Genetics of dyslexia

Dyslexia is a common disorder of reading and spelling which can negatively affect the development and attainment of school-aged children, with deficits emerging in early childhood and persisting into adulthood. The unstable definition of dyslexia poses challenges for identifying dyslexia and for research. Family studies show a familial aggregation of dyslexia, with twin studies estimating the heritability (the proportion of total variance due to genes) at around 40–60%. Genetic linkage and association methods focussing on high-risk families led the way in genetic research aiming to localise chromosomal regions and candidate genes associated with dyslexia, although with mixed success. Genome-wide association studies have recently made important genetic discoveries in dyslexia, revealing its polygenic nature and identifying genes and biological pathways, many of which were successfully replicated in independent samples. The potential to construct polygenic scores that predict the development of dyslexia may offer a new route for earlier and more refined diagnosis in future.