Identification of DCAF1 by Clinical Exome Sequencing and Methylation Analysis as a Candidate Gene for Autism and Intellectual Disability: A Case Report

Autism spectrum disorder (ASD) comprises a heterogeneous group of neurodevelopmental disorders and occurs in all racial, ethnic, and socioeconomic groups. Cutting-edge technologies are contributing to understanding genetic underpinnings in ASD. The reported patient is a 32-year-old male and as an infant was noted to have microcephaly, hypospadias, pulmonary vascular anomaly, and small stature. He was diagnosed with Cornelia De Lange Syndrome (CDLS) at that time based on the clinical features. As a child, he had autistic features and intellectual disabilities and as diagnoses with autism and intellectual disability. He was referred as an adult to our neurodiversity clinic and a full exome trio sequencing with reflex to mitochondrial genes identified a de novo variant of uncertain significance in a candidate gene, DCAF1. The specific variant was c.137 C > T (p.Thr46Ile) in exon 4 in the DCAF1 gene. In silico analysis supports a deleterious effect on protein structure/function. DCAF1 participates with DDB1 and CUL4 as a part of the E3 ubiquitin ligase complex. The E3 ligase complex has been associated with a syndromic form of X-linked intellectual disability. The DDB1/CUL4 E3 ubiquitination complex plays a role in methylation-dependent ubiquitination. Next, a methylation study identified a signature similar to the methylation pattern found in X- linked intellectual disability type 93. This is associated with variants of the BRWD3 gene, which is linked with the functioning of the DDB1/CUL4 E3 ubiquitination complex. Taken together, this suggests that the de novo DCAF1 variant may be a newly identified molecular cause of autism and intellectual disability

Molecular Dysregulation in Autism Spectrum Disorder

Autism Spectrum Disorder (ASD) comprises a heterogeneous group of neurodevelopmental disorders with a strong heritable genetic component. At present, ASD is diagnosed solely by behavioral criteria. Advances in genomic analysis have contributed to numerous candidate genes for the risk of ASD, where rare mutations and s common variants contribute to its susceptibility. Moreover, studies show rare de novo variants, copy number variation and single nucleotide polymorphisms (SNPs) also impact neurodevelopment signaling. Exploration of rare and common variants involved in common dysregulated pathways can provide new diagnostic and therapeutic strategies for ASD. Contributions of current innovative molecular strategies to understand etiology of ASD will be explored which are focused on whole exome sequencing (WES), whole genome sequencing (WGS), microRNA, long non-coding RNAs and CRISPR/Cas9 models. Some promising areas of pharmacogenomic and endophenotype directed therapies as novel personalized treatment and prevention will be discussed

A ten year, multicentre study of coagulase negative staphylococcal infections in Australasian neonatal units

Objective: To study late onset systemic infections with coagulase negative staphylococci. Methods: Prospective longitudinal study of coagulase negative staphylococcal infection in 18 Australasian neonatal nurseries. Results: From 1991 to 2000 inclusive, there were 1281 cases of coagulase negative staphylococcal (CoNS) sepsis, comprising 57.1% of all late onset infections. The male/female ratio was 1.27:1 (p < 0.05). The incidence of CoNS sepsis was 3.46 episodes per 1000 live births. Most infected babies (71%) were 24–29 weeks gestation at birth (mode 26 weeks). The first positive culture was day 7–14 in 49% of babies (mode 10 days). Five cases of meningitis were reported, an incidence of 0.4% of all CoNS infections. Twenty nine babies (2.3%) had concurrent necrotising enterocolitis and CoNS septicaemia. Four babies (0.3%) died from CoNS infection, but CoNS infection possibly contributed to the death of an additional 20 babies (1.6%). The mortality directly attributable to CoNS infection was significantly lower than that from late onset infections with Staphylococcus aureus (13.1%; relative risk (RR) = 36.1 (95% confidence interval (CI) 13.0 to 100.2) or with Gram negative bacilli (14.2%; RR = 45.5 (95% CI 16.8 to 123.3)). Conclusions: CoNS are currently responsible for most late onset neonatal infections. Most infected babies are < 30 weeks gestation at birth, and usually present between 7 and 14 days of age. CoNS infections may be associated with necrotising enterocolitis, although causality is unproven. Neonatal CoNS infections are relatively benign: meningitis is rare and mortality low compared with infection from other organisms. Over-vigorous attempts to reduce the incidence of CoNS infections using prophylactic antibiotics are not advisable