Hospital-treated psychosis and suicide in a rural community (1877-2005). Part 2: Genetic founder effects.
OBJECTIVE
To demonstrate the existence of genetic founder effects in hospital-treated cases of psychosis and self-harm in historical cohorts of a small rural population.


METHODS
These cohorts consist of named persons born after 1845. The cumulative case registers were linked to the purported pedigrees of three presumed mentally ill founders living in the community in the 17th and 18th centuries. We compared the incidence of psychosis and self-harm in the genetically unexposed population and in three exposed founder populations.


RESULTS
We found a preponderance of organic mental disorders and schizophrenia in the twice-exposed founder population and of other non-organic psychosis and self-harm in the thrice-exposed founder population.


CONCLUSIONS
The genetic impact of the founders seems to have affected the incidence rates of severe psychiatric disorders of their descendants in two ways. A founder effect is detected in organic mental disorders and schizophrenia, and it seems to run independently of that detected in affective psychotic disorders and intentional self-harm.
Andersen
J E
JE
Department of Child and Adolescent Psychiatry, Division of Psychiatry, Tynset, Innlandet Hospital Trust, Tynset, Norway.
Hynnekleiv
T
T
D015331:Cohort Studies; D018703:Founder Effect; D006760:Hospitalization / Q000706:statistics & numerical data; D006801:Humans; D015994:Incidence; D009664:Norway / Q000453:epidemiology; D011618:Psychotic Disorders / Q000453:epidemiology / Q000235:genetics*; D012424:Rural Population / Q000706:statistics & numerical data*; D012559:Schizophrenia / Q000453:epidemiology / Q000235:genetics; D013405:Suicide / Q000706:statistics & numerical data*