Introduction: Data suggest a potential role for vitamin D in autism spectrum disorder (ASD) prevention and treatment. It is likely that the serum response to vitamin D supplementation contributes to its effectiveness. Multiple factors affect serum vitamin D 25(OH)D response to supplementation. Methods: We conducted post-hoc analysis of two double-blind, randomized, placebo-controlled trials (RCT) of vitamin D₃ supplementation, one RCT involving children with ASD and another involving children with asthma. Both trials were conducted in the same geographic location (Dublin, Ireland, 53°N), conducted over Winter season and utilized the same vitamin D₃ dose (2000 IU/day). Results: We included 18 children with ASD and 17 children with asthma. There was no significant difference in 25(OH)D or age at baseline, however, BMI was significantly lower in ASD (P = 0.03). Compliance with vitamin D supplementation was high in both trials. Despite a significantly longer intervention period (20w vs. 15w; P < 0.0001), ASD children had a significantly lower absolute increase (+26 vs. +45 nmol/l) in 25(OH)D (P = 0.04). Conclusions: Despite similar demographics, children with ASD had a lower increase in 25(OH)D levels with supplementation. Potential mechanisms include altered absorption/metabolism as well as well genetic factors. Clinical and research work relating to vitamin D is ASD should measure 25(OHO)D response to supplementation to assess therapeutic doses.

Cystic fibrosis (CF) is an inherited genetic disorder which manifests primarily in airway disease. Recent advances in molecular technologies have unearthed the diverse polymicrobial nature of the CF airway. Numerous studies have characterised the genus-level composition of this airway community using targeted 16S rDNA sequencing. Here, we employed whole-genome shotgun metagenomics to provide a more comprehensive understanding of the early CF airway microbiome. We collected 48 sputum samples from 11 adolescents and children with CF over a 12-month period and performed shotgun metagenomics on the Illumina NextSeq platform. We carried out functional and taxonomic analysis of the lung microbiome at the species and strain levels. Correlations between microbial diversity measures and independent demographic and clinical variables were performed. Shotgun metagenomics detected a greater diversity of bacteria than culture-based methods. A large proportion of the top 25 most-dominant species were anaerobes. Samples dominated by Staphylococcus aureus and Prevotella melaninogenica had significantly higher microbiome diversity, while no CF pathogen was associated with reduced microbial diversity. There was a diverse resistome present in all samples in this study, with 57.8% agreement between shotgun metagenomics and culture-based methods for detection of resistance. Pathogenic sequence types (STs) of S. aureus, Pseudomonas aeruginosa, Haemophilus influenzae and Stenotrophomonas maltophilia were observed to persist in young CF patients, while STs of S. aureus were both persistent and shared between patients. This study provides new insight into the temporal changes in strain level composition of the microbiome and the landscape of the resistome in young people with CF. Shotgun metagenomics could provide a very useful one-stop assay for detecting pathogens, emergence of resistance and conversion to persistent colonisation in early CF disease.