Hum Hered 2001;52:121–131

Multipoint Estimation of Identity-by-Descent Probabilities at Arbitrary Positions among Marker Loci on General Pedigrees

Sobel E.a,b · Sengul H.c · Weeks D.E.c
aDepartment of Human Genetics, University of California, Los Angeles, Calif., USA, bCentre National de Génotypage, Paris, France, and cDepartment of Human Genetics, University of Pittsburgh, Pa., USA
email Corresponding Author

 goto top of outline Key Words

  • Identity by descent
  • Algorithm
  • Comparison
  • SimWalk2 computer package

 goto top of outline Abstract

Objectives: To describe, implement, and test an efficient algorithm to obtain multipoint identity-by-descent (IBD) probabilities at arbitrary positions among marker loci for general pedigrees. Unlike existing programs, our algorithm can analyze data sets with large numbers of people and markers. The algorithm has been implemented in the SimWalk2 computer package. Methods: Using a rigorous testing regimen containing five pedigrees of various sizes with realistic marker data, we compared several widely used IBD computation programs: Allegro, Aspex, GeneHunter, MapMaker/Sibs, Mendel, Sage, SimWalk2, and Solar. Results: The testing revealed a few discrepancies, particularly on consanguineous pedigrees, but overall excellent results in the deterministic multipoint packages. SimWalk2 was also found to be in good agreement with the deterministic multipoint programs, usually matching to two decimal places the kinship coefficient that ranges from 0 to 1. However, the packages based on single-point IBD estimation, while consistent with each other, often showed poor results, disagreeing with the multipoint kinship results by as much as 0.5. Conclusions: Our testing has clearly shown that multipoint IBD estimation is much better than single-point estimation. In addition, our testing has validated our algorithm for estimating IBD probabilities at arbitrary positions on general pedigrees.

Copyright © 2001 S. Karger AG, Basel

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 goto top of outline Author Contacts

Daniel E. Weeks, PhD
Crabtree Hall, Room A310
Department of Human Genetics, University of Pittsburgh
130 DeSoto Street, Pittsburgh, PA 15261 (USA)
Tel. +1 412 624 5388, Fax +1 412 624 3020, E-Mail

 goto top of outline Article Information

Received: Received: June 30, 2000
Accepted: October 24, 2000
Revision received: October 19, 2000
Number of Print Pages : 11
Number of Figures : 3, Number of Tables : 3, Number of References : 33

 goto top of outline Publication Details

Human Heredity (International Journal of Human and Medical Genetics)
Founded 1950 as Acta Genetica et Statistica Medica by Gunnar Dahlberg; Continued by M. Hauge (1965–1983)

Vol. 52, No. 3, Year 2001 (Cover Date: Released September 2001)

Journal Editor: J. Ott, New York, N.Y.
ISSN: 0001–5652 (print), 1423–0062 (Online)

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