MOLECULAR-GENETICS OF SCHIZOPHRENIA

Schizophrenia is aggregated in families because of underlying genetic factors. The application of efficient molecular-genetic techniques hav e produced findings of several linkages on the genome, with independen t replications on chromosomes 5q, 6p, 8p, 13q and 22q. Susceptibility genes are probably localized in these regions and have to be identifie d. The multiplicity of suggestive regions showing linkage to schizophr enia argues against a single causal or major operating gene for schizo phrenia. Despite replications, the observed strength of linkages is mo dest, as is the strength of associations. These observations suggest t hat the effect sizes of the single susceptibility genes are small, tha t complex interactions with environmental factors are operating, or bo th.