Dopamine D4 Receptor Gene Polymorphism in a Sample of Egyptian Children With Attention-Deficit Hyperactivity Disorder (ADHD)

Attention-deficit/hyperactivity disorder and dopamine receptor D4 (DRD4) exon 3 variable number of tandem repeats (VNTR) 2-repeat allele

To investigate the association of attention-deficit/hyperactivity disorder (ADHD) with the 48-base pair (bp) variable number of tandem repeats (VNTR) in exon 3 of the dopamine receptor D4 (DRD4) gene, we genotyped 240 ADHD patients and their parents from Hong Kong. The 4R allele was most common, followed by 2R. We examined association between the 2R allele (relative to 4R) and ADHD by Transmission Disequilibrium Test (TDT). The odds ratio (OR) (95% confidence interval) was 0.90 (0.64-1.3). The p-value was 0.6. Examining subgroups revealed nominally significant association of 2R with inattentive ADHD: OR = 0.33 (0.12-0.92) and p = 0.03. Because our study used TDT analysis, we meta-analyzed the association of 2R with ADHD in Asians (1329 patient alleles), revealing results similar to ours: OR = 0.97 (0.80-1.2) and p = 0.8. To examine the association of 2R with inattentive ADHD, we meta-analyzed all studies (regardless of analysis type or ethnicity, in order to increase statistical power): 702 patient alleles, 1420 control alleles, OR = 0.81 (0.57-1.1) and p = 0.2. Overall, there is no evidence of association between ADHD and the 2R allele, but the suggestive association with the inattentive type warrants further investigation.

Potential Targets and Action Mechanism of Gastrodin in the Treatment of Attention-Deficit/Hyperactivity Disorder: Bioinformatics and Network Pharmacology Analysis

Objective

Gastrodin is a main medicinal component of traditional Chinese medicine (TCM) Gastrodia elata Blume (G. elata), presenting the potential for the treatment of attention-deficit/hyperactivity disorder (ADHD). However, the underlying targets and action mechanisms of the treatment have not been identified.

Methods

The gastrodin-related microarray dataset GSE85871 was obtained from the GEO database and analyzed by GEO2R to obtain differentially expressed genes (DEGs). Subsequently, the targets of gastrodin were supplemented by the Encyclopedia of Traditional Chinese Medicine (ETCM), PubChem, STITCH, and SwissTargetPrediction databases. ADHD-associated genes were collected from six available disease databases (i.e., TTD, DrugBank, OMIM, PharmGKB, GAD, and KEGG DISEASE). The potential targets of gastrodin during ADHD treatment were obtained by mapping gastrodin-related targets with ADHD genes, and their protein–protein interaction (PPI) relationship was constructed by the STRING database. The GO function and KEGG pathway enrichment analyses were performed using the ClueGO plug-in in the Cytoscape software and DAVID database, respectively. Finally, the binding affinity between gastrodin and important targets was verified by molecular docking.

Results

A total of 460 gastrodin-related DEGs were identified from GSE85871, and 124 known gastrodin targets were supplemented from 4 databases, including ETCM. A total of 440 genes were collected from the above 6 disease databases, and 267 ADHD-relevant genes were obtained after duplicate removal. Through mapping the 584 gastrodin targets to the 267 ADHD genes, 16 potential therapeutic targets were obtained, among which the important ones were DRD2, DRD4, CHRNA3, CYP1A1, TNF, IL6, and KCNJ3. The enrichment analysis results indicated that 16 potential targets were involved in 25 biological processes (e.g., dopamine (DA) transport) and 22 molecular functions (e.g., postsynaptic neurotransmitter receptor activity), which were mainly localized at excitatory synapses. The neuroactive ligand-receptor interaction, cholinergic synapse, and dopaminergic synapse might be the core pathways of gastrodin in ADHD treatment. Through molecular docking, it was preliminarily verified that gastrodin showed good binding activity to seven important targets and formed stable binding conformations.

Conclusions

Gastrodin might exert an anti-ADHD effect by upgrading the dopaminergic system and central cholinergic system, inhibiting the inflammatory response and GIRK channel, and exerting a synergistic effect with other drugs on ADHD. For this reason, gastrodin should be considered a multitarget drug for ADHD treatment.

Association between circulating zinc/ferritin levels and parent Conner's scores in children with attention deficit hyperactivity disorder

ADHD is one of the most common neurobehavioral disorders among children and adolescents. In this prospective study, we aimed to measure circulating zinc and ferritin levels in children with ADHD, pick up the deficient ones to give zinc and iron supplements then compare before and after treatment according to their Conner's scores and Wecsler IQ test. Current study included fifty children diagnosed as having ADHD by DSMV criteria, their zinc and ferritin levels were measured by Colorimetric method and enzyme-linked immunosorbent assay (ELISA) respectively. They were divided into: group I (zinc only deficient),group II (zinc and ferritin deficient),group III (non-deficient), cases with mineral deficiency received zinc (55 mg/day) and/or iron (6 mg/kg/day) for 6 months then reassessed by parent Conner's rating scale. In group 1, there was no significant difference between the Wecsler verbal and non-verbal IQ scores and oppositional and cognitive problems in Conner's scores before and after zinc supplements, although there was significant improvement in attention, hyperactivity, emotional liability and impulsivity. In group II, there was significant improvement in verbal and total IQ but not in performance IQ, also there was significant improvement in hyperactivity, emotional liability and impulsivity with no significant difference in oppositional, cognitive problems and inattention before and after zinc/ iron supplements. In Conclusion, Zinc supplements in adjuvant to the main treatment significantly improved symptoms of ADHD children. However, a combined zinc and iron supplements was superior to zinc alone in alleviating ADHD symptoms as well as IQ improvement.

Dynamic interaction between fetal adversity and a genetic score reflecting dopamine function on developmental outcomes at 36 months

Background

Fetal adversity, evidenced by poor fetal growth for instance, is associated with increased risk for several diseases later in life. Classical cut-offs to characterize small (SGA) and large for gestational age (LGA) newborns are used to define long term vulnerability. We aimed at exploring the possible dynamism of different birth weight cut-offs in defining vulnerability in developmental outcomes (through the Bayley Scales of Infant and Toddler Development), using the example of a gene vs. fetal adversity interaction considering gene choices based on functional relevance to the studied outcome.

Methods

36-month-old children from an established prospective birth cohort (Maternal Adversity, Vulnerability, and Neurodevelopment) were classified according to birth weight ratio (BWR) (SGA ≤0.85, LGA >1.15, exploring a wide range of other cut-offs) and genotyped for polymorphisms associated with dopamine signaling (TaqIA-A1 allele, DRD2-141C Ins/Ins, DRD4 7-repeat, DAT1-10- repeat, Met/Met-COMT), composing a score based on the described function, in which hypofunctional variants received lower scores.

Results

There were 251 children (123 girls and 128 boys). Using the classic cut-offs (0.85 and 1.15), there were no statistically significant interactions between the neonatal groups and the dopamine genetic score. However, when changing the cut-offs, it is possible to see ranges of BWR that could be associated with vulnerability to poorer development according to the variation in the dopamine function.

Conclusion

The classic birth weight cut-offs to define SGA and LGA newborns should be seen with caution, as depending on the outcome in question, the protocols for long-term follow up could be either too inclusive—therefore most costly, or unable to screen true vulnerabilities—and therefore ineffective to establish early interventions and primary prevention.