No abstract

Combinations of inhibitors of Ataxia Telangiectasia- and Rad3-related kinase (ATRi) and poly(ADP-ribose) polymerases (PARPi) synergistically kill tumor cells through modulation of complementary DNA repair pathways, but their tolerability is limited by hematological toxicities. To address this we performed a genome-wide CRISPR/Cas9 screen to identify genetic alterations that hypersensitize cells to a combination of the ATRi RP-3500 with PARPi, including deficiency in RNase H2, RAD51 paralog mutations or the Alternative Lengthening of Telomeres telomere maintenance mechanism. We show that RP-3500 and PARPi combinations kill cells carrying these genetic alterations at doses sub-therapeutic as single agents. We also demonstrate the mechanism of combination hypersensitivity in RNase H2-deficient cells, where we observe an irreversible replication catastrophe, allowing us to design a highly efficacious and tolerable in vivo dosing schedule. Altogether, we present a comprehensive dataset to inform development of ATRi and PARPi combinations and an experimental framework applicable to other drug combination strategies.

No abstract

Pleiotropy and variable expressivity have been cited to explain the seemingly distinct neurodevelopmental disorders due to a common genetic etiology within the same family. Here we present a family with a de novo 1 Mb duplication involving 18 genes on chromosome 19. Within the family there are multiple cases of neurodevelopmental disorders including: Autism Spectrum Disorder, Attention Deficit/Hyperactivity Disorder, Intellectual Disability, and psychiatric disease in individuals carrying this Copy Number Variant (CNV). Quantitative PCR confirmed the CNV was de novo in the mother and inherited by both sons. Whole exome sequencing did not uncover further genetic risk factors segregating within the family. Transcriptome analysis of peripheral blood demonstrated a ~1.5-fold increase in RNA transcript abundance in 12 of the 15 detected genes within the CNV region for individuals carrying the CNV compared with their non-carrier relatives. Examination of transcript abundance across the rest of the transcriptome identified 407 differentially expressed genes (pvalue < 0.05; adjusted p-value < 0.1) mapping to immune response, response to endoplasmic reticulum stress, and regulation of epithelial cell proliferation pathways. 16S microbiome profiling demonstrated compositional difference in the gut bacteria between the half-brothers. These results raise the possibility that the observed CNV may contribute to the varied phenotypic characteristics in family members through alterations in gene expression and/or dysbiosis of the gut microbiome. More broadly, there is growing evidence that different neurodevelopmental and psychiatric disorders can share the same genetic variant which lays a framework for later neurodevelopmental and psychiatric manifestations.