Both gain-and loss-of-function variants of KCNA1 are associated with paroxysmal kinesigenic dyskinesia

KCNA1 is the coding gene for Kv1.1 voltage-gated potassium-channelαsubunit.Three variants of KCNA1 have been reported to manifest as paroxysmal kinesigenic dyskinesia(PKD),but the correlation between them remains unclear due to the phenotypic complexity of KCNA1 variants as well as the rarity of PKD cases.Using the whole exome sequencing followed by Sanger sequencing,we screen for potential pathogenic KCNA1 variants in patients clinically diagnosed with paroxysmal movement disorders and identify three previously unreported missense variants of KCNA1 in three unrelated Chinese families.The proband of one family(c.496G>A,p.A166T)manifests as episodic ataxia type 1,and the other two(c.877G>A,p.V293I and c.1112C>A,p.T371A)manifest as PKD.The pathogenicity of these variants is confirmed by functional studies,suggesting that p.A166T and p.T371A cause a loss-of-function of the channel,while p.V293I leads to a gain-of-function with the property of voltage-dependent gating and activation kinetic affected.By reviewing the locations of PKD-manifested KCNA1 variants in Kv1.1 protein,we find that these variants tend to cluster around the pore domain,which is similar to epilepsy.Thus,our study strengthens the correlation between KCNA1 variants and PKD and provides more information on genotype–phenotype correlations of KCNA1 channelopathy.

Rare loss-of-function variants in FLNB cause non-syndromic orofacial clefts

Orofacial clefts (OFCs) are the most common congenital craniofacial disorders, of which the etiology is closely related to rare coding variants. Filamin B (FLNB) is an actin-binding protein implicated in bone formation. FLNB mutations have been identified in several types of syndromic OFCs and previous studies suggest a role of FLNB in the onset of non-syndromic OFCs (NSOFCs). Here, we report two rare heterozygous variants (p.P441T and p.G565R) in FLNB in two unrelated hereditary families with NSOFCs. Bioinformatics analysis suggests that both variants may disrupt the function of FLNB. In mammalian cells, p.P441T and p.G565R variants are less potent to induce cell stretches than wild type FLNB, suggesting that they are loss-of-function mutations. Immunohistochemistry analysis demonstrates that FLNB is abundantly expressed during palatal development. Importantly, Flnb^(−/−) embryos display cleft palates and previously defined skeletal defects. Taken together, our findings reveal that FLNB is required for development of palates in mice and FLNB is a bona fide causal gene for NSOFCs in humans.

A novel loss-of-function variant in PNLDC1 inducing oligo-astheno-teratozoospermia and male infertility

Male infertility is a major reproductive disorder,which is clinically characterized by highly heterogeneous phenotypes of abnormal sperm count or quality.To date,five male patients with biallelic loss-of-function(LOF)variants of PARN-like ribonuclease domain-containing exonuclease 1(PNLDC1)have been reported to experience infertility with nonobstructive azoospermia.The aim of this study was to identify the genetic cause of male infertility with oligo-astheno-teratozoospermia(OAT)in a patient from a Chinese Han family.Whole-exome and Sanger sequencing analyses identified a homozygous LOF variant(NM_173516.2,c.l42C>T,p.Gln48Ter)in PNLDC1.Hematoxylin and eosin staining revealed that the spermatozoa of the patient with OAT had an irregular head phenotype,including microcephaly,head tapering,and globozoospermia.Consistently,peanut agglutinin staining of the spermatozoa revealed a complete or partial loss of the acrosome.Furthermore,the disomy rate of chromosomes in the patient’s spermatozoa was significantly increased compared with that of a fertile control sample.We reported an LOF variant of the PNLDC1 gene responsible for OAT.

Less Is More, Natural Loss-of-Function Mutation Is a Strategy for Adaptation

Gene gain and loss are crucial factors that shape the evolutionary success of diverse organisms.In the past two decades,more attention has been paid to the significance of gene gain through gene duplication or de novo genes.However,gene loss through natural loss-of-function(LoF)mutations,which isprevalent in the genomes of diverse organisms,has been largely ignored.With the development of sequencing techniques,many genomes have been sequenced across diverse species and can be used to study the evolutionary patterns of gene loss.In this review,we summarize recent advances in research on various aspects of LoF mutations,including their identification,evolutionary dynamics in natural populations,and functional effects.In particular,we discuss how LoF mutations can provide insights into the minimum gene set(or the essential gene set)of an organism.Furthermore,we emphasize their potential impact on adaptation.At the genome level,although most LoF mutations are neutral or deleterious,at least some of them are under positive selection and may contribute to biodiversity and adaptation.Overall,we highlight the importance of natural LoF mutations as a robust framework for understanding biological questions in general.

Pharmacologic inducers of the uric acid exporter ABCG2 as potential drugs for treatment of gouty arthritis

Uric acid is the end product of purine catabolism and its plasma levels are maintained below its maximum solubility in water(6–7 mg/dl).The plasma levels are tightly regulated as the balance between the rate of production and the rate of excretion,the latter occurring in urine(kidney),bile(liver)and feces(intestinal tract).Reabsorption in kidney is also an important component of this process.Both excretion and reabsorption are mediated by specific transporters.Disruption of the balance between production and excretion leads to hyperuricemia,which increases the risk of uric acid crystallization as monosodium urate with subsequent deposition of the crystals in joints causing gouty arthritis.Loss-of-function mutations in the transporters that mediate uric acid excretion are associated with gout.The ATP-Binding Cassette exporter ABCG2 is important in uric acid excretion at all three sites:kidney(urine),liver(bile),and intestine(feces).Mutations in this transporter cause gout and these mutations occur at significant prevalence in general population.However,mutations that are most prevalent result only in partial loss of transport function.Therefore,if the expression of these partially defective transporters could be induced,the increased number of the transporter molecules would compensate for the mutation-associated decrease in transport function and hence increase uric acid excretion.As such,pharmacologic agents with ability to induce the expression of ABCG2 represent potentially a novel class of drugs for treatment of gouty arthritis.

A Traceable Cancer Model: DNA Damage, Fragile Site-SMGs, Mitotic Slippage, 4n-Genome-Reduction to Fitness-Gained, Initiating, 2n First Cells

We have known since 1976 that cancer evolves clonally from one initiated normal human cell, the first cell. Today we see that this fact has been overshadowed from federal funding choice of the mutation theory (MT), which not yet has shown tumorigenesis-initiation in normal human cells. Our suggested, death signaled, stress model from time delayed S-period (replication slowness), causing repair instability from under-replicated lesions in repetitive DNAs, herein has the objective of revealing, significant literature support from a mini-review. We reasoned that early versus late S-period stress would have different outcomes: early the slowness affecting mitotic slippage with diploid re-replication to 4n cells whereas late-S, with milder stress effect, producing diploid cells. In cancer burden, near-half is diploid, but tetraploid solid tumors have the attention. The initial 4n cells were special with orderly genomic reductive division to diploid first cells with measurable fitness-gain from hours-reduced total cell cycle time. Experimental data from Coxsakie-B3 virus infected normal fibroblasts, reiterated 4n cell production from death-signaled recovery-cells with progressive cell-phenotypic changes to polygonal and roundness cell-shapes, indistinguishable from diagnostic/prognostic cancer morphology. The 4n cells showed a self-inflicted 90° turn of the 4n nucleus before division, affecting a perpendicular orientation of the fitness-gained first cells relative to neighboring cells. In an illustrated cell cycle drawing with early and late S-period stress, it became clear that coding genes on borders of repair unstable satellite, repetitive DNA regions, could become mutated. We found these mutations to be tumor SMGs (significantly mutated genes). Evidential material was presented for loss of function genetics driving tumorigenesis to a parasitic lifestyle.

Understanding neurodevelopmental proteasomopathies as new rare disease entities:A review of current concepts,molecular biomarkers,and perspectives

The recent advances in high throughput sequencing technology have drastically changed the practice of medical diagnosis,allowing for rapid identification of hundreds of genes causing human diseases.This unprecedented progress has made clear that most forms of intellectual disability that affect more than 3%of individuals worldwide are monogenic dis-eases.Strikingly,a substantial fraction of the mendelian forms of intellectual disability is asso-ciated with genes related to the ubiquitin-proteasome system,a highly conserved pathway made up of approximately 1200 genes involved in the regulation of protein homeostasis.Within this group is currently emerging a new class of neurodevelopmental disorders specifically caused by proteasome pathogenic variants which we propose to designate"neurodevelopmen-tal proteasomopathies".Besides cognitive impairment,these diseases are typically associated with a series of syndromic clinical manifestations,among which facial dysmorphism,motor delay,and failure to thrive are the most prominent ones.While recent efforts have been made to uncover the effects exerted by proteasome variants on cell and tissue landscapes,the mo-lecular pathogenesis of neurodevelopmental proteasomopathies remains ill-defined.In this re-view,we discuss the cellular changes typically induced by genomic alterations in proteasome genes and explore their relevance as biomarkers for the diagnosis,management,and potential treatment of these new rare disease entities.

A mutation in TBXT causes congenital vertebral malformations in humans and mice

T-box transcription factor T(TBXT;T)is required for mesodermal formation and axial skeletal development.Although it has been extensively studied in various model organisms,human congenital vertebral malformations(CVMs)involving T are not well established.Here,we report a family with 15 CVM patients distributed across 4 generations.All affected individuals carry a heterozygous mutation,T c.596A>G(p.Q199R),which is not found in unaffected family members,indicating co-segregation of the genotype and phenotype.In vitro assays show that T p.Q199R increases the nucleocytoplasmic ratio and enhances its DNA-binding affinity,but reduces its transcriptional activity compared to the wild-type.To determine the pathogenicity of this mutation in vivo,we generated a Q199R knock-in mouse model that recapitulates the human CVM phenotype.Most heterozygous Q199R mice show subtle kinked or shortened tails,while homozygous mice exhibit tail filaments and severe vertebral deformities.Overall,we show that the Q199R mutation in T causes CVM in humans and mice,providing previously unreported evidence supporting the function of T in the genetic etiology of human CVM.

The CRISPR/Cas9 revolution continues: From base editing to prime editing in plant science

The ability to precisely inactivate or modify genes in model organisms helps us understand the mysteries of life. Clustered regularly interspaced short palindromic repeats(CRISPR)/CRISPR-associated protein 9(Cas9), a revolutionary technology that could generate targeted mutants, has facilitated notable advances in plant science. Genome editing with CRISPR/Cas9 has gained great popularity and enabled several technical breakthroughs. Herein, we briefly introduce the CRISPR/Cas9, with a focus on the latest breakthroughs in precise genome editing(e.g., base editing and prime editing), and we summarize various platforms that developed to increase the editing efficiency, expand the targeting scope, and improve the specificity of base editing in plants. In addition, we emphasize the recent applications of these technologies to plants. Finally, we predict that CRISPR/Cas9 and CRISPR/Cas9-based genome editing will continue to revolutionize plant science and provide technical support for sustainable agricultural development.

Novel oncogenes and tumor suppressor genes in hepatocellular carcinoma

Hepatocellular carcinoma(HCC)is a very deadly disease.HCC initiation and progression involve multiple genetic events,including the activation of proto-oncogenes and disruption of the function of specific tumor suppressor genes.Activation of oncogenes stimulates cell growth and survival,while loss-of-function mutations of tumor suppressor genes result in unrestrained cell growth.In this review,we summarize the new findings that identified novel proto-oncogenes and tumor suppressors in HCC over the past five years.These findings may inspire the development of novel therapeutic strategies to improve the outcome of HCC patients.