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. 2012 Jun 1;22(3):365-369.
doi: 10.1016/j.lindif.2012.01.011. Epub 2012 Feb 16.

Genetic and environmental etiologies of reading difficulties: DeFries-Fulker analysis of reading performance data from twin pairs and their nontwin siblings

Raven L Astrom  1 , Sally J Wadsworth, Richard K Olson, Erik G Willcutt, John C Defries
Affiliations

Genetic and environmental etiologies of reading difficulties: DeFries-Fulker analysis of reading performance data from twin pairs and their nontwin siblings

Raven L Astrom et al. Learn Individ Differ. .

Abstract

Reading performance data from 254 pairs of identical (MZ) and 420 pairs of fraternal (DZ) twins, 8.0 to 20.0 years of age, were subjected to multiple regression analyses. An extension of the DeFries-Fulker (DF) analysis (DeFries & Fulker, 1985, 1988) that facilitated inclusion of data from 303 of their nontwin siblings was employed. In addition to providing estimates of heritability, this analysis yields a test of the difference between shared environmental influences for twins versus siblings (Astrom et al., 2011). Results suggest that proband reading deficits are due substantially to genetic factors (.67 ± .07, p < .001), and that shared environmental influences are significantly higher for members of twin pairs than for those of twins and their nontwin siblings (viz., .25 versus .17, p = .02).

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Figures

Figure 1
Figure 1
Hypothetical distributions of reading performance of an unselected sample of twins (with mean μ) and of the identical (MZ) and fraternal (DZ) co-twins of probands with a reading disability. Proband and co-twin means are symbolized P̄ and C̄, respectively. The deficit of probands (P̄ − μ) is due to heritable influences (h2g) and to environmental influences that are either shared (c2g) or not shared (e2g) by members of twin pairs. The differential regression of the MZ and DZ co-twin means toward the mean of the unselected population (μ) provides a test of genetic etiology (After DeFries and Fulker, 1988).
Figure 2
Figure 2
Transformed proband, and co-twin and co-sib means.
See this image and copyright information in PMC

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References

    1. Astrom R, Wadsworth SJ, DeFries JC. Etiology of the stability of reading difficulties: The Longitudinal Twin Study of Reading Disabilities. Twin Res & Hum Gen. 2007;10:434–439. - PubMed
    1. Astrom RL, Wadsworth SJ, Olson RK, Willcutt EG, DeFries JC. DeFries-Fulker analysis of longitudinal reading performance data from twin pairs ascertained for reading difficulties and from their nontwin siblings. Behavior Genetics. 2011;41:660–667. - PMC - PubMed
    1. Bakwin H. Reading disability in twins. Dev Med Child Neurol. 1973;15:184–187. - PubMed
    1. Decker SN, Vandenberg SG. Colorado Twin Study of Reading Disability. In: Gray DB, Kavanagh JF, editors. Biobehavioral measures of dyslexia. Parkton, MD: York Press; 1985.
    1. DeFries JC. Colorado Reading Project. In: Gray DB, Kavanagh JF, editors. Biobehavioral measures of dyslexia. Parkton, MD: York Press; 1985. pp. 107–122.

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