Genetics of schizophrenia: a review of linkage findings.

Background: Family, twin and adoption studies have demonstrated the genetic basis of schizophrenia. Several genes, acting synergistically with each other and with the environment probably underlie the disorder. Different genes for schizophrenia are surely present in different populations. Parametric and nonparametric linkage analyses are the main methods employed in the search for schizophrenia genes. Only one study, published recently, has aspired to report the cloning of such a gene, and its significance is debated.

Method: This review covers the significant and suggestive evidence found in linkage studies for localization of schizophrenia genes. Support for these results from other sources is also described.

Results: Significant and suggestive linkage results were reported for at least 18 different chromosomal regions. The more convincing evidence is for loci on 1q, 5q, 6p, 6q, 8p, 10p, 13q, 22q and Xp.

Conclusions: Current methods of genetic analysis are limited in their power to detect genes for complex disorders such as schizophrenia. Technological advances and the use of special populations such as genetic isolates could overcome these limitations.