Loss-of-function of KMT5B leads to neurodevelopmental disorder and impairs neuronal development and neurogenesis

Autism spectrum disorder(ASD)is a group of neurodevelopmental disorders that cause severe social,communication,and behavioral problems.Recent studies show that the variants of a histone methyltransferase gene KMT5B cause neurodevelopmental disorders(NDDs),including ASD,and the knockout of Kmt5b in mice is embryonic lethal.However,the detailed genotype-phenotype correlations and functional effects of KMT5B in neurodevelopment are unclear.By targeted sequencing of a large Chinese ASD cohort,analyzing published genome-wide sequencing data,and mining literature,we curated 39 KMT5B variants identified from NDD individuals.A genotype-phenotype correlation analysis for 10 individuals with KMT5B pathogenic variants reveals common symptoms,including ASD,intellectual disability,languages problem,and macrocephaly.In vitro knockdown of the expression of Kmt5b in cultured mouse primary cortical neurons leads to a decrease in neuronal dendritic complexity and an increase in dendritic spine density,which can be rescued by expression of human KMT5B but not that of pathogenic de novo missense mutants.In vivo knockdown of the Kmt5b expression in the mouse embryonic cerebral cortex by in utero electroporation results in decreased proliferation and accelerated migration of neural progenitor cells.Our findings reveal essential roles of histone methyltransferase KMT5B in neuronal development,prenatal neurogenesis,and neuronal migration.

Rare inherited missense variants of POGZ associate with autism risk and disrupt neuronal development

Excess de novo likely gene-disruptive and missense variants within dozens of genes have been identified in autism spectrum disorder(ASD)and other neurodevelopmental disorders.However,many rare inherited missense variants of these high-risk genes have not been thoroughly evaluated.In this study,we analyzed the rare missense variant burden of POGZ in a large cohort of ASD patients from the Autism Clinical and Genetic Resources in China(ACGC)and further dissected the functional effect of diseaseassociated missense variants on neuronal development.Our results showed a significant burden of rare missense variants in ASD patients compared to the control population(P=4.6×10-5,OR=3.96),and missense variants in ASD patients showed more severe predicted functional outcomes than those in controls.Furthermore,by leveraging published large-scale sequencing data of neurodevelopmental disorders(NDDs)and sporadic case reports,we identified 8 de novo missense variants of POGZ in NDD patients.Functional analysis revealed that two inherited,but not de novo,missense variants influenced the cellular localization of POGZ and failed to rescue the defects in neurite and dendritic spine development caused by Pogz knockdown in cultured mouse primary cortical neurons.Significantly,L1CAM,an autism candidate risk gene,is differentially expressed in POGZ deficient cell lines.Reduced expression of L1cam was able to partially rescue the neurite length defects caused by Pogz knockdown.Our study showed the important roles of rare inherited missense variants of POGZ in ASD risk and neuronal development and identified the potential downstream targets of POGZ,which are important for further molecular mechanism studies.