Optimization of Zygosity Determination by Questionnaire and DNA Genotyping in Chinese Adolescent Twins

Abstract

The main aim of this study was to develop and optimize a questionnaire-based zygosity determination method in Chinese adolescent twins. Participants were 471 pairs of same-sex twins (345 monozygotic, 126 dizygotic) with a mean age of 14.56 years (SD = 2.62). A second sample was recruited for cross-validation, including 382 pairs of same-sex twins (261 monozygotic, 121 dizygotic) with a mean age of 12.53 years (SD = 2.22). The questionnaire consisted of 12 questions dealing with co-twin similarity or frequency of confusion. Two means were put forward to improve the predictive accuracy of the questionnaire — adding parent-reports to the analysis, and using a 2-point rather than 3-point response format. DNA genotyping was performed on nine short tandem repeat loci, with an estimated zygosity classification accuracy very close to 100%. The validity of all questionnaires was assessed by being compared to the results of DNA analysis. Results of stepwise logistic regression analysis showed that the predictive accuracy of the 3-point self-reported questionnaire is 83.8%. Using parent-reports and 2-point scale led to 3.9% and 4.6% increase in predictive accuracy, respectively. When using the parent-reports and children's self-reports jointly, the predictive accuracy was enhanced to 90.6%. For the cross-validation, the equations and cut-offs derived from the first sample led to an acceptable accuracy (91.3%) in the second sample. In conclusion, the method we developed can be used in future studies among Chinese adolescent twins. Multiple-rater and 2-point response format were suggested for all twin studies for enhancing the predictive accuracy of questionnaires.

Nonshared Environment and Monozygotic Adolescent Twin Differences in Effortful Control

“…This method of determination has an accuracy rate of 99.0% (Rogers, Cole, Lan, Crossa, & Demerath, 2007). Reliability and validity have been supported in a Chinese sample (Chen et al, 2010;Zhang & Ji, 2008).…”

Does the Environment Have an Enduring Effect on ADHD? A Longitudinal Study of Monozygotic Twin Differences in Children

“…Data was gathered from both monozygotic and dizygotic twins, but only data from monozygotic twins was included in the current study. Zygosity was determined by DNA samples in 83% of children, a method that is close to 100% accurate (Chen et al, 2010), and structured questioning in the remaining children, which is 95% accurate (Nichols & Bilbro, 1966). There was more attrition among participants in Australia (50%) and Sweden (51%) than the United States (6%) and Norway (7%), but the cohort of participants in the final wave did not differ from the full cohort in gender ratio, mean age, or difference scores (unique environmental variance).…”

The Beijing Twin Study (BeTwiSt): A Longitudinal Study of Child and Adolescent Development

“…The validity of the questionnaire method was examined through the comparison with the results of DNA analyses. The predictive accuracy of the questionnaire method used in this study reached 91% (Chen et al, 2010). 50 59 26 19 47 1 202 11 36 47 17 16 28 2 146 12 63 38 22 21 37 0 181 13 50 52 20 32 28 2 184 14 56 60 22 23 40 4 205 15 37 49 10 13 28 0 137 16 36 33 12 12 26 4 123 17 22 30 4 8 14 3 81 18+ 30 47 13 21 14 3 128 Total (pairs) 380 415 146 165 262 19 1,387 Note: OST = opposite sex twins; MZ = monozygotic twins; DZ = dizygotic twins.…”