OBJECTIVEAttention deficit hyperactivity disorder (ADHD) is one of the most common behavior disorders in childhood and adolescent. The etiology of ADHD is unknown. The aim of this study was to investigate the relationship between each of the 14 polymorphisms in the five candidate genes and ADHD, and between the combination of some polymorphisms in those genes and ADHD, in attempting to examine whether combinations of genotypes would confer a significant susceptibility to ADHD.

METHODSOne hundred and thirty-nine children with ADHD and one hundred and nineteen normal children were enrolled. Eight single nucleotide polymorphisms (SNP) of three candidate genes were examined with PCR and RFLP techniques. 48 bp VNTR in DRD4 gene was examined with PCR, nondenaturing polyacrylamide gel electrophoresis and silver staining. Five microsatellites (MS) of three candidate genes were examined with genotyping. The relationship between the combinations of 12 polymorphisms and ADHD was examined with logistic regression analysis.

RESULTS1.The frequency of 1065T/1065T genotype and the 1065T allele were significantly higher in ADHD children than that in normal controls (P<0.05). The frequency of -48G/-48G genotype of the A-48G polymorphism of DRD1 gene was significantly lower in ADHD children than that in normal controls (P<0.05). 2. A specific combination of three polymorphisms in the two genes showing an association with ADHD gave a prediction level of 77.5%.

CONCLUSIONSThe T1065G polymorphism in the SNAP-25 may be associated with ADHD. The 1065T/1065T genotype and the 1065T allele may be a risk factor for ADHD. The A-48G polymorphism of DRDI may be associated with ADHD. The -48G/-48G genotype may be a protective factor for ADHD. The specific combination of three sites of SNP in SNAP-25 gene and DRDI gene is found and shows an association with ADHD in 12 polymorphisms of the five candidate genes on glutamatergic/dopaminergic pathway.

Adolescent ; Attention Deficit Disorder with Hyperactivity ; genetics ; Child ; Female ; Humans ; Logistic Models ; Male ; Minisatellite Repeats ; Polymorphism, Single Nucleotide ; Receptors, Dopamine D3 ; genetics ; Receptors, Dopamine D4 ; genetics ; Receptors, Dopamine D5 ; genetics ; Receptors, N-Methyl-D-Aspartate ; genetics ; Synaptosomal-Associated Protein 25 ; genetics

OBJECTIVE: To reveal the genetic polymorphisms of four SNP loci (rs77434921, rs2076907, rs6283, rs1800762) in D5 gene of dopamine receptor (DRD5) in Northern Chinese Han population. METHODS: Four SNP loci of the DRD5 gene of 206 unrelated individuals in Northern Chinese Han population were separately amplified and sequenced by PCR technique and statistically analyzed by Haploview v4.1 software. RESULTS: In Northern Chinese Han population, the genotype frequency distribution of rs77434921, rs2076907, rs6283 and rs1800762 loci in the DRD5 gene were all in accordance with Hardy-Weinberg equilibrium. DP value was 0.145, 0.532, 0.602 and 0.159, while PE value was 0.004, 0.079, 0.196 and 0.007. A linkage disequilibrium among these four SNP loci was also demonstrated, which might infer five haplotypes. CONCLUSION rs2076907 and rs6283 loci of DRD5 gene in the Northern Chinese Han population have high genetic polymorphisms, which can be useful for forensic identification of individuals.
Asian People/genetics* ; China/ethnology* ; DNA Primers/genetics* ; Forensic Genetics ; Gene Frequency ; Genetic Markers ; Genotype ; Haplotypes ; Humans ; Linkage Disequilibrium ; Polymerase Chain Reaction ; Polymorphism, Single Nucleotide ; Receptors, Dopamine D5/genetics*

OBJECTIVETo explore the possible differential trafficking properties of the dopamine D1-like receptor subtypes, D1 receptor and D5 receptor.

METHODSTo visualize distributions of dopamine D1-like receptor subtypes at subcellular level, the yellow and cyan variants of green fluorescent protein (GFP) were used to tag D1 and D5 receptors. After transfection with the tagged dopamine receptors, the neuroblastoma cells NG108-15 were treated with D1 agonist SKF38393 or acetylcholine (ACh). Then we observed the subcellular distributions of the tagged receptors under the confocal microscopy and tried to determine trafficking properties by comparing their distribution patterns before and after the drug treatment.

RESULTSIn resting conditions, D1 receptors located in the plasma membrane of NG108-15 cells, while D5 receptors located in both plasma membrane and cytosol. With the pre-treatment of SKF38393, the subcellular distribution of D1 receptors was changed. The yellow particle-like fluorescence of tagged D1 receptors appeared in the cytosol, indicating that D1 receptors were internalized into cytosol from the cell surface. Same situation also occurred in ACh pre-treatment. In contrast, the subcellular distribution of D5 receptors was not changed after SKF38393 or ACh treatment, indicating that D5R was not translocated to cell surface. Interestingly, when D1 and D5 receptors were co-expressed in the same cell, both kept their distinct subcellular distribution patterns and the trafficking properties.

CONCLUSIONOur present study reveals that in NG108-15 nerve cells, dopamine D1 and D5 receptors exhibit differential subcellular distribution patterns, and only D1 receptor has a marked trafficking response to the drug stimulation. We further discuss the potential role of the differential trafficking properties of D1-like receptors in complex modulation of DA signaling.

2,3,4,5-Tetrahydro-7,8-dihydroxy-1-phenyl-1H-3-benzazepine ; pharmacology ; Acetylcholine ; pharmacology ; Animals ; Cell Line ; Dopamine Agonists ; pharmacology ; HeLa Cells ; Humans ; Luminescent Proteins ; genetics ; Mice ; Microscopy, Confocal ; methods ; Neuroblastoma ; Protein Transport ; drug effects ; Rats ; Receptors, Dopamine D1 ; metabolism ; Receptors, Dopamine D5 ; metabolism ; Subcellular Fractions ; metabolism ; ultrastructure ; Transfection ; methods