Monoallelic de novo AJAP1 loss-of-function variants disrupt trans-synaptic control of neurotransmitter release.

Adherens junction-associated protein 1 (AJAP1) has been implicated in brain diseases; however, a pathogenic mechanism has not been identified. AJAP1 is widely expressed in neurons and binds to γ-aminobutyric acid type B receptors (GBRs), which inhibit neurotransmitter release at most synapses in the brain. Here, we show that AJAP1 is selectively expressed in dendrites and trans-synaptically recruits GBRs to presynaptic sites of neurons expressing AJAP1. We have identified several monoallelic AJAP1 variants in individuals with epilepsy and/or neurodevelopmental disorders. Specifically, we show that the variant p.(W183C) lacks binding to GBRs, resulting in the inability to recruit them. Ultrastructural analysis revealed significantly decreased presynaptic GBR levels in Ajap1-/- and Ajap1W183C/+ mice. Consequently, these mice exhibited reduced GBR-mediated presynaptic inhibition at excitatory and inhibitory synapses, along with impaired synaptic plasticity. Our study reveals that AJAP1 enables the postsynaptic neuron to regulate the level of presynaptic GBR-mediated inhibition, supporting the clinical relevance of loss-of-function AJAP1 variants.

Validation of a whole blood machine learning strategy for distinguishing between bacterial and viral infection in a pediatric hospital setting.

Similar symptoms between viral and bacterial diseases often make diagnosis difficult. This study assessed the clinical performance of the newly cleared whole-blood Bacterial versus Viral Score assay in our pediatric cohort to the previously validated serum assay and emergency department physician diagnosis. This assay shows excellent agreement (R = 0.997) with the serum assay and has great diagnostic accuracy when compared to physician diagnosis.

Cystic fibrosis-related diabetes screening at a large pediatric center.

OBJECTIVE: Cystic Fibrosis Foundation guidelines recommend annual diabetes screening by oral glucose tolerance test (OGTT) in pediatric patients with cystic fibrosis (CF) starting at the age of 10 years. Adherence to these guidelines proves to be challenging, and the nationwide screening rates are still considered suboptimal. The aim of this study was to assess and improve the screening rates at our large pediatric center. METHODS: A 4-year retrospective audit of OGTT completion among pediatric patients with CF of age ≥10 years who are not yet diagnosed with diabetes was conducted. A collaborative working group was formed to identify the barriers to screening and formulate a quality improvement plan, which was monitored and evaluated for a 9-month period. RESULTS: Diabetes screening rates determined by OGTT completion at our center showed a gradual decline during the COVID-19 pandemic from 2019 to 2022. Following the implementation of the quality improvement plan during the summer of 2023, there was a marked increase in OGTT ordering compliance by providers as well as test completion by patients. Notably, the fractional OGTT completion rate rose from 45% during the preintervention phase (January-April 2023) to 70% during the postintervention phase (May-September 2023). CONCLUSION: Diabetes screening in pediatric patients with CF can be effectively improved by refining practices related to patient experience, care coordination, and laboratory testing strategies.