The Development of Morphosyntax in Fragile X Syndrome

An objective of research in developmental disabilities is the comparison of language phenotypes. Disorders with similar symptomology, such as autism and fragile X syndrome (FXS) are of particular interest. One area of inquiry within language development is morphosyntax (the interplay between grammatical morphology and syntactic structure). The purpose of this study was to examine morphosyntax in a group of children with FXS, while examining the impact of autism on FXS. Differences in gender were also examined. Twenty-six boys and 7 girls between 7-16 years participated. Children completed standardized tests and a language sample. The examiner completed an autism rating scale. The data indicated that boys with FXS do have a deficit in morphosyntax, relative to language comprehension. The presence of autism had a negative impact. Some of the females in this study had low nonverbal IQ, and receptive language scores. Females had low percentage correct for irregular past tense verbs

Finiteness Marking in Boys with Fragile X Syndrome

Purpose This study investigated finite marking (e.g., he walks, he walked) in boys with fragile X syndrome; the boys were grouped based on receptive vocabulary (i.e., borderline, or impaired vocabulary). Method Twenty-one boys with the full mutation of fragile X, between the ages of 8 to 16 years participated. The boys completed probes from the Test of Early Grammatical Impairment (Rice & Wexler, 2001), a language sample, a nonverbal IQ test (Leiter-R, Roid & Miller, 1997), a receptive vocabulary test (PPVT-IV Dunn & Dunn, 2007), and a measure of autistic symptoms (CARS; Schopler et al., 2002). Results There were group differences for finiteness responses on the third person singular probe; the group with impaired vocabulary omitted markers with greater frequency compared to borderline vocabulary group. There were not significant differences on the past tense probe, although boys with borderline and impaired vocabulary were delayed relative to language expectations. Nonverbal IQ was not correlated with the measures of finiteness marking. Conclusion Boys with FXS demonstrate delays in finiteness marking, in particular on past tense verbs. Boys with impaired vocabulary show a unique profile unlike children with SLI, in which their use of tense markers may exceed expectations benchmarked to clause length

The effect of sustained maternal responsivity on later vocabulary development in children with Fragile X Syndrome

Purpose The research question addressed was whether sustained maternal responsivity (a parent-child interaction style characterized by warmth, nurturance and stability as well as specific behaviors such as contingent positive responses to child initiations) was a significant variable predicting vocabulary development of children with FXS through age 9 years. Method Fifty-five mother-child dyads were followed longitudinally when children were between 2 and 10 years of age. Measures of maternal responsivity and child vocabulary were obtained at regular intervals starting at age 2.9 years. Sustained responsivity was indicated by the average responsivity measured over observations 2–5. Responsivity at the first time period, autism symptoms, and cognitive development were used as control variables. Results After controlling for development and autism symptoms, we found significant effects for sustained responsivity on receptive vocabulary, expressive vocabulary, and the rate of different words children produced through age 9. Conclusions Maternal responsivity, which is typically a variable of interest during early childhood, continues to be a significant variable, predicting vocabulary development through the middle childhood period. Thus, responsivity is a potential target for language interventions through this age period

Parenting Young Children with and Without Fragile X Syndrome

The purpose of this study was to examine maternal parenting styles across age-matched siblings using a within-family design, in which one child has Fragile X syndrome. Thirteen families participated; children were aged 16 to 71 months. Mothers completed several videotaped activities with each child separately as well as an interview. Mothers used a consistent, responsive style with both children, using the same degree of positive affect and warmth. Differences included using more behavior management strategies with the child with Fragile X and a conversational style of interaction with the sibling. Differences in approaches suggest the mothers adapted to the developmental differences between the children. The interview data supported these findings; mothers were aware of the changes made to accommodate the developmental differences

Inhibition Deficits Are Modulated by Age and CGG Repeat Length in Carriers of the \u3ci\u3eFMR1\u3c/i\u3e Premutation Allele Who Are Mothers of Children With Fragile X Syndrome

Individuals who carry a premutation (PM) allele on the FMR1 gene may experience executive limitations associated with their genetic status, including inhibition deficits. However, poor understanding of individualized risk factors has limited clinical management of this group, particularly in mothers who carry the PM allele who have children with fragile X syndrome (FXS). The present study examined CGG repeat length and age as factors that may account for variable expressivity of inhibition deficits. Participants were 134 carriers of the PM allele who were mothers of children with FXS. Inhibition skills were measured using both self-report and direct behavioral assessments. Increased vulnerability for inhibition deficits was observed at mid-range CGG lengths of approximately 80-100 repeats, with some evidence of a second zone of vulnerability occurring at approximately 130-140 CGG repeats. Risk associated with the genotype also became more pronounced with older age. This study identifies personalized risk factors that may be used to tailor the clinical management of executive deficits in carriers of the PM allele. Inhibition deficits may contribute to poor outcomes in carriers of the PM allele and their families, particularly in midlife and early old age, and clinical monitoring may be warranted

Maternal Responsivity Predicts Language Development in Young Children With Fragile X Syndrome

The relationship between early maternal responsivity and later child communication outcomes in young children with fragile X syndrome was investigated. Data were obtained from 55 mother–child dyads over a 36-month period. Performance data were obtained at each measurement point from video observations of four different contexts. These were coded for (a) child communication behaviors, (b) parent responsivity, and (c) behavior management behaviors. Results indicate that early maternal responsivity predicts the level of four important child language outcomes at 36 months of age after controlling for child developmental level and autism symptomology

Finishing the euchromatic sequence of the human genome

The sequence of the human genome encodes the genetic instructions for human physiology, as well as rich information about human evolution. In 2001, the International Human Genome Sequencing Consortium reported a draft sequence of the euchromatic portion of the human genome. Since then, the international collaboration has worked to convert this draft into a genome sequence with high accuracy and nearly complete coverage. Here, we report the result of this finishing process. The current genome sequence (Build 35) contains 2.85 billion nucleotides interrupted by only 341 gaps. It covers ∼99% of the euchromatic genome and is accurate to an error rate of ∼1 event per 100,000 bases. Many of the remaining euchromatic gaps are associated with segmental duplications and will require focused work with new methods. The near-complete sequence, the first for a vertebrate, greatly improves the precision of biological analyses of the human genome including studies of gene number, birth and death. Notably, the human enome seems to encode only 20,000-25,000 protein-coding genes. The genome sequence reported here should serve as a firm foundation for biomedical research in the decades ahead

The impact of autism spectrum disorder symptoms on gesture use in fragile X syndrome and Down syndrome

Background & aims This study compared gesture rate and purpose in participants with Down syndrome and fragile X syndrome, and the impact of autism spectrum disorder symptoms on each syndrome. Methods Twenty individuals with fragile X syndrome and 20 individuals with Down syndrome between nine and 22 years of age participated in this study. We coded gesture rate and purpose from an autism spectrum disorder evaluation, the Autism Diagnostic Observation Schedule – Second Edition. Results We did not find between-group differences (Down syndrome compared to fragile X syndrome) in gesture rate or purpose. Notably, as autism spectrum disorder symptoms increased, the group with Down syndrome produced a lower rate of gestures, but used gestures for the same purpose. Gesture rate did not change based on autism spectrum disorder symptoms in the participants with fragile X syndrome, but as autism spectrum disorder symptoms increased, the participants with fragile X syndrome produced a larger proportion of gestures to regulate behavior and a smaller proportion for joint attention/social interaction. Conclusions Overall, the amount or purpose of gestures did not differentiate individuals with Down syndrome and fragile X syndrome. However, the presence of autism spectrum disorder symptoms had a significant and unique impact on these genetic disorders. In individuals with Down syndrome, the presence of more autism spectrum disorder symptoms resulted in a reduction in the rate of gesturing, but did not change the purpose. However, in fragile X syndrome, the rate of gestures remained the same, but the purpose of those gestures changed based on autism spectrum disorder symptoms. Implications Autism spectrum disorder symptoms differentially impact gestures in Down syndrome and fragile X syndrome. Individuals with Down syndrome and more autism spectrum disorder symptoms are using gestures less frequently. Therefore, clinicians may need to consider children with Down syndrome demonstrating symptoms of autism spectrum disorder as distinctly different from children with Down syndrome and few to no symptoms of autism spectrum disorder when implementing interventions or therapy techniques. Severity of autism spectrum disorder symptoms in fragile X syndrome affects qualitative gesture use and motivation to communicate through social gestures, which may be an appropriate goal to target in children with fragile X syndrome and heightened autism spectrum disorder symptoms

Opportunities to Respond During Dyadic Caregiver-Child and Naturalistic Family Interactions among Children with Down Syndrome: A Preliminary Investigation

Preprint and supplemental materials related to AJSLP manuscript submissio

Opportunities to Respond During Dyadic Caregiver-Child and Naturalistic Family Interactions among Children with Down Syndrome: A Preliminary Investigation

Purpose: Dyadic caregiver-child interactions are commonly used to examine children's language learning environments. However, children frequently interact with multiple caregivers and/or siblings if they come from homes with multiple caregivers and siblings. Thus, we examined if and how caregiver opportunities to respond (OTRs) varied when sampled across three interaction configurations. Method: Twelve children with Down syndrome (DS; mean age = 40.82 months) and their biological parents participated in the current study. We collected separate mother-child and father-child dyadic interactions, and one family choice interaction (i.e., both caregivers present and occasionally siblings) in families' homes. We analyzed if differences in the caregiver’s OTR frequency and type—explicit and implicit—existed among dyadic and family choice configurations. Results: We found that, during family choice interactions, children were exposed to fewer OTRs when combining the total number of father and mother OTRs compared to dyadic caregiver-child interactions. This effect was large for explicit OTRs (mother-dyadic vs. combined family choice: g = -1.99, CI [-3.00, -1.00]; father-dyadic vs. combined family choice: g = -0.84, CI [-1.84, -0.11]). For implicit OTRs, effects were small for mother-dyadic versus combined family choice (g = -0.34, CI [-1.17, 0.48]) and negligible when comparing father-dyadic with combined family choice (g = -0.08, CI [-0.90, 0.73]). Conclusions: Our preliminary findings highlight the need for a more nuanced understanding of children's language learning environments to better understand how caregivers support their children's language development