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Research article - Peer-reviewed, 2008

The effect of pedigree structure on detection of deletions and other null alleles

Johansson, Anna M.; Sall, Torbjorn


Deletions and other null alleles for genetic markers can be detected as a special case of non-Mendelian inheritance, ie when a parent and a child appear to be homozygous for different alleles. The probability to detect a deletion for a fixed overall number of investigated individuals was calculated for biallelic and multiallelic markers with varying allele frequencies. To determine the effect of increasing the number of parents and grandparents, the probability for this event was derived for a parent and one child, a trio, a trio with one grandparent and a trio with two grandparents. The results for biallelic markers show that for a fixed total number of individuals, a sample of trios with two grandparents is always more efficient than the other family types, despite a lower total number of founder chromosomes in the sample. For multiallelic markers the outcome varies. The effect of adding additional children to a nuclear family was also investigated. For nuclear families, the optimal number of children is two or three, depending on the allele frequencies. It is shown that adding children is more efficient than adding grandparents.


deletion; null allele; pedigree; genetic marker

Published in

European Journal of Human Genetics
2008, volume: 16, number: 10, pages: 1225-1234

Authors' information

Swedish University of Agricultural Sciences, Department of Animal Breeding and Genetics
Lund University
Säll, Torbjörn
Lund University

UKÄ Subject classification

Animal and Dairy Science
Veterinary Science

Publication Identifiers


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