Diagnostic issues in the study of schizophrenia genetics

Abstract

Brvnjólfsson J, Pétursson H, Gurling H, Sherrington R. Diagnostic issues in the study of schizophrenia genetics. As a result of a series of collaborative studies, we have reported preliminary evidence of linkage between a locus on chromosome 5 and schizophrenia in Icelandic and British families. The purpose of this article is to describe the part of our work carried out in Iceland, in particular the population background, as well as the methods of selection, diagnostic assessment, interview schedules, and clinical aspects. The project group chose to study high-density pedigrees with schizophrenia in at least three generations. Extensive pedigree tracing work aimed at selecting families without manic depression (bipolar disorder) and in which there was only one possible source for a schizophrenia allele segregating into the kindred. Diagnosis included schizophrenia, schizophreniform disorder, unspecified functional psychosis, schizoid personality disorder with and without schizotypal features, and other psychiatric disorders. Most of the schizophrenic cases were deemed chronic or subchronic. One third of the schizophrenia subtypes were undifferentiated, and almost a half were of the paranoid type. Other aspects of the results are discussed, as are implications for further work.