Family and genetic specificity of adhd phenotypes in north american and australian general population twin samples

E. R. Rasmussen, R. J. Neuman, A. C. Heath, F. Levy, D. A. Hay, R. D. Todd

Research output: Contribution to journalArticle

Abstract

Two recent approaches for detecting ADHD liability genes use DSM-IV and latent class criteria. The family/genetic specificity of these approaches was examined in 4,036 North American twins, 2,802 Australian twins and 1,013 Australian non-twin siblings. A multinomial logit model was used to predict each twins ADHD phenotype from the phenotype of their co-twin (and non-twin sibling). All estimated sibling coefficients predicting the same and different twin phenotype were significant, indicating both classification systems are familial, but non-specific. However, when the MZ:DZ odds ratio was examined, differences in the classification systems became apparent. Prediction of different DSM-IV subtype combinations resulted in evidence for genetic non-specificity in the North American sample only; given a DSM-IV Combined co-twin, the MZ:DZ ratio for DSM-IV Inattention was 12.4 (2.4-63.4), χ2 = 9.1, P = 0.01. Similarly, given a DSM-IV Inattentive cotwin, the MZ:DZ ratio for DSM-IV Combined was 6.1 (1.4-26.5), χ2 = 5.9, P = 0.06. Predicting different latent class combinations, co-twin Inattentive-Impulsive had a significant genetic influence on Mild Inattention class membership for Australians (MZ:DZ = 5.2 (1.8-15.2), χ2 = 9.2, P = 0.03) and a significant genetic influence on Talkative-Impulsive class membership among North American females (MZ:DZ = 17.0 (2.1-23.4). χ2 = 9.9, P = 0.1 ). Overall, clinically relevant ADHD latent classes showed more genetic specificity than DSM-IV subtypes across samples.

Original languageEnglish
Pages (from-to)572-573
Number of pages2
JournalAmerican Journal of Medical Genetics - Neuropsychiatric Genetics
Volume105
Issue number7
StatePublished - Oct 8 2001

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