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	Squassina A, 200818164132
Citation	Squassina A., Lanktree M., De Luca V., Jain U., Krinsky M., Kennedy J. L. and Muglia P. (2008) "Investigation of the dopamine D5 receptor gene (DRD5) in adult attention deficit hyperactivity disorder." Neurosci Lett, 432(1): 50-3.
Study Design	case-control and family-based
Study Type	Candidate-gene association study
Sample Size	57 trios, 88 cases and controls
Predominant Ethnicity	Caucasian
Population	Canada
Gender	males/females: 97(69%)/44(31%) in the family sample males/females: 59(67%)/39(33%) in the case-control sample;
Age Group	Adults : mean age 34.7,SD=12.7 years in the family sample; mean age for cases: 34.2; SD=11.2; mean age for controls: 34.8; SD=11.5

Detail Info

Summary	They tested for an association between the (CA)n repeat and adult ADHD in a sample comprised of 119 families with adult ADHD probands and 88 unrelated adult ADHD cases with a corresponding number of controls matched for age, ethnicity and sex. In the family sample they found a non-significant trend for association between the 148 bp allele and ADHD. An excess of non-transmissions was detected for the 150 and 152 bp alleles. Quantitative analysis performed using the Brown Attention Deficit Disorder Scale (BADDS) showed association between the 150 bp allele and lower total score, and lower effort, activation and attention cluster scores. They did not replicate association findings in the case-control group, likely due to the lack of statistical power of this sample. Their findings add to the literature suggesting DRD5 (CA)n repeat has a modest effect in modulating susceptibility to adult ADHD but further studies are required.
Total Sample	The family sample was comprised of 338 individuals in 57 complete trios, 41 trios with a missing parent, 17 families with 1 affected and 1 unaffected child, 3 families with 2 affected children, and 1 family with 1 affected and 2 unaffected children. The case-control sample consisted of 88 cases with controls matched for age, ethnicity and sex.
Sample Collection	mixed European Caucasian ancestry (94%) and probands of African or Chinese descent (6%)
Diagnosis Description	The diagnosis of ADHD was based on fulfilling the ADHD DSM-IV criteria both at the time of the interview and during childhood, as recalled by the patient and by at least one first-degree relative involved in the study. Most of the patients met criteria for the ADHD inattentive or combined subtypes, with few patients meeting criteria for the hyperactive/impulsive subtype. For broad assessment of psychiatric conditions, the Structured Clinical Interview for DSM-IV (axis I) was administered.
Technique	Blood samples were collected from patients and relatives and the DNA was extracted following standard high salt procedures. The (CA)n repeat was amplified using the method provided by Sherrington et al. The forward primer was labeled with HEX.PCR products were separated using an ABI 3100 Avant Automated Genetic Analyzer. Allele assignment was performed using Genotyper 3.7^TM.
Analysis Method	The Family Based Association Test (FBAT) was used to investigate the presence of biased transmission of alleles to probands. For each allele the expected transmissions under the null hypothesis (E), observed transmissions (S), Z statistic and two-sided P-value are computed. A global chi-square and associated P-value are also calculated. To assess the significance of differences in allele frequencies between cases and controls the X² test was used.
Result Description	In the family sample they found a non-significant trend for association between the 148 bp allele and ADHD. An excess of non-transmissions was detected for the 150 and 152 bp alleles. They did not replicate association findings in the case-control group, likely due to the lack of statistical power of this sample. Their findings add to the literature suggesting DRD5 (CA)n repeat has a modest effect in modulating susceptibility to adult ADHD but further studies are required.

Other variant reported by this study (count: 1)

Variant Name	Allele Change	Risk Allele	Statistical Values	Author Comments	Result of Statistical Analysis
DRD5 5'-flanking (CT/GT/GA)n	136-152bp		allele 136-bp: FBAT P-value=0.275, Z=1.09; allele 138-bp: FB...... allele 136-bp: FBAT P-value=0.275, Z=1.09; allele 138-bp: FBAT P-value=0.371, Z=0.89; allele 146-bp: FBAT P-value=0.201, Z=1.28; allele 148-bp: FBAT P-value=0.055, Z=1.91; allele 150-bp: FBAT P-value=0.023, Z=-2.26; allele 152-bp: FBAT P-value=0.028, Z=-2.20. More...	non-significant trend of associations were found for allele 136-, 138-, 146-, 148-bp, but allele 150-, 152-bp showed possible protective effect against ADHD.	Significant

Genes reported by this study (count: 1)