Developmental dyslexia: an update

Abstract

Dyslexia is the most common and carefully studied of the learning disabilities in school-age children. It is characterized by a marked impairment in the development of reading skills, and affects a large number of people (5-10%). Reading difficulties may also arise from poor vision, emotional problems, decreased hearing ability, and behavioral disorders, such as attention-deficit hyperactivity (ADHD). Although many areas of the brain are involved in reading, analysis of postmortem brain specimens by a variety of imaging techniques most consistently suggests that deficiency within a specific component of the language system-the phonologic module-in the temporo-parietal-occipital brain region underlies dyslexia. It is a highly familial and heritable disorder with susceptibility loci on chromosomes 1, 2, 3, 6, 11, 13, 15 and 18. Recently, four candidate genes (KIAA 0319, DYX1C1, DCDC2 and ROBO1) are shown to be associated with dyslexia. Although some of these results are controversial because of the genetic heterogeneity of the disorder, the available evidence suggests that dyslexia could be due to the abnormal migration and maturation of neurons during early development. Interestingly, in spite of genetic heterogeneity, the pathology appears to involve common phonological coding deficits. The condition can be managed by a highly structured educational training exercise.

A common haplotype of KIAA0319 contributes to the phonological awareness skill in Chinese children

“…It is the most common form of learning disability and affects 5-17% of western populations [1]. Several putative loci ( DYX1 – DYX9 ) and candidate genes ( KIAA0319, DYX1C1, DCDC2 and ROBO1 ) [2] have been identified in DD including the recent findings of the MRPL19/C2ORF3 genes of DYX3 locus and the GRIN2B gene [3,4]. …”

Endocytosis Regulates Cell Soma Translocation and the Distribution of Adhesion Proteins in Migrating Neurons

“…Disruptions in migration have been implicated in neurological disorders such as epilepsy, mental retardation, schizophrenia, and dyslexia [1], [2], [3]. Many of these disruptions are linked to cytoskeletal dysregulation, which impairs the directed motility of migrating neurons and prevents them from reaching their final destination.…”

A thirteen‐year follow‐up study of young Norwegian adults with dyslexia in childhood: reading development and educational levels

“…n the ICD-10 and DSM-IV classification systems dyslexia is grouped among the specific developmental and learning disorders, affecting 2-10% of school children (Beitchman & Young, 1997;Shastry, 2007;Snowling, 2000). These definitions are based on exclusion of factors like insufficient education, brain damage or mental retardation as causes for reading problems.…”