ADHD is a neurodevelopmental disorder that children and adults can develop. A complex interplay of genetic and environmental factors may underlie interindividual variability in ADHD and potentially related aggressive behavior. Using high-resolution molecular biology techniques, we investigated the impact of some MAOA and SLC6A4 variations on ADHD and aggressive behavior in a group of 80 Italian children with ADHD and in 80 healthy controls. We found that homozygous genotypes of MAOA rs6323 and rs1137070 were associated with an increased risk of ADHD (p = 0.02 and p = 0.03, respectively), whereas the heterozygous genotypes (GT of rs6323 and CT of rs1137030) (p = 0.0002 and p = 0.0006) were strongly linked to a lower risk of developing this disorder. In patients with aggressive behavior, we highlighted only a weak negative association of both MAOA polymorphisms (heterozygous genotypes) with aggressiveness, suggesting that these genotypes may be protective towards specific changes in behavior (p = 0.05). Interestingly, an increase in the GG genotype of rs6323 (p = 0.01) and a decrease in GT genotype (p = 0.0005) was also found in patients without aggressive behavior compared to controls. Regarding 5HTT gene genotyping, no allele and genotype differences have been detected among patients and controls. Our work shows that defining a genetic profile of ADHD may help in the early detection of patients who are more vulnerable to ADHD and/or antisocial and aggressive behavior and to design precision-targeted therapies.

Mast cells can release different kinds of molecules as a response to different stimuli, particularly proinflammatory mediators that contribute to neuroinflammation. The enrichment of mast cells in specific areas of the nervous system and gastrointestinal tract, together with their degranulation, histamine and neuropeptide secretion, such as substance P, and mast cell–microglia interactions, may promote neuroinflammatory signaling in neurological and psychiatric disorders during childhood and adolescence. The aim of this review is to explore the mast cell-related molecular aspects of the main neuropsychiatric disorders of the developmental period, such as ADHD, autism spectrum disorder, and epilepsy, as well as anxiety and depression. The translational analysis of molecular pathways and the relationships involved may contribute to the development of innovative and targeted therapeutic approaches.

ADHD is a neurodevelopmental disorder that children and also adults can develop. A complex interplay of genetic and environmental factors may underlie interindividual variability in ADHD and potentially related aggressive behavior. Using high-resolution molecular biology techniques, we investigated the impact of some MAOA and SLC6A4 variations on ADHD and aggressive behavior in a group of 80 Italian children with ADHD and in 80 healthy controls.We found that homozygous genotypes of MAOA rs6323 and rs1137070 were associated with an increased risk of ADHD (p=0.02 and p=0.03, respectively), instead the heterozygous genotypes (GT of rs6323 and CT of rs1137030) (p=0.0002 and p=0.0006) were strongly linked to a lower risk of developing this disorder. In patients with aggressive behavior, we highligted only a weak negative association of both MAOA polymorphisms (heterozygous genotypes) with aggressiveness then, suggesting that these genotypes maybe protective towards specific changes in behavior (p=0.05). Interestingly, an increase of the GG genotype of rs6323 (p=0.01) and a decrease of GT genotype (p=0.0005) was also found in patients without aggressive behavior compared with controls. Regarding 5HTT gene genotyping, no allele and genotype differences have been detected among patients and controls. Our work shows that defining a genetic profile of ADHD may help to early detect those patients who are more vulnerable to ADHD and/or antisocial and aggressive behavior and to design precision-targeted therapies.

Background: Attention-deficit/hyperactivity disorder (ADHD) is a neurodevelopmental condition frequently accompanied by behavioral dysregulation. While genetic factors involving monoaminergic systems have been implicated, emerging evidence suggests a role for mitochondrial dysfunction in ADHD pathophysiology. Mitochondrial DNA copy number (mtDNA-cn), a surrogate marker of mitochondrial biogenesis and cellular energy demand, may reflect underlying neurobiological alterations and oxidative stress-related mechanisms relevant to ADHD. Methods: We assessed mtDNA-cn in the peripheral blood of 56 Italian children and adolescents with ADHD and 27 age- and sex-matched healthy controls. ADHD symptoms and aggressive behavior were evaluated using DSM-5 criteria and the Conners’ 3 Rating Scales. Genotyping was performed for MAOA (rs6323, rs1137070) and 5-HTT (rs4795541) polymorphisms. Results: ADHD patients showed significantly higher mtDNA-cn than controls (p = 0.002), supporting mitochondrial dysregulation. Comparing the ADHD patient subgroups with aggressive behavior and those without, a non-significant reduction in mtDNA-cn was observed in the first subgroup. Notably, individuals with the TT genotype (rs6323) or CC genotype (rs1137070) had significantly higher mtDNA-cn compared to controls with the same genotypes (p = 0.031). Similar increases were seen across all 5-HTT rs4795541 genotypes in ADHD patients. Conclusions: Our findings suggest that mitochondrial alterations may contribute to ADHD pathophysiology. The association between mtDNA-cn and monoaminergic gene variants highlights a potential link between neurotransmitter metabolism, oxidative stress, and mitochondrial function. Thus, mtDNA-cn may serve as a peripheral biomarker and therapeutic target in ADHD.