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PMID |
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TITLE |
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A simulation study of the effects of assignment of prior identity-by-descent probabilities to unselected sib pairs, in covariance-structure modeling of a quantitative-trait locus. |
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ABSTRACT |
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Sib pair-selection strategies, designed to identify the most informative sib pairs in order to detect a quantitative-trait locus (QTL), give rise to a missing-data problem in genetic covariance-structure modeling of QTL effects. After selection, phenotypic data are available for all sibs, but marker data-and, consequently, the identity-by-descent (IBD) probabilities-are available only in selected sib pairs. One possible solution to this missing-data problem is to assign prior IBD probabilities (i.e., expected values) to the unselected sib pairs. The effect of this assignment in genetic covariance-structure modeling is investigated in the present paper. Two maximum-likelihood approaches to estimation are considered, the pi-hat approach and the IBD-mixture approach. In the simulations, sample size, selection criteria, QTL-increaser allele frequency, and gene action are manipulated. The results indicate that the assignment of prior IBD probabilities results in serious estimation bias in the pi-hat approach. Bias is also present in the IBD-mixture approach, although here the bias is generally much smaller. The null distribution of the log-likelihood ratio (i.e., in absence of any QTL effect) does not follow the expected null distribution in the pi-hat approach after selection. In the IBD-mixture approach, the null distribution does agree with expectation. |
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DATE PUBLISHED |
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HISTORY |
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PUBSTATUS |
PUBSTATUSDATE |
pubmed |
1999/01/23 19:27 |
medline |
2000/03/21 09:00 |
entrez |
1999/01/23 19:27 |
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AUTHORS |
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NAME |
COLLECTIVENAME |
LASTNAME |
FORENAME |
INITIALS |
AFFILIATION |
AFFILIATIONINFO |
Dolan CV |
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Dolan |
C V |
CV |
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Psychology Faculty, University of Amsterdam, The Netherlands. op_dolan@macmail.psy.uva.nl |
Boomsma DI |
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Boomsma |
D I |
DI |
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Neale MC |
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Neale |
M C |
MC |
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INVESTIGATORS |
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JOURNAL |
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VOLUME: 64 |
ISSUE: 1 |
TITLE: American journal of human genetics |
ISOABBREVIATION: Am. J. Hum. Genet. |
YEAR: 1999 |
MONTH: Jan |
DAY: |
MEDLINEDATE: |
SEASON: |
CITEDMEDIUM: Print |
ISSN: 0002-9297 |
ISSNTYPE: Print |
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MEDLINE JOURNAL |
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MEDLINETA: Am J Hum Genet |
COUNTRY: United States |
ISSNLINKING: 0002-9297 |
NLMUNIQUEID: 0370475 |
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PUBLICATION TYPE |
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PUBLICATIONTYPE TEXT |
Journal Article |
Research Support, Non-U.S. Gov't |
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COMMENTS AND CORRECTIONS |
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GRANTS |
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GENERAL NOTE |
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KEYWORDS |
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MESH HEADINGS |
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DESCRIPTORNAME |
QUALIFIERNAME |
Alleles |
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Gene Frequency |
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Genetic Markers |
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Humans |
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Models, Genetic |
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Nuclear Family |
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Quantitative Trait, Heritable |
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Software |
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SUPPLEMENTARY MESH |
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GENE SYMBOLS |
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CHEMICALS |
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REGISTRYNUMBER |
NAMEOFSUBSTANCE |
0 |
Genetic Markers |
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OTHER ID's |
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