Panoramic variation analysis of a family with neurodevelopmental disorders caused by biallelic loss-of-function variants in TMEM141,DDHD2,and LHFPL5

Highly clinical and genetic heterogeneity of neurodevelopmental disorders presents a major challenge in clinical genetics and medicine.Panoramic variation analysis is imperative to analyze the disease phenotypes resulting from multilocus genomic variation.Here,a Pakistani family with parental consanguinity was presented,characterized with severe intellectual disability(ID),spastic paraplegia,and deafness.Homozygosity mapping,integrated single nucleotide polymorphism(SNP)array,whole-exome sequencing,and whole-genome sequencing were performed,and homozygous variants in TMEM141(c.270G>A,p.Trp90^(*)),DDHD2(c.411+767_c.1249-327del),and LHFPL5(c.250delC,p.Leu84^(*))were identified.A Tmem141^(p.Trp90^(*)/p.Trp90^(*))mouse model was generated.Behavioral studies showed impairments in learning ability and motor coordination.Brain slice electrophysiology and Golgi staining demonstrated deficient synaptic plasticity in hippocampal neurons and abnormal dendritic branching in cerebellar Purkinje cells.Transmission electron microscopy showed abnormal mitochondrial morphology.Furthermore,studies on a human in vitro neuronal model(SH-SY5Y cells)with stable shRNA-mediated knockdown of TMEM141 showed deleterious effect on bioenergetic function,possibly explaining the pathogenesis of replicated phenotypes in the cross-species mouse model.Conclusively,panoramic variation analysis revealed that multilocus genomic variations of TMEM141,DDHD2,and LHFPL5 together caused variable phenotypes in patient.Notably,the biallelic loss-of-function variants of TMEM141 were responsible for syndromic ID.

Novel PLCZ1 mutation caused polyspermy during in vitro fertilization

Failure of oocyte activation,including polyspermy and defects in pronuclear(PN)formation,triggers early embryonic developmental arrest.Many studies have shown that phospholipase C zeta 1(PLCZ1)mutations cause failure of PN formation following intracytoplasmic sperm injection(ICSI);however,whether PLCZ1 mutation is associated with polyspermy during in vitro fertilization(IVF)remains unknown.Whole-exome sequencing(WES)was performed to identify candidate mutations in couples with primary infertility.Sanger sequencing was used to validate the mutations.Multiple PLCZ1-mutated sperm were injected into human and mouse oocytes to explore whether PN formation was induced.Assisted oocyte activation(AOA)after ICSI was performed to overcome the failure of oocyte activation.We identified three PLCZ1 mutations in three patients who experienced polyspermy during IVF cycles,including a novel missense mutation c.1154C>T,p.R385Q.PN formation failure was observed during the ICSI cycle.However,injection of multiple PLCZ1-mutated sperm induced PN formation,suggesting that the Ca2+oscillations induced by the sperm exceeded the necessary threshold for PN formation.AOA after ICSI enabled normal fertilization,and all patients achieved successful pregnancies.These findings expand the mutational spectrum of PLCZ1 and suggest an important role for PLCZ1 in terms of blocking polyspermy.Furthermore,this study may benefit genetic diagnoses in cases of abnormal fertilization and provide potential appropriate therapeutic measures for these patients with sperm-derived polyspermy.