ADHDgene Database

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Large-scale studies

Data Summary

Published Variant
- SNP: 1391
- CNV: 398
- Others: 173
Published Gene: 359
Published Region: 128
Pathway by PBA: 8
Study: 361

Study Report

Basic Info

Reference	Jiang S, 200010898902
Citation	Jiang S., Xin R., Wu X., Lin S., Qian Y., Ren D., Tang G. and Wang D. (2000) "Association between attention deficit hyperactivity disorder and the DXS7 locus." Am J Med Genet, 96(3): 289-92.
Study Design	family-based
Study Type	Candidate-gene association study
Sample Size	72 ADHD children and their parents
Predominant Ethnicity	Mongoloid
Population	China
Gender	51 boys and 21 girls
Age Group	Children/Adolescents : mean age 10.30 years (SD=0.78)

Detail Info

Summary	In the present work, the DXS7 locus of chromosome X, which is closely linked to MAO genes, was selected as a marker to study the possible association between ADHD and MAO genes in the Chinese population. Haplotype-based haplotype relative risk (HHRR) and the transmission disequilibrium test (TDT) methods were employed to analyze the association and the linkage disequilibrium, respectively. Significant association (P<0.001) and linkage (P<0.001) were detected between the 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 suggested that ADHD was associated and in linkage with DXS7 locus.
Total Sample	The families reported in this study were 72 ADHD children and their parents. The average IQ of these ADHD children was 97.83 (SD=15.97). Parents of these children were used as controls.
Sample Collection	ADHD subjects in this study were selected from the Hyperactivity, Attention, and Learning Problems (HALP) School at Shanghai. This study was performed with the consent of each participating individual who provided blood and allowed the subsequent analyses.
Diagnosis Description	The clinical diagnostic criteria for ADHD were from DSM-III-R [USAn Psychiatric Association, 1987]. Each diagnosis was performed separately by at least two different child psychiatrists.
Technique	DNA was extracted from whole blood by standard procedure. The DXS7 locus contains a varying number of 2-bp repeats within a specific DNA region as described by Moore et al. [1992]. Polymerase chain reaction (PCR) was used to specifically amplifies that DNA region.
Analysis Method	Allele frequencies of the DXS7 locus in ADHD children and their parents were obtained based on the size of PCR product, and the Hardy-Weinberg equilibrium was calculated using these allele frequencies. Haplotype relative risk and transmission/disequilibrium test analyses were performed to study the association between ADHD and DXS7 locus.
Result Description	In this present study, five alleles were detected at this locus through genotyping of 72 ADHD children and their parents. The corresponding size of PCR product was 155, 157, 159, 165, or 167 bp. The most common allele detected in this study was 157-bp allele with a frequency of 0.5913 and 0.4834 in ADHD children and their parents, respectively. The 165-bp allele was the second common allele with a frequency of 0.3118 and 0.3839 in ADHD children and the parents, respectively. The remaining three alleles were relatively rare and their combined frequency was around 0.1. Chi-squared tests were performed to test the statistical difference of allele frequencies of DXS7 locus between ADHD children and their control parents. No significant difference was detected (P>0.05). For the 157-bp allele, the calculated HHRR X² was 15.86, df=1, P<0.001, suggesting a significant association between this allele and ADHD. Subsequently Woolf's method was used to calculate the relative risk. A significant relative risk of 3.36 (P<0.001) was obtained. McNemar method [Terwilliger and Ott, 1992] was used to test if there is any linkage between ADHD and the DXS7 locus. According to this method, X²=14.88; df=1; P<0.001. TDT result suggested that there might be a linkage between ADHD and DXS7 locus.

Other variant reported by this study (count: 1)

Variant Name	Allele Change	Risk Allele	Statistical Values	Author Comments	Result of Statistical Analysis
MAOA DXS7	155, 157, 159, 165, 167 bp		Chi-squared test for difference of allele frequencies: P>0.0...... Chi-squared test for difference of allele frequencies: P>0.05; HHRR for haplotype frequency: P-value<0.001; TDT for linkage test: P-value<0.001 More...	Significant association and linkage were detected between the 157-bp allele of the DXS7 locus and the DSM-III-R-diagnosed ADHD in trios	Significant

Genes reported by this study (count: 1)