GENOME SCANNING FOR SEGMENTS SHARED IDENTICAL BY DESCENT AMONG DISTANT RELATIVES IN ISOLATED POPULATIONS

In this paper, we address some of the statistical issues concerning fa lse-positive rates that arise when the whole genome, or a portion ther eof, is scanned in distantly related individuals, to search for a dise ase locus. We derive a method for correcting false-positive probabilit ies for the large number of comparisons that are performed when scanni ng a large portion of the genome. We consider both the idealized situa tion of a dense set of fully informative markers and the more realisti c data-collection strategy of an initial scan at low resolution to ide ntify promising areas, which then are typed with markers at high resol ution. We also examine the accuracy of false-positive rates approximat ed using a conservative estimate of the separation distance between af fected individuals in the current generation and the common ancestral couple. Calculation of false-positive rates when inbreeding is present in the pedigree also is considered.