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Autism spectrum disorder (ASD) is one of the most complex behavioral disorders with a strong genetic influence. The objectives of this article are to review the current status of genetic research in ASD, and to provide information regarding the potential candidate genes, mutations, and genetic loci possibly related to pathogenesis in ASD. Investigations on monogenic causes of ASD, candidate genes among common variants, rare de novo mutations, and copy number variations are reviewed. The current possible clinical applications of the genetic knowledge and their future possibilities are highlighted.

Neurobiological and pharmacological research has suggested that dysregulation of the central noradrenergic systems might be involved in the pathophysiology of attention deficit hyperactivity disorder (ADHD). Previous studies have demonstrated that the norepinephrine transporter gene (SLC6A2) is associated with ADHD. The aims of this study were to examine the association of the SLC6A2 G1287A and –3081(A/T) polymorphisms with ADHD in Korean children and adolescents, and to determine the relationships of the genotypes of these two polymorphisms with continuous performance test results and the Junior Temperament and Character Inventory profiles of ADHD. In a case-control study, we assessed 186 ADHD probands and 150 normal controls; 109 trios were studied in a family-based association analysis. There were no significant differences in the genotype or allele frequencies of the SLC6A2 G1287A and –3081(A/T) polymorphisms between the ADHD and control groups (p > 0.05). In the transmission disequilibrium test analyses, there was no evidence for biased transmission of any of the alleles of the SLC6A2 G1287A and –3081(A/T) polymorphisms. In the haplotype analyses of these two polymorphisms, the global and individual χ² tests showed no significant associations between any of the haplotypes and ADHD. There were no significant differences with respect to the continuous performance test results and the Junior Temperament and Character Inventory profiles in the ADHD probands according to the genotypes of the SLC6A2 G1287A and –3081(A/T) polymorphisms. Our findings do not support SLC6A2 as a major genetic susceptibility factor in ADHD.

Autism spectrum disorder (ASD) is a complex neurodevelopmental disorder with a strong genetic component and environmental risk factors. Nitric oxide (NO), which is produced by nitric oxide synthase (NOS), may play a role in the development of ASD. We genotyped nine single nucleotide polymorphisms (SNPs) in the NOS-I gene and nine SNPs in the NOS-IIA gene and carried out the transmission disequilibrium test (TDT) and haplotype analysis in 151 Korean ASD trios. We found preferential transmission of the A allele of rs8068149 (P = 0.039) and G allele of rs1060826 (P = 0.035) of NOS-IIA in ASD and the haplotype analysis revealed that the two haplotypes had significant associations (P = 0.014 and 0.031, respectively). The behavioral subdomain score of failure to use nonverbal behaviors to regulate social interaction in Autism Diagnostic Interview-Revised (ADI-R) was significantly higher in subjects with the GG or AG allele in rs1060826 of NOS-IIA compared to those who had the AA allele (P = 0.027). These results provide significant but weak evidence for an association between NOS-IIA and ASD in the Korean population.

BackgroundIt is known that there are various factors associated with children's screen overuse. The aim of this study was to examine the effect of maternal depression on 2–5-year-old children's overuse of various household screen devices.MethodsParticipants were from the Internet-Cohort for Understanding of internet addiction Risk factors/Rescue in Early livelihood (I-CURE) study, an observational prospective cohort study in Korea. Screen time for six types of screen devices (smartphone, television, computer, tablet, video gaming console, and portable gaming console) were assessed by parental questionnaire. Maternal depression was measured by the Korean version of the Beck Depression Inventory II. Logistic regression models were run to determine the association between maternal depression and children's screen overuse.ResultsMaternal depression was associated with children's television overuse after adjusting for other factors (odds ratio, 1.954; P = 0.034). Contrary to expectation, the relationship between maternal depression and screen time was not present on other devices such as smartphones, computers and tablets.ConclusionMaternal depression is related with 2–5-year-old children's television overuse. Interventions in maternal depressive symptoms and the associated changes in parent-child relationship can be useful for preventing children's television overuse.