2 STATISTICAL TESTS FOR MEIOTIC BREAKPOINT ANALYSIS

Meiotic breakpoint analysis (BPA), a statistical method for ordering g enetic markers, is increasing in importance as a method for building g enetic maps of human chromosomes. Although BPA does not provide estima tes of genetic distances between markers, it efficiently locates new m arkers on already defined dense maps, when likelihood analysis becomes cumbersome or the sample size is small. However, until now no assessm ents of statistical significance have been available for evaluating th e possibility that the results of a BPA were produced by chance. In th is paper, we propose two statistical tests to determine whether the si ze of a sample and its genetic information content are sufficient to d istinguish between ''no linkage'' and ''linkage'' of a marker mapped b y BPA to a certain region. Both tests are exact and should be conducte d after a BPA has assigned the marker to an interval on the map. Appli cations of the new tests are demonstrated by three examples: (1) a syn thetic data set, (2) a data set of five markers on human chromosome 8p , and (3) a data set of four markers on human chromosome l7q.