Zygosity diagnosis in the absence of genotypic data: An approach using latent class analysis

Heath, A. C., Nyholt, D. R., Neuman, R., Madden, P. A., Bucholz, K. K., Todd, R. D., Nelson, E. C., Montgomery, G. W., & Martin, N. G. (2003) Zygosity diagnosis in the absence of genotypic data: An approach using latent class analysis. Twin Research and Human Genetics, 6(1), pp. 22-26.

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For zygosity diagnosis in the absence of genotypic data, or in the recruitment phase of a twin study where only single twins from same-sex pairs are being screened, or to provide a test for sample duplication leading to the false identification of a dizygotic pair as monozygotic, the appropriate analysis of respondents' answers to questions about zygosity is critical. Using data from a young adult Australian twin cohort (N = 2094 complete pairs and 519 singleton twins from same-sex pairs with complete responses to all zygosity items), we show that application of latent class analysis (LCA), fitting a 2-class model, yields results that show good concordance with traditional methods of zygosity diagnosis, but with certain important advantages. These include the ability, in many cases, to assign zygosity with specified probability on the basis of responses of a single informant (advantageous when one zygosity type is being oversampled); and the ability to quantify the probability of misassignment of zygosity, allowing prioritization of cases for genotyping as well as identification of cases of probable laboratory error. Out of 242 twins (from 121 like-sex pairs) where genotypic data were available for zygosity confirmation, only a single case was identified of incorrect zygosity assignment by the latent class algorithm. Zygosity assignment for that single case was identified by the LCA as uncertain (probability of being a monozygotic twin only 76%), and the co-twin's responses clearly identified the pair as dizygotic (probability of being dizygotic 100%). In the absence of genotypic data, or as a safeguard against sample duplication, application of LCA for zygosity assignment or confirmation is strongly recommended.

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66 citations in Scopus
60 citations in Web of Science®
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ID Code: 92172
Item Type: Journal Article
Refereed: Yes
Additional Information: Heath, Andrew C
Nyholt, Dale R
Neuman, Rosalind
Madden, Pamela A F
Bucholz, Kathleen K
Todd, Richard D
Nelson, Elliot C
Montgomery, Grant W
Martin, Nicholas G
Research Support, U.S. Gov't, P.H.S.
2003/03/11 04:00
Twin Res. 2003 Feb;6(1):22-6.
Keywords: Adult, Female, Genotype, Humans, Male, Sex Factors, *Twins, Dizygotic, *Twins, Monozygotic
DOI: 10.1375/twin.6.1.22
ISSN: 1369-0523
Divisions: Current > Schools > School of Biomedical Sciences
Current > QUT Faculties and Divisions > Faculty of Health
Current > Institutes > Institute of Health and Biomedical Innovation
Copyright Owner: Copyright 2003 Cambridge University Press
Deposited On: 27 Jan 2016 23:03
Last Modified: 27 Jan 2016 23:03

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