A Deep Intronic PKHD1 Variant Identified by SpliceAI in a Deceased Neonate With Autosomal Recessive Polycystic Kidney Disease.

The etiologies of newborn deaths in neonatal intensive care units usually remain unknown, even after genetic testing. Whole-genome sequencing, combined with artificial intelligence-based methods for predicting the effects of non-coding variants, provide an avenue for resolving these deaths. Using one such method, SpliceAI, we identified a maternally inherited deep intronic PKHD1 splice variant (chr6:52030169T>C), in trans with a pathogenic missense variant (p.Thr36Met), in a newborn who died of autosomal recessive polycystic kidney disease at age 2 days. We validated the deep intronic variant's impact in maternal urine-derived cells expressing PKHD1. Reverse transcription polymerase chain reaction followed by Sanger sequencing showed that the variant causes inclusion of 147bp of the canonical intron between exons 29 and 30 of PKHD1 into the mRNA, including a premature stop codon. Allele-specific expression analysis at a heterozygous site in the mother showed that the mutant allele completely suppresses canonical splicing. In an unrelated healthy control, there was no evidence of transcripts including the novel splice junction. We returned a diagnostic report to the parents, who underwent in vitro embryo selection.

Khdc3 Regulates Metabolism Across Generations in a DNA-Independent Manner.

Genetic variants can alter the profile of heritable molecules such as small RNAs in sperm and oocytes, and in this manner ancestral genetic variants can have a significant effect on offspring phenotypes even if they are not themselves inherited. Here we show that wild type female mice descended from ancestors with a mutation in the mammalian germ cell gene Khdc3 have hepatic metabolic defects that persist over multiple generations. We find that genetically wild type females descended from Khdc3 mutants have transcriptional dysregulation of critical hepatic metabolic genes, which persist over multiple generations and pass through both female and male lineages. This was associated with dysregulation of hepatically-metabolized molecules in the blood of these wild type mice with mutational ancestry. The oocytes of Khdc3-null females, as well as their wild type descendants, had dysregulation of multiple small RNAs, suggesting that these epigenetic changes in the gametes transmit the phenotype between generations. Our results demonstrate that ancestral mutation in Khdc3 can produce transgenerational inherited phenotypes, potentially indefinitely.

A quality improvement initiative to reduce antibiotic use in transient tachypnea of the newborn.

OBJECTIVE: Evidence suggests that antibiotics are unnecessary in infants with transient tachypnea of the newborn (TTN) that are low-risk for early-onset sepsis. The aim was to reduce ampicillin and gentamicin days of therapy (DOT) in infants with suspected TTN by 10% within 12 months. STUDY DESIGN: We used the Model for Improvement to test interventions from August 2019 to September 2021 to decrease antibiotic utilization in low-risk infants with TTN. Interventions included the creation of an evidence-based clinical pathway, admission huddles, and prescriber audit and feedback. RESULTS: We reduced ampicillin and gentamicin use by 26% and 23%, respectively. In 123 infants with suspected TTN, we sequentially decreased starting antibiotics in this group from 71% to 41%, 13% and 0%. There were no cases of missed bacteremia. CONCLUSION: Creation of a multidisciplinary antimicrobial stewardship QI team and subsequent interventions were successful in safely reducing antibiotic use in infants with TTN.