Background: Molecular genetics, one of the most energetic and exciting areas of science, is slowly but surely coming to educational psychology.
Aims: We review recent molecular genetic research on learning disabilities as a sign of things to come in educational psychology. We also consider some misconceptions about genetics that have slowed the acceptance of genetics in educational psychology.
Samples: Diverse samples of children with learning disabilities have been studied, primarily in the UK and the USA.
Methods: Linkage analysis can detect genes that have large effects on learning disabilities. Association analysis can detect genes of much smaller effect size, which is important because common disorders such as learning disabilities are likely to be influenced by many genes as well as by many environmental factors.
Results: For reading disability, replicated linkages have been identified on chromosomes 6, 15 and 18. A gene responsible for a rare type of language impairment has recently been identified. For common language impairment, linkages on chromosomes 16 and 19 have recently been reported. More than 200 genetic disorders, most extremely rare, include mental retardation among their symptoms, and chromosomal abnormalities are a major cause of mental retardation.
Conclusions: Although finding specific genes associated with learning disabilities is unlikely to have much of a direct application for teachers in the classroom, such findings will have far-reaching implications for diagnosis, treatment and prevention of learning disabilities and for research in educational psychology. Educational psychology has been slower to accept evidence for the importance of genetics than other areas of psychology in part because of misconceptions about what it means to say that genetics is important for common complex disorders such as learning disabilities.