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	Guimaraes AP, 200919756364
Citation	Guimaraes A. P., Schmitz M., Polanczyk G. V., Zeni C., Genro J., Roman T., Rohde L. A. and Hutz M. H. (2009) "Further evidence for the association between attention deficit/hyperactivity disorder and the serotonin receptor 1B gene." J Neural Transm, 116(12): 1675-80.
Study Design	family-based
Study Type	Candidate-gene association study
Sample Size	343 families
Predominant Ethnicity	Caucasian
Population	Brazil
Gender	275 (77.9%) males
Age Group	Children/Adolescents : mean age 10.65 years (SD=3.21)

Detail Info

Summary	The aim of this study was to investigate HTR1B gene polymorphisms to determine if there was evidence for biased transmission of haplotypes derived from the 861G>C, -161A>T, and -261T>G from parents to 343 families with ADHD children. They also sought to replicate the findings from Li et al. (2005) and Smoller et al. (2006) that the association between HTR1B is preferentially with ADHD-I. Using a transmission disequilibrium test they found evidence for an excess transmission of haplotype. -261G/-161T/ 861G (P-value=0.014) for affected children in the total sample. When the analysis was repeated with 143 families with ADHD-Inattentive subtype no significant associations were observed. The results provide additional evidence that HRT1B gene may be an important risk factor for the development of ADHD, but this effect seems not to be attributable to inattentive cases.
Total Sample	A total of 343 families with an ADHD child were included in the study. The largest sample was composed of 243 children with ADHD clinical diagnosis. The remaining 100 families were of children with ADHD-inattentive type. from the 343 families investigated, 316 (92%) were informative for the family-based association analyses.
Sample Collection	Patients were predominantly of European-Brazilian descent (82.1%). The largest sample composed of 243 children with ADHD clinical diagnosis were predominantly of European descent (92.1%).
Diagnosis Description	The largest sample was composed of 243 children with ADHD clinical diagnosis recruited at the Child and Adolescent Psychiatric Division of the Hospital de Clinicas de Porto Alegre (HCPA). An ADHD consensus diagnosis based on DSM-IV criteria was achieved as described in detail previously (Roman et al. 2001). The remaining 100 families were of children with ADHD-inattentive type. This group was ascertained from 12 public schools. Inclusion and diagnostic criteria for this sample have been fully described elsewhere (Schmitz et al. 2006).
Technique	DNA was extracted from whole blood by a salting out procedure (Lahiri and Nurnberger 1991). The three polymorphisms 861G>C, -161A>T, and -261T>G were genotyped by PCR using primers and methods described elsewhere (Nothen et al. 1994; Lappalainen et al. 1995; Sun et al. 2002).
Analysis Method	Pairwise linkage disequilibrium (LD) was estimated using the Multiple Locus Haplotype software (mlocusSNP) (Long 1999). The haplotype family-based association analyses were performed using the statistical program TRANSMIT (Clayton 1999).
Result Description	All SNPs investigated were in pairwise significant LD; therefore, all analyses were carried out with haplotypes derived from these three SNPs. Haplotype analyses detected an over-transmission of -261G/-161T/861G haplotype. This haplotype was detected in 30% of the affected subjects. Haplotype -261G/-161T/861C which occurred in a low frequency was under-transmitted. However, when the same analyses were carried out only with 143 families with ADHD-I subtype no preferential transmission of alleles from parents to probands was observed. No association was observed between the HTR1B gene haplotypes and ADHD with any specific comorbid condition.

Genes reported by this study (count: 1)