Purpose: The biological mechanisms underlying developmental stuttering remain unclear. In a previous investigation, we showed that there is significant spatial correspondence between regional gray matter structural anomalies and the expression of genes linked to energy metabolism. In the current study, we sought to further examine the relationship…

Purpose: Individuals with proximal 16p11.2 copy number variants (CNVs), either deletions (16p11.2DS) or duplications (16p11.2Dup), are predisposed to neurodevelopmental difficulties and disorders, such as language disorders, intellectual disability, and autism spectrum disorder. The purpose of the current study was to characterize language…

This research examines how the human genome and SES jointly and interactively shape verbal ability among youth in the U.S. The youth are aged 12-18 when the study starts. The research draws on findings from the latest GWAS as well as a rich set of longitudinal SES measures at individual, family and neighborhood levels from Add Health (N = 7194).…

Given the importance of writing for academic achievement, this study aimed to understand how early oral language contributes to later writing skills. The first objective was to determine if preschool language skills were associated with high school writing, and if so, whether they contributed directly or indirectly through school age language. The…

This study assessed the utility of a brief assessment (the Peabody Picture Vocabulary Test-4th Edition; PPVT4) as a proxy for verbal IQ (VIQ) in large-scale studies of autism spectrum disorder (ASD). In a sample of 2,420 proband with ASD, PPVT4:IQ correlations were strong. PPVT4 scores were, on average, 5.46 points higher than VIQ; 79% of children…

Purpose: Multiple factors impact reading acquisition in individuals with reading disability, including genetic disorders such as Williams syndrome (WS). Despite a relative strength in oral language, individuals with WS usually have an intellectual disability and tend to display deficits in areas associated with reading. There is substantial…

Purpose: The aim of this study was to investigate language growth in individuals with fragile X syndrome (FXS) from early childhood to adolescence and the influence of maternal responsivity on language growth. Method: We conducted a longitudinal analysis of language development in 55 youths (44 males, 11 females) with FXS. Data collection spanned…

This study investigates the knowledge of binding in 21 English-speaking children with SLI, aged 6;08-16;05, compared to 21 children with WS, language- and age-matched, and 21 language-matched control children, aged 4-7;10. Our results demonstrate no difficulties in the interpretation of reflexive or personal pronouns in SLI, revealing an intact…

This twin study examined the genetic and environmental etiology of vocabulary, syntax, and their association in first graders. French-speaking same-sex twins (n = 555) completed two vocabulary tests, and two scores of syntax were calculated from their spontaneous speech at 7 years of age. Multivariate latent factor genetic analyses showed that…

Recent studies have begun to uncover the genetic architecture of educational attainment. We build on this work using genome-wide data from siblings in the National Longitudinal Study of Adolescent to Adult Health (Add Health). We measure the genetic predisposition of siblings to educational attainment using polygenic scores. We then test how…

Background: Williams syndrome (WS) phenotype is described as unique and intriguing. The aim of this study was to investigate the associations between speech-language abilities, general cognitive functioning and behavioural problems in individuals with WS, considering age effects and speech-language characteristics of WS sub-groups. Methods: The…

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…

Variable language outcomes have been reported in children with the metabolic disorder galactosaemia (GAL), but these outcomes do not appear to be related to the severity of symptoms in the neonatal period, compliance with the non-dairy diet, or IQ. Currently, there is no means by which at-risk children with GAL can be identified early to initiate…

Williams syndrome (WS) is a neurogenetic developmental disorder characterized by peaks and valleys of cognitive abilities. One peak that has been understudied is the affinity that many individuals with WS have with music. It remains unknown whether their high levels of musical interest, skill, and expressivity are related to their sociable…

There has been significant interest in examining the developmental factors that predispose individuals to chronic criminal offending. This body of research has identified some social-environmental risk factors as potentially important. At the same time, the research producing these results has generally failed to employ genetically sensitive…