Investigating the numerical effects of ascertainment bias in linkage analysis: development of methods and preliminary results

Genetic Epidemiology
S L Slager, Veronica J Vieland

Abstract

It is general practice to have nonsingle ascertainment of pedigrees for linkage studies, along with intrafamilial sampling that is dependent on who among the related individuals was initially ascertained (Proband dependent or PD sampling). Vieland and Hodge [1995; 1996] have shown that under these conditions, the likelihood used in calculating the lod score is not strictly correct and can produce asymptotically biased estimates of the recombination fraction, theta. However they speculated that this bias would be small in most applications. This paper presents preliminary work aimed at quantifying the numerical magnitude of the bias introduced by PD sampling and nonsingle ascertainment in linkage analysis. We considered five generating models where we varied the ascertainment procedure, intrafamilial sampling scheme, and the sample size for each model. In this limited initial set of simulations, asymptotic bias in theta appears to be trivial, while PD sampling procedures can increase the efficiency of theta. These preliminary results support the view that the advantages of unsystematic ascertainment may offset any small estimation bias that may arise.

References

Oct 1, 1977·Clinical Genetics·C Cannings, E A Thompson
Oct 1, 1986·Annals of Human Genetics·W J Ewens, N C Shute
Dec 1, 1986·Theoretical Population Biology·W J Ewens, N C Shute
Jul 1, 1994·Human Heredity·A A SchäfferR W Cottingham
Nov 1, 1996·Genetics·A MochizukiY Iwasa

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Citations

Dec 25, 2004·Clinical Genetics·A AzzamL G Biesecker
Dec 23, 2011·Human Heredity·Veronica J VielandWilliam Valentine-Cooper
Jan 5, 2000·Journal of Bone and Mineral Research : the Official Journal of the American Society for Bone and Mineral Research·E L DuncanJ A Wass
Aug 12, 2004·Genetic Epidemiology·Emil GinsburgRobert C Elston
Nov 14, 2017·Human Heredity·Markus BruggerKonstantin Strauch
Nov 24, 2006·Genetic Epidemiology·Christopher W Bartlett, Veronica J Vieland
Dec 4, 2004·Genetic Epidemiology·Veronica J Vieland, Susan E Hodge

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