecular mechanisms influencing human speech and language acquisition. In multiple members of the well-studied KE family, a heterozygous missense mutation in FOXP2 causes problems in sequencing muscle movements required for articulating speech (developmental verbal dyspraxia), accompanied by wider deficits in linguistic and grammatical processing. Chromosomal rearrangements involving this locus have also been identified. Analyses of FOXP2 coding sequence in typical forms of specific language impairment (SLI), autism, and dyslexia have not uncovered any etiological variants. However, no previous study has performed mutation screening of children with a primary diagnosis of verbal dyspraxia, the most overt feature of the disorder in affected members of the KE family. Here, we report investigations of the entire coding region of FOXP2, including alternatively spliced exons, in 49 probands affected with verbal dyspraxia. We detected variants that alter FOXP2 protein sequence in three probands. One such variant is a heterozygous nonsense mutation that yields a dramatically truncated protein product and cosegregates with speech and language difficulties in the proband, his affected sibling, and their mother. Our discovery of the first nonsense mutation in FOXP2 now opens the door for detailed investigations of neurodevelopment in people carrying different etiological variants of the gene. This endeavor will be crucial for gaining insight into the role of FOXP2 in human cognition.

Moriarty BC, Gillon GT.
Phonological awareness intervention for children with childhood apraxia of speech.
Int J Lang Commun Disord. 2006 Nov-Dec;41(6):713-34.
AIMS: To investigate the effectiveness of an integrated phonological awareness intervention to improve the speech production, phonological awareness and printed word decoding skills for three children with childhood apraxia of speech (CAS) aged 7;3, 6;3 and 6;10. The three children presented with severely delayed phonological awareness skills before intervention. METHODS & PROCEDURES: In consideration for the heterogeneity in the population with CAS, the study employed a multiple single-subject design with repeated measures. Baseline and post-intervention measures for speech, phonological awareness and decoding were compared. Each child received intervention for three 45-min sessions per week for 3 weeks (approximately 7 h of individual treatment). Sessions focused on developing phoneme awareness, linking graphemes to phonemes and providing opportunities for targeted speech production practice. Phonological awareness activities were linked with each child’s speech production goals. OUTCOMES & RESULTS: Two participants significantly improved target speech and phonological awareness skills during intervention. These participants also generalized the phonological awareness skills from trained to untrained items and were able to transfer newly acquired knowledge to improved performance on a non-word reading task. CONCLUSIONS: The results suggest that integrated phonological awareness intervention may be an effective method simultaneously to treat speech production, phonological awareness and decoding skills in some children with CAS. The findings are discussed within the context of the phonological representational theory of CAS.

Peter, B. and Stoel-Gammon, C.
Timing errors in two children with suspected childhood apraxia of speech (sCAS) during speech and music-related tasks
Clinical Linguistics and Phonetics
Volume 19, Issue 2, March 2005
Impaired speech prosody has been identified as a critical feature of suspected childhood apraxia of speech (sCAS). Lexical stress productions of children with sCAS have been characterized as ‘excessive/equal/misplaced’. This investigation examines two potential explanations of this particular deficit, articulatory difficulty and impaired intrinsic timing. Two children with a diagnosis of sCAS (ages 4 years, 3 months and 9 years, 5 months) and two age-matched controls were observed during three speech and three music tasks. Acoustic analysis revealed that in all tasks, the performance of the controls was more accurate than that of the children with sCAS. Timing structures and accuracy are discussed with respect to diagnostic status, age, speech and music tasks, and timing unit size.

Shriberg LD, Ballard KJ, Tomblin JB, Duffy JR, Odell KH, Williams CAJ
Speech, prosody, and voice characteristics of a mother and daughter with a 7;13 translocation affecting FOXP2.
Speech Lang Hear Res. 2006 Jun;49(3):500-25.
PURPOSE: The primary goal of this case study was to describe the speech, prosody, and voice characteristics of a mother and daughter with a breakpoint in a balanced 7;13 chromosomal translocation that disrupted the transcription gene, FOXP2 (cf. J. B. Tomblin et al., 2005). As with affected members of the widely cited KE family, whose communicative disorders have been associated with a point mutation in the FOXP2 gene, both mother and daughter had cognitive, language, and speech challenges. A 2nd goal of the study was to illustrate in detail, the types of speech, prosody, and voice metrics that can contribute to phenotype sharpening in speech-genetics research. METHOD: A speech, prosody, and voice assessment protocol was administered twice within a 4-month period. Analyses were aided by comparing profiles from the present speakers (the TB family) with those from 2 groups of adult speakers: 7 speakers with acquired (with one exception) spastic or spastic-flaccid dysarthria and 14 speakers with acquired apraxia of speech. RESULTS: The descriptive and inferential statistical findings for 13 speech, prosody, and voice variable supported the conclusion that both mother and daughter had spastic dysarthria, an apraxia of speech, and residual developmental distortion errors. CONCLUSION: These findings are consistent with, but also extend, the reported communicative disorders in affected members of the KE family. A companion article (K. J. Ballard, L. D. Shriberg, J. R. Duffy, & J. B. Tomblin, 2006) reports information from the orofacial and speech motor control measures administered to the same family; reports on neuropsychological and neuroimaging findings are in preparation.

Vargha-Khadem F, Gadian DG, Copp A, Mishkin M.
FOXP2 and the neuroanatomy of speech and language.
Nat Rev Neurosci. 2005 Feb;6(2):131-8
That speech and language are innate capacities of the human brain has long been widely accepted, but only recently has an entry point into the genetic basis of these remarkable faculties been found. The discovery of a mutation in FOXP2 in a family with a speech and language disorder has enabled neuroscientists to trace the neural expression of this gene during embryological development, track the effects of this gene mutation on brain structure and function, and so begin to decipher that part of our neural inheritance that culminates in articulate speech.

Vernes SC, Nicod J, Elahi FM, Coventry JA, Kenny N, Coupe AM, Bird LE, Davies KE, Fisher SE.
Functional genetic analysis of mutations implicated in a human speech and language disorder.
Hum Mol Genet. 2006 Nov 1;15(21):3154-67.
Mutations in the FOXP2 gene cause a severe communication disorder involving speech deficits (developmental verbal dyspraxia), accompanied by wide-ranging impairments in expressive and receptive language. The protein encoded by FOXP2 belongs to a divergent subgroup of forkhead-box transcription factors, with a distinctive DNA-binding domain and motifs that mediate hetero- and homodimerization. Here we report the first direct functional genetic investigation of missense and nonsense mutations in FOXP2 using human cell-lines, including a well-established neuronal model system. We focused on three unusual FOXP2 coding variants, uniquely identified in cases of verbal dyspraxia, assessing expression, subcellular localization, DNA-binding and transactivation properties. Analysis of the R553H forkhead-box substitution, found in all affected members of a large three-generation family, indicated that it severely affects FOXP2 function, chiefly by disrupting nuclear localization and DNA-binding properties. The R328X truncation mutation, segregating with speech/language disorder in a second family, yields an unstable, predominantly cytoplasmic product that lacks transactivation capacity. A third coding variant (Q17L) observed in a single affected child did not have any detectable functional effect in the present study. In addition, we used the same systems to explore the properties of different isoforms of FOXP2, resulting from alternative splicing in human brain. Notably, one such isoform, FOXP2.10+, contains dimerization domains, but no DNA-binding domain, and displayed increased cytoplasmic localization, coupled with aggresome formation. We hypothesize that expression of alternative isoforms of FOXP2 may provide mechanisms for post-translational regulation of transcription factor function.

Zeesman S, Nowaczyk MJ, Teshima I, Roberts W, Cardy JO, Brian J, Senman L, Feuk L, Osborne LR, Scherer SW.
Speech and language impairment and oromotor dyspraxia due to deletion of 7q31 that involves FOXP2.
Am J Med Genet A. 2006 Mar 1;140(5):509-14.
We report detailed clinical, cytogenetic, and molecular findings in a girl with a deletion of chromosome 7q31-q32. This child has a severe communication disorder with evidence of oromotor dyspraxia, dysmorphic features, and mild developmental delay. She is unable to cough, sneeze, or laugh spontaneously. Her deletion is on the paternally inherited chromosome and includes the FOXP2 gene, which has recently been associated with speech and language impairment and a similar form of oromotor dyspraxia in at least three other published cases. We hypothesize that our patient’s communication disorder and oromotor deficiency are due to haploinsufficiency for FOXP2 and that her dysmorphism and developmental delay are a consequence of the absence of the other genes involved in the microdeletion. We propose that this patient, together with others reported in the literature, may define a new contiguous gene deletion syndrome encompassing the 7q31-FOXP2 region. Cytogenetic and molecular analysis of this region should be considered for other individuals displaying similar characteristics.