title: Familiality of Psychotic Disorders: A Polynosologic Study in Multiplex Families.
abstract: Phenotype definition of psychotic disorders has a strong impact on the degree of familial aggregation. Nevertheless, the extent to which distinct classification systems affect familial aggregation (ie, familiality) remains an open question. This study was aimed at examining the familiality associated with 4 nosologic systems of psychotic disorders (DSM-IV, ICD-10, Leonhard's classification and a data-driven approach) and their constituting diagnoses in a sample of multiplex families with psychotic disorders.
  
  
  
  Participants were probands with a psychotic disorder, their parents and at least one first-degree relative with a psychotic disorder. The sample was made of 441 families comprising 2703 individuals, of whom 1094 were affected and 1709 unaffected.
  
  
  
  The Leonhard classification system had the highest familiality (h (2) = 0.64), followed by the empirical (h (2) = 0.55), DSM-IV (h (2) = 0.50), and ICD-10 (h (2) = 0.48). Familiality estimates for individual diagnoses varied considerably (h (2) = 0.25-0.79). Regarding schizophrenia diagnoses, Leonhard's systematic schizophrenia (h (2) = 0.78) had the highest familiality, followed by latent class core schizophrenia (h (2) = 0.74), DSM-IV schizophrenia (h (2) = 0.48), and ICD-10 schizophrenia (h (2) = 0.41). Psychotic mood disorders showed substantial familiality across nosologic systems (h (2) = 0.60-0.77). Domains of psychopathology other than reality-distortion symptoms showed moderate familiality irrespective of diagnosis (h (2) = 0.22-0.52) with the deficit syndrome of schizophrenia showing the highest familiality (h (2) = 0.66).
  
  
  
  While affective psychoses showed relatively high familiality estimates across classification schemes, those of nonaffective psychoses varied markedly as a function of the diagnostic scheme with a narrow schizophrenia phenotype maximizing its familial aggregation. Leonhard's classification of psychotic disorders may be better suited for molecular genetic studies than the official diagnostic systems.
authors.affiliation: Department of Psychiatry, Complejo Hospitalario of Navarra, Pamplona, Spain; Instituto de Investigación Sanitaria de Navarra (IdiSNa), Pamplona, Spain; victor.peralta.martin@cfnavarra.es.
authors.forename: Victor
authors.initials: V
authors.lastname: Peralta
authors.affiliation: Unitat d' Antropologia, Department of Biologia Animal, Facultat de Biologia, Universitat de Barcelona, Barcelona, Spain; Centro de Investigación Biomédica en Red de Salud Mental (CIBERSAM), Instituto de Salud Carlos III, Madrid, Spain.
authors.forename: Ximena
authors.initials: X
authors.lastname: Goldberg
authors.affiliation: Department of Psychiatry, Complejo Hospitalario of Navarra, Pamplona, Spain;
authors.forename: María
authors.initials: M
authors.lastname: Ribeiro
authors.affiliation: Department of Psychiatry, Complejo Hospitalario of Navarra, Pamplona, Spain; Instituto de Investigación Sanitaria de Navarra (IdiSNa), Pamplona, Spain;
authors.forename: Ana M
authors.initials: AM
authors.lastname: Sanchez-Torres
authors.affiliation: Unitat d' Antropologia, Department of Biologia Animal, Facultat de Biologia, Universitat de Barcelona, Barcelona, Spain; Centro de Investigación Biomédica en Red de Salud Mental (CIBERSAM), Instituto de Salud Carlos III, Madrid, Spain.
authors.forename: Lourdes
authors.initials: L
authors.lastname: Fañanás
authors.affiliation: Department of Psychiatry, Complejo Hospitalario of Navarra, Pamplona, Spain; Instituto de Investigación Sanitaria de Navarra (IdiSNa), Pamplona, Spain;
authors.forename: Manuel J
authors.initials: MJ
authors.lastname: Cuesta
mesh_terms: D000293:Adolescent; D000328:Adult; D000341:Affective Disorders, Psychotic / Q000145:classification*; D000368:Aged; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009679:Nuclear Family; D010375:Pedigree; D010641:Phenotype; D011618:Psychotic Disorders / Q000145:classification*; D012559:Schizophrenia / Q000145:classification*; D055815:Young Adult
keywords: affective psychoses; classification; familial coaggregation; heritability; nosology; schizophrenia