Linkage analysis of schizophrenia: challenges and promise.

Schizophrenia is a serious mental illness affecting nearly 1 per cent of the general population. Family, twin, and adoption studies suggest that genetics plays a major role in the etiology of schizophrenia. The inheritance pattern appears complex, similar to that of other common conditions like heart disease. To uncover a causal genetic factor, researchers have recently begun to apply a linkage analysis strategy to schizophrenia. Early results suggest that there are many challenges facing scientists who undertake schizophrenia genetics research. While one study has shown significant linkage of schizophrenia to a region on chromosome 5, several other studies have not found linkage to this area. The likelihood that there are several major genes predisposing to the illness and uncertainties about inheritance patterns and diagnostic boundaries are potential difficulties to overcome. Many more families need to be studied, and creative complementary research strategies pursued, to achieve the potential success offered by a genetic linkage approach.