Genetic and environmental influences on early speech, language and literacy development

Unweighting infants reveals hidden motor skills

We investigated the role of rate limiting factors in development using walking as a model system. The achievement of bipedal posture and locomotion are among the most significant achievements in an infant's first year, with poor balance and weak muscles long proposed as the rate limiting factors. Compensating for either may reveal upright motor skill that has not yet emerged in the infant's natural repertoire. To probe this question, we unweighted prewalking infants and measured their performance in various standing and walking behaviors while unweighted compared to baseline. Our secondary objective was to determine if the influence of unweighting was related to infants' locomotor experience. Infants stood unsupported for longer durations with 20% or 40% unweighting. Infants took more independent steps and more steps with one hand held with 40% unweighting. No differences in transition to/from standing were observed. Locomotor experience was related to the influence of unweighting during cruising and walking with a push toy. This is the first report of more advanced motor skills-longer periods of unsupported standing and the emergence of independent walking-revealed by unweighting infants. We interpret our observations to suggest that the refinement of motor control needed to support bipedal posture and locomotion precedes the functional emergence of these skills in infants. In other words, the musculoskeletal components required for walking are slower to develop than the neurological factors - and consequently may be the rate limiters. We further suggest that training regimens including unweighting should be explored in infants with motor delays.

The Musical Abilities, Pleiotropy, Language, and Environment (MAPLE) Framework for Understanding Musicality-Language Links Across the Lifespan

Using individual differences approaches, a growing body of literature finds positive associations between musicality and language-related abilities, complementing prior findings of links between musical training and language skills. Despite these associations, musicality has been often overlooked in mainstream models of individual differences in language acquisition and development. To better understand the biological basis of these individual differences, we propose the Musical Abilities, Pleiotropy, Language, and Environment (MAPLE) framework. This novel integrative framework posits that musical and language-related abilities likely share some common genetic architecture (i.e., genetic pleiotropy) in addition to some degree of overlapping neural endophenotypes, and genetic influences on musically and linguistically enriched environments. Drawing upon recent advances in genomic methodologies for unraveling pleiotropy, we outline testable predictions for future research on language development and how its underlying neurobiological substrates may be supported by genetic pleiotropy with musicality. In support of the MAPLE framework, we review and discuss findings from over seventy behavioral and neural studies, highlighting that musicality is robustly associated with individual differences in a range of speech-language skills required for communication and development. These include speech perception-in-noise, prosodic perception, morphosyntactic skills, phonological skills, reading skills, and aspects of second/foreign language learning. Overall, the current work provides a clear agenda and framework for studying musicality-language links using individual differences approaches, with an emphasis on leveraging advances in the genomics of complex musicality and language traits.

Study protocol: a comprehensive multi-method neuroimaging approach to disentangle developmental effects and individual differences in second language learning

BACKGROUND

While it is well established that second language (L2) learning success changes with age and across individuals, the underlying neural mechanisms responsible for this developmental shift and these individual differences are largely unknown. We will study the behavioral and neural factors that subserve new grammar and word learning in a large cross-sectional developmental sample. This study falls under the NWO (Nederlandse Organisatie voor Wetenschappelijk Onderzoek [Dutch Research Council]) Language in Interaction consortium (website: https://www.languageininteraction.nl/ ).

METHODS

We will sample 360 healthy individuals across a broad age range between 8 and 25 years. In this paper, we describe the study design and protocol, which involves multiple study visits covering a comprehensive behavioral battery and extensive magnetic resonance imaging (MRI) protocols. On the basis of these measures, we will create behavioral and neural fingerprints that capture age-based and individual variability in new language learning. The behavioral fingerprint will be based on first and second language proficiency, memory systems, and executive functioning. We will map the neural fingerprint for each participant using the following MRI modalities: T1-weighted, diffusion-weighted, resting-state functional MRI, and multiple functional-MRI paradigms. With respect to the functional MRI measures, half of the sample will learn grammatical features and half will learn words of a new language. Combining all individual fingerprints allows us to explore the neural maturation effects on grammar and word learning.

DISCUSSION

This will be one of the largest neuroimaging studies to date that investigates the developmental shift in L2 learning covering preadolescence to adulthood. Our comprehensive approach of combining behavioral and neuroimaging data will contribute to the understanding of the mechanisms influencing this developmental shift and individual differences in new language learning. We aim to answer: (I) do these fingerprints differ according to age and can these explain the age-related differences observed in new language learning? And (II) which aspects of the behavioral and neural fingerprints explain individual differences (across and within ages) in grammar and word learning? The results of this study provide a unique opportunity to understand how the development of brain structure and function influence new language learning success.

Cross-Sectional and Longitudinal Associations Between Quality of Parent-Child Interaction and Language Ability in Preschool-Age Children With Developmental Language Disorder

PURPOSE

This study explores whether the quality of parent-child interaction is associated with language abilities cross-sectionally and longitudinally up to preschool-age among children with developmental language disorder (DLD).

METHOD

Participants were 97 monolingual children with DLD and their parents from the Helsinki Longitudinal SLI study, HelSLI (baseline, age in years;months, M = 4;3, SD = 0;10), of which 71 pairs were followed longitudinally (age in years;months, M = 6;6, SD = 0;5). Video recordings from three play sessions were scored for child, parent, and dyadic behavior using Erickson's sensitivity scale protocol and mutually responsive orientation at baseline. Children's expressive and receptive language and language reasoning ability were assessed at baseline, and expressive and receptive language were assessed at follow-up.

RESULTS

At baseline, engaged child behavior, parent's supportive guidance, and fluent and attuned dyadic behavior were associated with better receptive language ability, and engaged child behavior and dyadic synchrony were positively associated with language reasoning ability in 3- to 6-year-olds. The child's positive engagement and fluent and attuned dyadic behavior at baseline were associated with better expressive and receptive language abilities at follow-up in 6- to 7-year-olds, respectively.

CONCLUSIONS

Fluent and attuned dyadic behavior is associated with better receptive language ability in preschool-age children. Parent behavior alone was not associated with language ability. A connected and mutually attuned parent-child relationship could be a protective factor for language development for children with DLD.

Sex differences in early language delay and in developmental language disorder

Developmental language disorder (DLD) is a neurodevelopmental condition, occurring in about 3% to 7% of preschoolers, that can impair communication and negatively impact educational and social attainments, in spite of adequate neurological, cognitive, emotional, social development, and educational opportunities for language learning. Significant risk factors for DLD are male sex, familial history of early language delay, low parental education, and various perinatal factors. A strong sex effect with a higher prevalence of language delay and DLD in males than in females has been consistently reported. Neurobiological and environmental risk factors, interacting with each other, are probably responsible for the phenotypic expression of DLD. The aim of this brief review is to further the knowledge of the role of sex in early language delay and DLD by analyzing the evidence from four significant sources: epidemiological studies, studies on twins, family aggregation studies, and studies on sex chromosome trisomies. Data pertaining only to sex differences (biological and physiological characteristics of females and males) will be analyzed. Studies on family aggregations and twins confirm the role of genetic factors and of sex in determining language abilities and disabilities, but genes alone do not determine outcomes. Sex chromosome trisomies represent a unique example of the relationship between a genetic alteration and a language disorder. Clarification of how sex acts in determining DLD could provide new information on early risk factors and, thus, contribute to improve diagnosis and clinical management.

Musical instrument engagement in adolescence predicts verbal ability 4 years later: A twin and adoption study

Individual differences in music traits are heritable and correlated with the development of cognitive and communication skills, but little is known about whether diverse modes of music engagement (e.g., playing instruments vs. singing) reflect similar underlying genetic/environmental influences. Moreover, the biological etiology underlying the relationship between musicality and childhood language development is poorly understood. Here we explored genetic and environmental associations between music engagement and verbal ability in the Colorado Adoption/Twin Study of Lifespan behavioral development & cognitive aging (CATSLife). Adolescents (N = 1,684) completed measures of music engagement and intelligence at approximately age 12 and/or multiple tests of verbal ability at age 16. Structural equation models revealed that instrument engagement was highly heritable (a² = .78), with moderate heritability of singing (a² = .43) and dance engagement (a² = .66). Adolescent self-reported instrument engagement (but not singing or dance engagement) was genetically correlated with age 12 verbal intelligence and still was associated with age 16 verbal ability, even when controlling for age 12 full-scale intelligence, providing evidence for a longitudinal relationship between music engagement and language beyond shared general cognitive processes. Together, these novel findings suggest that shared genetic influences in part accounts for phenotypic associations between music engagement and language, but there may also be some (weak) direct benefits of music engagement on later language abilities. (PsycInfo Database Record (c) 2021 APA, all rights reserved).

Left lateralization of neonatal caudate microstructure affects emerging language development at 24 months

The complex interaction between brain and behaviour in language disorder is well established. Yet to date, the imaging literature in the language disorder field has continued to pursue heterogeneous and relatively small clinical cross‐sectional samples, with emphasis on cortical structures and volumetric analyses of subcortical brain structures. In our current work, we aimed to go beyond this state of knowledge to focus on the microstructural features of subcortical brain structures (specifically the caudate nucleus) in a large cohort of neonates and study its association with emerging language skills at 24 months. Variations in neonatal brain microstructure could be interpreted as a proxy for in utero brain development. As language development is highly dependent on cognitive function and home literacy environment, we also examined their effect on the caudate–language function relationship utilizing a conditional process model. Our findings suggest that emerging language development at 24 months is influenced by the degree of left lateralization of neonatal caudate microstructure, indexed by diffusion tensor imaging (DTI)‐derived fractional anisotropy (FA). FA is an indirect measure of neuronal and dendritic density within grey matter structures. We also found that the caudate–language function relationship is partially mediated by cognitive function. The conditional indirect effect of left caudate FA on language composite score through cognitive function was only statistically significant at low levels of home literacy score (−1 standard deviation [SD]). The authors proposed that this may be related to ‘compensatory’ development of cognitive skills in less favourable home literacy environments.

Factors affecting the ability to speak in children with autism spectrum disorders

BACKGROUND

Communication deficit is one of the characteristics of autism spectrum disorder. Some children with this condition cannot communicate verbally and some have very limited speech skills. This study aims to analyze the factors that affect speaking ability in children with autism, namely age, sex, emotions, attention, and memory.

DESIGN AND METHODS

This study used a correlational analytical design with a retrospective cohort design. Data were obtained using questionnaires and scales. Furthermore, emotional factors, attention, memory, and age were analyzed for their effects on speaking ability using the Pearson test, while sex was analyzed for their effects on speaking ability using the Eta test.

RESULTS

The results showed that there was a significant effect of attention and age on the speaking ability of children with autism spectrum disorders. Furthermore, it showed that there was a significant effect of emotion on attention.

CONCLUSIONS

It was concluded that attention and age affect the speaking ability of children with autism spectrum disorder. Meanwhile, attention in affecting speaking ability is influenced by emotions. Therefore, to improve speaking ability, good emotional management and increased attention is required.

Measuring the Impact of Genetic and Environmental Risk and Protective Factors on Speech, Language, and Communication Development-Evidence from Australia

Speech and language acquisition is one of the key development indicators of optimal literacy development in infancy and early childhood. Over the last decade there has been increasing interest in the development of theoretical frameworks which underpin the underlying complexity of a child's language developmental landscapes. This longitudinal study aims to measure the impact of genetic and environmental risk and protective factors on speech, language, and communication development (SLCN) among 5000 infants in Australia. Using robust panel fixed-effects models, the results demonstrate that there are clear and consistent effects of protective factors and SLCN associated with the infant's family [coefficient (SD) = 0.153, 95% standard error (SE) = 8.76], the in utero environment [coefficient (SD) = 0.055, standard error (SE) = 3.29] and early infant health [coefficient (SD) = 0.074, standard error (SE) = 5.28]. The impact of family and in utero health is dominant at aged 2 to 3 years (relative to 0 to 1 years) across the domains of language and communication and more dominant from birth to 1 years for speech acquisition. In contrast, the evidence for the impact of genetics on SLCN acquisition in infancy, is less clear. The evidence from this study can be used to inform intervention policies.

The heritability of reading and reading-related neurocognitive components: A multi-level meta-analysis

Reading ability is a complex task requiring the integration of multiple cognitive and perceptual systems supporting language, visual and orthographic processes, working memory, attention, motor movements, and higher-level comprehension and cognition. Estimates of genetic and environmental influences for some of these reading-related neurocognitive components vary across reports. By using a multi-level meta-analysis approach, we synthesized the results of behavioral genetic research on reading-related neurocognitive components (i.e. general reading, letter-word knowledge, phonological decoding, reading comprehension, spelling, phonological awareness, rapid automatized naming, and language) of 49 twin studies spanning 4.1-18.5 years of age, with a total sample size of more than 38,000 individuals. Except for language for which shared environment seems to play a more important role, the causal architecture across most of the reading-related neurocognitive components can be represented by the following equation a² > e² > c². Moderators analysis revealed that sex and spoken language did not affect the heritability of any reading-related skills; school grade levels moderated the heritability of general reading, reading comprehension and phonological awareness.

Identification of novel loci associated with infant cognitive ability

It is believed that genetic factors play a large role in the development of many cognitive and neurological processes; however, epidemiological evidence for the genetic basis of childhood neurodevelopment is very limited. Identification of the genetic polymorphisms associated with early-stage neurodevelopment will help elucidate biological mechanisms involved in neuro-behavior and provide a better understanding of the developing brain. To search for such variants, we performed a genome-wide association study (GWAS) for infant mental and motor ability at two years of age with mothers and children recruited from cohorts in Bangladesh and Mexico. Infant ability was assessed using mental and motor composite scores calculated with country-specific versions of the Bayley Scales of Infant Development. A missense variant (rs1055153) located in the gene WWTR1 reached genome-wide significance in association with mental composite score (meta-analysis effect size of minor allele βmeta = -6.04; 95% CI: -8.13 to -3.94; P = 1.56×10-8). Infants carrying the minor allele reported substantially lower cognitive scores in both cohorts, and this variant is predicted to be in the top 0.3% of most deleterious substitutions in the human genome. Fine mapping and region-based association testing provided additional suggestive evidence that both WWTR1 and a second gene, LRP1B, were associated with infant cognitive ability. Comparisons with recently conducted GWAS in intelligence and educational attainment indicate that our phenotypes do not possess a high genetic correlation with either adolescent or adult cognitive traits, suggesting that infant neurological assessments should be treated as an independent outcome of interest. Additional functional studies and replication efforts in other cohorts may help uncover new biological pathways and genetic architectures that are crucial to the developing brain.

Is atypical rhythm a risk factor for developmental speech and language disorders?

Although a growing literature points to substantial variation in speech/language abilities related to individual differences in musical abilities, mainstream models of communication sciences and disorders have not yet incorporated these individual differences into childhood speech/language development. This article reviews three sources of evidence in a comprehensive body of research aligning with three main themes: (a) associations between musical rhythm and speech/language processing, (b) musical rhythm in children with developmental speech/language disorders and common comorbid attentional and motor disorders, and (c) individual differences in mechanisms underlying rhythm processing in infants and their relationship with later speech/language development. In light of converging evidence on associations between musical rhythm and speech/language processing, we propose the Atypical Rhythm Risk Hypothesis, which posits that individuals with atypical rhythm are at higher risk for developmental speech/language disorders. The hypothesis is framed within the larger epidemiological literature in which recent methodological advances allow for large-scale testing of shared underlying biology across clinically distinct disorders. A series of predictions for future work testing the Atypical Rhythm Risk Hypothesis are outlined. We suggest that if a significant body of evidence is found to support this hypothesis, we can envision new risk factor models that incorporate atypical rhythm to predict the risk of developing speech/language disorders. Given the high prevalence of speech/language disorders in the population and the negative long-term social and economic consequences of gaps in identifying children at-risk, these new lines of research could potentially positively impact access to early identification and treatment. This article is categorized under: Linguistics > Language in Mind and Brain Neuroscience > Development Linguistics > Language Acquisition.

Variation near MTNR1A associates with early development and interacts with seasons

Melatonin is a circadian regulatory hormone with neuroprotective properties. We have previously demonstrated the association of the genetic variant rs12506228 near the melatonin receptor 1A gene (MTNR1A) with intolerance to shift-work. Furthermore, this variant has been connected to Alzheimer's disease. Because of the previously suggested role of melatonin signalling in foetal neurocognitive and sleep development, we studied here the association of rs12506228 with early development. The study sample comprised 8-month-old infants from the Finnish CHILD-SLEEP birth cohort (n = 1,301). Parental questionnaires assessed socioemotional, communication and motor development, as well as sleep length and night awakenings. The A allele of rs12506228 showed an association with slower socioemotional (p = .025) and communication (p = .0098) development, but no direct association with sleep. However, the association of the Finnish seasons with infant sleep length interacted with rs12506228. Taken together, rs12506228 near MTNR1A, which has been previously linked to adult and elderly traits, is shown here to associate with slower early cognitive development. In addition, these results suggest that the darker seasons associate with longer infant sleep time, but only in the absence of the rs12506228 AA genotype. Because the risk allele has been connected to fewer brain MT1 melatonin receptors, these associations may reflect the influence of decreased melatonin signalling in early development.

The Interaction of Social, Physical and Nutritive Factors in Triggering Early Developmental Language Delay in a Sample of Egyptian Children

BACKGROUND

Language acquisition and child development during the early years of life depend on multiple interacting factors.

AIM

To explore potential factors that can impact language development in 2 groups of Egyptian children, one with normal language development and the second with delayed development. Also, to explore to what extent can the involvement of impaired motor development potentiate the risk of developmental language delay.

METHODS

This cross-sectional case-control study involved Egyptian children belonging to the middle socioeconomic class between 18 and 36 months of age. Children were classified according to their performance on language domain of Bayley Scales of Infant and Toddler Development (Bayley-III) into two groups, infants with the average or above score (control group) and those having below-average scores (cases). Motor development was assessed on the same scale. Factors affecting language development were tested, including socio-demographic, obstetric, and maternal medical factors in addition to Infant Feeding Practices.

RESULTS

The independent factors lowering the language scores were early introduction of complementary food, low family income, history of delivery problems, pregnancy-related diseases of the mother, and maternal education. Impaired motor development appears as a further highly significant risk factor to the previously mentioned factors.

CONCLUSION

In Egyptian children, delayed language development is severely affected by the interaction of medical, social and nutritional factors. Providing adequate maternal health care during pregnancy and childbirth, regular developmental monitoring at each child visit, and screening for such risk factors, can reduce size of the problem and promote child's social and psychological development.

Birth weight, verbal cognition in early adolescence, and lexical and reading skills in late adolescence: a formal mediation analysis using a potential outcomes approach

BACKGROUND

Oral and written language in late adolescence are influenced by many pre- and postnatal factors, including cognitive performance at earlier ages. We investigated whether the association between birth weight and lexical knowledge and reading comprehension in late adolescence (14-16 years) is mediated by verbal cognition during early adolescence (10-11 years).

METHODS

We conducted a mediation analysis via a potential outcomes approach to data from three United Kingdom (UK) prospective birth cohorts - The National Child Development Study (NCDS; year of birth (Y.B.) = 1,958; analytic sample size (A.N.) = 9,399; original sample size (O.N.) = 18,558), British Cohort Study (BCS70; Y.B. = 1,970; A.N. = 6,591; O.N. = 17,196), and Millennium Cohort Study (MCS; Y.B. = 2,000-2,001; A.N. = 3,950; O.N. = 18,552) - to evaluate the indirect effects of birth weight on lexical knowledge (BCS and MCS) and reading comprehension measures (NCDS) in adolescence.

RESULTS

We found an indirect effect but no statistically significant direct effects for the BCS and MCS cohorts. The proportion of the effect of birth weight on oral and written language in late adolescence mediated by early adolescence verbal cognition was 59.19% (BCS) and 8.41% (MCS) for lexical knowledge and 61.00% when the outcome was reading comprehension (NCDS). Sensitivity analyses, used to assess whether unmeasured variables could have affected our mediation estimates, showed that for reading comprehension, in NCDS, the indirect effect is robust; only unmeasured confounders highly correlated with the mediator and outcome (ρ = .68) would explain away the indirect effect. For lexical knowledge, smaller correlations with hypothetical confounders (ρ = .33 for BCS) would suffice to render the indirect effect non-significant; the indirect effect for MCS non statistical significant.

CONCLUSIONS

Birth weight affects oral and written language skills (lexical knowledge and reading comprehension) in late adolescence via verbal cognition in early adolescence in two cohorts born in 1958 and 1970, but not in a cohort born at the turn of the millennium. These indirect effects were stronger than the direct effects and are unlikely to be explained by unmeasured confounders when the outcome involves complex skills such as reading comprehension.

Reduced left-lateralized pattern of event-related EEG oscillations in infants at familial risk for language and learning impairment

The ability to rapidly discriminate successive auditory stimuli within tens-of-milliseconds is crucial for speech and language development, particularly in the first year of life. This skill, called Rapid Auditory Processing (RAP), is altered in infants at familial risk for language and learning impairment (LLI) and is a robust predictor of later language outcomes. In the present study, we investigate the neural substrates of RAP, i.e., the underlying neural oscillatory patterns, in a group of Italian 6-month-old infants at risk for LLI (FH+, n = 24), compared to control infants with no known family history of LLI (FH−, n = 32). Brain responses to rapid changes in fundamental frequency and duration were recorded via high-density electroencephalogram during a non-speech double oddball paradigm. Sources of event-related potential generators were localized to right and left auditory regions in both FH+ and FH− groups. Time-frequency analyses showed variations in both theta (Ɵ) and gamma (ɣ) ranges across groups. Our results showed that overall RAP stimuli elicited a more left-lateralized pattern of oscillations in FH− infants, whereas FH+ infants demonstrated a more right-lateralized pattern, in both the theta and gamma frequency bands. Interestingly, FH+ infants showed reduced early left gamma power (starting at 50 ms after stimulus onset) during deviant discrimination. Perturbed oscillatory dynamics may well constitute a candidate neural mechanism to explain group differences in RAP. Additional group differences in source location suggest that anatomical variations may underlie differences in oscillatory activity. Regarding the predictive value of early oscillatory measures, we found that the amplitude of the source response and the magnitude of oscillatory power and phase synchrony were predictive of expressive vocabulary at 20 months of age. These results further our understanding of the interplay among neural mechanisms that support typical and atypical rapid auditory processing in infancy.

•

Neural sources of RAP in infancy were identified at right/left auditory regions.

•

FH− infants demonstrated a mature left-lateralized pattern of neural oscillations.

•

FH+ infants demonstrated a more right-lateralized pattern of neural oscillations.

•

FH+ infants showed reduced left gamma power during rapid auditory discrimination.

•

Source and oscillatory measures are both associated with later language skills.

Family aggregation of language impairment in an isolated Chilean population from Robinson Crusoe Island

BACKGROUND

It has been reported that the inhabitants of the Chilean Robinson Crusoe Island have an increased frequency of specific language impairment (SLI) or developmental language disorder (DLD).

AIMS

To explore the familial aggregation of DLD in this community.

METHODS & PROCEDURES

We assessed the frequency of DLD amongst colonial children between the ages of 3 and 8;11 years (50 individuals from 45 nuclear families). Familial aggregation rates of language disorder were calculated by assessing all available first-degree relatives (n = 107, 77 parents, 25 siblings, five half-siblings) of the probands.

OUTCOMES & RESULTS

We found that 71% of the child population performed significantly below expected in measures of phonological production or expressive and receptive morphology. The majority of these children presented with severe expressive and/or receptive language difficulties. One-quarter of language-disordered probands primarily had phonological difficulties. Family members of affected probands experienced a higher risk of language disorder than those of typically developing probands. This increased risk was apparent regardless of non-verbal IQ.

CONCLUSIONS & IMPLICATIONS

The study substantiates the existence of a familial form of speech and language disorder on Robinson Crusoe Island. Furthermore, we find that the familiarity is stable regardless of non-verbal IQ, supporting the recent movement to reduce the importance of non-verbal IQ criterion in DLD diagnoses.

GENES AND GINI: WHAT INEQUALITY MEANS FOR HERITABILITY

Research has established that genetic differences among people explain a greater or smaller proportion of the variation in life outcomes in different environmental conditions. This review evaluates the results of recent educationally relevant behavioural genetic studies and meta-analyses in the context of recent trends in income and wealth distribution. The pattern of results suggests that inequality and social policies can have profound effects on the heritability of educational attainment and achievement in a population (Gene–Gini interplay). For example, heritability is generally higher at greater equality levels, suggesting that inequality stifles the expression of educationally relevant genetic propensities. The review concludes with a discussion of the mechanisms of Gene–Gini interplay and what the findings mean for efforts to optimize education for all people.

An Interprofessional Team Approach to the Differential Diagnosis of Children with Language Disorders

The ability to communicate effectively with others is central to children's development. Delays or disruptions due to isolated expressive language delay, articulation errors, multiple sound production errors with motor planning deficits, or mixed expressive and receptive language delay, often bring widespread consequences. Physical anomalies, neurologic and genetic disorder, cognitive and intellectual disabilities, and emotional disturbances may affect speech and language development. Communication disorders may be misdiagnosed as intellectual impairment or autism. Interdisciplinary evaluation should include speech and language assessment, physical and neurologic status, cognitive and emotional profile, and family and social history. This article describes assessment and reviews common pediatric communication disorders.

Longitudinal Study of Language and Speech of Twins at 4 and 6 Years: Twinning Effects Decrease, Zygosity Effects Disappear, and Heritability Increases

Purpose

This study investigates the heritability of language, speech, and nonverbal cognitive development of twins at 4 and 6 years of age. Possible confounding effects of twinning and zygosity, evident at 2 years, were investigated among other possible predictors of outcomes.

Method

The population-based twin sample included 627 twin pairs and 1 twin without a co-twin (197 monozygotic and 431 dizygotic), 610 boys and 645 girls, 1,255 children in total. Nine phenotypes from the same comprehensive direct behavioral assessment protocol were investigated at 4 and 6 years of age. Twinning effects were estimated for each phenotype at each age using general linear mixed models using maximum likelihood.

Results

Twinning effects decreased from 4 to 6 years; zygosity effects disappeared by 6 years. Heritability increased from 4 to 6 years across all 9 phenotypes, and the heritability estimates were higher than reported previously, in the range of .44-.92 at 6 years. The highest estimate, .92, was for the clinical grammar marker.

Conclusions

Across multiple dimensions of speech, language, and nonverbal cognition, heritability estimates are robust. A finiteness marker of grammar shows the highest inherited influences in this early period of children's language acquisition.

Single Nucleotide Polymorphisms Associated with Reading Ability Show Connection to Socio-Economic Outcomes

Impairments in reading and in language have negative consequences on life outcomes, but it is not known to what extent genetic effects influence this association. We constructed polygenic scores for difficulties with language and learning to read from genome-wide data in ~6,600 children, adolescents and young adults, and tested their association with health, socioeconomic outcomes and brain structure measures collected in adults (maximal N = 111,749). Polygenic risk of reading difficulties was associated with reduced income, educational attainment, self-rated health and verbal-numerical reasoning (p < 0.00055). Polygenic risk of language difficulties predicted income (p = 0.0005). The small effect sizes ranged 0.01-0.03 of a standard deviation, but these will increase as genetic studies for reading ability get larger. Polygenic scores for childhood cognitive ability and educational attainment were correlated with polygenic scores of reading and language (up to 0.09 and 0.05, respectively). But when they were included in the prediction models, the observed associations between polygenic reading and adult outcomes mostly remained. This suggests that the pathway from reading ability to social outcomes is not only via associated polygenic loads for general cognitive function and educational attainment. The presence of non-overlapping genetic effect is indicated by the genetic correlations of around 0.40 (childhood intelligence) and 0.70 (educational attainment) with reading ability. Mendelian randomization approaches will be important to dissociate any causal and moderating effects of reading and related traits on social outcomes.

The Home Literacy Environment Is a Correlate, but Perhaps Not a Cause, of Variations in Children's Language and Literacy Development

The home literacy environment is a well-established predictor of children's language and literacy development. We investigated whether formal, informal, and indirect measures of the home literacy environment predict children's reading and language skills once maternal language abilities are taken into account. Data come from a longitudinal study of children at high risk of dyslexia (N = 251) followed from preschool years. Latent factors describing maternal language were significant predictors of storybook exposure but not of direct literacy instruction. Maternal language and phonological skills respectively predicted children's language and reading/spelling skills. However, after accounting for variations in maternal language, storybook exposure was not a significant predictor of children's outcomes. In contrast, direct literacy instruction remained a predictor of children's reading/spelling skills. We argue that the relationship between early informal home literacy activities and children's language and reading skills is largely accounted for by maternal skills and may reflect genetic influences.

Cognitive, Linguistic, and Motor Abilities in a Multigenerational Family with Childhood Apraxia of Speech

Objective

This study describes the phenotype in a large family with a strong, multigenerational history of severe speech sound disorder (SSD) persisting into adolescence and adulthood in approximately half the cases. Aims were to determine whether a core phenotype, broader than speech, separated persistent from resolved SSD cases; and to ascertain the uniqueness of the phenotype relative to published cases.

Method

Eleven members of the PM family (9–55 years) were assessed across cognitive, language, literacy, speech, phonological processing, numeracy, and motor domains. Between group comparisons were made using the Mann–WhitneyU-test (p < 0.01). Participant performances were compared to normative data using standardized tests and to the limited published data on persistent SSD phenotypes.

Results

Significant group differences were evident on multiple speech, language, literacy, phonological processing, and verbal intellect measures without any overlapping scores. Persistent cases performed within the impaired range on multiple measures. Phonological memory impairment and subtle literacy weakness were present in resolved SSD cases.

Conclusion

A core phenotype distinguished persistent from resolved SSD cases that was characterized by a multiple verbal trait disorder, including Childhood Apraxia of Speech. Several phenotypic differences differentiated the persistent SSD phenotype in the PM family from the few previously reported studies of large families with SSD, including the absence of comorbid dysarthria and marked orofacial apraxia. This study highlights how comprehensive phenotyping can advance the behavioral study of disorders, in addition to forming a solid basis for future genetic and neural studies.

Reading and language disorders: the importance of both quantity and quality

Reading and language disorders are common childhood conditions that often co-occur with each other and with other neurodevelopmental impairments. There is strong evidence that disorders, such as dyslexia and Specific Language Impairment (SLI), have a genetic basis, but we expect the contributing genetic factors to be complex in nature. To date, only a few genes have been implicated in these traits. Their functional characterization has provided novel insight into the biology of neurodevelopmental disorders. However, the lack of biological markers and clear diagnostic criteria have prevented the collection of the large sample sizes required for well-powered genome-wide screens. One of the main challenges of the field will be to combine careful clinical assessment with high throughput genetic technologies within multidisciplinary collaborations.

Genome-wide association study of receptive language ability of 12-year-olds

PURPOSE

Researchers have previously shown that individual differences in measures of receptive language ability at age 12 are highly heritable. In the current study, the authors attempted to identify some of the genes responsible for the heritability of receptive language ability using a genome-wide association approach.

METHOD

The authors administered 4 Internet-based measures of receptive language (vocabulary, semantics, syntax, and pragmatics) to a sample of 2,329 twelve-year-olds for whom DNA and genome-wide genotyping were available. Nearly 700,000 single-nucleotide polymorphisms (SNPs) and 1 million imputed SNPs were included in a genome-wide association analysis of receptive language composite scores.

RESULTS

No SNP associations met the demanding criterion of genome-wide significance that corrects for multiple testing across the genome ( p < 5 × 10 -8). The strongest SNP association did not replicate in an additional sample of 2,639 twelve-year-olds.

CONCLUSIONS

These results indicate that individual differences in receptive language ability in the general population do not reflect common genetic variants that account for more than 3% of the phenotypic variance. The search for genetic variants associated with language skill will require larger samples and additional methods to identify and functionally characterize the full spectrum of risk variants.

Epigenetic analysis of neurocognitive development at 1 year of age in a community-based pregnancy cohort

Multiple studies show that molecular genetic changes and epigenetic modifications affect the risk of cognitive disability or impairment. However, the role of epigenetic variation in cognitive development of neurotypical young children remains largely unknown. Using data from a prospective, community-based study of mother-infant pairs, we investigated the association of DNA methylation patterns in neonatal umbilical cord blood with cognitive and language development at 1 year of age. No CpG loci achieved genome-wide significance, although a small number of weakly suggestive associations with Bayley-III Receptive Communication scales were noted. While umbilical cord blood is a convenient resource for genetic analyses of birth outcomes, our results do not provide conclusive evidence that its use for DNA methylation profiling yields epigenetic markers that are directly related to postnatal neurocognitive outcomes at 1 year of age.

Socioeconomic status, parental education, vocabulary and language skills of children who stutter

PURPOSE

The purpose of this project was to investigate the possible relation between standardized measures of vocabulary/language, mother and father education, and a composite measure of socioeconomic status (SES) for children who do not stutter (CWNS) and children who stutter (CWS).

METHODS

Participants were 138 CWNS and 159 CWS between the ages of 2;6 and 6;3 and their families. The Hollingshead Four Factor Index of Social Position (i.e., Family SES) was used to calculate SES based on a composite score consisting of weighted values for paternal and maternal education and occupation. Statistical regression analyses were conducted to investigate the relation between parental education and language and vocabulary scores for both the CWNS and CWS. Correlations were calculated between parent education, Family SES, and stuttering severity (e.g., SSI-3 score, % words stuttered).

RESULTS

Results indicated that maternal education contributed the greatest amount of variance in vocabulary and language scores for the CWNS and for participants from both groups whose Family SES was in the lowest quartile of the distribution. However, paternal education generally contributed the greatest amount of variance in vocabulary and language scores for the CWS. Higher levels of maternal education were associated with more severe stuttering in the CWS.

CONCLUSION

Results are generally consistent with existing literature on normal language development that indicates maternal education is a robust predictor of the vocabulary and language skills of preschool children. Thus, both father and mothers' education may impact the association between vocabulary/language skills and childhood stuttering, leading investigators who empirically study this association to possibly re-assess their participant selection (e.g., a priori control of parental education) and/or data analyses (e.g., post hoc covariation of parental education).

LEARNING OUTCOMES

The reader will be able to: (a) describe the influence of socioeconomic status on the development of vocabulary and language for children who do and do not stutter; (b) discuss the contribution of maternal education on vocabulary and language development; (c) describe possible reasons why paternal education contributes in unique ways to the vocabulary and language development of children who stutter as well as stuttering severity; and (d) explain possible reasons why socioeconomic status is an important variable for describing language related findings in young children.

Language development and affecting factors in 3- to 6-year-old children

The aim of this study was to assess factors affecting language developmental screening test results in 33.0- to 75.0-month-old children. The study group consists of 402 children, 172 (42.8%) boys and 230 (57.2%) girls, aged 33.0-75.0 months who were examined in four age groups: 3 years (33.0-39.0 months), 4 years (45.0-51.0 months), 5 years (57.0-63.0 months) and 6 years (69.0-75.0 months). Demographic data and medical history obtained by a standard questionnaire and Denver II Developmental Test results were evaluated. Maternal factors such as mother's age, educational level, and socioeconomic status (SES) correlated with language items in all age groups. Linear regression analysis indicated a significant effect of mother's education and higher SES on certain expressive and receptive language items at 3 and 4 years. Fine motor items were closely related to language items at all ages examined, while in the younger (3- and 4-year-old) group gross motor items also were related to language development. Maternal and socioeconomic factors influence language development in children: these effects, already discernible with a screening test, can be potential targets for social and educational interventions. The interpretation of screening test results should take into account the interaction between fine motor and language development in preschool children.

The genetics of reading disabilities: from phenotypes to candidate genes

This article provides an overview of (a) issues in definition and diagnosis of specific reading disabilities at the behavioral level that may occur in different constellations of developmental and phenotypic profiles (patterns); (b) rapidly expanding research on genetic heterogeneity and gene candidates for dyslexia and other reading disabilities; (c) emerging research on gene-brain relationships; and (d) current understanding of epigenetic mechanisms whereby environmental events may alter behavioral expression of genetic variations. A glossary of genetic terms (denoted by bold font) is provided for readers not familiar with the technical terms.

Speech-language pathologists' knowledge of genetics: perceived confidence, attitudes, knowledge acquisition and practice-based variables

The purpose of this study was to determine (a) the general knowledge bases demonstrated by school-based speech-language pathologists (SLPs) in the area of genetics, (b) the confidence levels of SLPs in providing services to children and their families with genetic disorders/syndromes, (c) the attitudes of SLPs regarding genetics and communication disorders, (d) the primary sources used by SLPs to learn about genetic disorders/syndromes, and (e) the association between general knowledge, confidence, attitudes, the number of years of experience working as an SLP, and the number of children currently provided services with genetic disorders/syndromes on SLPs' caseloads. Survey data from a nationwide sample of 533 SLPs was analyzed. Results showed SLPs earned a median knowledge score about genetics of 66% correct responses. Their mean confidence and attitude ratings were in the "unsure" categories while they reported they learned about genetics from three main sources, (a) self-study via web and internet-based searches, (b) on-the-job training and (c) popular press magazines and newspapers. Analyses revealed that Confidence summary scores, Attitude Summary scores, the number of children with genetic disorders/syndromes on SLPs' caseloads are positively associated with the ratings of participants with the highest Knowledge scores.

LEARNING OUTCOMES

Readers will be able to (a) explain the important links between developmental and communication disabilities and genetics, (b) describe the associations between knowledge about genetics and confidence, attitudes, and the number of children with genetic disorders/syndromes on their caseloads, and (c) outline the clinical and theoretical implications of the results from this study.

Individual differences in lexical processing at 18 months predict vocabulary growth in typically developing and late-talking toddlers

Using online measures of familiar word recognition in the looking-while-listening procedure, this prospective longitudinal study revealed robust links between processing efficiency and vocabulary growth from 18 to 30 months in children classified as typically developing (n = 46) and as "late talkers" (n = 36) at 18 months. Those late talkers who were more efficient in word recognition at 18 months were also more likely to "bloom," showing more accelerated vocabulary growth over the following year, compared with late talkers less efficient in early speech processing. Such findings support the emerging view that early differences in processing efficiency evident in infancy have cascading consequences for later learning and may be continuous with individual differences in language proficiency observed in older children and adults.

Literacy outcomes of children with early childhood speech sound disorders: impact of endophenotypes

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.

Reduced Sensory Oscillatory Activity during Rapid Auditory Processing as a Correlate of Language-Learning Impairment

Successful language acquisition has been hypothesized to involve the ability to integrate rapidly presented, brief acoustic cues in sensory cortex. A body of work has suggested that this ability is compromised in language-learning impairment (LLI). The present research aimed to examine sensory integration during rapid auditory processing by means of electrophysiological measures of oscillatory brain activity using data from a larger longitudinal study. Twenty-nine children with LLI and control participants with typical language development (n=18) listened to tone doublets presented at a temporal interval that is essential for accurate speech processing (70-ms interstimulus interval). The children performed a deviant (pitch change of second tone) detection task, or listened passively. The electroencephalogram was recorded from 64 electrodes. Data were source-projected to the auditory cortices and submitted to wavelet analysis, resulting in time-frequency representations of electrocortical activity. Results show significantly reduced amplitude and phase-locking of early (45-75 ms) oscillations in the gamma-band range (29-52 Hz), specifically in the LLI group, for the second stimulus of the tone doublet. This suggests altered temporal organization of sensory oscillatory activity in LLI when processing rapid sequences.

The impact of the perioperative period on neurocognitive development, with a focus on pharmacological concerns

Mounting evidence from animal studies has implicated that all commonly used anaesthetics and sedatives may induce widespread neuronal cell death and result in long-term neurological abnormalities. These findings have led to serious questions regarding the safe use of these drugs in young children. In humans, recent findings from retrospective, epidemiological studies do not exclude the possibility of an association between surgery with anaesthesia early in life and subsequent learning abnormalities. These results have sparked discussions regarding the appropriate timing of paediatric surgery and the safe management of paediatric anaesthesia. However, important questions need to be addressed before findings from laboratory studies and retrospective clinical surveys can be used to guide clinical practice. This article summarises the currently available preclinical and clinical information regarding the impact of anaesthetics, sedatives, opioids, pain and stress, inflammation, hypoxia-ischaemia, co-morbidities and genetic predisposition on brain structure and long-term neurological function. Moreover, this article outlines the putative mechanisms of anaesthetic neurotoxicity, and the phenomenon's implications for clinical practice in this rapidly emerging field.

Predicting individual differences in reading comprehension: a twin study

We examined the Simple View of reading from a behavioral genetic perspective. Two aspects of word decoding (phonological decoding and word recognition), two aspects of oral language skill (listening comprehension and vocabulary), and reading comprehension were assessed in a twin sample at age 9. Using latent factor models, we found that overlap among phonological decoding, word recognition, listening comprehension, vocabulary, and reading comprehension was primarily due to genetic influences. Shared environmental influences accounted for associations among word recognition, listening comprehension, vocabulary, and reading comprehension. Independent of phonological decoding and word recognition, there was a separate genetic link between listening comprehension, vocabulary, and reading comprehension and a specific shared environmental link between vocabulary and reading comprehension. There were no residual genetic or environmental influences on reading comprehension. The findings provide evidence for a genetic basis to the "Simple View" of reading.

Genetic advances in the study of speech and language disorders

Developmental speech and language disorders cover a wide range of childhood conditions with overlapping but heterogeneous phenotypes and underlying etiologies. This characteristic heterogeneity hinders accurate diagnosis, can complicate treatment strategies, and causes difficulties in the identification of causal factors. Nonetheless, over the last decade, genetic variants have been identified that may predispose certain individuals to different aspects of speech and language difficulties. In this review, we summarize advances in the genetic investigation of stuttering, speech-sound disorder (SSD), specific language impairment (SLI), and developmental verbal dyspraxia (DVD). We discuss how the identification and study of specific genes and pathways, including FOXP2, CNTNAP2, ATP2C2, CMIP, and lysosomal enzymes, may advance our understanding of the etiology of speech and language disorders and enable us to better understand the relationships between the different forms of impairment across the spectrum.

Behavioral genetic approach to the study of dyslexia

OBJECTIVE

Dyslexia is a prominent focus of practitioners, educators, and researchers because of the myriad consequences of failing to read proficiently. The aim of this study was to provide a brief overview of how twin studies can offer insight on the cause of many human behaviors and disorders including dyslexia, discuss common misconceptions regarding findings from behavioral genetic studies, briefly review the evidence on the relationship between genes, environment, and dyslexia, and finally present some findings from a large-scale twin study on reading and dyslexia.

METHOD

Participants were twins from a large ethnically and socioeconomically diverse twin sample in an ongoing longitudinal study of reading and dyslexia. Heritabilities of reading ability and dyslexia were calculated for 1,024 first grade twins on a standardized reading measure. Children were identified as dyslexic if they scored at the 15th percentile or below on a reading measure.

RESULTS

Relatively high heritabilities were observed for both reading ability and dyslexia indicating substantial genetic influences. Further, results indicated some overlap of genetic factors influencing reading ability and dyslexia.

CONCLUSIONS

Behavioral genetic studies offer a means of understanding the cause of dyslexia. This study extended research to a more diverse sample than extant studies and found lower heritability estimates of reading ability and dyslexia, but a similar pattern of results indicating possible genetic overlap. Twin studies provide perspective for discoveries of specific genes involved in dyslexia by quantifying the amount of variance waiting to be accounted for by genes while simultaneously providing an impetus to continue working on efforts for environmental intervention.

Unilateral hearing loss is associated with worse speech-language scores in children

OBJECTIVE

To determine whether children with unilateral hearing loss (UHL) demonstrate worse language skills than their siblings with normal hearing, and whether children with UHL are more likely to receive extra assistance at school.

PATIENTS AND METHODS

We conducted a case-control study of 6- to 12-year-old children with UHL compared with sibling controls (74 pairs, n = 148). Scores on the oral portion of the Oral and Written Language Scales (OWLS) were the primary outcome measure. Multivariable analysis was used to determine whether UHL independently predicted OWLS scores after we controlled for potential confounding variables.

RESULTS

Children with UHL had worse scores than their siblings on language comprehension (91 vs 98; P = .003), oral expression (94 vs 101; P = .007), and oral composite (90 vs 99; P < .001). UHL independently predicted these OWLS scores when multivariable regression was used with moderate effect sizes of 0.3 to 0.7. Family income and maternal education were also independent predictors of oral expression and oral composite scores. No differences were found between children with right- or left-ear UHL or with varying severity of hearing loss. Children with UHL were more likely to have an individualized education plan (odds ratio: 4.4 [95% confidence interval: 2.0-9.5]) and to have received speech-language therapy (odds ratio: 2.6 [95% confidence interval: 1.3-5.4]).

CONCLUSIONS

School-aged children with UHL demonstrated worse oral language scores than did their siblings with normal hearing. These findings suggest that the common practice of withholding hearing-related accommodations from children with UHL should be reconsidered and studied, and that parents and educators should be informed about the deleterious effects of UHL on oral language skills.

Twenty-year follow-up of children with and without speech-language impairments: family, educational, occupational, and quality of life outcomes

PURPOSE

Parents, professionals, and policy makers need information on the long-term prognosis for children with communication disorders. Our primary purpose in this report was to help fill this gap by profiling the family, educational, occupational, and quality of life outcomes of young adults at 25 years of age (N = 244) from the Ottawa Language Study, a 20-year, prospective, longitudinal study of a community sample of individuals with (n = 112) and without (n = 132) a history of early speech and/or language impairments. A secondary purpose of this report was to use data from earlier phases of the study to predict important, real-life outcomes at age 25.

METHOD

Participants were initially identified at age 5 and subsequently followed at 12, 19, and 25 years of age. Direct assessments were conducted at all 4 time periods in multiple domains (demographic, communicative, cognitive, academic, behavioral, and psychosocial).

RESULTS

At age 25, young adults with a history of language impairments showed poorer outcomes in multiple objective domains (communication, cognitive/academic, educational attainment, and occupational status) than their peers without early communication impairments and those with early speech-only impairments. However, those with language impairments did not differ in subjective perceptions of their quality of life from those in the other 2 groups. Objective outcomes at age 25 were predicted differentially by various combinations of multiple, interrelated risk factors, including poor language and reading skills, low family socioeconomic status, low performance IQ, and child behavior problems. Subjective well-being, however, was primarily associated with strong social networks of family, friends, and others.

CONCLUSION

This information on the natural history of communication disorders may be useful in answering parents' questions, anticipating challenges that children with language disorders might encounter, and planning services to address those issues.

Sprachentwicklungsstörungen bei Kindern

Wesentliche Voraussetzung für eine ungestörte Kindesentwicklung ist ein regelrechter Spracherwerb. Sprachentwicklungsstörungen (SES) im Kindesalter sind häufig. Für spezifische (isolierte) Sprachentwicklungsstörungen liegt die Prävalenz bei 6 – 8 %; hinzukommen SES, die mit anderen Störungen assoziiert sind. Da flächendeckende Sprachstandserfassungen im Kindergartenalter, die Kinder mit einem SES-Verdacht einer Diagnostik zuführen sollen, auch in Deutschland in den Blickpunkt rücken und eine erhebliche Unsicherheit in der Diagnosestellung von SES und der Verordnungspraxis für Sprachtherapie besteht, sollen die hier in gekürzter Form vorgestellten, überarbeiteten AWMF-Leitlinien der Deutschen Gesellschaft für Phoniatrie und Pädaudiologie ( Neumann et al., 2008 ) zum Verständnis der Pathogenese von SES, ihrer Begriffsbestimmung, Diagnostik und Therapie beitragen.

CMIP and ATP2C2 modulate phonological short-term memory in language impairment

Specific language impairment (SLI) is a common developmental disorder characterized by difficulties in language acquisition despite otherwise normal development and in the absence of any obvious explanatory factors. We performed a high-density screen of SLI1, a region of chromosome 16q that shows highly significant and consistent linkage to nonword repetition, a measure of phonological short-term memory that is commonly impaired in SLI. Using two independent language-impaired samples, one family-based (211 families) and another selected from a population cohort on the basis of extreme language measures (490 cases), we detected association to two genes in the SLI1 region: that encoding c-maf-inducing protein (CMIP, minP = 5.5 x 10(-7) at rs6564903) and that encoding calcium-transporting ATPase, type2C, member2 (ATP2C2, minP = 2.0 x 10(-5) at rs11860694). Regression modeling indicated that each of these loci exerts an independent effect upon nonword repetition ability. Despite the consistent findings in language-impaired samples, investigation in a large unselected cohort (n = 3612) did not detect association. We therefore propose that variants in CMIP and ATP2C2 act to modulate phonological short-term memory primarily in the context of language impairment. As such, this investigation supports the hypothesis that some causes of language impairment are distinct from factors that influence normal language variation. This work therefore implicates CMIP and ATP2C2 in the etiology of SLI and provides molecular evidence for the importance of phonological short-term memory in language acquisition.

Ethical and social implications of genetic testing for communication disorders

Advances in genetics and genomics have quickly led to clinical applications to human health which have far-reaching consequences at the individual and societal levels. These new technologies have allowed a better understanding of the genetic factors involved in a wide range of disorders. During the past decade, incredible progress has been made in the identification of genes involved in the normal process of hearing. The resulting clinical applications have presented consumers with new information and choices. Many of the same gene identification techniques are increasingly being applied to the investigation of complex disorders of speech and language. In parallel with gene identification, studies of the legal, ethical and psychosocial impacts of the clinical application of these advances and their influence on specific behaviors of individuals with communication disorders are paramount, but often lag behind. These studies will help to ensure that new technologies are introduced into clinical practice in a responsible manner.

LEARNING OUTCOMES

As a result of this activity, the participant will be able to (1) explain the differences between Mendelian and complex forms of inheritance and why these differences complicate the ethical impact of genetic testing, (2) explain how publicly funded genome research through the Human Genome Project, the International HapMap Project and others have examined the ethical, legal and social implications of genome research, (3) list some of the ethical complexities of prenatal, newborn and predictive testing for various genetic disorders and (4) discuss the importance of evidence-based practice to the development of public policy for the introduction and clinical use of genetic tests.