Polymorphisms of DBH have been reported to be associated with several neurological diseases, such as Parkinson's disease, Alzheimer's disease, schizophrenia and attention-deficit hyperactivity disorder, which have overlapping neurological symptoms with WD.
In common among cADHD and aADHD, the most significant findings are for oxidative stress proteins (MAD, SOD, PON1, ARES, TOS, TAS and OSI), and, in the second level, DISC1, DBH, DDC, microRNA and adiponectin.
We examined 4 SNPs located on genes previously associated to dyslexia (KIAA0319, DCDC2, DYX1C1 and FOXP2) and 3 SNPs within genes related to ADHD (COMT, MAOA and DBH) in a cohort of Spanish children (N = 2078) that met the criteria of having one, both or none of these disorders (dyslexia and ADHD).
These data demonstrate for the first time that a DBH gene variant, rs129882, which confers risk to ADHD is also associated with reduced in vitro gene expression.
The distribution of AA genotype and A allele frequencies of rs5320 in the dopamine beta-hydroxylase gene in ADHD children differed significantly from that in healthy controls; however, no associations were found between four other polymorphisms in dopaminergic/GABAergic genes and ADHD.
Based on this information we evaluated the contribution to ADHD of nine genes involved in dopaminergic neurotransmission (DRD1, DRD2, DRD3, DRD4, DRD5, DAT1, TH, DBH and COMT).
To investigate five top single nucleotide polymorphisms (SNPs) located in different genes and loci (CHRNA3, BDNF, DBH and LOC100188947) that were highly associated with different dimensions of smoking behaviour, in relation to attention-deficit hyperactivity disorder (ADHD).
Gene-gene interaction analysis revealed significant additive effect of DBHrs1108580 and DRD4 rs1800955 with significant main effects of DRD4 exon3 VNTR, DAT1 3'UTR and intron 8 VNTR, MAOA u-VNTR, rs6323, COMT rs4680, rs362204, DBHrs1611115 and rs1108580 thereby pointing towards a strong association of these markers with ADHD.
The present study examined associations between a putative functional single nucleotide polymorphism (SNP) at DBH with performance on the Stroop task in patients with ADHD and in healthy control subjects.
The present study hints toward the fact that DBH gene polymorphisms have some role in the etiology of ADHD in eastern Indian population and their study could be useful for therapeutic intervention.
The present study demonstrated an association between the neuropsychological performance of children with ADHD and a functional polymorphism in the promoter region of the DBH gene.
Our study supports the involvement of the dopamine pathway in the etiology of ADHD; specifically the genes DBH and DRD2 deserve more attention in further studies.
Another SNP, commonly known as DBH Taq1A (rs2519152; SNP2) is associated with attention-deficit/hyperactivity disorder (ADHD) in some (but not all) studies.
Several candidate gene polymorphisms have been implicated in attention deficit hyperactivity disorder (ADHD), including DAT1 40bp VNTR, DRD4 7+, and DBH TaqI A2 alleles.
Since catecholamines regulate visual attention, we examined whether participants with ADHD were impaired on a task requiring temporal attention and how DBH genotype influenced temporal attention in ADHD.
Several polymorphisms including a 5' flanking -1021C-->T polymorphism, was reported to be associated with changed DBH activity and an association between -1021C-->T polymorphism with ADHD was observed in Han Chinese children.
There are currently three studies (Daly et al., 1999; Roman et al., 2002; Wigg et al., 2002) that have found an association between the dopamine beta-hydroxylase gene (DBH) TaqI 2 allele and childhood ADHD.
These results indicate that the DBH TaqI A allele, or another polymorphism in linkage disequilibrium with this allele, may confer increased susceptibility towards ADHD.