CEP290 Research Articles

Astrogliosis and neuroinflammation underlie scoliosis upon cilia dysfunction.

Cilia defects lead to scoliosis in zebrafish, but the underlying pathogenic mechanisms are poorly understood and may diverge depending on the mutated gene. Here, we dissected the mechanisms of scoliosis onset in a zebrafish mutant for the rpgrip1l gene encoding a ciliary transition zone protein. rpgrip1l mutant fish developed scoliosis with near-total penetrance but asynchronous onset in juveniles. Taking advantage of this asynchrony, we found that curvature onset was preceded by ventricle dilations and was concomitant to the perturbation of Reissner fiber polymerization and to the loss of multiciliated tufts around the subcommissural organ. Rescue experiments showed that Rpgrip1l was exclusively required in foxj1a-expressing cells to prevent axis curvature. Genetic interactions investigations ruled out Urp1/2 levels as a main driver of scoliosis in rpgrip1 mutants. Transcriptomic and proteomic studies identified neuroinflammation associated with increased Annexin levels as a potential mechanism of scoliosis development in rpgrip1l juveniles. Investigating the cell types associated with annexin2 over-expression, we uncovered astrogliosis, arising in glial cells surrounding the diencephalic and rhombencephalic ventricles just before scoliosis onset and increasing with time in severity. Anti-inflammatory drug treatment reduced scoliosis penetrance and severity and this correlated with reduced astrogliosis and macrophage/microglia enrichment around the diencephalic ventricle. Mutation of the cep290 gene encoding another transition zone protein also associated astrogliosis with scoliosis. Thus, we propose astrogliosis induced by perturbed ventricular homeostasis and associated with immune cell activation as a novel pathogenic mechanism of zebrafish scoliosis caused by cilia dysfunction.

Determination of Health Concepts in β-Propeller Protein-Associated Neurodegeneration.

β-Propeller protein-associated neurodegeneration (BPAN) is a rare, X-linked condition caused by pathogenic variants in the WDR45 gene that result in a defect of autophagy. Classified as a disorder of neurodegeneration with brain iron accumulation, β-propeller protein-associated neurodegeneration is associated with severe neurologic impairments. With the anticipation of future therapeutic trials, this project characterizes the family's perspective of the impact of disease and defines Health Concepts (HC).Children with a molecularly confirmed diagnosis of β-propeller protein-associated neurodegeneration were enrolled in a prospective natural history study. We administered the Vineland Adaptive Behavior Scales-Third Edition and provided health-related quality of life questionnaires to 42 caregivers. Questionnaires included Pediatric Quality of Life Inventory-Generic Core and Pediatric Quality of Life Inventory-Family Impact modules, Caregiver Priorities and Child Health Index of Life with Disabilities, and Caregiver TBI-CareQoL.The Vineland Adaptive Behavior Scales-Third Edition (n = 42) captured the family's perspective that communication was more affected compared with socialization, activities of daily living (ADL), and motor skills (P < .0001, P < .0001, P = .0053, respectively). Similarly, on the Caregiver Priorities and Child Health Index of Life with Disabilities (n = 26), Pediatric Quality of Life Inventory-Generic Core (n = 27), CareQol (n = 26), and Pediatric Quality of Life Inventory-Family Impact (n = 27), communication abilities, as well as social functioning and activities of daily living, were noted to be most impacted.Through the use of standardized surveys and outcome assessments, we establish the effects of β-propeller protein-associated neurodegeneration on caregiver quality of life. Key health concepts identified by families included overall health, comfort, and communication. The identified HC will inform the future identification of concept of interest and selection of appropriate clinical outcome assessments through the administration of patient-reported outcomes.

Molecular genetics, neuroimaging outcomes, and structural analyses of novel and recurrent variants of WDR62 gene in two consanguineous Pakistani families with autosomal recessive primary microcephaly.

Autosomal recessive primary microcephaly (MCPH) is a rare neurodevelopmental and genetically heterogeneous disorder, characterized by small cranium size (> -3 SD below mean) and often results in varying degree of intellectual disability. Thirty genes have been identified for the etiology of this disorder due to its clinical and genetic heterogeneity. Here, we report two consanguineous Pakistani families affected with MCPH exhibiting mutation in WDR62 gene. The investigation approach involved Next Generation Sequencing (NGS) gene panel sequencing coupled with linkage analysis followed by validation of identified variants through automated Sanger sequencing and Barcode-Tagged (BT) sequencing. The molecular genetic analysis revealed one novel splice site variant (NM_001083961.2(WDR62):c.1372-1del) in Family A and one known exonic variant NM_001083961.2(WDR62):c.3936dup (p.Val1313Argfs*18) in Family B. Magnetic Resonance Imaging (MRI) scans were also employed to gain insights into the structural architecture of affected individuals. Neurological assessments showed the reduced gyral and sulcal patterns along with normal corpus callosum in affected individuals harboring novel variant. In silico assessments of the identified variants were conducted using different tools to confirm the pathogenicity of these variants. Through In silico analyses, both variants were identified as disease causing and protein modeling of exonic variant indicates subtle conformational alterations in prophesied protein structure. This study identifies a novel variant (c.1372-1del) and a recurrent pathogenic variant c.3936dup (p.Val1313Argfs*18) in the WDR62 gene among the Pakistani population, expanding the mutation spectrum for MCPH. These findings emphasize the importance of genetic counseling and awareness to reduce consanguinity and address the burden of this disorder.

Patient-derived and gene-edited pluripotent stem cells lacking NPHP1 recapitulate juvenile nephronophthisis in abnormalities of primary cilia and renal cyst formation.

Juvenile nephronophthisis is an inherited renal ciliopathy with cystic kidney disease, renal fibrosis, and end-stage renal failure in children and young adults. Mutations in the NPHP1 gene encoding nephrocystin-1 protein have been identified as the most frequently responsible gene and cause the formation of cysts in the renal medulla. The molecular pathogenesis of juvenile nephronophthisis remains elusive, and no effective medicines to prevent end-stage renal failure exist even today. No human cellular models have been available yet. Here, we report a first disease model of juvenile nephronophthisis using patient-derived and gene-edited human induced pluripotent stem cells (hiPSCs) and kidney organoids derived from these hiPSCs. We established NPHP1-overexpressing hiPSCs from patient-derived hiPSCs and NPHP1-deficient hiPSCs from healthy donor hiPSCs. Comparing these series of hiPSCs, we found abnormalities in primary cilia associated with NPHP1 deficiency in hiPSCs. Kidney organoids generated from the hiPSCs lacking NPHP1 formed renal cysts frequently in suspension culture with constant rotation. This cyst formation in patient-derived kidney organoids was rescued by overexpression of NPHP1. Transcriptome analysis on these kidney organoids revealed that loss of NPHP1 caused lower expression of genes related to primary cilia in epithelial cells and higher expression of genes related to the cell cycle. These findings suggested the relationship between abnormality in primary cilia induced by NPHP1 loss and abnormal proliferative characteristics in the formation of renal cysts. These findings demonstrated that hiPSC-based systematic disease modeling of juvenile nephronophthisis contributed to elucidating the molecular pathogenesis and developing new therapies.

A c.726C>G (p.Tyr242Ter) nonsense mutation-associated with splicing alteration (NASA) of WDR45 gene underlies β-propeller protein-associated neurodegeneration (BPAN)

Neurodegeneration with brain iron accumulation (NBIA) is a clinically and genetically heterogeneous disease characterized by increased iron deposition in the basal ganglia and progressive degeneration of the nervous system in adulthood. However, in early childhood, there were no characteristic features to perform early diagnosis. In our study, a female child exhibited global developmental delay, intellectual disability, and febrile seizure without other distinct clinical phenotypes. Through whole exome sequencing (WES), a de novo nonsense mutation (c.726C > G, p. Tyr242Ter) of WDR45 gene was identified in this child. She was finally diagnosed as β‐propeller protein-associated neurodegeneration (BPAN), one of the recently identified subtypes of NBIA. This mutation could act as a premature stop codon (PSC) which rendered the mutated transcripts to be degraded by nonsense-mediated mRNA decay (NMD), leading to decreased levels of PSC-containing mRNAs. Additionally, through mini-gene splicing assays, this mutation could result in an unprecedented novel transcript with the exon 9 of WDR45 excluded by nonsense-associated splicing alteration (NASA). Transcriptome sequencing (RNA-seq) on total RNAs from PBMCs of the trio revealed three types of alternative splicing events in the patient. Further research implied that downregulation of iron transport genes (TFRC, TFR2, SCARA5) might be the underlying mechanism for the iron accumulation in patients with deficient WDR45. This is the first report about NASA happening in WDR45. It implies that nonsense mutations approximal to splicing sites could affect the disease pathogenesis through more than one molecular mechanism and should be taken into consideration when conducting genetic counseling.

Asymmetrical parkinsonism due to novel WDR45 variant with beta-propeller protein-associated neurodegeneration (BPAN).

Beta-propeller protein-associated neurodegeneration (BPAN) encompasses a group of refractory neurodegenerative diseases that are caused by excessive iron deposition in the brain, especially in the basal ganglia. We reported a case of BPAN with a novel variant of the WDR45 gene at Xp11.23. Our patient was a 31-year-old woman who has had an intellectual disability since childhood. Approximately 3 years ago, she developed asymmetric parkinsonism affecting the distal right upper and lower limbs. Consistent with her neurological findings, dopamine transporter single-photon emission computed tomography demonstrated the differences between the left and right sides. She was diagnosed as BPAN according to genetic analysis, which showed a novel heterozygous variant (c.345-3C>G) in WDR45. To the best of our knowledge, only a few previous case reports on asymmetric BPAN have described the quantitative differences in neuroimaging parameters between the left and right sides. These neuroimaging features were similar to those of Parkinson's disease, among the other neurodegenerative diseases. Our report may provide clues to elucidate the pathological mechanism of BPAN which is a refractory neurodegenerative disease.

High Prevalence of Positive Genetic Obesity Variants in Postoperative Bariatric Surgery Patients with Weight Regain Presenting for Medical Obesity Intervention.

Genetic obesity susceptibility in postoperative bariatric surgery weight regain (PBSWR) remains largely unexplored. A retrospective case series of adult (N = 27) PBSWR patients who had undergone genetic obesity testing was conducted between Sept. 2020 and March 2022. frequency of genetic variants in patients experiencing weight regain following bariatric surgery. prevalence of obesity-related comorbidities, nadir BMI achieved post-bariatric surgery, and percent total body weight loss (%TBWL) achieved with obesity pharmacotherapies. Heterozygous mutations were identified in 22 (81%) patients, with the most prevalent mutations occurring in CEP290, RPGR1P1L, and LEPR genes (3 patients each). Median age was 56years (interquartile range (IQR) 46.8-65.5), 88% female. Types of surgery were 67% RYGB, 19% SG, 4% gastric band, and 13% revisions. Median nadir BMI postoperatively was 34.0kg/m2 (IQR 29.0-38.5). A high prevalence of metabolic derangements was noted; patients presented median 80months (IQR 39-168.5) postoperative for medical weight management with 40% weight regain. BMI at initiation of anti-obesity medication (AOMs) was 41.7kg/m2 (36.8-44.4). All received AOM and required at least 3 AOMs for weight regain. Semaglutide (N = 21), topiramate (N = 14), and metformin (N = 12) were most prescribed. Median %TBWL for the cohort at the first, second, and third visit was 1.7, 5.0, and 6.5 respectively. Fourteen (52%) achieved 5%TBWL, 10 (37%) achieved 10%TBWL, and 4 (15%) achieved 15%TBWL with combination AOMs and supervised medical intervention. An unusually high prevalence of genetic obesity variants in PBSWR was found, warranting further research.

Variants in the WDR45 Gene Within the OPA-2 Locus Associate With Isolated X-Linked Optic Atrophy.

To describe clinical and molecular findings of two families with X-linked optic atrophy and present two new pathogenic variants in the WDR45 gene. Case series and molecular analysis of two families of Jewish Ashkenazi descent with early onset bilateral optic atrophy. Whole-exome sequencing (WES) and bioinformatic analysis were performed, followed by Sanger sequencing and segregation analysis. In both families, male siblings (three in family 1, two in family 2) had early-onset isolated bilateral optic atrophy. The sibling's healthy mother (and in the second family also one healthy sister) had a mild presentation, suggesting a carrier state and an X-linked inheritance pattern. All participants were otherwise healthy, apart from mild learning disabilities and autism spectrum disorder in two siblings of the second family. Variants in known optic atrophy genes were excluded. Analysis revealed a point variant in the WDR45 gene-a missense variant in the first family, NM_001029896.2:c.107C>A; NP_001025067.1:p.Pro36His (variant ID: 1704205), and a splice site variant in the second family, NM_001029896.2:c.236-1G>T; NP_009006.2:p.Val80Leu (variant ID: 1704204), located on Xp11.23 (OPA2 locus). Both variants are novel and predicted as pathogenic. In both families, the variant was seen with full segregation with the disease, occurring in all affected male participants and in one allele of the carrier females, as well as none of the healthy participants. Among two families with isolated X-linked optic atrophy, molecular analysis revealed novel variants in the WDR45 gene in full segregation with the disease. This gene resides within the OPA2 locus, previously described to associate with X-linked optic atrophy. Taken together, these findings suggest that certain pathogenic variants in the WDR45 gene are associated with isolated X-linked optic atrophy.

Інноваційна діагностика розладів нейророзвитку в дітей

Today, genetic diagnosis methods are a powerful tool for a practicing doctor, which allows not only to establish the etiology of neurodevelopmental disorders in children, but also influences the further tactics of patient management, the choice of further diagnostic and therapeutic interventions, helps in predicting subsequent pregnancies for the family. Purpose - to analyze the information of modern specialized literature regarding the features of the use of modern cytogenetic methods of diagnosis, in particular, chromosomal micrometric analysis (СMA); give a clinical example of a child with a neurodevelopmental disorder and established chromosomal etiology. A review of the scientific literature regarding the advantages and features of using innovative methods of cytogenetic diagnostics (karyotyping, СMA), clinical manifestations of 2q13 microdeletion syndrome is given. A description of the clinical case of diagnosis of a child with 2q13 microdeletion syndrome is presented. A chromosomal micrometric analysis was performed, which revealed a heterozygous microdeletion on 2q13 with a size of 122 kilobases, which led to the loss of the NPHP1 and MALL genes. The obtained result of the CMA made it possible to optimize the tactics of monitoring the child, taking into account the increased risk of the development of kidney pathology and leukoencephalopathy, the recommended annual determination of the level of creatinine and urea in the blood, conducting an ultrasound of the kidneys and an MRI of the brain. Conclusions. The given clinical observation confirms the complexity of the diagnostic search for neurodevelopmental disorders in children. In children with autism spectrum disorder, developmental delay, intellectual disability, in the absence of epileptic seizures, regardless of the presence of dysmorphic facial features, it is recommended to begin the examination with CMA, and in children with epileptic encephalopathies, it is optimal to begin the examination with the next generation sequencing method (NGS), namely whole exome sequencing. The research was carried out in accordance with the principles of the Declaration of Helsinki. Informed consent of the children’s parents was obtained for the research. No conflict of interests was declared by the authors.

An early onset cone dystrophy due to CEP290 mutation: a case report

PurposeBiallelic mutations in the CEP290 gene cause early onset retinal dystrophy or syndromic disease such as Senior-Loken or Joubert syndrome. Here, we present an unusual non-syndromic case of a juvenile retinal dystrophy caused by biallelic CEP290 mutations imitating initially the phenotype of achromatopsia or slowly progressing cone dystrophy.MethodsWe present 13 years of follow-up of a female patient who presented first with symptoms and findings typical for achromatopsia. The patient underwent functional and morphologic examinations, including fundus autofluorescence imaging, spectral-domain optical coherence tomography, electroretinography, color vision and visual field testing.ResultsDiagnostic genetic testing via whole genome sequencing and virtual inherited retinal disease gene panel evaluation finally identified two compound heterozygous variants c.4452_4455del;p.(Lys1484Asnfs*4) and c.2414T > C;p.(Leu805Pro) in the CEP290 gene.ConclusionsCEP290 mutation causes a wide variety of clinical phenotypes. The presented case shows a phenotype resembling achromatopsia or early onset slowly progressing cone dystrophy.

Clinical phenotype characteristics and genetic analysis in children with nephronophthisis and related syndromes caused by different gene mutations

To improve the understanding of the clinical phenotypes and genetic characteristics of nephronophthisis (NPHP) and related syndromes in children. A retrospective analysis was performed on the medical data of eight children with NPHP and related syndromes who were diagnosed and treated in the Department of Pediatrics of the Second Hospital of Hebei Medical University, from January 2018 to November 2022. The clinical characteristics and genetic testing results were analyzed. Among these eight children, there were five boys and three girls, with an age of onset ranging from 15 months to 12 years. All 8 children exhibited different degrees of renal function abnormalities when they attended the hospital. Among the eight children, two had the initial symptom of delayed development, two had the initial symptom of anemia, and two were found to have abnormal renal function during physical examination. The extrarenal manifestations included cardiovascular abnormalities in two children, skeletal dysplasia in two children, liver dysfunction in one child, retinitis pigmentosa in one child, and visceral translocation in one child. All eight children had renal structural changes on ultrasound, and four children had mild to moderate proteinuria based on routine urine test. Of all eight children, five had NPHP1 gene mutations and one each had a gene mutation in the NPHP3, IFT140, and TTC21B genes, and four new mutation sites were discovered. Children with NPHP and related syndromes often have the initial symptom of delayed development or anemia, and some children also have extrarenal manifestations. NPHP and related syndromes should be considered for children with unexplained renal dysfunction, and high-throughput sequencing may help to make a confirmed diagnosis.

A genotype-to-phenotype approach suggests under-reporting of single nucleotide variants in nephrocystin-1 (NPHP1) related disease (UK 100,000 Genomes Project)

Autosomal recessive whole gene deletions of nephrocystin-1 (NPHP1) result in abnormal structure and function of the primary cilia. These deletions can result in a tubulointerstitial kidney disease known as nephronophthisis and retinal (Senior–Løken syndrome) and neurological (Joubert syndrome) diseases. Nephronophthisis is a common cause of end-stage kidney disease (ESKD) in children and up to 1% of adult onset ESKD. Single nucleotide variants (SNVs) and small insertions and deletions (Indels) have been less well characterised. We used a gene pathogenicity scoring system (GenePy) and a genotype-to-phenotype approach on individuals recruited to the UK Genomics England (GEL) 100,000 Genomes Project (100kGP) (n = 78,050). This approach identified all participants with NPHP1-related diseases reported by NHS Genomics Medical Centres and an additional eight participants. Extreme NPHP1 gene scores, often underpinned by clear recessive inheritance, were observed in patients from diverse recruitment categories, including cancer, suggesting the possibility of a more widespread disease than previously appreciated. In total, ten participants had homozygous CNV deletions with eight homozygous or compound heterozygous with SNVs. Our data also reveals strong in-silico evidence that approximately 44% of NPHP1 related disease may be due to SNVs with AlphaFold structural modelling evidence for a significant impact on protein structure. This study suggests historical under-reporting of SNVS in NPHP1 related diseases compared with CNVs.

Beta-propeller protein-associated neurodegeneration: A clinical update with a case report.

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IDENTYFIKACJA MUTACJI WYBRANYCH GENÓW POWODUJ ˛ACYCH ZWYRODNIENIE SIATKÓWKI U KOTA DOMOWEGO (FELIS CATUS) – ANALIZA IN SILICO

Retinal degenerations are a series of genetically inherited diseases resulting in significant visual impairment and blindness. Among domestic cat breeds, there are degenerations of different courses associated with mutations in CEP290, CRX, AIPL1 and KIF3B genes. The aim of this study was to design diagnostic tests to identify the mutated alleles. The primers for PCR and restriction enzymes for PCR-RFLP were designed to detect mutations in genes. Mutation in the nucleotide sequence encoding AIPL1 protein causes a change in the protein structure, where a monomer is formed instead of a homodimer. Interactions of CEP290, CRX, AIPL1 and KIF3B proteins with other proteins that play a role in the proper functioning of the retina were observed. The occurring interactions between some of these proteins suggest a possible link between diseases caused by mutations of genes encoding these proteins. In other animal species, co-expression of the analyzed genes with other genes affecting retinal functions was noted.

Hominoid SVA-lncRNA AK057321 targets human-specific SVA retrotransposons in SCN8A and CDK5RAP2 to initiate neuronal maturation

SINE-VNTR-Alu (SVA) retrotransposons arose and expanded in the genome of hominoid primates concurrent with the slowing of brain maturation. We report genes with intronic SVA transposons are enriched for neurodevelopmental disease and transcribed into long non-coding SVA-lncRNAs. Human-specific SVAs in microcephaly CDK5RAP2 and epilepsy SCN8A gene introns repress their expression via transcription factor ZNF91 to delay neuronal maturation. Deleting the SVA in CDK5RAP2 initiates multi-dimensional and in SCN8A selective sodium current neuronal maturation by upregulating these genes. SVA-lncRNA AK057321 forms RNA:DNA heteroduplexes with the genomic SVAs and upregulates these genes to initiate neuronal maturation. SVA-lncRNA AK057321 also promotes species-specific cortex and cerebellum-enriched expression upregulating human genes with intronic SVAs (e.g., HTT, CHAF1B and KCNJ6) but not mouse orthologs. The diversity of neuronal genes with intronic SVAs suggest this hominoid-specific SVA transposon-based gene regulatory mechanism may act at multiple steps to specialize and achieve neoteny of the human brain.

Scalp Tumor and Hydroureteronephrosis in Patients with Nephronophthisis and Homozygous NPHP1 Deletion.

Homozygous deletion of NPHP1 can lead to isolated nephronophthisis (NPHP) and syndromic disorders. However, the phenotype of scalp tumor and hydroureteronephrosis in NPHP patients with homozygous deletion of NPHP1 has not been reported. Clinical data, laboratory results, and genetic testing of 4 NPHP patients were collected. Examination of their eyes, heart, and urinary tract and of their hepatobiliary, skeletal, and central nervous systems was evaluated. Isolated NPHP was observed in 1 case, and syndromic disorders were observed in the other 3 patients. Their syndromic disorders showed NPHP combined with central nervous system defects, eye involvement, scalp tumor, arachnoid cyst, or hydroureteronephrosis. Large homozygous deletions covering the whole NPHP1 gene locus were identified in all 4 patients. We report a novel phenotype of scalp tumor and hydroureteronephrosis in NPHP patients with homozygous deletion of NPHP1, paving an avenue for further research on NPHP1-associated deformity in the skin and the urinary system.

Generation of induced pluripotent stem cell line carrying frameshift variants in NPHP1 (UCSFi001-A-68) using CRISPR/Cas9

NPHP1 (Nephrocystin 1) is a protein that localizes to the transition zone of the cilium, a small organelle that projects from the plasma membrane of most cells and allows for integration and coordination of signalling pathways during development and homeostasis. Loss of NPHP1 function due to biallelic NPHP1 gene mutations can lead to the development of ciliopathies – a heterogeneous spectra of disorders characterized by ciliary dysfunction. Here we report the generation of an NPHP1-null hiPSC line (UCSFi001-A-68) via CRISPR/Cas9-mediated non-homologous end joining in the UCSFi001-A background, for study of the role that this protein plays in different tissues.

Molecular genetics in diagnosis of Coats disease: combination of oligogenic variants associated with different forms of hereditary retinal dystrophy

Coats disease (OMIM 300216) is a form of hereditary retinal dystrophy, which occurs due to congenital abnormality of retinal vessels and features unilateral exudative vitreoretinopathy. Coats disease mostly occurs sporadically; its genetic cause is still undetermined. Molecular genetic research including whole exome sequencing by the NGS method was used to define a genetic cause of the observed phenotype. Two heterozygous variants in different genomic loci associated with other forms of hereditary retinal dystrophy were detected, a rare variant in the HMCN1 gene c.9571C>T, p.(Arg3191Cys), and a known pathogenic variant in the NPHP4 gene c.2930C>T, p.(Thr977Met). The HMCN1 gene is responsible for dominant age-related macular degeneration (OMIM 603075), pathogenic variants in the NPHP4 gene cause recessive Senior-Løken syndrome 4 (OMIM 266900). These genes encode the proteins that are involved in the regulation of integrity of the blood-retinal barrier in the vascular endothelium (NPHP4) and retinal pigment epithelium (HMCN1). The identified mutation in the NPHP4 gene could lead to decreased function of the NPHP4 protein and contribute to the development of retinal degeneration, potentially of oligogenic nature.

Clinical and genetic spectrum from a prototype of ciliopathy: Joubert syndrome

ObjectiveJoubert syndrome is a neurodevelopmental disorder with a distinctive hindbrain malformation called molar tooth sign, causing motor and cognitive impairments. More than 40 genes have been associated with Joubert syndrome. We aim to describe a group of Joubert syndrome patients clinically and genetically emphasizing organ involvement. MethodsWe retrospectively collected clinical information and molecular diagnosis data of 22 patients with Joubert syndrome from multiple facilities. Clinical exome or whole-exome sequencing were performed to identify causal variations in genes. ResultsThe most common variants were in the CPLANE1, CEP290, and TMEM67 genes, and other causative genes were AHI1, ARMC9, CEP41, CSPP1, HYLS1, KATNIP, KIAA0586, KIF7, RPGRIP1L, including some previously unreported variants in these genes. Multi-systemic organ involvement was observed in nine (40%) patients, with the eye being the most common, including Leber’s congenital amaurosis, ptosis, and optic nerve coloboma. Portal hypertension and esophageal varices as liver and polycystic kidney disease and nephronophthisis as kidney involvement was encountered in our patients. The HYLS1 gene, which commonly causes hydrolethalus syndrome 1, was also associated with Joubert syndrome in one of our patients. A mild phenotype with hypophyseal hormone deficiencies without the classical molar tooth sign was observed with compound heterozygous and likely pathogenic variants not reported before in the KATNIP gene. ConclusionSome rare variants that display prominent genetic heterogeneity with variable severity are first reported in our patients. In our study of 22 Joubert syndrome patients, CPLANE1 is the most affected gene, and Joubert syndrome as a ciliopathy is possible without a classical molar tooth sign, like in the KATNIP gene-affected patients.

Prime Editing for the Installation and Correction of Mutations Causing Inherited Retinal Disease: A Brief Methodology.

Inherited retinal diseases (IRDs) encompass a large heterogeneous group of rare blinding disorders whose etiology originates from mutations in the 280 genes identified to date. Clustered regularly interspaced short palindromic repeats (CRISPR)/CRISPR-associated (Cas) systems represent a promising avenue for the treatment of IRDs, as exemplified by FDA clinical trial approval of EDIT-101 (AGN-151587), which removes a deep intronic variant in the CEP290 gene that causes Leber congenital amaurosis (LCA) type 10. Prime editing is a novel double-strand break (DSB) independent CRISPR/Cas system which has the potential to correct all 12 possible transition and transversion mutations in addition to small deletions and insertions. Here, as a proof-of-concept study, we describe a methodology using prime editing for the in vitro installation and correction of the classical Pde6brd10 c.1678C>T (p.Arg560Cys) mutation which causes autosomal recessive retinitis pigmentosa (RP) in mice.