Utility of the affected sib pair method to detect linkage of a sex‐linked dominant disease with a sex‐linked recessive trait

Use of affected sib‐pairs for linkage determination of a sex‐linked dominant disease with a recessive X‐chromosome marker will require extremely large sample sizes, particularly when the marker is marginally polymorphic. In addition, this method should not be used without caution on data collected for a traditional LOD score analysis, without considering the parental mating types involved in the informative families. Nevertheless, ascertainment adjustment and correction for dependence of multiple pairs of affected sib‐pairs in families suggests that this method provides linkage inference concordant with that of the traditional LOD score analysis.