Association between attention deficit hyperactivity disorder and the DXS7 locus

Attention deficit hyperactivity disorder (ADHD) is a prevalent disorder in children. The etiology of this disease is not clear, Genetics studies have suggested the involvement of the dopamine DRD-4 receptor gene and dopamine transporter gene (DAT1). Clinical studies have shown that monoamine oxidase -B (MAO-B) inhibitors are effective in the treatment of ADHD. These finding s suggest that monoamine oxidase (MAO) genes might be involved in the origi n of ADHD, In the present work, the DXS7 locus of chromosome X, which is cl osely linked to MAO genes, was selected as a marker to study the possible a ssociation between ADHD and MAO genes in the Chinese population. Haplotype- based haplotype relative risk (HHRR) and the transmission disequilibrium te st (TDT) methods were employed to analyze the association and the linkage d isequilibrium, respectively, Significant association (X-2 = 15.86; 1 df; P < 0.001) and linkage (X-2 = 14.88; 1 df; P < 0.001) were detected between t he 157-bp allele of the DXS7 locus and the DSM-III-R-diagnosed ADHD (N = 72 ) in trios composed of father, mother, and affected offspring. The data sug gested that ADHD was associated and in linkage with DXS7 locus, Am. J, Med. Genet, (Neuropsychiatr. Genet.) 96: 289-292, 2000 (C) 2000 Wiley-Liss, Inc .