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Childhood apraxia of speech (CAS) is a severe and rare form of speech sound disorder (SSD) with an estimated prevalence of 0.01-2%. CAS typically occurs in isolation (sporadic), but may segregate in families with broader speech and language deficits. We hypothesized that disruptive genetic changes may be involved in the etiology of CAS, and were resolvable by examination of whole genome sequence. We sequenced 27 families with a CAS child within the Cleveland Family Speech and Reading Study, examining 101 individuals in all. CAS subjects displayed errors on single word articulation (75%), multisyllabic real word repetition (93%), multisyllabic non-word repetition (82%), and oral motor function (82%); many also exhibited problems with fine and gross motor skills. We identified 17 genomic regions including 19 unique structural variants (SVs) present in children with CAS. Three variants were shared across families, but the rest were unique; some events were de novo. In four families, siblings with milder phenotypes co-inherited the same SVs, suggesting that some SVs display variable expressivity. In an independent sample, we replicated eight SVs using microarray technology and found that many of these SVs were present in children with milder forms of SSD. Bioinformatic examination of the deletions/duplications identified four SVs with substantial functional consequences (cytobands 2q24.3, 6p12.3-6p12.2, 11q23.2-11q23.3, and 16p11.2). Of these, the 16p11.2 deletion is the most well-established variant that causes a broad array of neurological features. These discoveries show that SVs are a heterogeneous, but prevalent cause of CAS, identifiable by standard genetic testing.

Purpose Adolescent psychosocial outcomes of individuals with histories of childhood apraxia of speech (CAS) were compared to outcomes of individuals with histories of speech sound disorders (SSD) only and SSD with language impairment (LI). It was hypothesized that individuals with more severe and persistent disorders such as CAS would report poorer psychosocial outcomes. Method Groups were compared using analyses of variance on a psychosocial assessment battery that included measures of hyperactivity and inattention, anxiety, depression, internalizing and externalizing behaviors, thought problems, and social outcomes. Results Results revealed significant group differences on self-report of social problems and parent report of hyperactivity, thought problems, and social problems at adolescence. Compared to the SSD-only group, the CAS group had significantly higher parental ratings of hyperactivity and social problems in adolescence. The CAS and SSD + LI groups did not differ on psychosocial measures, possibly due to the high rate of comorbid LI in the CAS group. The CAS group also had more individuals who scored in the borderline/clinical range on self-report of social problems than the SSD-only group. The CAS group did not differ from the SSD + LI group in the number of participants scoring in the borderline/clinical range on measures. Conclusions Individuals with histories of CAS demonstrate increased rates of social problems and hyperactivity based on parent ratings compared to adolescents with histories of SSD only; however, most do not score within the clinical range. The persistence of speech sound errors combined with self-reported and parent-reported social difficulties suggests that speech-language pathologists should be sensitive to the social and emotional impact of CAS and make appropriate referrals to mental health professionals when warranted.

Speech sound disorders (SSD) manifest as difficulties in phonological memory and awareness, oral motor function, language, vocabulary, reading, and spelling. Families enriched for SSD are rare, and typically display a cluster of deficits. We conducted a genome-wide association study (GWAS) in 435 children from 148 families in the Cleveland Family Speech and Reading study (CFSRS), examining 16 variables representing 6 domains. Replication was conducted using the Avon Longitudinal Study of Parents and Children (ALSPAC). We identified 18 significant loci (combined p −8) that we pursued bioinformatically. We prioritized 5 novel gene regions with likely functional repercussions on neural pathways, including those which colocalized with differentially methylated regions in our sample. Polygenic risk scores for receptive language, expressive vocabulary, phonological awareness, phonological memory, spelling, and reading decoding associated with increasing clinical severity. In summary, neural-genetic influence on SSD is primarily multigenic and acts on genomic regulatory elements, similar to other neurodevelopmental disorders.

This study examined the spelling skills in middle childhood and adolescence in individuals with histories of early childhood speech sound disorders (SSD) with and without language impairment (LI). Youth without such histories were also included (No SSD/LI group). The heritability of spelling skills at each age level was estimated. Children with SSD were classified as SSD-only, SSD with LI but without childhood apraxia of speech (SSD + LI/ No CAS), and CAS and LI (CAS + LI). The SSD-only group did not differ in spelling from the No SSD/LI group, suggesting that SSD-only did not increase risk for poor spelling. The SSD + LI/No CAS and CAS + LI groups had poorer spelling skills than the SSD-only and No SSD/LI groups. Spelling was associated with phonological awareness in the middle childhood and adolescent samples and with rapid automatized naming in the adolescent sample. Heritability of spelling skills was stronger in adolescence than in middle childhood. Differences in the correlates of spelling and in heritability at the two ages suggest developmental changes in the factors contributing to spelling.

Purpose The goal of this study was to determine whether adolescent outcomes for individuals with histories of early speech sound disorders (SSD) could be differentiated by speech and language skills at earlier ages (preschool, 4–6 years, and school age, 7–10 years). Method The study used a retrospective longitudinal design. Participants with and without histories of early SSD were classified in adolescence as having no SSD, resolved SSD, low multisyllabic word (MSW; difficulty with MSW repetition but no errors in conversational speech), or persistent speech disorders (errors in both conversational speech and MSW repetition). Analysis of variance was employed to determine whether early speech, language, and literacy skills distinguished these adolescent outcome groups. Results Preschool and school-age skills differed for adolescents whose SSD had resolved from those who had persistent speech errors. Adolescents with errors solely in production of MSWs (Low MSW) did not differ in early speech and language skills from adolescents who had difficulty with both MSWs and persistent errors in conversation. Conclusions Speech and language assessments earlier in childhood can help establish risks for persistent SSD and other language and literacy difficulties in adolescence. Early identification of these clinically relevant subgroups of SSD may allow for early targeted interventions. Supplemental Material https://doi.org/10.23641/asha.9932279

Background Few studies have considered the long-term psychosocial outcomes of individuals with histories of early childhood speech sound disorders (SSD). Research on long-term psychosocial outcomes of individuals with language impairment (LI) have frequently failed to consider the effects of co-morbid SSD. The purpose of this study was to compare individuals with histories of SSD-only versus SSD with LI on these outcomes and to examine the contributions of other comorbid conditions including reading disorders (RD) and Attention Deficit Hyperactivity Disorder (ADHD). Methods Participants were adolescents aged 11–17 years ( N = 129) and young adults aged 18–33 years ( N = 98). Probands with SSD were originally recruited between 4 and 6 years of age and classified into SSD-only and SSD + LI groups. Siblings of these children were also assessed at this time and those without SSD or LI were followed as controls. Outcome measures at adolescence and adulthood included ratings of hyperactivity, inattention, anxiety, and depression, as well as internalizing, externalizing, social, and thought problems. Adult outcomes also included educational and employment status and quality of life ratings. Regression modeling was performed to examine the association of SSD, LI, RD, and ADHD with psychosocial outcomes using Generalized Estimating Equations. Results In the adolescent group, LI was associated with poorer ratings of psychosocial problems on all scales except depression. Histories of SSD-only, RD and ADHD did not independently predict any of the adolescent psychosocial measures. In contrast, LI in the adult sample was not significantly associated with any of the behavior ratings, though RD was related to higher ratings of hyperactivity and inattention and with higher parent ratings of internalizing and externalizing symptoms and thought problems. SSD did not predict any of the adult measures once other comorbid conditions were taken into account. Conclusions Poor adolescent psychosocial outcomes for individuals with early childhood SSD were primarily related to comorbid LI and not to SSD per se. At adulthood, comorbid RD and ADHD may influence outcomes more significantly than LI.

Purpose In this study, the authors determined adolescent speech, language, and literacy outcomes of individuals with histories of early childhood speech sound disorders (SSD) with and without comorbid language impairment (LI) and examined factors associated with these outcomes. Method This study used a prospective longitudinal design. Participants with SSD ( n = 170), enrolled at early childhood (4–6 years) were followed at adolescence (11–18 years) and were compared to individuals with no histories of speech or language impairment (no SSD; n = 146) on measures of speech, language, and literacy. Comparisons were made between adolescents with early childhood histories of no SSD, SSD only, and SSD plus LI as well as between adolescents with no SSD, resolved SSD, and persistent SSD. Results Individuals with early childhood SSD with comorbid LI had poorer outcomes than those with histories of SSD only or no SSD. Poorer language and literacy outcomes in adolescence were associated with multiple factors, including persistent speech sound problems, lower nonverbal intelligence, and lower socioeconomic status. Adolescents with persistent SSD had higher rates of comorbid LI and reading disability than the no SSD and resolved SSD groups. Conclusion Risk factors for language and literacy problems in adolescence include an early history of LI, persistent SSD, lower nonverbal cognitive ability, and social disadvantage.

OBJECTIVES Speech sound disorder (SSD) is one of the most common communication disorders, with a prevalence rate of 16% at 3 years of age, and an estimated 3.8% of children still presenting speech difficulties at 6 years of age. Several studies have identified promising associations between communication disorders and genes in brain and neuronal pathways; however, there have been few studies focusing on SSD and its associated endophenotypes. On the basis of the hypothesis that neuronal genes may influence endophenotypes common to communication disorders, we focused on three genes related to brain and central nervous system functioning: the dopamine D2 receptor (DRD2) gene, the arginine-vasopressin receptor 1a (AVPR1A) gene, and the microcephaly-associated protein gene (ASPM). METHODS We examined the association of these genes with key endophenotypes of SSD - phonological memory measured through multisyllabic and nonword repetition, vocabulary measured using the Expressive One Word Picture Vocabulary Test and Peabody Picture Vocabulary Test, and reading decoding measured using the Woodcock Reading Mastery Tests Revised - as well as with the clinical phenotype of SSD. We genotyped tag single nucleotide polymorphisms in these genes and examined 498 individuals from 180 families. RESULTS These data show that several single nucleotide polymorphisms in all three genes were associated with phonological memory, vocabulary, and reading decoding, with P less than 0.05. Notably, associations in AVPR1A (rs11832266) were significant after multiple testing correction. Gene-level tests showed that DRD2 was associated with vocabulary, ASPM with vocabulary and reading decoding, and AVPR1A with all three endophenotypes. CONCLUSION Endophenotypes common to SSD, language impairment, and reading disability are all associated with these neuronal pathway genes.

Purpose To demonstrate that early childhood speech sound disorders (SSD) and later school-age reading, written expression, and spelling skills are influenced by shared endophenotypes that may be in part genetic. Method Children with SSD and their siblings were assessed at early childhood (ages 4–6 years) and followed at school age (7–12 years). The relationship of shared endophenotypes with early childhood SSD and school-age outcomes and the shared genetic influences on these outcomes were examined. Results Structural equation modeling demonstrated that oral motor skills, phonological awareness, phonological memory, vocabulary, and speeded naming have varying influences on reading decoding, spelling, spoken language, and written expression at school age. Genetic linkage studies demonstrated linkage for reading, spelling, and written expression measures to regions on chromosomes 1, 3, 6, and 15 that were previously linked to oral motor skills, articulation, phonological memory, and vocabulary at early childhood testing. Conclusions Endophenotypes predict school-age literacy outcomes over and above that predicted by clinical diagnoses of SSD or language impairment. Findings suggest that these shared endophenotypes and common genetic influences affect early childhood SSD and later school-age reading, spelling, spoken language, and written expression skills. Supplemental Material https://doi.org/10.23641/asha.6170354

Speech sound disorders (SSD) are the largest group of communication disorders observed in children. One explanation for these disorders is that children with SSD fail to form stable phonological representations when acquiring the speech sound system of their language due to poor phonological memory (PM). The goal of this study was to examine PM in individuals with histories of SSD employing functional MR imaging (fMRI). Participants were six right-handed adolescents with a history of early childhood SSD and seven right-handed matched controls with no history of speech and language disorders. We performed an fMRI study using an overt non-word repetition (NWR). Right lateralized hypoactivation in the inferior frontal gyrus and middle temporal gyrus was observed. The former suggests a deficit in the phonological processing loop supporting PM, while the later may indicate a deficit in speech perception. Both are cognitive processes involved in speech production. Bilateral hyperactivation observed in the pre and supplementary motor cortex, inferior parietal, supramarginal gyrus and cerebellum raised the possibility of compensatory increases in cognitive effort or reliance on the other components of the articulatory rehearsal network and phonologic store. These findings may be interpreted to support the hypothesis that individuals with SSD may have a deficit in PM and to suggest the involvement of compensatory mechanisms to counteract dysfunction of the normal network.

PURPOSE: The present study examined associations of 5 endophenotypes (i.e., measurable skills that are closely associated with speech sound disorders and are useful in detecting genetic influences on speech sound production), oral motor skills, phonological memory, phonological awareness, vocabulary, and speeded naming, with 3 clinical criteria for classifying speech sound disorders: severity of speech sound disorders, our previously reported clinical subtypes (speech sound disorders alone, speech sound disorders with language impairment, and childhood apraxia of speech), and the comorbid condition of reading disorders. PARTICIPANTS AND METHOD: Children with speech sound disorders and their siblings were assessed at early childhood (ages 4-7 years) on measures of the 5 endophenotypes. Severity of speech sound disorders was determined using the z score for Percent Consonants Correct-Revised (developed by Shriberg, Austin, Lewis, McSweeny, & Wilson, 1997). Analyses of variance were employed to determine how these endophenotypes differed among the clinical subtypes of speech sound disorders. RESULTS AND CONCLUSIONS: Phonological memory was related to all 3 clinical classifications of speech sound disorders. Our previous subtypes of speech sound disorders and comorbid conditions of language impairment and reading disorder were associated with phonological awareness, while severity of speech sound disorders was weakly associated with this endophenotype. Vocabulary was associated with mild versus moderate speech sound disorders, as well as comorbid conditions of language impairment and reading disorder. These 3 endophenotypes proved useful in differentiating subtypes of speech sound disorders and in validating current clinical classifications of speech sound disorders.

Numerous studies have examined genetic influences on developmental problems such as speech sound disorders, language impairment, and reading disability. Disorders such as speech sound disorder (SSD) are often analyzed using their component endophenotypes. Most studies, however, have involved comparisons of twin pairs or siblings of similar age, or have adjusted for age ignoring effects that are peculiar to age-related trajectories for phenotypic change. Such developmental changes in these skills have limited the usefulness of data from parents or siblings who differ substantially in age from the probands. Employing parent-offspring correlation in heritability estimation permits a more precise estimate of the additive component of genetic variance, but different generations have to be measured for the same trait. We report on a smoothing procedure which fits a series of lines that approximate a curve matching the developmental trajectory. This procedure adjusts for changes in measures with age, so that the adjusted values are on a similar scale for children, adolescents, and adults. We apply this method to four measures of phonological memory and articulation in order to estimate their heritability. Repetition of multisyllabic real words showed the best heritability estimate of 45% in this sample. We conclude that differences in measurement scales across the age span can be reconciled through non-linear modeling of the developmental process.

Disorders of articulation or speech-sound disorders (SSD) are common in early childhood. Children with these disorders may be at risk for reading difficulties because they may have poor auditory, phonologic, and verbal memory skills.We sought to characterize the reading and writing readiness of preschool children with SSD and identify factors associated with preliteracy skills. Subjects were 125 children aged 3 to 6 years with moderate to severe SSD; 53% had comorbid language impairment (LI). Reading readiness was measured with the Test of Early Reading Ability-2 (TERA) and writing skills with the Test of Early Written Language-2 (TEWL), which assessed print concept knowledge. Linear regression was used to examine the association between SSD severity and TERA and TEWL scores and analysis of variance to examine the effect of comorbid LI. Performance on a battery of speech and language tests was reduced by way of factor analysis to composites for articulation, narrative, grammar, and word knowledge skills.Early reading and writing scores were significantly lower for children with comorbid LI but were not related to SSD severity once language status was taken into account. Composites for grammar and word knowledge were related to performance on the TERA and TEWL, even after adjusting for Performance IQ. Below average language skills in preschool place a child at risk for deficits in preliteracy skills, which may have implications for the later development of reading disability.Preschool children with SSD and LI may benefit from instruction in preliteracy skills in addition to language therapy.

The goal of this study was to classify children with speech sound disorders (SSD) empirically, using factor analytic techniques. Participants were 3-7-year olds enrolled in speech/language therapy (N = 185). Factor analysis of an extensive battery of speech and language measures provided support for two distinct factors, representing the skill dimensions of articulation/phonology and semantic/syntactic skills. To validate these factors, 38 of the children were followed to school age to re-evaluate speech and language skills and assess reading/spelling achievement. The validity of the two factors was supported by their differential associations with school-age reading and spelling achievement, persistence of SSD, and affection status in family members. A closer relationship of the family member to the proband and male gender predicted higher odds of a disorder. The findings suggest that articulation/phonology and language abilities are at least partially independent in children with SSD and that these constructs have distinct clinical and biological correlates.The reader will develop knowledge about subtypes of speech sound disorders, understand the relationship between early speech sound disorders and later reading and spelling difficulties, and obtain information concerning familial transmission of speech sound disorders.

Forty-two children (29 boys and 13 girls), ages 3–10 years, were referred from the caseloads of clinical speech-language pathologists for suspected childhood apraxia of speech (CAS). According to results from tests of speech and oral motor skills, 22 children met criteria for CAS, including a severely limited consonant and vowel repertoire, difficulty sequencing syllables, and inconsistent and unusual errors. Family pedigrees for these children were constructed through parent interviews and direct testing of nuclear family members. Familial aggregation for speech-sound and language disorders was demonstrated with 86% reporting at least one nuclear family member affected. Based on parent report, 13 of the 22 children (59%) had at least one affected parent. However, CAS was evident in only two siblings of probands with CAS and two probands with other speech-sound disorders. Based on testing, overall affection rates of speech-sound/language disorders were higher in families of children with CAS than in families of children with other speech-sound disorders. Mothers of children with CAS demonstrated a higher affection rate than mothers of children with other speech-sound disorders. A sex-related threshold model of transmission was also supported with brothers more often affected than sisters for male probands only. If our inclusionary criteria for CAS are valid, these findings support a general verbal trait deficit hypothesis. Learning outcomes (1) As a result of this activity, the participant will understand potential familial risk factors for CAS; (2) will differentiate aggregation for speech-sound and language disorders in families with CAS from families of children who have other speech-sound disorders; (3) will distinguish how familial aggregation differs in families of boys and girls with CAS; (4) will determine how children with CAS differ in severity from those with other speech-sound disorders.

Speech-sound disorder (SSD) is a complex behavioral disorder characterized by speech-sound production errors associated with deficits in articulation, phonological processes, and cognitive linguistic processes. SSD is prevalent in childhood and is comorbid with disorders of language, spelling, and reading disability, or dyslexia. Previous research suggests that developmental problems in domains associated with speech and language acquisition place a child at risk for dyslexia. Recent genetic studies have identified several candidate regions for dyslexia, including one on chromosome 3 segregating in a large Finnish pedigree. To explore common genetic influences on SSD and reading, we examined linkage for several quantitative traits to markers in the pericentrometric region of chromosome 3 in 77 families ascertained through a child with SSD. The quantitative scores measured several processes underlying speech-sound production, including phonological memory, phonological representation, articulation, receptive and expressive vocabulary, and reading decoding and comprehension skills. Model-free linkage analysis was followed by identification of sib pairs with linkage and construction of core shared haplotypes. In our multipoint analyses, measures of phonological memory demonstrated the strongest linkage (marker D3S2465, P =5.6×10 −5 , and marker D3S3716, P =6.8×10 −4 ). Tests for single-word decoding also demonstrated linkage (real word reading: marker D3S2465, P =.004; nonsense word reading: marker D3S1595, P =.005). The minimum shared haplotype in sib pairs with similar trait values spans 4.9 cM and is bounded by markers D3S3049 and D3S3045. Our results suggest that domains common to SSD and dyslexia are pleiotropically influenced by a putative quantitative trait locus on chromosome 3.

Purpose The relationship between phonological awareness, overall language, vocabulary, and nonlinguistic cognitive skills to decoding and reading comprehension was examined for students at 3 stages of literacy development (i.e., early elementary school, middle school, and high school). Students with histories of speech sound disorders (SSD) with and without language impairment (LI) were compared to students without histories of SSD or LI (typical language; TL). Method In a cross-sectional design, students ages 7;0 (years;months) to 17;9 completed tests that measured reading, language, and nonlinguistic cognitive skills. Results For the TL group, phonological awareness predicted decoding at early elementary school, and overall language predicted reading comprehension at early elementary school and both decoding and reading comprehension at middle school and high school. For the SSD-only group, vocabulary predicted both decoding and reading comprehension at early elementary school, and overall language predicted both decoding and reading comprehension at middle school and decoding at high school. For the SSD and LI group, overall language predicted decoding at all 3 literacy stages and reading comprehension at early elementary school and middle school, and vocabulary predicted reading comprehension at high school. Conclusion Although similar skills contribute to reading across the age span, the relative importance of these skills changes with children's literacy stages.

Speech sound disorders(SSD), language impairment (LI), and attention-deficit/hyperactivity disorder (ADHD) are common developmental disorders that can significantly impact academic success. The comorbidity of these disorders may substantially add to the difficulties experienced by the child and require a combined treatment approach. SSD and LI are often comorbid, with approximately 40%–60% of children with SSD at preschool (Shriberg & Kwiatkowski, 1994) and 11%–15% of 6-year-old children with SSD presenting with LI (Shriberg, Tomblin, & McSweeny, 1999). LI and ADHD are often comorbid as well, with rates of comorbidity reported to be 30%–50% in children seen at ADHD clinics (Tannock & Schachar, 1996). Although there are only a few reports on the comorbidity of SSD and ADHD, these studies have suggested that LI, rather than SSD, is associated with ADHD (McGrath, Hutaff-Lee, Scott, Boada, Shriberg, & Pennington, 2007; Short, Freebairn, Hansen, & Lewis, 2008). Children with SSD have varied academic outcomes depending on the constellation of deficits that they exhibit. In our previous studies, we found that children with SSD in isolation had better school-age outcomes on literacy measures than children with comorbid LI (Lewis, Freebairn, & Taylor, 2002). We also demonstrated that children with SSD and comorbid conditions of LI or reading disorder (RD) or both perform more poorly than children with isolated SSD on measures of endophenotypes, including phonological memory, phonological awareness, and speeded naming (Lewis, Avrich, Freebairn, Taylor, Iyengar, & Stein, 2011). Furthermore, we have reported that children with SSD and comorbid LI are rated more poorly by their parents on an ADHD rating scale (ARS) than children with isolated SSD (Short et al., 2008). In that study, we examined three groups of participants: children with SSD alone (n = 71), children with SSD and comorbid LI (n = 77), and typical children (n = 72). Children with SSD + LI were more likely to have been diagnosed with ADHD by a health care provider, and to have reading problems and spelling problems, than children with SSD alone or typical children. Although the ARS was the best predictor of ADHD, the combination of the ADHD rating score and a score on the Clinical Evaluation of Language Fundamentals 3 (CELF-3) improved the prediction of ADHD. This suggests that language abilities are predictive of ADHD over and above the ARS. However, in these studies the severity of SSD and the family history for disorders were not considered. This article extends these findings by examining differences in ADHD ratings in children with resolved, mild, mild–moderate, or moderate–severe SSD with and without comorbid LI. Furthermore, we consider the impact that family history for SSD reported for both parents (i.e., bilineal transmission of SSD) has on the presence of comorbid ADHD.

Background/Aims: Genetic studies have raised the possibility of common bases for cognitive linguistic disorders such as speech sound disorder (SSD), reading disorder (RD) and language impairment (LI). Thus, some of the same genes may jointly influence cognitive components within and between these three disorders. We examined the plausibility of this theory in a sample of families ascertained on the basis of a child with SSD. Methods: Using the method of generalized estimating equations to solve a bivariate family predictive model we obtained measures of comorbidity and familial aggregation of SSD and LI. We then used two methods of multipoint model-free linkage analysis to evaluate SSD and LI psychometric test measures over a region previously implicated in linkage studies of RD, DYX8 region, 1p34-p36. Results: Bivariate phenotypic analyses show evidence of comorbidity and within family aggregation and coaggregation of SSD and LI. In addition, two regions on chromosome 1 show suggestive evidence of linkage. The first region was previously reported in dyslexia studies. Our maximum linkage signal in this region measured articulation (p = 0.0009) in SSD sibling pairs. The second region is characterized by processes involved in language production, with the maximum linkage signal measuring listening comprehension (p = 0.0019) using all sibling pairs. Conclusion: We conclude that the DYX8 region could bear genes controlling pleiotropic effects on SSD, LI and RD.

Despite a growing body of evidence indicating that speech sound disorder (SSD) has an underlying genetic etiology, researchers have not yet identified specific genes predisposing to this condition. The speech and language deficits associated with SSD are shared with several other disorders, including dyslexia, autism, Prader-Willi Syndrome (PWS), and Angelman’s Syndrome (AS), raising the possibility of gene sharing. Furthermore, we previously demonstrated that dyslexia and SSD share genetic susceptibility loci. The present study assesses the hypothesis that SSD also shares susceptibility loci with autism and PWS. To test this hypothesis, we examined linkage between SSD phenotypes and microsatellite markers on the chromosome 15q14–21 region, which has been associated with autism, PWS/AS, and dyslexia. Using SSD as the phenotype, we replicated linkage to the 15q14 region (P = 0.004). Further modeling revealed that this locus influenced oral-motor function, articulation and phonological memory, and that linkage at D15S118 was potentially influenced by a parent-of-origin effect (LOD score increase from 0.97 to 2.17, P = 0.0633). These results suggest shared genetic determinants in this chromosomal region for SSD, autism, and PWS/AS.