Children whose experiences with early reading (e.g. preschool) are limited or of poor quality are at risk for reading failure. Dyslexia refers to reading that is impaired due to developmental neural and genetic anomalies that affect this skill, It focuses on reading impairments that are neurobiological and genetic rather than environmental. The proximal causes are impairments in cognitive, perceptual or motor functions that affects components of reading. Dysfluencies in reading words can arise from several causes (e.g. slow recognition of letter combinations). Genetics can contribute to understanding reading disorders by specifying mechanisms that influence brain development in ways that underlie the proximal causes. Dyslexia is also associated with several types of anomalies in the structure and function of the neural systems for reading. There are several common behaviours in children with dyslexia:PhonologyThe impaired performance on phonemic tasks includes deletion (1), matching (2) and blending (3). Reading aloudThe performance is often slow, dysfluent and error-prone. There is particular difficulty with irregularly pronounced words. Processing speedThe performance is often slow when it comes to naming familiar digits, colours and objects. OrthographyThe limited knowledge of orthographic structure expresses itself in difficulty distinguishing valid from invalid letter strings (1), weak knowledge of word spellings (2), misspellings (3), misidentification (4) and dysfluency in generating spellings (5). Working memoryThere is a deficit on working memory tasks.LanguageThere is a limit on vocabulary size and lexical quality (1), familiarity with a narrower range of sentence structures and expressions (2) and difficulty reading texts aloud with appropriate intonation (3). It was important to distinguish reading difficulties that result from a general intellectual impairment from readings-specific ones. There is no consensus...