The types and expectancy of mental disorders in the siblings of 74
probands with chronic schizophrenia were examined. The siblings were
classified according to whether 1) both parents had schizotypal personality
disorder, 2) one parent had the disorder and one was normal, or 3) both
parents were normal. Siblings whose parents both had the disorder were at
significantly greater risk for schizophrenia and schizotypal personality
disorder than siblings with at least one normal parent. Similarly, the
expectancy of schizotypal personality disorder alone and combined with
schizophrenia was higher among siblings with one parent with the disorder
than in siblings with two normal parents. The data suggest that schizotypal
traits may be genetically related to schizophrenia.Abstract Teaser