Genes for left-handedness: how to search for the needle in the haystack?

Although several genes that determine left-right asymmetry for structural syndromes such as situs inversus have been characterised in recent years (Supp, Witte, Potter, & Brueckner, 1997), there has been little progress in determining which genes or loci predispose to left-right handedness in humans. Linkage analysis has been used widely for the localisation of genes followed by their positional cloning. The complex genetics of handedness is one of the greatest problems for standard linkage analysis. Several genetic models have been proposed for the inheritance of handedness in humans. On the basis of these models, left-handedness can be considered a common single gene trait with a high gene frequency and a non-mendelian inheritance pattern. We report here a possible strategy, using these genetic models, that can be applied for the identification for genes determining handedness in humans.