@article{ref1,
title="A strategy for identifying phenotypic subtypes: concordance of symptom dimensions between sibling pairs who met screening criteria for a genetic linkage study of childhood-onset bipolar disorder using the Child Bipolar Questionnaire",
journal="Journal of affective disorders",
year="2007",
author="Papolos, Demitri and Hennen, John and Cockerham, Melissa S. and Lachman, Herbert",
volume="99",
number="1-3",
pages="27-36",
abstract="BACKGROUND: Specific symptom dimensions have been used to establish phenotypic subgroups in recent genetic studies of bipolar disorder. In preparation for a genetic linkage study of childhood-onset bipolar disorder (COBPD), we conducted an exploratory analysis of the concordance of prominent symptom dimensions between sibling pairs (N=260) who screened positive for COBPD. This report presents data on the potential usefulness of these dimensions in genotyping. METHOD: A principal components factor analysis was conducted on the symptoms of 2795 children who screened positive for COBPD on the Child Bipolar Questionnaire (CBQ). The resulting factors were used in a concordance analysis between 260 proband/sibling pairs and 260 proband/matched comparison pairs. RESULTS: Ten factors were extracted. The strongest concordance coefficients (rho) between probands and siblings, and the widest contrasts between proband/sibling vs. proband/comparison pairs, were for Factor 9 (Fear of harm), Factor 5 (Aggression), Factor 10 (Anxiety), Factor 4 (Sensory sensitivity), Factor 6 (Sleep-wake cycle disturbances), and Factor 2 (Attention/Executive function deficits). Based on factor loadings and multivariate analyses, CBQ items were selected for a &quot;Core Index&quot; subscale that had a robust concordance estimate in the sibpair group (rho=0.514, 95% CI 0.450-0.577) as compared to the proband-matched comparison group (rho=0.093, 95% CI 0.008 to 0.178). LIMITATIONS: Research diagnostic interviews (K-SADS P/L) were conducted to confirm bipolar diagnosis in only a subsample (N=100) of the children whose data were used for the concordance analysis. CONCLUSIONS: Our data suggest a profile of heritable clinical dimensions in addition to classic mood symptomatology in COBPD. These features may represent a more homogeneous phenotypic subtype of COBPD that may prove more useful for delineating the neurobiology and genetics of the disorder than standard diagnostic models.<p /><p>Language: en</p>",
language="en",
issn="0165-0327",
doi="10.1016/j.jad.2006.08.014",
url="http://dx.doi.org/10.1016/j.jad.2006.08.014"
}