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.

A novel DLL4 missense mutation in a Chinese patient with Adams-Oliver syndrome

To the Editor:Adams-Oliver syndrome (AOS,including 6 types) was initially reported in a three-generation family by Adams and Oliver in 1945,[1] with an estimated incidence of 1 in 225,000 live births.[2] Approximately 84% of AOS patients have terminal transverse limb defects,including amputations,syndactyly,brachydactyly,or oligodactyly.

Novel variants in LAMA3 and COL7A1 and recurrent variant in KRT5 underlying epidermolysis bullosa in five Chinese families

Epidermolysis bullosa(EB)is a group of clinically and genetically heterogeneous diseases characterized by trauma-induced mucocutaneous fragility and blister formation.Here,we investigated five Chinese families with EB,and eight variants including a novel nonsense variant(c.47G>A,p.W16*)in LAMA3,a known recurrent variant(c.74C>T,p.P25L)in KRT5,2 novel(c.2531T>A,p.V844E;c.6811_6814del,p.R2271fs)and 4 known(c.6187C>T,p.R2063W;c.7097G>A,p.G2366D;c.8569G>T,p.E2857*;c.3625_3635del,p.S1209fs)variants in COL7A1 were detected.Notably,this study identified a nonsense variant in LAMA3 that causes EB within the Chinese population and revealed that this variant resulted in a reduction in LAMA3 mRNA and protein expression levels by nonsense-mediated mRNA decay.Our study expands the mutation spectra of Chinese patients with EB.

Phenotypic and genetic characterization of novel variant in the NF1 gene underlying neurofibromatosis type 1 in five Chinese families

Dear Editor,Neurofibromatosis type 1(NF1;von Recklinghausen neurofibromatosis;OMIM 162200)is a neurocutaneous genetic disorder that affects approximately one in 2,500 people worldwide(Huson et al.,1989).NF1 is characterized by wide clinical variability,including multiple café-au-lait macules(CALMs),fibromatous tumors,axillary or inguinal freckling,Lisch nodules(iris hamartomas),skeletal anomalies,and cognitive impairments(Monroe et al.,2017).