Interrelationship and Familiality of Dyslexia Related Quantitative Measures

Abstract

SummaryDyslexia 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.

Genetic analysis of dyslexia candidate genes in the European cross-linguistic NeuroDys cohort

“…Third, one limitation of this study is that we have not included measures that cover the whole spectrum of dyslexia-related traits. 38,47 Previous association studies have reported an association between some of the herein reported genes and phonological processing, orthographic awareness, auditory memory, and rapid naming. 38 The missing analysis of relevant subtypes, quantitative measures, or the severity of dyslexia could be a further factor for the lack of association in this study.…”

Investigation of interaction between DCDC2 and KIAA0319 in a large German dyslexia sample

“…The dyslexia core phenotype, however, might differ between languages. On the cognitive level, for example, various processes such as phonological decoding, phoneme awareness or orthographic processing are involved in the dyslexia core phenotype (Ramus et al 2003;Schulte-Körne et al 2007). Languages of different transparencies, such as German and English, differently apply at least some of these distinct processes.…”

“…Our sample consisted of 244 German families with a severely affected child showing a discrepancy of at least 2 SD between expected and observed spelling score. The inclusion criteria and phenotypic measures have been previously described (Schulte-Körne et al 2007). Genotyping was performed using the iPlex-assay by Sequenom TM , and analytes were measured with a MALDI-TOF (matrix-assisted-laser desorption/ionisation time-offlight) mass spectrometry system (Bruker Daltonics).…”

Supporting evidence for LRRTM1 imprinting effects in schizophrenia

“…They found the three-marker haplotype to be paternally associated with human handedness in a set of reading-disabled sibships. We have access to a well-characterized dyslexia sample of German descent for which information on handedness is available (398 sib pairs with parents), 6 and analyzed the aforementioned 14 markers. Using the quantitative trait disequilibrium test QTDT, 7 seven markers out of 14 had nominally significant P-values < 0.05.…”