Biallelic variants in RBM42 cause a multisystem disorder with neurological,facial,cardiac,and musculoskeletal involvement

Here,we report a previously unrecognized syndromic neurodevelopmental disorder associated with biallelic loss-of-function variants in the RBM42 gene.The patient is a 2-year-old female with severe central nervous system(CNs)abnormalities,hypotonia,hearing loss,congenital heart defects,and dysmorphic facial features.Familial whole-exome sequencing(WEs)reveals that the patient has two compound heterozygous variants,c.304C>T(p.R102*)and c.1312G>A(p.A438T),in the RBM42 gene which encodes an integral component of splicing complex in the RNA-binding motif protein family.The p.A438T variant is in the RRM domain which impairs RBM42 pro-tein stability in vivo.Additionally,p.A438T disrupts the interaction of RBM42 with hnRNP K,which is the causa-tive gene for Au-Kline syndrome with overlapping disease characteristics seen in the index patient.The human R102*or A438T mutant protein failed to fully rescue the growth defects of RBM42 ortholog knockout△FgRbp1 in Fusarium while it was rescued by the wild-type(WT)human RBM42.A mouse model carying Rbm42 compound heterozygous variants,c.280C>T(p.Q94*)and c.1306_1308delinsACA(p.A436T),demonstrated gross fetal develop-mental defects and most of the double mutant animals died by E13.5.RNA-seq data confirmed that Rbm42 was involved in neurological and myocardial functions with an essential role in alternative splicing(As).Overall,we present clinical,genetic,and functional data to demonstrate that defects in RBM42 constitute the underlying etiology of a new neurodevelopmental disease which links the dysregulation of global AS to abnormal embryonic development.

Leaky Gut Plays a Critical Role in the Pathophysiology of Autism in Mice by Activating the Lipopolysaccharide‑Mediated Toll‑Like Receptor 4-Myeloid Differentiation Factor 88-Nuclear Factor Kappa B Signaling Pathway

Increased intestinal barrier permeability,leaky gut,has been reported in patients with autism.However,its contribution to the development of autism has not been determined.We selected dextran sulfate sodium(DSS)to disrupt and metformin to repair the intestinal barrier in BTBR T+tf/J autistic mice to test this hypothesis.DSS treatment resulted in a decreased affinity for social proximity;however,autistic behaviors in mice were improved after the administration of metformin.We found an increased affinity for social proximity/social memory and decreased repetitive and anxiety-related behaviors.The concentration of lipopolysaccharides in blood decreased after the administration of metformin.The expression levels of the key molecules in the toll-like receptor 4(TLR4)–myeloid differentiation factor 88(MyD88)–nuclear factor kappa B(NF-κB)pathway and their downstream inflammatory cytokines in the cerebral cortex were both repressed.Thus,“leaky gut”could be a trigger for the development of autism via activation of the lipopolysaccharide-mediated TLR4–MyD88–NF-κB pathway.

Antibody upstream sequence diversity and its biological implications revealed by repertoire sequencing

The sequence upstream of the antibody variable region(antibody upstream sequence[AUS])consists of a 5′untranslated region(5′UTR)and a preceding leader region.The sequence variations in AUS affect antibody engineering and PCR based antibody quantification and may also be implicated in mRNA transcription and translation.However,the diversity of AUSs remains elusive.Using 5′rapid amplification of cDNA ends and high-throughput antibody repertoire sequencing technique,we acquired full-length AUSs for human,rhesus macaque,cynomolgus macaque,mouse,and rat.We designed a bioinformatics pipeline and identified 3307 unique AUSs,corresponding to 3026 and 1457 unique sequences for 5′UTR and leader region,respectively.Comparative analysis indicated that 928(63.69%)leader sequences are novel relative to those recorded in the international ImMunoGeneTics information system.Evolutionarily,leader sequences are more conserved than 5′UTR and seem to coevolve with their downstream V genes.Besides,single-nucleotide polymorphisms are position dependent for leader regions and may contribute to the functional reversal of the downstream V genes.Finally,the AUGs in AUSs were found to have little impact on gene expression.Taken together,our findings can facilitate primer design for capturing antibodies efficiently and provide a valuable resource for antibody engineering and molecule-level antibody studies.

The Biological Significance of Multi-copy Regions and Their Impact on Variant Discovery

Identification of genetic variants via high-throughput sequencing(HTS)technologies has been essential for both fundamental and clinical studies.However,to what extent the genome sequence composition affects variant calling remains unclear.In this study,we identified 63,897 multi-copy sequences(MCSs)with a minimum length of 300 bp,each of which occurs at least twice in the human genome.The 151,749 genomic loci(multi-copy regions,or MCRs)harboring these MCSs account for 1.98% of the genome and are distributed unevenly across chromosomes.MCRs containing the same MCS tend to be located on the same chromosome.Gene Ontology(GO)analyses revealed that 3800 genes whose UTRs or exons overlap with MCRs are enriched for Golgirelated cellular component terms and various enzymatic activities in the GO biological function category.MCRs are also enriched for loci that are sensitive to neocarzinostatin-induced double-strand breaks.Moreover,genetic variants discovered by genome-wide association studies and recorded in dbSNP are significantly underrepresented in MCRs.Using simulated HTS datasets,we show that false variant discovery rates are significantly higher in MCRs than in other genomic regions.These results suggest that extra caution must be taken when identifying genetic variants in the MCRs via HTS technologies.