The changing role of gesture in linguistic development : a developmental trajectory and a cross-cultural comparison between British and Finnish children.

We studied how gesture use changes with culture, age and increased spoken language competence. A picture-naming task was presented to British (N = 80) and Finnish (N = 41) typically developing children aged 2–5 years. British children were found to gesture more than Finnish children and, in both cultures, gesture production decreased after the age of two. Two-year-olds used more deictic than iconic gestures than older children, and gestured more before the onset of speech, rather than simultaneously or after speech. The British 3- and 5-year-olds gestured significantly more when naming praxic (manipulable) items than non-praxic items. Our results support the view that gesture serves a communicative and intrapersonal function, and the relative function may change with age. Speech and language therapists and psychologists observe the development of children’s gestures and make predictions on the basis of their frequency and type. To prevent drawing erroneous conclusions about children’s linguistic development, it is important to understand developmental and cultural variations in gesture use.Peer reviewe

Joubert Syndrome: A Model for Untangling Recessive Disorders with Extreme Genetic Heterogeneity

Background Joubert syndrome (JS) is a recessive neurodevelopmental disorder characterised by hypotonia, ataxia, cognitive impairment, abnormal eye movements, respiratory control disturbances and a distinctive mid-hindbrain malformation. JS demonstrates substantial phenotypic variability and genetic heterogeneity. This study provides a comprehensive view of the current genetic basis, phenotypic range and gene-phenotype associations in JS. Methods We sequenced 27 JS-associated genes in 440 affected individuals (375 families) from a cohort of 532 individuals (440 families) with JS, using molecular inversion probe-based targeted capture and next-generation sequencing. Variant pathogenicity was defined using the Combined Annotation Dependent Depletion algorithm with an optimised score cut-off. Results We identified presumed causal variants in 62% of pedigrees, including the first B9D2 mutations associated with JS. 253 different mutations in 23 genes highlight the extreme genetic heterogeneity of JS. Phenotypic analysis revealed that only 34% of individuals have a 'pure JS' phenotype. Retinal disease is present in 30% of individuals, renal disease in 25%, coloboma in 17%, polydactyly in 15%, liver fibrosis in 14% and encephalocele in 8%. Loss of CEP290 function is associated with retinal dystrophy, while loss of TMEM67 function is associated with liver fibrosis and coloboma, but we observe no clear-cut distinction between JS subtypes. Conclusions This work illustrates how combining advanced sequencing techniques with phenotypic data addresses extreme genetic heterogeneity to provide diagnostic and carrier testing, guide medical monitoring for progressive complications, facilitate interpretation of genome-wide sequencing results in individuals with a variety of phenotypes and enable gene-specific treatments in the future.WoSScopu