Although the concept of meta-analysis of multiple linkage scans of a genetic trait is not new, it can be difficult to apply to published data given the lack of consistency in the presentation of linkage results. In complex inheritance common diseases, there are many instances where one or two studies meet genome-wide criteria for significant or suggestive linkage but several other studies do not show even nominally significant results with the same region. One possibility for resolving differences between study results would be to combine an available result parameter of several studies. We describe here a method of regional meta-analysis, the multiple-scan probability (MSP), which can be used on published results. It combines the reported P-values of individual studies, after correcting each value for the size of the region containing a minimum P-value. Analyses of the power of MSP and of its type I error rates are presented. The type I error rate is at least as low as that for a single genome scan and thus genome-wide significance criteria may be applied. We also demonstrate appropriate criteria for this type of meta-analysis when the most significant study is included, and when that study is used to define a region of interest and then excluded. In our simulations, meta-analysis is at least as powerful as pooling data. Finally, we apply this method of meta-analysis to the evidence for linkage of autism susceptibility loci and demonstrate evidence for a susceptibility locus at 7q.

The use of preimplantation diagnosis for sex determination and detection of exon deletion means that unaffected babies can be born to parents suffering from Duchenne muscular dystrophy (DMD). However, those who do not have exon deletion should also be considered for further investigation. A new method, known as linkage analysis, has been developed to diagnose the presence of non-deletion DMD in preimplantation embryos. Linkage analysis uses informative intragenic and flanking markers to track the chromosome bearing the mutated gene. The present study reports the analysis of two polymorphic sites, in blastomeres biopsied from embryos from a female carrier of DMD. A single male embryo was obtained who had inherited alternate maternal alleles to the woman's affected surviving son, and this embryo was transferred.