DeFries-Fulker analysis of longitudinal reading performance data from twin pairs ascertained for reading difficulties and from their nontwin siblings.
Reading difficulties are both heritable and stable; however, little is known about the etiology of this stability. Results from a preliminary analysis of data from 56 twin pairs who participated in the Colorado Longitudinal Twin Study of Reading Disability (Astrom et al., Twin Res Hum Genet 10:434-439, 2007) suggested that about two-thirds of the proband deficit at follow-up was due to genetic factors that also influenced deficits at their initial assessment. Although our proband sample is now nearly twice as large, it is still relatively small; thus, to increase power, we subjected data from probands, co-twins and their nontwin siblings to a novel extension of DeFries-Fulker analysis (DeFries and Fulker, Behav Genet 15:467-473, 1985; DeFries and Fulker, Acta Genet Med Gemellol, 37, 205-216, 1988). In addition to providing estimates of univariate and bivariate heritability, this analysis facilitates a test of the difference between shared environmental influences for twins versus siblings. Longitudinal composite reading performance scores at 10.6 and 15.5 years of age, on average, were analyzed from 33 MZ and 64 DZ twin pairs in which at least one member of each pair had reading difficulties, and from 44 siblings of the probands. Scores were highly stable (.86 ± .03, across probands, co-twins and siblings) and heritability of the group deficit at initial assessment was .67 ± .22. Longitudinal bivariate heritability was .59 ± .21, suggesting that nearly 60% of the proband reading deficit at follow-up is due to genetic factors that influenced reading difficulties at the initial assessment. However, tests for special twin environmental influences were nonsignificant.
Institute for Behavioral Genetics, University of Colorado, 447 UCB, Boulder, CO 80309, USA. raven.astrom@colorado.edu
Raven L
RL
Astrom
Sally J
SJ
Wadsworth
Richard K
RK
Olson
Erik G
EG
Willcutt
John C
JC
DeFries
D000293:Adolescent; D016022:Case-Control Studies; D002648:Child; D003120:Colorado; D004200:Diseases in Twins; D004410:Dyslexia / Q000175:diagnosis / Q000235:genetics*; D005260:Female; D020022:Genetic Predisposition to Disease; D006801:Humans; D007859:Learning Disabilities / Q000175:diagnosis / Q000235:genetics*; D008297:Male; D015233:Models, Statistical; D011932:Reading; D012044:Regression Analysis; D012574:Schools; D013997:Time Factors; D014429:Twins, Dizygotic; D014430:Twins, Monozygotic
Ann Dyslexia. 2013 Apr;63(1):25-43
21842316
Acta Genet Med Gemellol (Roma). 1988;37(3-4):205-16
3254013
Twin Res. 2003 Apr;6(2):119-30
12723998
Dev Psychol. 1998 Nov;34(6):1373-99
9823518
Twin Res. 2003 Apr;6(2):97-105
12723996
Psychol Sci. 2008 Nov;19(11):1124-30
19076484
Sci Stud Read. 2011;15(1):26-46
21132077
Ann Dyslexia. 1988 Jan;38(1):120-30
24235036
Behav Genet. 2006 Jul;36(4):603-15
16619135
Read Writ. 2007 Feb 1;20(1-2):127-146
19829751
Child Dev. 1983 Apr;54(2):388-95
6872630
Psychol Med. 2007 Nov;37(11):1635-44
17592667
Dev Neuropsychol. 2001;20(2):465-81
11892948
J Child Psychol Psychiatry. 2005 Apr;46(4):373-84
15819646
Sci Stud Read. 2010 Mar 1;14(2):111-136
20563241
Acta Genet Stat Med. 1966;16(3):265-75
4959152
N Engl J Med. 1992 Jan 16;326(3):145-50
1727544
Ann Dyslexia. 2007 Dec;57(2):139-60
18060583
J Child Psychol Psychiatry. 1987 Mar;28(2):229-47
3584294
Child Dev. 2007 Jan-Feb;78(1):116-31
17328696
Twin Res Hum Genet. 2007 Jun;10(3):434-9
17564501
Dev Psychol. 1997 May;33(3):468-79
9149925
J Learn Disabil. 1995 Feb;28(2):96-106
7884303
Behav Genet. 1995 Jan;25(1):17-23
7755515
Behav Genet. 1985 Sep;15(5):467-73
4074272
Dev Neuropsychol. 2001;20(2):483-507
11892949