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Free Content Interrelationship and Familiality of Dyslexia Related Quantitative Measures

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Dyslexia is a complex gene-environment disorder with poorly understood etiology that affects about 5% of school-age children. Dyslexia occurs in all languages and is associated with a high level of social and psychological morbidity for the individual and their family; approximately 40-50% have persistent disability into adulthood. The core symptoms are word reading and spelling deficits, but several other cognitive components influence the core phenotype.

A broad spectrum of dyslexia related phenotypes, including phonological decoding, phoneme awareness, orthographic processing, short-term memory, rapid naming and basic mathematical abilities, were investigated in large sample of 287 German dyslexia families. We explored the interrelationship between the component phenotypes using correlation and principal component analyses (PCA). In addition, we estimated familiality for phenotypes as well as for the factors suggested by PCA.

The correlation between the component phenotypes varied between −0.1 and 0.7. The PCA resulted in three factors: a general dyslexia factor, a speed of processing factor and a mathematical abilities factor. The familiality estimates of single components and factors ranged between 0.25 and 0.63.

Instead of analyzing single dyslexia-related components, multivariate analyses including factor analytic approaches may help in the identification of susceptibility genes.
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Keywords: chromosome 18; dyslexia; familiality; genetics; heritability; linkage; principal component analysis

Document Type: Research Article

Affiliations: 1: Institute of Medical Biometry and Statistics, University Hospital Schleswig-Holstein - Campus Lübeck, Lübeck, Germany 2: Department of Child and Adolescent Psychiatry and Psychotherapy, University of Marburg, Marburg, Germany 3: Institute of Human Genetics, University of Bonn, Bonn, Germany 4: Department of Child and Adolescent Psychiatry and Psychotherapy, University of Würzburg, Würzburg, Germany 5: Department of Genomics, Life & Brain Center, University of Bonn, Bonn, Germany

Publication date: March 1, 2007

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