Two de novo variations identified by massively parallel sequencing in 13 Chinese families with children diagnosed with autism spectrum disorder

Expression analysis of selected genes involved in tryptophan metabolic pathways in Egyptian children with Autism Spectrum Disorder and learning disabilities

Autism Spectrum Disorder (ASD) and learning disabilities are neurodevelopmental disabilities characterized by dramatically increasing incidence rates, yet the exact etiology for these disabilities is not identified. Impairment in tryptophan metabolism has been suggested to participate in the pathogenesis of ASD, however, further validation of its involvement is required. Additionally, its role in learning disabilities is still uninvestigated. Our objective was to evaluate some aspects of tryptophan metabolism in ASD children (N = 45) compared to children with learning disabilities (N = 44) and healthy controls (N = 40) by measuring the expression levels of the MAOA, HAAO and AADAT genes using real-time RT-qPCR. We also aimed to correlate the expression patterns of these genes with parental ages at the time of childbirth, levels of serum iron, and vitamin D3 and zinc/copper ratio, as possible risk factors for ASD. Results demonstrated a significant decrease in the expression of the selected genes within ASD children (p < 0.001) relative to children with learning disabilities and healthy controls, which significantly associated with the levels of our targeted risk factors (p < 0.05) and negatively correlated to ASD scoring (p < 0.001). In conclusion, this study suggests that the expression of the MAOA, HAAO and AADAT genes may underpin the pathophysiology of ASD.

De novo variants of DEAF1 cause intellectual disability in six Chinese patients

BACKGROUND

It has been reported that de novo heterozygous variants of DEAF1 can cause DEAF1-associated neurodevelopmental disorder. The purpose of this article is to explore the clinical and genetic characteristics of Chinese patients harboring de novo DEAF1 variants.

METHODS

We assembled a cohort of six unrelated patients with de novo variants in DEAF1. Clinical and genetic features of these patients were summarized.

RESULTS

Each child showed intellectual disability (ID)/ global developmental delay (GDD). Severe language impairment was prominent. Behavior problems, seizures, sleep disturbance, and a high pain threshold were common features. DEAF1-related seizures were reported to be difficult to treat or intractable. Seizures in our cohort were almost all treatable. Valproic acid was the most commonly used drug. Five heterozygous missense mutations of DEAF1 gene were identified, three of which (p.W234C, p.L203P, p.H275Q) were not published in literature before.

CONCLUSION

Mutations of DEAF1 gene should be considered in ID/GDD patients with a nonspecific phenotype, comprising intellectual disability, prominent speech delay, abnormal behaviors, especially autism. In our study, DEAF1-related epilepsy is completely treatable in Eastern-Asian individuals when compared to patients in other regions, and valproic acid can be used as a first choice. The knowledge of DEAF1-related neurodevelopmental disorder and the de novo variant database of DEAF1 were expanded.

Novel alterations of CC2D1A as a candidate gene in a Turkish sample of patients with autism spectrum disorder

BACKGROUND

Autism spectrum disorder (ASD) is a neurodevelopmental disorder with large genetic background, but identification of pathogenic variants has proceeded slowly because hundreds of loci are involved in this complex disorder. CC2D1A gene firstly associated with the intellectual disability (ID) in a family with a large deletion. We aimed to contribute to the literature by sequencing this gene and by this way we report novel CC2D1A variations in patients with ASD.

METHODS

Forty families who have a child with a diagnosis of ASD were enrolled to the study. DNA samples were obtained from each family member. Bidirectional CC2D1A gene sequencing was performed with CEQ Cycle Sequencing Kit, and the products were analyzed on the Beckman CEQ 8000. All of the genetic analysis was conducted in Erciyes University Genome and Stem Cell Center (GENKOK).

RESULTS

According to the sequencing results, we defined new alterations in this gene with two SNPs in exon 15 and 19 (rs747172992 and rs1364074600) in our patients. We found a pathogenic variant in one patient. This variant was located in the acceptor region. Six of the variants were missense mutations. Additionally, six different benign variants were detected in 30 patients; however, they were not associated with ASD. Two patients carried multiple rare variants.

CONCLUSION

In vitro and in vivo functional analysis with this gene will help to understand its contribution to ASD pathogenesis. Future studies may help to elucidate the underlying biological mechanisms of these variants leading to the autism phenotype.

De novo and biallelic DEAF1 variants cause a phenotypic spectrum

PURPOSE

To investigate the effect of different DEAF1 variants on the phenotype of patients with autosomal dominant and recessive inheritance patterns and on DEAF1 activity in vitro.

METHODS

We assembled a cohort of 23 patients with de novo and biallelic DEAF1 variants, described the genotype-phenotype correlation, and investigated the differential effect of de novo and recessive variants on transcription assays using DEAF1 and Eif4g3 promoter luciferase constructs.

RESULTS

The proportion of the most prevalent phenotypic features, including intellectual disability, speech delay, motor delay, autism, sleep disturbances, and a high pain threshold, were not significantly different in patients with biallelic and pathogenic de novo DEAF1 variants. However, microcephaly was exclusively observed in patients with recessive variants (p < 0.0001).

CONCLUSION

We propose that different variants in the DEAF1 gene result in a phenotypic spectrum centered around neurodevelopmental delay. While a pathogenic de novo dominant variant would also incapacitate the product of the wild-type allele and result in a dominant-negative effect, a combination of two recessive variants would result in a partial loss of function. Because the clinical picture can be nonspecific, detailed phenotype information, segregation, and functional analysis are fundamental to determine the pathogenicity of novel variants and to improve the care of these patients.