Exploratory genetic analysis in children with autism spectrum disorder and other developmental disorders using whole exome sequencing.

Developmental disorders (DDs), such as autism spectrum disorder (ASD), incorporate various conditions; once identified, further diagnostics are necessary to specify their type and severity. The aim of this exploratory study was to identify genetic variants that can help differentiate ASD early from other DDs. We selected 36 children (mean age 60.1 months) with DDs using Developmental Behavioral Scales (DBS) through "EDUS-Education for All", an organization providing services for children with developmental disorders in Bosnia and Herzegovina. We further rated children's autistic traits with the preschool version of the Childhood Autism Rating Scale, second edition (CARS-II). We defined ASD if scores were >25.5 and other DDs if scores were <25.5. Diagnosis of ASD and DD were independently confirmed by child psychiatrists. Whole exome sequencing (WES) was performed by Veritas Genetics, USA, using Illumina NovaSeq 6000 (Illumina Inc., San Diego, CA, USA) next-generation sequencing (NGS) apparatus. We tested genetic association by applying SKAT-O, which optimally combines the standard Sequence Kernel Association Test (SKAT) and burden tests to identify rare variants associated with complex traits in samples of limited power. The analysis yielded seven genes (DSE, COL10A1, DLK2, CSMD1, FAM47E, PPIA, PYDC2) to potentially differentiate observed phenotypic characteristics between our cohort participants with ASD and other DDs. Our exploratory study in a small sample of participants with ASD and other DDs contributed to gene discovery in differentiating ASD from DDs. A replication study is needed in a larger sample to confirm our results.

DNA methylation at birth and fine motor ability in childhood: an epigenome-wide association study with replication.

Lower fine motor performance in childhood has been associated with poorer cognitive development and neurodevelopmental conditions such as autism spectrum disorder, yet, biological underpinnings remain unclear. DNA methylation (DNAm), an essential process for healthy neurodevelopment, is a key molecular system of interest. In this study, we conducted the first epigenome-wide association study of neonatal DNAm with childhood fine motor ability and further examined the replicability of epigenetic markers in an independent cohort. The discovery study was embedded in Generation R, a large population-based prospective cohort, including a subsample of 924 ~ 1026 European-ancestry singletons with available data on DNAm in cord blood and fine motor ability at a mean (SD) age of 9.8 (0.4) years. Fine motor ability was measured using a finger-tapping test (3 subtests including left-, right-hand and bimanual), one of the most frequently used neuropsychological instruments of fine motor function. The replication study comprised 326 children with a mean (SD) age of 6.8 (0.4) years from an independent cohort, the INfancia Medio Ambiente (INMA) study. Four CpG sites at birth were prospectively associated with childhood fine motor ability after genome-wide correction. Of these, one CpG (cg07783800 in GNG4) was replicated in INMA, showing that lower levels of methylation at this site were associated with lower fine motor performance in both cohorts. GNG4 is highly expressed in the brain and has been implicated in cognitive decline. Our findings support a prospective, reproducible association between DNAm at birth and fine motor ability in childhood, pointing to GNG4 methylation at birth as a potential biomarker of fine motor ability.

Identification of developmental disorders including autism spectrum disorder using salivary miRNAs in children from Bosnia and Herzegovina.

Autism spectrum disorder (ASD) is a neurodevelopmental disorder characterized by major social, communication and behavioural challenges. The cause of ASD is still unclear and it is assumed that environmental, genetic and epigenetic factors influence the risk of ASD occurrence. MicroRNAs (miRNAs) are short 21-25 nucleotide long RNA molecules which post-transcriptionally regulate gene expression. MiRNAs play an important role in central nervous system development; therefore, dysregulation of miRNAs is connected to changes in behaviour and cognition observed in many disorders including ASD. Based on previously published work, on diagnosing ASD using miRNAs, we hypothesized that miRNAs can be used as biomarkers in children with suspected developmental disorders (DD) including ASD within Bosnian-Herzegovinian (B&H) population. 14 selected miRNAs were tested on saliva of children with suspected developmental disorders including ASD. The method of choice was qRT-PCR as a relatively cheap method available in most diagnostic laboratories in low to mid-income countries (LMIC). Out of 14 analysed miRNAs, 6 were differentially expressed between typically developing children and children with some type of developmental disorder including autism spectrum disorder. Using the most optimal logistic regression, we were able to distinguish between ASD and typically developing (TD) children. We have found 5 miRNAs as potential biomarkers. From those, 3 were differentially expressed within the ASD cohort. All 5 miRNAs had shown good chi-square statistics within the logistic regression performed on all 14 analysed miRNAs. The accuracy of 5-miRNAs model training set was 90.2%, while the validation set had a 90% accuracy. This study has shown that miRNAs may be considered as biomarkers for ASD detection and may be used to identify children with ASD along with standard developmental screening tests. By combining these methods we may be able to reach a reliable and accessible diagnostic model for children with ASD in LMIC such as B&H.

Analysis of miRNA expression under stress in Arabidopsis thaliana.

MicroRNAs (miRNAs) are a class of small, 21-24 nucleotides long, non-coding RNAs involved in the post-transcriptional regulation of gene expression. Using the array analysis on Arabidopsis thaliana infected with the Oil-seed Rape Mosaic Virus (ORMV), we have found 28 up-regulated miRNAs. From them, six were selected for further validation by Northern blot analysis: miRNA172a, miRNA161, miRNA167a&b, miRNA168a&b, miRNA171a, and miRNA159. In addition, 29 miRNAs were detected in plants exposed to drought stress, 13 of those detected miRNAs were up-regulated and 16 down-regulated miRNAs. Out of 29 differentially expressed miRNAs during the abiotic stress, six miRNAs (167a&b, 168a&b, 173, 171b&c, 399d and 447c) were chosen for Northern blot and RT-PCR analysis to confirm the array results. Interestingly, four out of these six miRNAs, 171b&c, 168a&b, 399d, and 447c, showed very high abundance of pri-miRNAs and pre-miRNAs. Furthermore, mature forms of miRNAs171b&c, 399d, and 447c, were not detectable in the rosette leaves, indicating that miRNA processing is tissue specific. In conclusion, using the array analysis we show that 28 miRNAs are involved in the plant response to viral infection and 29 miRNAs are involved in the regulation of drought stress. We also demonstrate that at least some miRNAs involved in the stress response in Arabidopsis thaliana are regulated at the maturation level. One such example is miRNA 171b&c. This miRNA is transcribed in all tissues, evidenced by its detected pri and pre-miRNA forms; however, its mature form is constitutively or transiently expressed depending on the tissue type.