Public Release: 

Reading ability and ADHD affected by same genes

Molecular Psychiatry

Attention deficit hyperactivity disorder (ADHD) and reading disability (RD) are common disorders of childhood that often co-occur. About 20-25% of children and adolescents with ADHD have a reading disability but the cause of this association is unknown. Twin and family studies suggest that genes, strongly indicated for both conditions, may underlie their association.

In a systematic genome-wide investigation of reading ability in a sample of 233 siblings diagnosed with ADHD, four chromosomal regions emerged as potential locations for genes underlying reading ability. Reading ability was measured by three types of reading tests including a spelling task, a reading recognition task, and a reading comprehension task. Because performance on all three measures was highly correlated, a reading factor representing performance on all three was used in the analysis, as well as the individual test scores. A dense set of highly informative molecular markers covering the human genome at about a 10cM density was used to investigate linkage. Linkage was determined based on increased sharing of molecular markers across the 233 sibling pairs against that expected for siblings due to their degree of genetic relationship.

Four regions found on chromosomes 2p, 10q, 16p, and 17q, showed suggestive evidence for linkage. Three of the locations (10q, 16p, 17q) overlapped regions suggested from previous investigations of ADHD and one region (2p) overlapped that suggested from previous studies of RD. These findings support the idea that common genes may underlie ADHD and RD but also that reading ability and RD have genetic underpinnings that differ from those underlying ADHD as well. However, since each region that overlaps ADHD and reading ability harbors hundreds of genes, further work is required to identify specific genetic variants underlying ADHD and RD and to determine if they are actually the same or different.


ARTICLE: "Genome-wide scan of reading ability in affected sibling pairs with attention-deficit/hyperactivity disorder: unique and shared genetic effects"

AUTHORS: Sandra K. Loo, Simon E. Fisher, Clyd Francks, Matt N. Ogdie, I.Lawrence MacPhie, May Yang, James T. McCracken, James J. McGough, Stanley F. Nelson, Anthony P. Monaco, Susan L. Smalley

Center for Neurobehavioral Genetics, University of California, Los Angeles, USA; Wellcome Trust Centre for Human Genetics, University of Oxford, Oxford, UK; Department of Human Genetics, UCLA, Los Angeles, CA, USA; Department of Psychiatry and Biobehavioral Sciences, University of California, Los Angeles, USA

Citation source: Molecular Psychiatry advance online publication, December 2003. (doi:10.1038/

For further information on this work, please contact Sandra K. Loo, Ph.D., Neuropsychiatric Research Institute, 760 Westwood Plaza, Los Angeles, CA 90024. Phone: 310-825-9204; Fax: 310-206-4446; Email:

Molecular Psychiatry is published by the Nature Publishing Group.

Editor: Julio Licinio, M.D.; phone: 310-825-7113; FAX: 310-206-6715; e-mail:

For a copy of this article, please contact Aimee Midei, Editorial Assistant, e-mail:


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