The genetic Variants and Haplotypes of Tryptophan Hydroxylase 2 and Reelin Genes May Be Linked with Attention Deficit Hyperactivity Disorder in Egyptian Children.

Attention-deficit hyperactivity disorder (ADHD) has been proposed to stem from multiple etiologies, perhaps genetic in nature with biological and psychosocial motivates. Tryptophan Hydroxylase 2 (TPH2) and Reelin (RELN) genes may play a key role in triggering ADHD. The purpose of this case-controlled study was to explore the linkage of the genetic variants of TPH2 and RELN genes with ADHD. One-hundred Egyptian children with ADHD and 105 age and sex matched controls constituted the study samples. Genotyping was performed for TPH2 (rs11179027; rs1843809) and RELN (rs736707; rs362691) gene polymorphisms using real time-PCR assay. The alleles and genotype frequencies of TPH2 and RELN gene polymorphisms were assessed in all study participants. The frequencies of the alleles of TPH2-rs11179027( OR=1.75, 95% CI=1.08-2.85, p=0.022), TPH2-rs1843809 (OR=3.67, 95% CI=1.82-7.43, p=<0.001), RELN-rs736707 (OR=1.61, 95% CI=1.03-2.51, p=0.035) were significantly associated with ADHD, while there was no significant difference between ADHD patients and controls regarding the frquency of RELN-rs362691 (OR=1.34, 95% CI=0.73-2.48, p=0.34). The frequencies of CTAG, CTGG, CTAC, CTGC, and GTAC haplotypes were significantly higher in ADHD patients than controls (p=0.011, 0.005, 0.015, 0.001 and 0.027 respectively). In conclusion, TPH2 rs11179027, TPH2 rs1843809 and RELN rs736707 gene alleles and haplotypes might be significantly correlated with the genetic susceptibility to ADHD in Egyptian children.