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Additional file 2. Post-operative complications. Number of patients presenting with a post-operative complication

Additional file 1. BPSU Questionnaire

Additional file 3. Post-operative complication sub-group analysis. Post-operative complications sorted by gestational age and weight

Additional file 4. Mortality sub-group analysis. Mortality rates sorted by gestational age and weight

Additional file 5. NICOR data. NICOR data by year

INTRODUCTION Only 2.4% of the 16.5-kb mitochondrial DNA (mtDNA) genome shows homoplasmic variation at >1% frequency in humans. Migration patterns have contributed to geographic differences in the frequency of common genetic variants, but population genetic evidence indicates that selection shapes the evolving mtDNA phylogeny. The mechanism and timing of this process are not clear. Unlike the nuclear genome, mtDNA is maternally transmitted and there are many copies in each cell. Initially, a new genetic variant affects only a proportion of the mtDNA (heteroplasmy). During female germ cell development, a reduction in the amount of mtDNA per cell causes a “genetic bottleneck,” which leads to rapid segregation of mtDNA molecules and different levels of heteroplasmy between siblings. Although heteroplasmy is primarily governed by random genetic drift, there is evidence of selection occurring during this process in animals. Yet it has been difficult to demonstrate this convincingly in humans. RATIONALE To determine whether there is selection for or against heteroplasmic mtDNA variants during transmission, we studied 12,975 whole-genome sequences, including 1526 mother–offspring pairs of which 45.1% had heteroplasmy affecting >1% of mtDNA molecules. Harnessing both the mtDNA and nuclear genome sequences, we then determined whether the nuclear genetic background influenced mtDNA heteroplasmy, validating our findings in another 40,325 individuals. RESULTS Previously unknown mtDNA variants were less likely to be inherited than known variants, in which the level of heteroplasmy tended to increase on transmission. Variants in the ribosomal RNA genes were less likely to be transmitted, whereas variants in the noncoding displacement (D)–loop were more likely to be transmitted. MtDNA variants predicted to affect the protein sequence tended to have lower heteroplasmy levels than synonymous variants. In 12,975 individuals, we identified a correlation between the location of heteroplasmic sites and known D-loop polymorphisms, including the absence of variants in critical sites required for mtDNA transcription and replication. We defined 206 unrelated individuals for which the nuclear and mitochondrial genomes were from different human populations. In these individuals, new population-specific heteroplasmies were more likely to match the nuclear genetic ancestry than the mitochondrial genome on which the mutations occurred. These findings were independently replicated in 654 additional unrelated individuals. CONCLUSION The characteristics of mtDNA in the human population are shaped by selective forces acting on heteroplasmy within the female germ line and are influenced by the nuclear genetic background. The signature of selection can be seen over one generation, ensuring consistency between these two independent genetic systems.

Purpose With growing evidence that rare single gene disorders present in the neonatal period, there is a need for rapid, systematic, and comprehensive genomic diagnoses in ICUs to assist acute and long-term clinical decisions. This study aimed to identify genetic conditions in neonatal (NICU) and paediatric (PICU) intensive care populations. Methods We performed trio whole genome sequence (WGS) analysis on a prospective cohort of families recruited in NICU and PICU at a single site in the UK. We developed a research pipeline in collaboration with the National Health Service to deliver validated pertinent pathogenic findings within 2–3 weeks of recruitment. Results A total of 195 families had whole genome analysis performed (567 samples) and 21% received a molecular diagnosis for the underlying genetic condition in the child. The phenotypic description of the child was a poor predictor of the gene identified in 90% of cases, arguing for gene agnostic testing in NICU/PICU. The diagnosis affected clinical management in more than 65% of cases (83% in neonates) including modification of treatments and care pathways and/or informing palliative care decisions. A 2–3 week turnaround was sufficient to impact most clinical decision-making. Conclusions The use of WGS in intensively ill children is acceptable and trio analysis facilitates diagnoses. A gene agnostic approach was effective in identifying an underlying genetic condition, with phenotypes and symptomatology being primarily used for data interpretation rather than gene selection. WGS analysis has the potential to be a first-line diagnostic tool for a subset of intensively ill children. Electronic supplementary material The online version of this article (10.1007/s00134-019-05552-x) contains supplementary material, which is available to authorized users.

Funder: Alma Mater Studiorum - Università di Bologna, Patent ductus arteriosus (PDA) is common among extremely preterm infants. In selected cases, surgical PDA ligation may be required. The timing for PDA ligation may depend upon a variety of factors, with potential clinical implications. We aimed to investigate the impact of different surgical PDA managements on ligation timing and neonatal outcomes. Inborn infants < 32 weeks of gestation and < 1500 g admitted at two tertiary Neonatal Intensive Care Units that underwent PDA ligation between 2007 and 2018 were enrolled in this retrospective cohort study and split into the following groups based on their surgical management: on-site bedside PDA ligation (ONS) vs. referral to an off-site pediatric cardiac surgery (OFS). Neonatal characteristics, surgical timing, and clinical outcomes of the enrolled infants were compared between the groups. Multivariate analysis was performed to evaluate the impact of PDA ligation timing on significantly different outcomes. Seventy-eight neonates (ONS, n = 39; OFS, n = 39) were included. Infants in the ONS group underwent PDA ligation significantly earlier than those in the OFS group (median age 12 vs. 36 days, p < 0.001) with no increase in postoperative mortality and complications. The multivariate analysis revealed a significant association between PDA ligation timing, late-onset sepsis prevalence (OR 1.045, 0.032), and oxygen need at discharge (OR 1.037, p = 0.025).Conclusions: Compared with off-site surgery, on-site bedside ligation allows an earlier surgical closure of PDA, with no apparent increase in mortality or complications. Earlier PDA ligation may contribute to reduced rates of late-onset sepsis and post-discharge home oxygen therapy, with possible cost-benefit implications. What is known: • Ineffective or contraindicated pharmacological closure of a hemodynamically significant PDA may require a surgical ligation. • Available literature comparing the effect of early vs. late PDA ligation on the main neonatal morbidities has yield contrasting results. What is new: • The availability of a cardiac surgery service performing bedside PDA ligation allows an earlier intervention compared to patient referral to an off-site center, with no difference in postoperative mortality and complications compared to off-site surgery. • Earlier PDA ligation was associated with a lower prevalence of late-onset sepsis and of oxygen need at discharge, with possible cost-benefit implications.