Article comprehension in monolingual Spanish-speaking children with developmental language disorder: A longitudinal eye tracking study.

PURPOSE: Article-noun disagreement in spoken language is a marker of children with developmental language disorder (DLD). However, the evidence is less clear regarding article comprehension. This study investigates article comprehension in monolingual Spanish-speaking children with and without DLD. METHOD: Eye tracking methodology used in a longitudinal experimental design enabled the examination of real time article comprehension. The children at the time 1 were 40 monolingual Spanish-speaking preschoolers (20 with DLD and 20 with typical language development [TLD]). A year later (time 2), 27 of these children (15 with DLD and 12 with TLD) were evaluated. Children listened to simple phrases while inspecting a four object visual context. The article in the phrase agreed in number and gender with only one of the objects. RESULT: At the time 1, children with DLD did not use articles to identify the correct image, while children with TLD anticipated the correct picture. At the time 2, both groups used the articles' morphological markers, but children with DLD showed a slower and weaker preference for the correct referent compared to their age-matched peers. CONCLUSION: These findings suggest a later emergence, but a similar developmental trajectory, of article comprehension in children with DLD compared to their peers with TLD.

The Genetic Population Structure of Robinson Crusoe Island, Chile.

Studies examining genetic conditions common in Latin America are highly underrepresented in the scientific literature. Understanding of the population structure is limited, particularly Chile, in part due to the lack of available population specific data. An important first-step in elucidating disease mechanisms in Latin America countries is to understand the genetic structure of isolated populations. Robinson Crusoe Island (RCI) is a small land mass off the coast of Chile. The current population of over 900 inhabitants are primarily descended from a small number of founders who colonized the island in the late 1800s. Extensive genealogical records can trace the ancestry of almost the entire population. We perform a comprehensive genetic analysis to investigate the ancestry of the island population, examining ancestral mitochondrial and Y chromosome haplogroups, as well as autosomal admixture. Mitochondrial and Y chromosome haplogroups indicated a substantial European genetic contribution to the current RCI population. Analysis of the mitochondrial haplogroups found in the present-day population revealed that 79.1% of islanders carried European haplogroups, compared to 60.0% of the mainland Chilean controls from Santiago. Both groups showed a substantially lower contribution of indigenous haplogroups than expected. Analysis of the Y chromosome haplogroups also showed predominantly European haplogroups detected in 92.3% of male islanders and 86.7% of mainland Chilean controls. Using the near-complete genealogical data collected from the RCI population, we successfully inferred the ancestral haplogroups of 16/23 founder individuals, revealing genetic ancestry from Northern and Southern Europe. As mitochondrial and Y investigations only provide information for direct maternal and paternal lineages, we expanded this to investigate genetic admixture using the autosomes. Admixture analysis identified substantial indigenous genetic admixture in the RCI population (46.9%), higher than that found in the Santiago mainland Chilean controls (43.4%), but lower than a more representative Chilean population (Chile_GRU) (49.1%). Our study revealed the Robinson Crusoe Island population show a substantial genetic contribution for indigenous Chileans, similar to the level reported in mainland Chileans. However, direct maternal and paternal haplogroup analysis revealed strong European genetic contributions consistent with the history of the Island.

The impact of vocabulary, grammar and decoding on reading comprehension among children with SLI: a longitudinal study.

Predictors of reading comprehension among children with SLI have been rarely studied in Spanish. Even more sparse are longitudinal studies inspecting the evolution of their reading abilities. The aim of the present study is to inspect how decoding, production of grammatical/ungrammatical sentences, production of simple/complex sentences, and vocabulary (measured with two instruments) predict reading comprehension among Spanish-speaking monolingual school-age children with SLI in two grades: 2nd grade and 4th grade. Forty-eight children were recruited for this study, evenly grouped in two conditions: SLI and Typical. Groups were balanced by gender with no differences in months of age. All children were assessed twice: when in 2nd grade and when in 4th grade. Several multiple regression analyses were conducted. Findings revealed differences in terms of which particular predictors significantly impacted reading comprehension in each group. Vocabulary and syntax complexity are the most consistent predictors of reading performance. Decoding predicted reading comprehension performance only in the observed early stage (2nd grade), becoming non-significant over time. Grammaticality was found to have no impact on reading comprehension in both groups. Reported results suggest that vocabulary and complex syntax solidly predict reading comprehension, while decoding and grammaticality play a minor or even negligible role. Thus, interventions designed to improve reading comprehension among children with SLI might benefit from targeting these two particular dimensions of language.

Habilidades lingüísticas y decodificación en niños con trastorno específico del lenguaje con y sin dificultades de comprensión lectora / Linguistic skills and decoding among children with specific language impairment with and without reading comprehension difficulties

Los niños con TEL son considerados un grupo de riesgo para el aprendizaje del lenguaje escrito, dado que sus dificultades lingüísticas pueden influir en su desempeño en comprensión lectora, aunque esto no necesariamente ocurre en todos los niños con TEL. El objetivo de este estudio es comparar el desempeño en las habilidades lingüísticas y decodificación entre niños con TEL que se agruparon según la presencia o ausencia de dificultades en comprensión lectora. La muestra estuvo constituida por 60 niños con TEL de primer año básico, 42 de ellos con problemas de comprensión lectora y 18 niños que no presentaban dificultad en este aspecto. Se evaluaron habilidades lectoras (decodificación y comprensión lectora) y habilidades lingüísticas (conciencia fonológica, vocabulario y discurso narrativo expresivo y comprensivo). Los resultados muestran que no existen diferencias estadísticamente significativas en las habilidades lingüísticas entre niños con y sin dificultades de comprensión lectora. En cuanto a la decodificación, se observa un rendimiento significativamente inferior en el grupo de niños con dificultades de comprensión lectora. En este grupo, conciencia fonológica y decodificación están altamente correlacionadas con la comprensión lectora, mientras que estas mismas variables no se correlacionan en los niños sin problemas de comprensión lectora.

Children with Specific Language Impairment (SLI) are deemed to be a group at risk in learning written language. Their linguistic deficit may impact on their reading comprehension performance, although this not the case for all children with SLI. The aim ofthis study is to observe the possible differences in linguistic and decoding skills in children with SLI with and without reading comprehension problems. The sample consisted of 60 first grade children with SLI, of which 42 are poor comprehenders and 18 are good comprehenders. Reading skills (decoding and reading comprehension) and linguistic skills (phonological awareness, vocabulary as well as expressive and comprehensive narrative speech) were assessed. Results show that there are no statistically significant differences in linguistic skills between good comprehenders and poor comprehender. Significant differences were found for decoding, with children with reading comprehension problems performing significantly lower than good comprehenders. In the group of children with reading comprehension problems, phonological awareness and decoding highly correlate with reading comprehension, while the very same variables have no correlation among children with good reading comprehension.

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.

Exome sequencing in an admixed isolated population indicates NFXL1 variants confer a risk for specific language impairment.

Children affected by Specific Language Impairment (SLI) fail to acquire age appropriate language skills despite adequate intelligence and opportunity. SLI is highly heritable, but the understanding of underlying genetic mechanisms has proved challenging. In this study, we use molecular genetic techniques to investigate an admixed isolated founder population from the Robinson Crusoe Island (Chile), who are affected by a high incidence of SLI, increasing the power to discover contributory genetic factors. We utilize exome sequencing in selected individuals from this population to identify eight coding variants that are of putative significance. We then apply association analyses across the wider population to highlight a single rare coding variant (rs144169475, Minor Allele Frequency of 4.1% in admixed South American populations) in the NFXL1 gene that confers a nonsynonymous change (N150K) and is significantly associated with language impairment in the Robinson Crusoe population (p = 2.04 × 10-4, 8 variants tested). Subsequent sequencing of NFXL1 in 117 UK SLI cases identified four individuals with heterozygous variants predicted to be of functional consequence. We conclude that coding variants within NFXL1 confer an increased risk of SLI within a complex genetic model.

Consanguinity on Robinson Crusoe Island, an isolated Chilean population.

The population of Robinson Crusoe Island is estimated at 633 inhabitants. The current population has a common origin from the first eight families who colonized the island at the end of the 19th century. The objective of this study was to determine the rates of consanguinity, the average coefficients of inbreeding, the types of consanguineous marriages and the inbreeding evolution between 1900 and 2000 on the island. All marriages registered on the island, from the last colonization until 2000 (417 in total), were included in the analysis. In addition, extended genealogies were obtained. The consanguinity rate was 14.9% and the average coefficient of inbreeding (α) 54.05 × 10(-4). The most frequent type of consanguineous marriages was between second cousins, followed by first cousins. The average value of the first/second cousin ratio was 1.11. The population of Robinson Crusoe Island has a high rate of inbreeding. The unique characteristic of the island - its small current population, originating from just a few families, with small rate of gene flow - could explain the observed high and increasing consanguinity.

Genome-wide analysis of genetic susceptibility to language impairment in an isolated Chilean population.

Specific language impairment (SLI) is an unexpected deficit in the acquisition of language skills and affects between 5 and 8% of pre-school children. Despite its prevalence and high heritability, our understanding of the aetiology of this disorder is only emerging. In this paper, we apply genome-wide techniques to investigate an isolated Chilean population who exhibit an increased frequency of SLI. Loss of heterozygosity (LOH) mapping and parametric and non-parametric linkage analyses indicate that complex genetic factors are likely to underlie susceptibility to SLI in this population. Across all analyses performed, the most consistently implicated locus was on chromosome 7q. This locus achieved highly significant linkage under all three non-parametric models (max NPL = 6.73, P = 4.0 × 10(-11)). In addition, it yielded a HLOD of 1.24 in the recessive parametric linkage analyses and contained a segment that was homozygous in two affected individuals. Further, investigation of this region identified a two-SNP haplotype that occurs at an increased frequency in language-impaired individuals (P = 0.008). We hypothesise that the linkage regions identified here, in particular that on chromosome 7, may contain variants that underlie the high prevalence of SLI observed in this isolated population and may be of relevance to other populations affected by language impairments.

Proceso de innovación curricular en la Facultad de Medicina de la Universidad de Chile / Process of curricular innovation in the Medicine Faculty of the University of Chile

During the year 2006, the Faculty of Medicine started a process of curricular innovation in its eight schools. For that aim it was decided to implement a competency-based curriculum, thus defining a conceptual framework to guide changes. To organize the new system a Central Commission was established, with sub commissions in the units to collect and assure the participation of all relevant actors involved. As a main task for academicformation, it has been restudied and proposed the actualized graduate profiles for each school. A common training that identifies our professionals, constitutes a seal of our Faculty. To achieve the expected changes is essential to have an institutionalpolitical framework and the full commitment of the authorities, academic and student community to this project. To give guarantee to the quality and accomplishment of this process is essential; therefore, there must be internal and external controls tomonitor each of the stages to be covered with eagerness and success.

[High prevalence of specific language impairment in Robinson Crusoe Island. A possible founder effect]. / Alta prevalencia de trastorno específico de lenguaje en isla Robinson Crusoe y probable efecto fundador.

BACKGROUND: Specific language impairment (SLI) occurs in 2% to 8% of preschool children. Major and candidate genes are probably involved. Genetic drift is a cause for the presence of high frequencies of deleterious alíeles of a specific disease and the founder effect is one of its forms. Robinson Crusoe Island has 633 inhabitants and its actual population began with 8 families that repopulated the island at the end of XIXth century. AIM: To assess the frequency of specific language impairment among children living in Robinson Crusoe Island. MATERIAL AND METHODS: All 66 children aged between 3 and 9 years living in the island, were studied. Parents were interviewed and in children, non verbal intelligence, audiometric parameters, comprehension and expression of oral language were assessed. Extended genealogies were also performed. RESULTS: Forty children had at least one parent that was descending of founder families. Among these, 35% had SLI. Eighth five percent of SLI affected children came from the same colonizer family. CONCLUSIONS: The prevalence of SLI in Robinson Crusoe Island is higher than that reported in mainland Chile and abroad. This high prevalence, associated to a high frequency of consanguinity, supports the influence of genetic mechanisms in SLI transmission, based on a founder effect.

La escritura en niños con trastorno específico de lenguaje desde una perspectiva psicogenética / The handwriting in children with specific language disorder from a psychogenetic perspective

El propósito del presente trabajo es conocer el desempeño escrito que tienen los niños con Trastorno Específico del Lenguaje (TEL). Este estudio se basa en la Teoría Psicogenética que propone que el lenguaje escrito comienza a desarrollarse en etapas previas a su enseñanza formal. Se confeccionó una pauta que incluye una serie de tareas para elicitar la escritura y criterios que permiten analizarla. Se compararon las producciones escritas de niños con TEL expresivo con las realizadas por niños sin problemas de lenguaje. Los resultados indican que los niños con TEL expresivo presentan un desarrollo similar al del grupo control, pero más lento. Además, se observó que los niños con TEL que tenían dificultades en la fonología y en la morfosintaxis evidenciaban un desempeño inferior en la escritura que los menores que solo presentaban trastorno fonológico.

Bases genéticas del trastorno específico del lenguaje / Genetic basis of specific language disorder

El propósito del presente trabajo es ofrecer una revisión de la evidencia existente sobre las bases genéticas del trastorno específico del lenguaje (TEL). Estudios de afiliación, de comparación en mellizos monocigóticos y dicigóticos con TEL, y de genealogía indican que esta condición presenta una alta heredabilidad o transmisión genética. Además, estudios de ligamiento y análisis molecular aportan evidencia sobre la localización de algunos genes involucrados en la condición. Regiones de los cromosomas 7,13,16 y 19 parecen ser los mejores candidatos. Estos últimos hallazgos han sido posibles gracias a avances en el diagnóstico del TEL. El mejor criterio parece ser la búsqueda de marcadores fenotípicos o indicadores clínicos precisos del TEL. De acuerdo con lo anterior, se discuten las proyecciones de los hallazgos señalados.