title: A psychometric-genetic study of schizotypal disorder.
abstract: This study aimed to clarify the structure and the etiological constituents of schizotypal disorder (SPD) by directly interviewing pairs of twins. A latent class analysis was applied to each individual's outcome for specified SPD items, such that each subject's phenotype could be redefined in terms of individual probabilities of class membership. Intraclass correlations were then calculated for each twin pair, and a standard univariate twin model applied. The best latent class analysis solution encompassed a model with four latent classes (three latent classes of SPD subjects, one of non-SPD). The intraclass correlations revealed a moderate to high heritability for two out of three SPD classes and for the modal class (a class composed of subjects that possessed a conditional probability of belonging to any of the SPD classes). Model fittings revealed considerable variation in the extent to which the different classes of SPD were influenced by additive genetic constituents or non-genetic factors. Although these data confirm the importance of genetic contributors in determining liability to SPD and the schizophrenia spectrum, they indicate that there is a relationship between psychometric multidimensionality and etiological heterogeneity in SPD.
authors.affiliation: Istituto Scientifico H. San Raffaele, Department of Neuropsychiatric Sciences, Milan, Italy. marco.battaglia@hsr.it
authors.forename: M
authors.initials: M
authors.lastname: Battaglia
authors.forename: A
authors.initials: A
authors.lastname: Fossati
authors.forename: S
authors.initials: S
authors.lastname: Torgersen
authors.forename: S
authors.initials: S
authors.lastname: Bertella
authors.forename: S
authors.initials: S
authors.lastname: Bajo
authors.forename: C
authors.initials: C
authors.lastname: Maffei
authors.forename: L
authors.initials: L
authors.lastname: Bellodi
authors.forename: E
authors.initials: E
authors.lastname: Smeraldi
mesh_terms: D000328:Adult; D004200:Diseases in Twins / Q000235:genetics*; D006801:Humans; D007558:Italy; D011569:Psychiatric Status Rating Scales; D012569:Schizotypal Personality Disorder / Q000235:genetics* / Q000523:psychology