Mutation In Family Research Articles

Identification of novel CDH23 variants linked to hearing loss in a Chinese family: A case report.

Deafness is associated with both environmental and genetic factors, with hereditary deafness often caused by mutations in deafness-related genes. Identifying and analyzing deafness-related genes will aid in early diagnosis and pave the way for treating inherited deafness through gene therapy in the future. A 15-month-old girl underwent audiological examination at the outpatient clinic of the hospital due to hearing loss and her brother was diagnosed with profound bilateral sensorineural hearing loss at the age of 3. The diagnosis was determined as extremely severe sensorineural hearing loss caused by genetic factors. Clinical data of the patient were collected, and peripheral blood samples were obtained from both the patient and her family members for DNA extraction and sequencing. By utilizing targeted capture next-generation sequencing to further screen for deafness-related genes, 2 novel variants in CDH23 were identified as the causative factors for the patient's deafness. This study identified 2 novel heterozygous mutations in a Chinese family. Both the proband and her sibling have non-syndromic hearing loss (NSHL) and carry distinct heterozygous mutations of cadherin-like 23 (CDH23). One mutation, CDH23:c.2651 A>G, originated from their mother and paternal family, affecting the exon23 domain of CDH23. The other mutation, CDH23:c.2113 G>T, was inherited from their paternal grandmother, impacting the exon19 domain of CDH23. These 2 novel mutations likely cause NSHL by affecting protein function. This finding suggests that identifying 2 novel mutations in CDH23 contributes to the genetic basis of NSHL.

Impaired TGF-β signaling via AHNAK family mutations elicits an esophageal cancer subtype with sensitivities to genotoxic therapy and immunotherapy

BackgroundGenome instability (GI) is a hallmark of esophageal squamous cell carcinoma (ESCC) while factors affecting GI remain unclear.MethodsHere, we aimed to characterize genomic events representing specific mechanisms of GI based on 201 ESCC samples and validated our findings at the patient, single-cell and cancer cell-line levels, including a newly generated multi-omics dataset of the trial NCT04006041.ResultsA two-gene (AHNAK and AHNAK2) mutation signature was identified to define the “AHNAK1/2-mutant” cancer subtype. Single-cell-assisted multi-omics analysis showed that this subtype had a higher neoantigen load, active antigen presentation, and proficient CD8 + T cell infiltrations, which were validated at pan-cancer levels. Mechanistically, AHNAK1/2-mutant ESCC was characterized by impaired response of TGF-β and the inefficient alternative end-join repair (Alt-EJ) that might promote GI. Knockdown of AHNAK in ESCC cell lines resulted in more Alt-EJ events and increased sensitivities to cisplatin. Furthermore, this two-gene signature accurately predicted better responses to DNA-damaging therapy in various clinical settings (HR ≈ 0.25). The two-gene signature predicted higher pCR rates in ESCCs receiving neoadjuvant immunotherapy-involved treatment. Finally, a molecular classification scheme was built and outperformed established molecular typing models in the prognosis stratification of ESCC patients.ConclusionOur study extended our understanding of the AHNAK family in promoting GI and selecting treatment responders of ESCC.

The relationship between hypergonadotropic hypogonadism and gene variations? New mutations discovered by familial mutation screening and a review of the literature

The relationship between hypergonadotropic hypogonadism and gene variations? New mutations discovered by familial mutation screening and a review of the literature

ATAXIN-2 intermediate-length polyglutamine expansions elicit ALS-associated metabolic and immune phenotypes

Intermediate-length repeat expansions in ATAXIN-2 (ATXN2) are the strongest genetic risk factor for amyotrophic lateral sclerosis (ALS). At the molecular level, ATXN2 intermediate expansions enhance TDP-43 toxicity and pathology. However, whether this triggers ALS pathogenesis at the cellular and functional level remains unknown. Here, we combine patient-derived and mouse models to dissect the effects of ATXN2 intermediate expansions in an ALS background. iPSC-derived motor neurons from ATXN2-ALS patients show altered stress granules, neurite damage and abnormal electrophysiological properties compared to healthy control and other familial ALS mutations. In TDP-43Tg-ALS mice, ATXN2-Q33 causes reduced motor function, NMJ alterations, neuron degeneration and altered in vitro stress granule dynamics. Furthermore, gene expression changes related to mitochondrial function and inflammatory response are detected and confirmed at the cellular level in mice and human neuron and organoid models. Together, these results define pathogenic defects underlying ATXN2-ALS and provide a framework for future research into ATXN2-dependent pathogenesis and therapy.

Non-syndromic congenital sideroblastic anaemia; phenotype, and genotype of 15 Indian patients.

Sideroblastic anaemias are a diverse group of congenital and acquired bone marrow failure disorders marked by the presence of ring sideroblasts, ineffective erythropoiesis, and systemic iron overload. Congenital Sideroblastic anaemia (CSA) is mainly caused by gene mutations associated with heme synthesis, iron-sulfur [Fe-S] cluster, and mitochondrial protein synthesis pathways. The most prevalent form of CSA is caused by mutations in the erythroid-specific -amino levulinate synthase (ALAS2) gene, which encodes the first enzyme in the heme synthesis pathway in red blood cells. The second most prevalent form of CSA is caused by a mutation in the Solute carrier family 25 member 38 (SLC25A38) gene, which codes for an erythroid-specific protein of the inner mitochondrial membrane. Additionally, 15-20 genes are altogether associated with CSA. In this study, we aim to identify the CSA patients, understand their genetics and establish genotype-phenotype correlation. We have identified fifteen cases of CSA using our targeted NGS (t-NGS) panel. The major clinical findings in our cohort were microcytic anaemia, ring sideroblasts, and dyserythropoiesis in the bone marrow. Currently, two patients are responsive to pyridoxine, while the rest are on blood transfusion support. We have identified ten variants in three different genes of CSA (ALAS2, SLC25A38 & HSPA9). Five patients harbour four hemizygous variants- p.Ala282Ser, p.Arg170Cys, p.Arg204Gln and exon 2 duplication in the ALAS2 gene. In seven patients, we have identified three homozygous mutations - p.Pro190Arg, p.Arg187Gln and p.Arg134Cys in the SLC25A38 gene. These mutations have been predominantly identified in the European population. Three patients revealed three heterozygous variants p. Thr463Ile, D326Tyr, and Arg284Trp in the HSPA9 gene. PyMoL was used to evaluate the functional effects of these variations and understand their effect on the structure of the protein. We believe that by combining a bone marrow examination with genetic sequencing, CSA patients can acquire a definitive diagnosis.

Perspectives on CRISPR Genome Editing to Prevent Prion Diseases in High-Risk Individuals.

Prion diseases are neurodegenerative disorders caused by misfolded prion proteins. Although rare, the said diseases are always fatal; they commonly cause death within months of developing clinical symptoms, and their diagnosis is exceptionally difficult pre-mortem. There are no known cures or treatments other than symptomatic care. Given the aggressiveness of prion diseases on onset, therapies after disease onset could be challenging. Prevention to reduce the incidence or to delay the disease onset has been suggested to be a more feasible approach. In this perspective article, we summarize our current understandings of the origin, risk factors, and clinical manifestations of prion diseases. We propose a PCR testing of the blood to identify PRNP gene polymorphisms at codons 129 and 127 in individuals with familial PRNP mutations to assess the risk. We further present the CRISPR/Cas9 gene editing strategy as a perspective preventative approach for these high-risk individuals to induce a polymorphic change at codon 127 of the PRNP gene, granting immunity to prion diseases in selected high-risk individuals, in particular, in individuals with familial PRNP mutations.

Four mutations identified in Chinese families with autosomal dominant congenital cataracts by next-generation sequencing.

Congenital cataracts, which can arise due to a combination of factors like environmental influences and genetic predisposition, significantly impact children's visual health globally. The occurrence rate of congenital cataracts varies from 0. 63 to 9.74 per 10,000 births. There are 7.4 instances per 10,000 children, with the highest occurrence seen in Asia. Symptoms of the disease include clouding of the lens and visual impairment. Timely identification of the condition plays a crucial role in the management and outlook of pediatric patients. This investigation aimed to discover causative mutations in four separate Chinese family lineages. The detailed clinical data and family history of four Chinese families with autosomal dominant congenital cataracts were carefully documented. Examination of the Whole Exome Sequencing was utilized to identify the genetic anomalies present in the familial cases. Subsequent validation of the identified mutations was carried out using PCR and Sanger sequencing. Following this, various computational predictive programs were utilized to evaluate how the mutations impact the structure and function of the protein. The sequencing results reveal four potential disease-causing mutations: c.436G > A (p.V146M) of CRYBB2 Family 1, c.26G > T (p.R9I) of GJA3 in family 2, c.227G > A (p.R76H) of GJA8 in family 3, c.-168G > T of FTL in family 4. Among them, the causative mutation in Family GJA3 is novel, and Family FTL is a rare cataract syndrome. These familial mutations showed complete co-segregation with the affected individuals, with no presence in unaffected family members or the 100 controls. Several bioinformatic prediction tools also support the likely pathogenicity of these mutations. Our findings expand the mutational and phenotypic spectrum of genes associated with congenital cataracts and provide clues to the pathogenesis of congenital cataracts. These data also demonstrate the importance of NGS technology for the molecular diagnosis of congenital cataract patients.

Generation of a human SLC12A3 knock-in human induced pluripotent stem cell line (CMCi014-A-82) using CRISPR-Cas9 system

Gitelman’s disease is caused by a genetic mutation in the solute carrier family 12 member 3 (SLC12A3) gene, which encodes the sodium chloride cotransporter. In this study, we generated a stable human induced pluripotent stem cell (hiPSC) line, WTC11-SLC12A3 (CMCi014-A-82), by knocking in the entire SLC12A3 gene at the SHS231 locus in healthy wild-type control hiPSCs (WTC11). We verified that WTC11-SLC12A3 expressed pluripotency markers and exhibited normal stem cell morphology. Furthermore, this cell line maintains a normal karyotype and can differentiate into the three germ layers. Therefore, this cell line may provide a basis for gene therapy for Gitelman’s disease.

Pulmonary Alveolar Microlithiasis in a Young Man Undergoing Lung Transplantation: A Case Report.

Pulmonary alveolar microlithiasis is a rare disease characterized by the deposition of microliths in the alveoli, attributed to mutations in the solute carrier family 34 member 2 (SLC34A2) gene. Diagnosis is often incidental to chest imaging, most frequently occurring between the second and fourth decades of life. The disease follows a progressive course and manifests with a clinical-radiological dissociation. No effective treatment is known except for lung transplantation.We report on a 28-year-old Hispanic male patient with no relevant personal or family history, presenting with progressive exertional dyspnea and intermittent dry cough. He was referred for evaluation by pulmonology due to abnormal findings on chest x-ray. High-resolution computed tomography revealed diffuse lung opacities caused by multiple microcalcifications, suggesting pulmonary alveolar microlithiasis with additional signs of pulmonary hypertension. Throughout his clinical course, he experienced a decline in functional class with severe impairment in pulmonary function tests. He underwent transplant evaluation, and the procedure was performed, with reported complications including airway stenosis, which were managed. Despite these challenges, the patient eventually showed positive progress and maintained an adequate functional class.Pulmonary alveolar microlithiasis is a rare disease with a chronic clinical course and variable manifestations. Its progressive deterioration leads to chronic respiratory failure. A high index of suspicion is required when evaluating characteristic radiological findings and conducting relevant differential diagnoses. No specific treatment guidelines are available, and lung transplantation emerges as the only effective therapy, as illustrated in the described patient.

Adult-onset deletion of ATP13A2 in mice induces progressive nigrostriatal pathway dopaminergic degeneration and lysosomal abnormalities

Although most cases of Parkinson’s disease (PD) are sporadic, mutations in over 20 genes are known to cause heritable forms of the disease. Recessive loss-of-function mutations in ATP13A2, a lysosomal transmembrane P5B-type ATPase and polyamine exporter, can cause early-onset familial PD. Familial ATP13A2 mutations are also linked to related neurodegenerative diseases, including Kufor-Rakeb syndrome, hereditary spastic paraplegias, neuronal ceroid lipofuscinosis, and amyotrophic lateral sclerosis. Despite the severe effects of ATP13A2 mutations in humans, ATP13A2 knockout (KO) mice fail to exhibit neurodegeneration even at advanced ages, making it challenging to study the neuropathological effects of ATP13A2 loss in vivo. Germline deletion of ATP13A2 in rodents may trigger the upregulation of compensatory pathways during embryonic development that mask the full neurotoxic effects of ATP13A2 loss in the brain. To explore this idea, we selectively deleted ATP13A2 in the adult mouse brain by the unilateral delivery of an AAV-Cre vector into the substantia nigra of young adult mice carrying conditional loxP-flanked ATP13A2 KO alleles. We observe a progressive loss of striatal dopaminergic nerve terminals at 3 and 10 months after AAV-Cre delivery. Cre-injected mice also exhibit robust dopaminergic neuronal degeneration in the substantia nigra at 10 months. Adult-onset ATP13A2 KO also recreates many of the phenotypes observed in aged germline ATP13A2 KO mice, including lysosomal abnormalities, p62-positive inclusions, and neuroinflammation. Our study demonstrates that the adult-onset homozygous deletion of ATP13A2 in the nigrostriatal pathway produces robust and progressive dopaminergic neurodegeneration that serves as a useful in vivo model of ATP13A2-related neurodegenerative diseases.

Novel GNAI3 mutation in a Chinese family with auriculocondylar syndrome and treatment of severe dentofacial deformities: a 5-year follow-up case report

BackgroundAuriculocondylar syndrome (ARCND) is an extremely rare autosomal dominant or recessive condition that typically manifests as question mark ears (QMEs), mandibular condyle hypoplasia, and micrognathia. Severe dental and maxillofacial malformations present considerable challenges in patients’ lives and clinical treatment. Currently, only a few ARCND cases have been reported worldwide, but most of them are related to genetic mutations, clinical symptoms, and ear correction; there are few reports concerning the treatment of dentofacial deformities.Case presentationHere, we report a rare case of ARCND in a Chinese family. A novel insertional mutation in the guanine nucleotide-binding protein alpha-inhibiting activity polypeptide 3 (GNAI3) was identified in the patient and their brother using whole-exome sequencing. After a multidisciplinary consultation and examination, sequential orthodontic treatment and craniofacial surgery, including distraction osteogenesis and orthognathic surgery, were performed using three-dimensional (3D) digital technology to treat the patient’s dentofacial deformity. A good prognosis was achieved at the 5-year follow-up, and the patient returned to normal life.ConclusionsARCND is a monogenic and rare condition that can be diagnosed based on its clinical triad of core features. Molecular diagnosis plays a crucial role in the diagnosis of patients with inconspicuous clinical features. We present a novel insertion variation in GNAI3, which was identified in exon 2 of chromosome 110116384 in a Chinese family. Sequential therapy with preoperative orthodontic treatment combined with distraction osteogenesis and orthognathic surgery guided by 3D digital technology may be a practical and effective method for treating ARCND.

Total pulmonary arterial reconstruction in a patient with arterial tortuosity syndrome affecting the pulmonary artery: a case report and review of the literature

BackgroundArterial tortuosity syndrome is a rare Autosomal recessive disease that leads to a loss of function of the connective tissues of the body, this happens due to a mutation in the solute carrier family 2 member 10 (SLC2A10) gene. ATS is more likely to occur in Large and medium-sized arteries including the aorta and pulmonary arteries. This syndrome causes the arteries to be elongated and tortuous, This tortuosity disturbs the blood circulation resulting in stenosis and lack of blood flow to organs and this chronic turbulent flow increases the risk of aneurysm development, dissection and ischemic events.Case presentationA 2 years old Arabian female child was diagnosed with ATS affecting the pulmonary arteries as a newborn, underwent a pulmonary arterial surgical reconstruction at the age of 2 years old due to the development of pulmonary artery stenosis with left pulmonary artery having a peak gradient of 73 mmHg with a peak velocity of 4.3 m/s and the right pulmonary artery having a peak gradient of 46 mmHg with a peak velocity of 3.4 m/s causing right ventricular hypertension. After surgical repair the left pulmonary artery has a peak pressure gradient of 20 mmHg, with the right pulmonary artery having a peak pressure gradient of 20 mmHg.ConclusionATS is a rare genetic condition that affects the great arteries especially the pulmonary arteries causing stenotic and tortuous vessels that may be central branches or distal peripheral branches that leads to severe right ventricular dysfunction and hypertension. We believe that surgical treatment provides the optimum outcomes when compared to transcather approaches especially when the peripheral arteries are involved. Some challenges and hiccups might occur, especially lung reperfusion injury that needs to be diagnosed and treated accordingly.

Eta-secretase-like processing of the amyloid precursor protein (APP) by the rhomboid protease RHBDL4

The amyloid precursor protein (APP) is a key protein in Alzheimer’s disease synthesized in the endoplasmic reticulum (ER) and translocated to the plasma membrane where it undergoes proteolytic cleavages by several proteases. Conversely to other known proteases, we previously elucidated rhomboid protease RHBDL4 as a novel APP processing enzyme where several cleavages likely occur already in the ER. Interestingly, the pattern of RHBDL4-derived large APP C-terminal fragments resemble those generated by the η-secretase or MT5-MMP, which was described to generate so called Aη fragments. The similarity in large APP C-terminal fragments between both proteases raised the question whether RHBDL4 may contribute to η-secretase activity and Aη-like fragments. Here, we identified two cleavage sites of RHBDL4 in APP by mass spectrometry, which, intriguingly, lie in close proximity to the MT5-MMP cleavage sites. Indeed, we observed that RHBDL4 generates Aη-like fragments in vitro without contributions of α-, β-, or γ-secretases. Such Aη-like fragments are likely generated in the ER since RHBDL4-derived APP-C-terminal fragments do not reach the cell surface. Inherited, familial APP mutations appear to not affect this processing pathway. In RHBDL4 knockout mice, we observed increased cerebral full length APP in comparison to wild type (WT) in support of RHBDL4 being a physiologically relevant protease for APP. Furthermore, we found secreted Aη fragments in dissociated mixed cortical cultures from WT mice, however significantly less Aη fragments in RHBDL4 knockout cultures. Our data underscores that RHBDL4 contributes to η-secretease-like processing of APP and that RHBDL4 is a physiologically relevant protease for APP.

Structurally targeted mutagenesis identifies key residues supporting -synuclein misfolding in multiple system atrophy.

Multiple system atrophy (MSA) and Parkinson's disease (PD) are caused by misfolded -synuclein spreading throughout the central nervous system. While familial PD is linked to several point mutations in -synuclein, there are no known mutations associated with MSA. Our previous work investigating differences in -synuclein misfolding between the two disorders showed that the familial PD mutation E46K inhibits replication of MSA prions both in vitro and in vivo, providing key evidence to support the hypothesis that -synuclein adopts unique strains in patients. Here, to further interrogate -synuclein misfolding, we engineered a panel of cell lines harboring both PD-linked and novel mutations designed to identify key residues that facilitate -synuclein misfolding in MSA. These data were paired with in silico analyses using Maestro software to predict the effect of each mutation on the ability of -synuclein to misfold into one of the reported MSA cryo-electron microscopy conformations. In many cases, our modeling accurately identified mutations that facilitated or inhibited MSA replication. However, Maestro was occasionally unable to predict the effect of a mutation on MSA propagation in vitro, demonstrating the challenge of using computational tools to investigate intrinsically disordered proteins. Finally, we used our cellular models to determine the mechanism underlying the E46K-driven inhibition of MSA replication, finding that the E46/K80 salt bridge is necessary to support -synuclein misfolding. Overall, our studies use a structure-based approach to investigate -synuclein misfolding, resulting in the creation of a powerful panel of cell lines that can be used to interrogate MSA strain biology.

Bibliometric visualization analysis of thiamine-responsive megaloblastic anemia syndrome

Visual analysis of the current status, research hotspots, evolving trends, and future prospects in the field of thiamine-responsive megaloblastic anemia syndrome (TRMA), providing new insights and directions for subsequent research on the pathogenic mechanisms and prevention strategies of TRMA. Taking the core database of Web of Science as the literature source, selecting TRMA-related literature records published from 1997 to 2023 as the research object, and using R software and Citexs database to conduct visual analysis and discussion of the research content. The results showed that a total of 89 publications related to the topic were published from 1997 to 2023, with an average annual publication volume of 3 papers. Classified by country, it was found that the United States, and Israel among other countries and institutions, published a significant number of papers. Through keyword frequency analysis, high frequencies of keywords such as diabetes, deafness, thiamine-responsive megaloblastic anemia, and mutations in the solute carrier family 19 member 2 (SLC19A2) gene were observed, indicating that to date, these keywords have been the main research directions, highlighting a gradually reached consensus on the mechanism exploration of TRMA. In conclusion, TRMA research focuses on the mechanisms of hot topics such as diabetes, deafness, and thiamine-responsive megaloblastic anemia, and the core gene SLC19A2 research may currently become a new breakthrough point for future molecular studies.

A novel homozygous LRRC6 mutation causes male infertility with asthenozoospermia and primary ciliary dyskinesia in humans.

Dysfunction of motile cilia, including respiratory cilia and sperm flagella, typically leads to primary ciliary dyskinesia and male infertility or low fertility in humans. Genetic defects of LRRC6 have been associated with primary ciliary dyskinesia and asthenozoospermia due to abnormal ultrastructure of ciliated axonemes. To identify novel mutations of the LRRC6 gene related to multiple morphological abnormalities of the sperm flagella and male infertility and investigate the underlying molecular mechanisms involved. The LRRC6 mutations were identified by whole exome sequencing and confirmed with Sanger sequencing. Papanicolaou staining, scanning, and transmission electron microscopy were performed to investigate the morphological and ultrastructural characteristics of spermatozoa. Further tandem mass tagging proteomics analyses were performed to explore the effect of mutations and confirmed by immunostaining and western blotting. Intracytoplasmic sperm injection was applied for the assisted reproductive therapy of males harboring biallelic LRRC6 mutations. In this study, we identified a novel homozygous LRRC6 mutation in a consanguineous family, characterized by asthenozoospermia and primary ciliary dyskinesia. Further Semen parameter and morphology analysis demonstrate that the novel LRRC6 mutation leads to a significant reduction in sperm flagella length, a decrease in sperm progressive motility parameters, and abnormalities of sperm ultrastructure. Specifically, the absence of outer dynein arms and inner dynein arms, and incomplete mitochondrial sheath in the flagellar mid-piece were observed by transmission electron microscopy. In addition, tandem mass tagging proteomics analysis revealed that spermatozoa obtained from patients harboring the LRRC6 mutation exhibited a significant decrease in the expression levels of proteins related to the assembly and function of dynein axonemal arms. Functional analysis revealed that this novel LRRC6 mutation disrupted the function of the leucine-rich repeat containing 6 protein, which in turn affects the expression of the dynein arm proteins and leucine-rich repeat containing 6-interacting proteins CCDC40, SPAG1, and ZMYND10. Finally, we reported a successful pregnancy through assisted reproductive technology with intracytoplasmic sperm injection in the female partner of the proband. This study highlights the identification of a novel homozygous LRRC6 mutation in a consanguineous family and its impact on sperm progressive motility, morphology, and sperm kinetics parameters, which could facilitate the genetic diagnosis of asthenozoospermia and offer valuable perspectives for future genetic counseling endeavors.

Liver-specific DICER1 syndrome model mice develop cystic liver tumors with defective primary cilia.

DICER1 syndrome is a tumor predisposition syndrome caused by familial genetic mutations in DICER1. Pathogenic variants of DICER1 have been discovered in many rare cancers, including cystic liver tumors. However, the molecular mechanisms underlying liver lesions induced by these variants remain unclear. In the present study, we sought to gain a better understanding of the pathogenesis of these variants by generating a mouse model of liver-specific DICER1 syndrome. The mouse model developed bile duct hyperplasia with fibrosis, similar to congenital hepatic fibrosis, as well as cystic liver tumors resembling those in Caroli's syndrome, intrahepatic cholangiocarcinoma, and hepatocellular carcinoma. Interestingly, the mouse model of DICER1 syndrome showed abnormal formation of primary cilia in the bile duct epithelium, which is a known cause of bile duct hyperplasia and cyst formation. These results indicated that DICER1 mutations contribute to cystic liver tumors by inducing defective primary cilia. The mouse model generated in this study will be useful for elucidating the potential mechanisms of tumorigenesis induced by DICER1 variants and for obtaining a comprehensive understanding of DICER1 syndrome. © 2024 The Pathological Society of Great Britain and Ireland.

A novel SALL1 C757T mutation in a Chinese family causes a rare disease --Townes-Brocks syndrome

BackgroundTownes-Brocks syndrome (TBS) is a rare genetic disorder characterized by imperforate anus, dysplastic ears, thumb malformations, and other abnormalities. Previous studies have revealed that mutations in the SALL1 gene can disrupt normal development, resulting in the characteristic features of Townes-Brocks syndrome. Spalt-like transcription factors (SALLs) are highly conserved proteins that play important roles in various cellular processes, including embryonic development, cell differentiation, and cell survival. Over 400 different variants or mutations have been reported in the SALL1 gene in individuals with TBS. Most of these variants lead to the formation of premature termination codons (PTCs), also known as nonsense mutations. The majority of these PTCs occur in a specific region of the SALL1 gene called the “hotspot region”, which is particularly susceptible to mutation.MethodsIn this study, we conducted whole-exome sequencing on a three-generation Chinese family with anorectal malformations.ResultsWe identified a novel heterozygous mutation (chr16:51175376:c.757 C > T p.Gln253*) in the SALL1 gene. Molecular analysis revealed a heterozygous C to T transition at nucleotide position 757 in exon 2 of the SALL1 (NM_002968) gene. This mutation is predicted to result in the substitution of the Gln253 codon with a premature stop codon (p.Gln253*). The glutamine-rich domain forms a long alpha helix, enabling the mutant protein to interact with the wild-type SALL1 protein. This interaction may result in steric hindrance effects on the wild-type SALL1 protein.ConclusionsOur findings have expanded the mutation database of the SALL1 gene, which is significant for genetic counseling and clinical surveillance in the affected family. Furthermore, our study enhances the understanding of Townes-Brocks syndrome and has the potential to improve its diagnosis and treatment.

Neuroinflammation and Lysosomal Abnormalities Characterise the Essential Role for Oxidation Resistance 1 in the Developing and Adult Cerebellum.

Loss-of-function mutations in the TLDc family of proteins cause a range of severe childhood-onset neurological disorders with common clinical features that include cerebellar neurodegeneration, ataxia and epilepsy. Of these proteins, oxidation resistance 1 (OXR1) has been implicated in multiple cellular pathways related to antioxidant function, transcriptional regulation and cellular survival; yet how this relates to the specific neuropathological features in disease remains unclear. Here, we investigate a range of loss-of-function mouse model systems and reveal that constitutive deletion of Oxr1 leads to a rapid and striking neuroinflammatory response prior to neurodegeneration that is associated with lysosomal pathology. We go on to show that neuroinflammation and cell death in Oxr1 knockouts can be completely rescued by the neuronal expression of Oxr1, suggesting that the phenotype is driven by the cell-intrinsic defects of neuronal cells lacking the gene. Next, we generate a ubiquitous, adult inducible knockout of Oxr1 that surprisingly displays rapid-onset ataxia and cerebellar neurodegeneration, establishing for the first time that the distinctive pathology associated with the loss of Oxr1 occurs irrespective of developmental stage. Finally, we describe two new homozygous human pathogenic variants in OXR1 that cause neurodevelopmental delay, including a novel stop-gain mutation. We also compare functionally two missense human pathogenic mutations in OXR1, including one newly described here, that cause different clinical phenotypes but demonstrate partially retained neuroprotective activity against oxidative stress. Together, these data highlight the essential role of Oxr1 in modulating neuroinflammatory and lysosomal pathways in the mammalian brain and support the hypothesis that OXR1 protein dosage may be critical for pathological outcomes in disease.

A novel CSF1R missense mutation in a Chinese family with adult-onset leukoencephalopathy with axonal spheroids and pigmented glia: A case report

Adult-onset leukoencephalopathy with axonal spheroids and pigmented glia (ALSP) is a rare autosomal dominant disorder caused by mutations in the colony-stimulating factor 1 receptor (CSF1R) gene. We report a case of a 41-year-old man with rapid decline in cognition within 7 months of onset. Magnetic resonance imaging showed periventricular confluent white matter changes and atrophy of the corpus callosum. Clinical exome sequencing showed a mutation (c.2390T>G) in exon 18 of the CSF1R gene. In conclusion, the differential diagnosis of adult-onset leukodystrophy is extensive. Neuroimaging and genetic analysis greatly aid in the differential diagnosis of leukoencephalopathy.