Localization of a susceptibility locus for schizophrenia on chromosome 5.

Schizophrenia is a common disorder with a life time prevalence of approximately 1 per cent1. The illness often develops in young adults, who were previously normal, and is characterized by a constellation of symptoms including hallucinations and delusions (psychotic symptoms) and symptoms such as severely inappropriate emotional responses, a disorder of thinking and concentration, erratic behaviour as well as social and occupational deterioration2. A considerable proportion of the variance in the liability to develop schizophrenia may be genetic3,4, but segregation analysis, to establish a mode of transmission, has not produced a consistent result5–19. One of these studies was carried out in Iceland and made use of the large family size and extensive geneaological information present in that country16,17. Here we demonstrate genetic linkage of two DNA polymorphisms on the long arm of human chromosome 5 to schizophrenia in seven British and Icelandic families with multiple affected members. The results indicate the existence of a gene locus with a dominant schizophrenia-susceptibility allele. Inheritance of the allele in the families studied suggests that it may also predispose to psychiatric conditions such as schizophrenia spectrum disorders and a variety of other disorders. This report provides the first strong evidence for the involvement of a single gene in the causation of schizophrenia.