Learning written language in the case of Williams' syndrome

Williams syndrome (WS), a rare genetic disorder with intellectual disability, is a better opportunity to understand the evolution of phonological and visual precursors contributing to the reading mechanisms activation. A part of the variability of access to written code can be explain by independent phonological and visual-spatial deficits in the syndrome, despite the relative preservation of the lexicon. Using a multidimensional approach, the aim of this three-year longitudinal study was to identify the nature and evolution of phonological and visual precursors recognized as contributing to the good development of written code skills. We met 7 young people with WS aged 5 to 8 years matched, case-by-case, to 30 typical control children according to sex and chronological age. Several tasks were administered to assess code knowledge and its phonological precursors (epi- and meta-phonology, auditory-verbal memory, and rapid naming) and visual (visuospatial reasoning and visual attention). The results indicate that the atypical and delayed evolution of certain precursors leads to a time lag in the activation of the reading mechanisms and, consequently, of the developmental trajectories in the written code mastery in this syndrome. The discussion will focus on a possible classification of developmental trajectories, according to a multidimensional approach of the variabilities observed in the access to written code.