Joubert syndrome-derived induced pluripotent stem cells show altered neuronal differentiation in vitro

Joubert syndrome (JS) is a recessively inherited congenital ataxia characterized by hypotonia, psychomotor delay, abnormal ocular movements, intellectual disability, and a peculiar cerebellar and brainstem malformation, the "molar tooth sign." Over 40 causative genes have been reported, all encoding for proteins implicated in the structure or functioning of the primary cilium, a subcellular organelle widely present in embryonic and adult tissues. In this paper, we developed an in vitro neuronal differentiation model using patient-derived induced pluripotent stem cells (iPSCs), to evaluate possible neurodevelopmental defects in JS. To this end, iPSCs from four JS patients harboring mutations in distinct JS genes (AHI1, CPLANE1, TMEM67, and CC2D2A) were differentiated alongside healthy control cells to obtain mid-hindbrain precursors and cerebellar granule cells. Differentiation was monitored over 31 days through the detection of lineage-specific marker expression by qRT-PCR, immunofluorescence, and transcriptomics analysis. All JS patient-derived iPSCs, regardless of the mutant gene, showed a similar impairment to differentiate into mid-hindbrain and cerebellar granule cells when compared to healthy controls. In addition, analysis of primary cilium count and morphology showed notable ciliary defects in all differentiating JS patient-derived iPSCs compared to controls. These results confirm that patient-derived iPSCs are an accessible and relevant in vitro model to analyze cellular phenotypes connected to the presence of JS gene mutations in a neuronal context.

Joubert syndrome presenting bilateral peroneal neuropathies: A case report

RATIONALE

Joubert syndrome (JS) is a rare genetic disorder that presents with various neurological symptoms, primarily involving central nervous system dysfunction. Considering the etiology of JS, peripheral nervous system abnormalities cannot be excluded; however, cases of JS accompanied by peripheral nervous system abnormalities have not yet been reported. Distinct radiological findings on brain magnetic resonance imaging were considered essential for the diagnosis of JS. However, recently, cases of JS with normal or nearly normal brain morphology have been reported. To date, there is no consensus on the most appropriate diagnostic method for JS when imaging-based diagnostic approach is challenging. This report describes the case of an adult patient who exhibited bilateral peroneal neuropathies and was finally diagnosed with JS through genetic testing.

PATIENT CONCERNS AND DIAGNOSIS

A 27-year-old man visited our outpatient clinic due to a gait disturbance that started at a very young age. The patient exhibited difficulty maintaining balance, especially when walking slowly. Oculomotor apraxia was observed on ophthalmic evaluation. During diagnostic workups, including brain imaging and direct DNA sequencing, no conclusive findings were detected. Only nerve conduction studies revealed profound bilateral peroneal neuropathies. We performed whole genome sequencing to obtain a proper diagnosis and identify the gene mutation responsible for JS.

LESSONS

This case represents the first instance of peripheral nerve dysfunction in JS. Further research is needed to explore the association between JS and peripheral nervous system abnormalities. Detailed genetic testing may serve as a valuable tool for diagnosing JS when no prominent abnormalities are detected in brain imaging studies.

The Phenotypic Variability Associated with Hepatocyte Nuclear Factor 1B Genetic Defects Poses Challenges in Both Diagnosis and Therapy

The evolving landscape of clinical genetics is becoming increasingly relevant in the field of nephrology. HNF1B-associated renal disease presents with a diverse array of renal and extrarenal manifestations, prominently featuring cystic kidney disease and diabetes mellitus. For the genetic analyses, whole exome sequencing (WES) and multiplex ligation-dependent probe amplification (MLPA) were performed. Bioinformatics analysis was performed with Ingenuity Clinical Insights software (Qiagen). The patient's electronic record was utilized after receiving informed consent. In this report, we present seven cases of HNF1B-associated kidney disease, each featuring distinct genetic abnormalities and displaying diverse extrarenal manifestations. Over 12 years, the mean decline in eGFR averaged -2.22 ± 0.7 mL/min/1.73 m2. Diabetes mellitus was present in five patients, kidney dysplastic lesions in six patients, pancreatic dysplasia, hypomagnesemia and abnormal liver function tests in three patients each. This case series emphasizes the phenotypic variability and the fast decline in kidney function associated with HNF-1B-related disease. Additionally, it underscores that complex clinical presentations may have a retrospectively straightforward explanation through the use of diverse genetic analytical tools.

Development of crizotinib-associated renal cyst in a non-small cell lung cancer patient with ALK fusion: a case report and review of the literature

BACKGROUND

Crizotinib, an oral first-generation tyrosine kinase inhibitor (TKI), is superior to systemic chemotherapy for the treatment of non-small cell lung cancer (NSCLC) with positive rearrangement of anaplastic lymphoma kinase (ALK). However, an increased incidence of renal and hepatic cysts has been reported in the patients on crizotinib treatment.

CASE PRESENTATION

Here, we describe a case of a 71-year-old Chinese women developed multiple cystic lesions in kidney and liver during crizotinib treatment for the primary and metastatic NSCLC. The renal and hepatic cysts were noted by CT scan 3 months after crizotinib treatment, which were spontaneously and significantly regressed after stopping crizotinib.

CONCLUSIONS

Based on literature review and our experience in this case report, we concluded that crizotinib-associated renal cyst (CARCs) has features of malignancy and abscess in radiographic imaging, and thus, pathological confirmation is necessary to avoid inappropriate treatment decision. In addition, to benefit the patients with progress-free survival (PFS), switching from crizotinib to alectinib is recommended for the treatment of NSCLC patients who developed CARCs.

[A case of crizotinib-associated renal cysts]

Crizotinib-associated renal cysts (CARC) are the development of new renal cysts or pre-existing renal cysts after the treatment with crizotinib. Most CARC disappear after crizotinib is stopped. A few CARC showed aggressive behavior that could go beyond the invasion of the renal cortex into nearby structures, including perirenal space, psoas major muscle, intestine, and abdominal wall. A case of EML4-ALK fusion mutation in invasive lung adenocarcinoma has been reported. Multiple cystic changes occurred repeatedly in both kidneys, right rectus muscle, and psoas major muscle after treatment with crizotinib, and spontaneous absorption and resolution after discontinuation of the drug.

Novel compound heterozygous variants in ARL13B lead to Joubert syndrome

Joubert syndrome (JBTS) is a systematic developmental disorder mainly characterized by a pathognomonic mid-hindbrain malformation. All known JBTS-associated genes encode proteins involved in the function of antenna-like cellular organelle, primary cilium, which plays essential roles in cellular signal transduction and development. Here, we identified four unreported variants in ARL13B in two patients with the classical features of JBTS. ARL13B is a member of the Ras GTPase family and functions in ciliogenesis and cilia-related signaling. The two missense variants in ARL13B harbored the substitutions of amino acids at evolutionarily conserved positions. Using model cell lines, we found that the accumulations of the missense variants in cilia were impaired and the variants showed attenuated functions in ciliogenesis or the trafficking of INPP5E. Overall, these findings expanded the ARL13B pathogenetic variant spectrum of JBTS.

New Insights into the Neuropsychological Profile and Intellectual Quotient Variability in Joubert Syndrome Compared to Other Congenital Cerebellar Malformations

The neuropsychological characteristics of the cerebellar cognitive affective syndrome (CCAS) in congenital, non-progressive malformations of the cerebellum have been scarcely investigated, and even less is known for Joubert syndrome (JS), an inherited, non-progressive cerebellar ataxia characterized by the so-called molar tooth sign. The few studies on this topic reported inconsistent results about intellectual functioning and specific neuropsychological impairments. The aim of this research is to examine the neuropsychological profile of JS compared to other congenital cerebellar malformations (CM), considering individual variability of intellectual quotient (IQ) in the two groups. Fourteen patients with JS and 15 patients with CM aged 6-25 years were tested through a comprehensive, standardized neuropsychological battery. Their scores in the neuropsychological domains were inspected through descriptive analysis and compared by mean of MANOVA and ANOVA models, then replicated inserting IQ as covariate. The two groups showed a largely overlapping neuropsychological profile, consistent with CCAS. However, the JS group showed worse performance in visual-spatial memory compared to CM patients, although this difference was mitigated when considering IQ. These findings highlight a divergence between JS and other CM in visual-spatial memory, which might suggest a critical role of the cerebellum in recalling task-relevant memories and might inform rehabilitative interventions.

High Incidence of CPLANE1-Related Joubert Syndrome in the Products of Conceptions from Early Pregnancy Losses

Background

The fetal monogenic causes of early pregnancy losses (EPLs) are mainly unknown, with only a few articles on the subject published. In our previous study of EPLs using whole-exome sequencing analysis, we confirmed a genetic diagnosis of CPLANE1-related Joubert syndrome (JS) in three EPLs from two couples and identified a relatively common CPLANE1 allele among our population (NM_001384732.1:c.1819delT;c.7817T>A, further after referred as “complex allele”). Pathogenic variants in the CPLANE1 (C5orf42) gene are reported to cause JS type 17, a primary ciliopathy with various system defects.

Aims

To examine the hypothesis that the CPLANE1 “complex allele,” whether homozygous or compound heterozygous, is a common cause of EPLs in our population.

Study Design

Cohort study/case-control study.ontrol study.

Methods

In this study, we used polymerase chain reaction-based methods to screen for CPLANE1 “complex allele” presence among 246 euploid EPLs (< 12 gestational weeks) from families in North Macedonia. We also investigated the impact of this allele in 650 women with EPLs versus 646 women with no history of pregnancy loss and at least one livebirth, matched by ethnic origin.

Results

We found a high incidence of JS in the total study group of EPLs (2.03%), with a considerably higher incidence among Albanian families (6.25%). Although not statistically significant, women with EPLs had a higher allele frequency of the CPLANE1 “complex allele” (AF = 1.38%) than the controls (AF = 0.85%; p = 0.2). Albanian women had significantly higher frequency of the “complex allele” than the Macedonians (AF = 1.65% and 0.39%, respectively; p = 0.003).

Conclusion

To the best of our knowledge, this is the highest reported incidence of fetal monogenic disease that might cause EPLs. Targeted screening for the CPLANE1 “complex allele” would be warranted in Albanian ethnic couples because it would detect one JS in every 16 euploid EPLs. Our findings have a larger impact on the pathogenesis of pregnancy loss and contribute to a better understanding of the pathogenicity of the variants in the CPLANE1 gene.

Characterization of the prenatal renal phenotype associated with 17q12, HNF1B, microdeletions

OBJECTIVE

Recurrent deletions involving 17q12 are associated with a variety of clinical phenotypes, including congenital abnormalities of the kidney and urinary tract (CAKUT), maturity onset diabetes of the young, type 5, and neurodevelopmental disorders. Structural and/or functional renal disease is the most common phenotypic feature, although the prenatal renal phenotypes and the postnatal correlates have not been well characterized.

METHOD

We reviewed pre- and postnatal medical records of 26 cases with prenatally or postnatally identified 17q12/HNF1B microdeletions (by chromosomal microarray or targeted gene sequencing), obtained through a multicenter collaboration. We specifically evaluated 17 of these cases (65%) with reported prenatal renal ultrasound findings.

RESULTS

Heterogeneous prenatal renal phenotypes were noted, most commonly renal cysts (41%, n = 7/17) and echogenic kidneys (41%), although nonspecific dysplasia, enlarged kidneys, hydronephrosis, pelvic kidney with hydroureter, and lower urinary tract obstruction were also reported. Postnatally, most individuals developed renal cysts (73%, 11/15 live births), and there were no cases of end-stage renal disease during childhood or the follow-up period.

CONCLUSION

Our findings demonstrate that copy number variant analysis to assess for 17q12 microdeletion should be considered for a variety of prenatally detected renal anomalies. It is important to distinguish 17q12 microdeletion from other etiologies of CAKUT as the prognosis for renal function and presence of associated findings are distinct and may influence pregnancy and postnatal management.

Phenotypic variability in Joubert syndrome is partially explained by ciliary pathophysiology

INTRODUCTION

Joubert syndrome (JS) arises from defects of primary cilia resulting in potential malformations of the brain, kidneys, eyes, liver, and limbs. Several of the 35+ genes associated with JS have recognized genotype/phenotype correlations, but most genes have not had enough reported individuals to draw meaningful conclusions.

METHODS

A PubMed literature review identified 688 individuals with JS across 32 genes and 112 publications to bolster known genotype/phenotype relationships and identify new correlations. All included patients had the "molar tooth sign" and a confirmed genetic diagnosis. Individuals were categorized by age, ethnicity, sex and the presence of developmental disability/intellectual disability, hypotonia, abnormal eye movements, ataxia, visual impairment, renal impairment, polydactyly, and liver abnormalities.

RESULTS

Most genes demonstrated unique phenotypic profiles. Grouping proteins based on physiologic interactions established stronger phenotypic relationships that reflect known ciliary pathophysiology. Age-stratified data demonstrated that end-organ disease is progressive in JS. Most genes demonstrated a significant skew towards having variants with either residual protein function or no residual protein function.

CONCLUSION

This cohort demonstrates that clinically meaningful genotype/phenotype relationships exist within most JS-related genes and can be referenced to allow for more personalized clinical care.

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.

Novel mutation in RPGRIP1L gene causing Joubert syndrome: A case report

INTRODUCTION

Joubert syndrome is a rare disease of genetic origin with autosomal recessive inheritance and extreme genetic heterogeneity with more than 40 causative genes. Joubert syndrome 7 is caused by mutations in the RPGRIP1L gene.

PATIENT CONCERNS

Our report describes a pediatric patient with clinical features compatible with JS type 7 such as hypotonia, developmental delay and aplasia of the cerebellar vermis.

DIAGNOSIS

The clinical features and the MRI of the head and neck which showed alterations at the level of the posterior fossa, with absence of the vermis and horizontal disposition of the cerebellar peduncles, were compatible with Joubert syndrome. Whole exome sequencing detected the variants RPGRIP1L (NM_015272.2) c.697A > T (p. Lys233Ter) and RPGRIP1L (NM_015272.2) c.3545 del (p.Pro1182LeufsTer25).

INTERVENTIONS

Resection was performed to correct the polydactyly. At age 2 years umbilical hernia, adenoid surgery and ventilatory tubes surgery were performed. Renal biopsy confirmed interstitial fibrosis and focally accentuated mild tubular atrophy with focal tubular hypertrophy, compatible with the clinical suspicion of Joubert syndrome. Congenital hip dislocation surgery was performed. The patient underwent surgery for correction of concomitant divergent strabismus and continued with glasses for astigmatism and hyperopia.

OUTCOMES

Sanger sequencing confirmed the patient´s results and the father was found to be a carrier of RPGRIP1L (NM_015272.2) c.697A > T (p. Lys233Ter) and the mother and maternal grandmother as carriers of RPGRIP1L (NM_015272.2) c.3545del (p.Pro1182LeufsTer25). RPGRIP1L:c.3545del novel variant is a deletion which changes the reading frame, altering the RPGR1_C terminal domain and giving rise to an incomplete protein whose functions will be altered.

CONCLUSION

This is the first genetically confirmed case of JS in Colombia, the first carrier of biallelic RPGRIP1L gene mutations with hip dislocation and incomplete glottic closure and the first report of the novel c.3545del likely pathogenic variant causing JS.

A novel mutation of the RPGRIP1L gene in a Chinese boy with Joubert syndrome with oculorenal involvement

BACKGROUND

Joubert syndrome (JS) is a rare genetically heterogeneous primary ciliopathy characterized by a pathognomonic cerebellar and brainstem malformation, the "molar tooth sign", and variable organ involvement (such as eye, kidney, liver, and skeleton). Here, we present a case of JS in a Chinese boy.

CASE PRESENTATION

An 11-year-old Chinese boy presented with neonatal asphyxiation and hypoxia, strabismus, subsequent developmental delay, ataxia and end-stage kidney disease (ESKD). Routine blood tests showed severe anemia, increasing blood urea nitrogen and creatinine, elevated parathyroid hormone, hypocalcemia, hypokalemia and metabolic acidosis. Urine tests showed mild proteinuria. Ultrasound showed two small kidneys. Brain magnetic resonance imaging (MRI) showed dysplasia of the cerebellar vermis and extension of the upper cerebellar feet with the "molar tooth sign". Genetic analysis showed novel compound heterozygous mutations in the RPGRIP1L gene [p.L447fs*7(p.Leu447fsTer7) and p.G908V (p.Gly908Val)].

CONCLUSION

In the present study, we identified novel compound heterozygous mutations in the RPGRIP1L gene in a Chinese boy. The clinical and genetic findings of this study will expand the understanding of JS.

Autosomal Recessive Adolescent Syndromic Nephronophthisis Caused by a Novel Compound Heterozygous Pathogenic Variant

BACKGROUND Nephronophthisis, an autosomal recessive ciliopathy involving mutations in primary cilium genes, is characterized by chronic tubulointerstitial nephritis and a defective urine concentrating capacity. It accounts for about 5% of renal failure in children and adolescents and usually progresses to end-stage renal disease before the age of 30 years. Nephronophthisis is associated with extrarenal manifestations, including retinitis pigmentosa in Senior-Loken syndrome (SLS), and liver fibrosis in 10-20% of cases. While some presenting patterns could be characteristic, patients may have atypical presentation, making diagnosis difficult. Tubulointerstitial fibrosis is the predominant feature on histology and as such, diagnosis depends mostly on genetic testing. Despite advances in renal genomics over the years with a better understanding of primary cilia and ciliary theory, about 40% of nephronophthisis cases go undiagnosed. As the underlying genetic etiologies are not fully understood, morphologic pathologic findings are non-specific, and treatment options are limited to dialysis and transplantation. CASE REPORT We describe a unique case of a patient with adolescent nephronophthisis who presented with advanced chronic kidney disease and severe pancytopenia, who progressed to end-stage renal disease at the age of 19, and was found to have syndromic nephronophthisis with compound heterozygous inheritance. CONCLUSIONS This report highlights the atypical presentation patterns that can be seen in syndromic nephronophthisis, the importance of genetic diagnosis when there is a high index of suspicion, and the need to further study genetic variants to better understand and diagnose the disease and to develop targeted therapy.

Case Report: Diabetes mellitus type MODY5 as a feature of 17q12 deletion syndrome with diabetic gastroparesis

Background

Maturity-onset diabetes of the young type 5 (MODY5) is an uncommon, underrecognized condition that can be encountered in several clinical contexts. It is challenging to diagnose because it is considered rare and therefore overlooked in the differential diagnosis. Moreover, no typical clinical features or routine laboratory tests can immediately inform the diagnosis.

Case presentation

We report a 28-year-old man who was once misdiagnosed with type 1 diabetes due to decreased islet function and recurrent diabetic ketosis or ketoacidosis. However, he had intermittent nausea, vomiting, abdominal distension, and abdominal pain 6 months prior. Further examinations revealed agenesis of the dorsal pancreas, complex renal cyst, kidney stone, prostate cyst, hypomagnesaemia, and delayed gastric emptying. Accordingly, whole-exon gene detection was performed, and a heterozygous deletion mutation was identified at [GRCh37 (hg19)] chr17:34842526-36347106 (1.5 Mb, including HNF1B gene). The patient was eventually diagnosed with 17q12 deletion syndrome with gastroparesis.

Conclusion

We report a novel case of diabetes mellitus type MODY5 as a feature of 17q12 deletion syndrome caused by a new 17q12 deletion mutation, which will further broaden the genetic mutation spectrum of this condition. With the help of gene detection technology, these findings can assist endocrinologists in making the correct diagnosis of MODY5 or 17q12 deletion syndrome. Additionally, they can formulate an appropriate therapy and conduct genetic screening counseling for their family members to guide and optimize fertility.

A case of Joubert syndrome caused by novel compound heterozygous variants in the TMEM67 gene

Joubert syndrome (JS) is a recessive disorder that is characterized by midbrain-hindbrain malformation and shows the "molar tooth sign" on magnetic resonance imaging. Mutations in 40 genes, including Abelson helper integration site 1 (AHI1), inositol polyphosphate-5-phosphatase (INPP5E), coiled-coil and c2 domain-containing protein 2A (CC2D2A), and ARL2-like protein 1 (ARL13B), can cause JS. Classic JS is a part of a group of diseases associated with JS, and its manifestations include various neurological signs such as skeletal abnormalities, ocular coloboma, renal disease, and hepatic fibrosis. Here, we present a proband with the molar tooth sign, ataxia, and developmental and psychomotor delays in a Dagestan family from Russia. Molecular genetic testing revealed two novel heterozygous variants, c.2924G>A (p.Arg975His) in exon 28 and c.1241C>G (p.Pro414Arg) in exon 12 of the transmembrane protein 67 (TMEM67) gene. These TMEM67 gene variants significantly affected the development of JS type 6. This case highlights the importance of whole exome sequencing for a proper clinical diagnosis of children with complex motor and psycho-language delays. This case also expands the clinical phenotype and genotype of TMEM67-associated diseases.

Novel variants identified in five Chinese families with Joubert Syndrome: a case report

BACKGROUND

Joubert syndrome (JS) is a group of rare ciliopathies, mainly characterized by cerebellar dysplasia representing the "molar tooth sign (MTS)" on neuroimaging, hypotonia, and developmental delay. Having a complicated genotype-phenotype correlation due to its rich genetic heterogeneity, JS is usually combined with other organic defects affecting the retina, kidney, and liver. This report aimed to present new cases and novel variants of JS.

CASE PRESENTATION

Five unrelated patients who were diagnosed with JS, with or without typical clinical characteristics, received integrated examinations, including whole-exome sequencing (WES) and Sanger sequencing. We identified nine pathogenic variants in the TCTN2, CPLANE1, INPP5E, NPHP1, and CC2D2A genes.

CONCLUSION

Four novel pathogenic mutations in the TCTN2, CPLANE1, and INPP5E genes were reported. The findings broadened the genotypic spectrum of JS and contributed to a better understanding of genotype-phenotype correlation.

Recurrent, founder and hypomorphic variants contribute to the genetic landscape of Joubert syndrome

BACKGROUND

Joubert syndrome (JS) is a neurodevelopmental ciliopathy characterised by a distinctive mid-hindbrain malformation, the 'molar tooth sign'. Over 40 JS-associated genes are known, accounting for two-thirds of cases.

METHODS

While most variants are novel or extremely rare, we report on 11 recurring variants in seven genes, including three known 'founder variants' in the Ashkenazi Jewish, Hutterite and Finnish populations. We evaluated variant frequencies in ~550 European patients with JS and compared them with controls (>15 000 Italian plus gnomAD), and with an independent cohort of ~600 JS probands from the USA.

RESULTS

All variants were markedly enriched in the European JS cohort compared with controls. When comparing allele frequencies in the two JS cohorts, the Ashkenazim founder variant (TMEM216 c.218G>T) was significantly enriched in American compared with European patients with JS, while MKS1 c.1476T>G was about 10 times more frequent among European JS. Frequencies of other variants were comparable in the two cohorts. Genotyping of several markers identified four novel European founder haplotypes.Two recurrent variants (MKS1 c.1476T>G and KIAA0586 c.428delG), have been detected in homozygosity in unaffected individuals, suggesting they could act as hypomorphic variants. However, while fibroblasts from a MKS1 c.1476T>G healthy homozygote showed impaired ability to form primary cilia and mildly reduced ciliary length, ciliary parameters were normal in cells from a KIAA0586 c.428delG healthy homozygote.

CONCLUSION

This study contributes to understand the complex genetic landscape of JS, explain its variable prevalence in distinct geographical areas and characterise two recurrent hypomorphic variants.

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

OBJECTIVES

To improve the understanding of the clinical phenotypes and genetic characteristics of nephronophthisis (NPHP) and related syndromes in children.

METHODS

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.

RESULTS

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.

CONCLUSIONS

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.

Ciliary ARL13B inhibits developmental kidney cystogenesis in mouse

ARL13B is a small GTPase enriched in cilia. Deletion of Arl13b in mouse kidney results in renal cysts and an associated absence of primary cilia. Similarly, ablation of cilia leads to kidney cysts. To investigate whether ARL13B functions from within cilia to direct kidney development, we examined kidneys of mice expressing an engineered cilia-excluded ARL13B variant, ARL13BV358A. These mice retained renal cilia and developed cystic kidneys. Because ARL13B functions as a guanine nucleotide exchange factor (GEF) for ARL3, we examined kidneys of mice expressing an ARL13B variant that lacks ARL3 GEF activity, ARL13BR79Q. We found normal kidney development with no evidence of cysts in these mice. Taken together, our results show that ARL13B functions within cilia to inhibit renal cystogenesis during mouse development, and that this function does not depend on its role as a GEF for ARL3.

TOPORS as a novel causal gene for Joubert syndrome

Joubert syndrome (JBTS) is a Mendelian disorder of the primary cilium defined by the clinical triad of hypotonia, developmental delay, and a distinct cerebellar malformation called the molar tooth sign. JBTS is inherited in an autosomal recessive, autosomal dominant, or X-linked recessive manner. Though over 40 genes have been identified as causal for JBTS, molecular diagnosis is not made in 30%-40% of individuals who meet clinical criteria. TOPORS encodes topoisomerase I-binding arginine/serine-rich protein, and homozygosity for a TOPORS missense variant (c.29C > A; p.(Pro10Gln)) was identified in individuals with the ciliopathy oral-facial-digital syndrome in two families of Dominican descent. Here, we report an additional proband of Dominican ancestry with JBTS found by exome sequencing to be homozygous for the identical p.(Pro10Gln) TOPORS missense variant. Query of the Mount Sinai BioMe biobank, which includes 1880 individuals of Dominican ancestry, supports a high carrier frequency of the TOPORS p.(Pro10Gln) variant in individuals of Dominican descent. Our data nominates TOPORS as a novel causal gene for JBTS and suggests that TOPORS variants should be considered in the differential of ciliopathy-spectrum disease in individuals of Dominican ancestry.

Pathogenic Variants in CEP290 or IQCB1 Cause Earlier-Onset Retinopathy in Senior-Loken Syndrome Compared to Those in INVS, NPHP3, or NPHP4

PURPOSE

Senior-Loken syndrome (SLSN) is an autosomal recessive disorder characterized by retinopathy and nephronophthisis. This study aimed to evaluate whether different phenotypes are associated with different variants or subsets of 10 SLSN-associated genes based on an in-house data set and a literature review.

DESIGN

Retrospective case series.

METHODS

Patients with biallelic variants in SLSN-associated genes, including NPHP1, INVS, NPHP3, NPHP4, IQCB1, CEP290, SDCCAG8, WDR19, CEP164, and TRAF3IP1, were recruited. Ocular phenotypes and nephrology medical records were collected for comprehensive analysis.

RESULTS

Variants in 5 genes were identified in 74 patients from 70 unrelated families, including CEP290 (61.4%), IQCB1 (28.6%), NPHP1 (4.2%), NPHP4 (2.9%), and WDR19 (2.9%). The median age at the onset of retinopathy was approximately 1 month (since birth). Nystagmus was the most common initial sign in patients with CEP290 (28 of 44, 63.6%) or IQCB1 (19 of 22, 86.4%) variants. Cone and rod responses were extinguished in 53 of 55 patients (96.4%). Characteristic fundus changes were observed in CEP290- and IQCB1-associated patients. During follow-up, 70 of the 74 patients were referred to nephrology, among whom nephronophthisis was not detected in 62 patients (88.6%) at a median age of 6 years but presented in 8 patients (11.4%) aged approximately 9 years.

CONCLUSIONS

Patients with pathogenic variants in CEP290 or IQCB1 presented early with retinopathy, whereas other patients with INVS, NPHP3, or NPHP4 variants first developed nephropathy. Therefore, awareness of the genetic and clinical features may facilitate the clinical management of SLSN, especially early intervention of kidney problems for patients with eyes affected first.

[Unexpected diagnosis of nephronopthisis in the genetic study of hypertension due to histological diagnosis of benign nephroangioesclerosis evolved in a young caucasian patient]

We present the case of a young Caucasian patient with renal disease of unclear cause, with a final diagnosis of advanced benign nephroangiosclerosis established by renal biopsy. Due to the possibility of having hypertension in pediatric age (without study or treatment), with the renal biopsy findings, the genetic study showed polymorphisms risk in the APOL1 and MYH9, and also an unexpected diagnosis of a complete deletion of the NPHP1 gene in homozygosis, associated with the development of nephronophthisis. In conclusion, this case illustrates the importance of carrying out a genetic study in youngs patients with renal disease unclear cause, even having a histological diagnosis of nephroangiosclerosis.

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.

Bilateral Intraorbital Opticmeningoceles in Joubert Syndrome

Congenital opticmeningoceles was the term coined to describe large pseudocystic lesions of the intraorbital segment of the optic nerve. This extremely rare congenital anomaly was reported unilaterally only in nonsyndromic patients with fully developed eyes. The authors describe here a 10-month-old girl with a previous diagnosis of Joubert syndrome who presented with the same type of optic nerve malformation in OU. Molecular genetic analysis disclosed a pathogenic variant of the TMEM67 gene which is associated with various types of ciliopathies.

Exome Analysis Reveals Novel Missense and Deletion Variants in the CC2D2A Gene as Causative of Joubert Syndrome

The CC2D2A gene is essential for primary cilia formation, and its disruption has been associated with Joubert Syndrome-9 (JBTS9), a ciliopathy with typical neurodevelopmental features. Here, we describe an Italian pediatric patient with typical features of Joubert Syndrome (JBTS): “Molar Tooth Sign”, global developmental delay, nystagmus, mild hypotonia, and oculomotor apraxia. Whole exome sequencing and segregation analysis identified in our infant patient a novel heterozygous germline missense variant c.3626C > T; p.(Pro1209Leu) inherited from the father and a novel 7.16 kb deletion inherited from the mother. To the best of our knowledge, this is the first report showing a novel missense and deletion variant involving exon 30 of the CC2D2A gene.

HNF1B Alters an Evolutionarily Conserved Nephrogenic Program of Target Genes

SIGNIFICANCE STATEMENT

Mutations in hepatocyte nuclear factor-1 β ( HNF1B ) are the most common monogenic causes of congenital renal malformations. HNF1B is necessary to directly reprogram fibroblasts to induced renal tubule epithelial cells (iRECs) and, as we demonstrate, can induce ectopic pronephric tissue in Xenopus ectodermal organoids. Using these two systems, we analyzed the effect of HNF1B mutations found in patients with cystic dysplastic kidney disease. We found cross-species conserved targets of HNF1B, identified transcripts that are differentially regulated by the patient-specific mutant protein, and functionally validated novel HNF1B targets in vivo . These results highlight evolutionarily conserved transcriptional mechanisms and provide insights into the genetic circuitry of nephrogenesis.

BACKGROUND

Hepatocyte nuclear factor-1 β (HNF1B) is an essential transcription factor during embryogenesis. Mutations in HNF1B are the most common monogenic causes of congenital cystic dysplastic renal malformations. The direct functional consequences of mutations in HNF1B on its transcriptional activity are unknown.

METHODS

Direct reprogramming of mouse fibroblasts to induced renal tubular epithelial cells was conducted both with wild-type HNF1B and with patient mutations. HNF1B was expressed in Xenopus ectodermal explants. Transcriptomic analysis by bulk RNA-Seq identified conserved targets with differentially regulated expression by the wild-type or R295C mutant. CRISPR/Cas9 genome editing in Xenopus embryos evaluated transcriptional targets in vivo .

RESULTS

HNF1B is essential for reprogramming mouse fibroblasts to induced renal tubular epithelial cells and induces development of ectopic renal organoids from pluripotent Xenopus cells. The mutation R295C retains reprogramming and inductive capacity but alters the expression of specific sets of downstream target genes instead of diminishing overall transcriptional activity of HNF1B. Surprisingly, targets associated with polycystic kidney disease were less affected than genes affected in congenital renal anomalies. Cross-species-conserved transcriptional targets were dysregulated in hnf1b CRISPR-depleted Xenopus embryos, confirming their dependence on hnf1b .

CONCLUSIONS

HNF1B activates an evolutionarily conserved program of target genes that disease-causing mutations selectively disrupt. These findings provide insights into the renal transcriptional network that controls nephrogenesis.

The Landscape of HNF1B Deficiency: A Syndrome Not Yet Fully Explored

The hepatocyte nuclear factor 1β (HNF1B) gene is involved in the development of specialized epithelia of several organs during the early and late phases of embryogenesis, performing its function mainly by regulating the cell cycle and apoptosis pathways. The first pathogenic variant of HNF1B (namely, R177X) was reported in 1997 and is associated with the maturity-onset diabetes of the young. Since then, more than 230 different HNF1B variants have been reported, revealing a multifaceted syndrome with complex and heterogenous genetic, pathologic, and clinical profiles, mainly affecting the pediatric population. The pancreas and kidneys are the most frequently affected organs, resulting in diabetes, renal cysts, and a decrease in renal function, leading, in 2001, to the definition of HNF1B deficiency syndrome, including renal cysts and diabetes. However, several other organs and systems have since emerged as being affected by HNF1B defect, while diabetes and renal cysts are not always present. Especially, liver involvement has generally been overlooked but recently emerged as particularly relevant (mostly showing chronically elevated liver enzymes) and with a putative relation with tumor development, thus requiring a more granular analysis. Nowadays, HNF1B-associated disease has been recognized as a clinical entity with a broader and more variable multisystem phenotype, but the reasons for the phenotypic heterogeneity are still poorly understood. In this review, we aimed to describe the multifaceted nature of HNF1B deficiency in the pediatric and adult populations: we analyzed the genetic, phenotypic, and clinical features of this complex and misdiagnosed syndrome, covering the most frequent, unusual, and recently identified traits.

[Clinical features and genetic analysis of two Chinese pedigrees affected with Joubert syndrome]

OBJECTIVE

To explore the clinical characteristics and genetic basis of two Chinese pedigrees affected with Joubert syndrome.

METHODS

Clinical data of the two pedigrees was collected. Genomic DNA was extracted from peripheral blood samples and subjected to high-throughput sequencing. Candidate variants were verified by Sanger sequencing. Prenatal diagnosis was carried out for a high-risk fetus from pedigree 2.

RESULTS

The proband of pedigree 1 was a fetus at 23⁺⁵ weeks gestation, for which both ultrasound and MRI showed "cerebellar vermis malformation" and "molar tooth sign". No apparent abnormality was noted in the fetus after elected abortion. The fetus was found to harbor c.812+3G>T and c.1828G>C compound heterozygous variants of the INPP5E gene, which have been associated with Joubert syndrome type 1. The proband from pedigree 2 had growth retardation, mental deficiency, peculiar facial features, low muscle tone and postaxial polydactyly of right foot. MRI also revealed "cerebellar dysplasia" and "molar tooth sign". The proband was found to harbor c.485C>G and c.1878+1G>A compound heterozygous variants of the ARMC9 gene, which have been associated with Joubert syndrome type 30. Prenatal diagnosis found that the fetus only carried the c.485C>G variant. A healthy infant was born, and no anomalies was found during the follow-up.

CONCLUSION

The compound heterozygous variants of the INPP5E and ARMC9 genes probably underlay the disease in the two pedigrees. Above finding has expanded the spectrum of pathogenic variants underlying Joubert syndrome and provided a basis for genetic counseling and prenatal diagnosis.

Non-syndromic Retinal Degeneration Caused by Pathogenic Variants in Joubert Syndrome Genes

Inherited retinal degenerations (IRDs) are a group of genetic disorders characterized by progressive dysfunction and loss of photoreceptors. IRDs are classified as non-syndromic or syndromic, depending on whether retinal degeneration manifests alone or in combination with other associated symptoms. Joubert syndrome (JBTS) is a genetically and clinically heterogeneous disorder affecting the central nervous system and other organs and tissues, including the neuroretina. To date, 39 genes have been associated with JBTS, a majority of which encode structural or functional components of the primary cilium, a specialized sensory organelle present in most post-mitotic cells, including photoreceptors. The use of whole exome and IRD panel next-generation sequencing in routine diagnostics of non-syndromic IRD cases led to the discovery of pathogenic variants in JBTS genes that cause photoreceptor loss without other syndromic features. Here, we recapitulate these findings, describing the JBTS gene defects leading to non-syndromic IRDs.

Different Clinical Courses of Nephronophthisis in Dizygotic Twins

Siblings with nephronophthisis occasionally show different clinical courses; however, the reasons for this remain unclear. We herein report cases of nephronophthisis in a pair of dizygotic twins with different clinical courses. The brother developed end-stage kidney disease at 17 years old; however, his sister did not show kidney insufficiency. Kidney biopsies revealed severe tubulointerstitial damage at 14 and 22 years old in the brother and sister, respectively. Both had a homozygous NPHP1 deletion with different heterozygous mutations related to hereditary cystic kidney disease. Since the dizygotic twins were exposed to similar environmental factors, genetic factors may have influenced their clinical course more strongly than environmental factors.

[Clinical phenotype analysis of 6 cases of TTC21B gene related nephronophthisis]

Objective: To analyze the clinical characteristics of 6 children with TTC21B-related nephronophthisis to provide reference for early clinical diagnosis. Methods: The general condition, clinical manifestations, laboratory tests and other clinical data of 6 children from 4 families diagnosed with nephronophthisis by genetic testing in Shanghai Children's Hospital from January 2015 to December 2020 were analyzed retrospectively. Results: A total of 6 children (3 males and 3 females) developed proteinuria and progressive renal dysfunction in early infancy. The onset age of proteinuria was 18 (6, 25) months. The age at the onset of renal impairment was 22 (10, 36) months. All 6 children progressed to end-stage renal disease (ESRD) within 10 (4, 65) months of onset. Five children had hypertension, 3 children with abnormal liver function, 2 children with visceral translocation and 1 child with growth retardation. The genetic results suggested that all children carried variations TTC21B gene p.C518R. Conclusions: Children with TTC21B gene p.C518R nephronophthisis had proteinuria and progressed to ESRD at the early stage of life. These nephronophthisis patients commonly presented with liver and renal dysfunction.

Molecular diagnoses in the congenital malformations caused by ciliopathies cohort of the 100,000 Genomes Project

BACKGROUND

Primary ciliopathies represent a group of inherited disorders due to defects in the primary cilium, the 'cell's antenna'. The 100,000 Genomes Project was launched in 2012 by Genomics England (GEL), recruiting National Health Service (NHS) patients with eligible rare diseases and cancer. Sequence data were linked to Human Phenotype Ontology (HPO) terms entered by recruiting clinicians.

METHODS

Eighty-three prescreened probands were recruited to the 100,000 Genomes Project suspected to have congenital malformations caused by ciliopathies in the following disease categories: Bardet-Biedl syndrome (n=45), Joubert syndrome (n=14) and 'Rare Multisystem Ciliopathy Disorders' (n=24). We implemented a bespoke variant filtering and analysis strategy to improve molecular diagnostic rates for these participants.

RESULTS

We determined a research molecular diagnosis for n=43/83 (51.8%) probands. This is 19.3% higher than previously reported by GEL (n=27/83 (32.5%)). A high proportion of diagnoses are due to variants in non-ciliopathy disease genes (n=19/43, 44.2%) which may reflect difficulties in clinical recognition of ciliopathies. n=11/83 probands (13.3%) had at least one causative variant outside the tiers 1 and 2 variant prioritisation categories (GEL's automated triaging procedure), which would not be reviewed in standard 100,000 Genomes Project diagnostic strategies. These include four structural variants and three predicted to cause non-canonical splicing defects. Two unrelated participants have biallelic likely pathogenic variants in LRRC45, a putative novel ciliopathy disease gene.

CONCLUSION

These data illustrate the power of linking large-scale genome sequence to phenotype information. They demonstrate the value of research collaborations in order to maximise interpretation of genomic data.

Unusual manifestations of young woman with MODY5 based on 17q12 recurrent deletion syndrome

BACKGROUND

Maturity-onset diabetes of the young type 5 (MODY5) is a rare subtype of MODYs. It is caused by mutations of the hepatocyte nuclear factor 1 homeobox b gene (HNF1B). 17q12 recurrent deletion syndrome usually results in MODY5 because of the deletion of HNF1B. These patients often have other clinical manifestations besides diabetes. Refractory hypomagnesemia was a clue for further examination in this patient. But she lacked structural abnormalities of the genitourinary system and neurodevelopmental disorders that are common manifestations in patients with 17q12 recurrent deletion syndrome. Some atypical patients deserved attention.

CASE PRESENTATION

A 21-year-old young woman was admitted to our hospital for severe malnutrition and gastrointestinal symptoms. At age 20, she was diagnosed with type 2 diabetes mellitus (T2DM) and was administered oral antidiabetic drugs. Soon afterward, the patient discontinued the medication on her own accord and then went to the hospital again due to diabetic ketoacidosis. After insulin treatment, diabetic ketoacidosis was cured and blood glucose was controlled satisfactorily. But intractable nausea, vomiting, and persistent weight loss were stubborn. Further examination revealed that the patient had hypokalemia and hard rectification hypomagnesemia. Genetic testing revealed about 1.85 Mb heterozygous fragment deletion on chromosome 17 and deletion of exons 1-9 of HNF1B heterozygosity missing was approved. Finally, the patient was diagnosed MODY5.

DISCUSSION AND CONCLUSIONS

The 17q12 recurrent deletion syndrome is characterized by MODY5, structural or functional abnormalities of the kidney and urinary tract, and neurodevelopmental or neuropsychiatric disorders. This patient did not have any structural abnormalities of the genitourinary system and neuropsychiatric disorders, which is rare. She had experienced a period of misdiagnosis before being diagnosed with 17q12 recurrent deletion syndrome, and hypomagnesemia was an important clue for her diagnosis. Therefore, diabetic physicians should be alert to a special type of diabetes if patients have unexplained signs and symptoms. The absence of well-known features of HNF1B disease does not exclude MODY5.

Systematic analysis of physical examination characteristics of 94 individuals with Joubert syndrome: Keys to suspecting the diagnosis

Joubert syndrome (JS) is a neurodevelopmental disorder characterized by hypotonia and developmental delay, as well as the obligatory molar tooth sign on brain imaging. Since hypotonia and developmental delay are nonspecific features, there must be a high level of clinical suspicion of JS so that the diagnostic brain imaging and/or molecular testing for the >38 genes associated with JS is/are obtained. The goal of this study was to analyze clinical photographs of a cohort of patients with JS to define a list of physical examination features that should prompt investigation for JS. Analysis of photographs from 94 individuals with JS revealed that there is a recognizable pattern of facial features in JS that changes over time as individuals age. Macrocephaly, head tilting even when looking straight ahead, eye movement abnormalities (oculomotor apraxia, nystagmus, strabismus), and ptosis are common in those with JS. Distinctive features in younger children include triangular-shaped open mouth with tongue protrusion; in older children and adults, mandibular prognathia and prominent nasal bridge are common.

Genetic Etiologies, Diagnosis, and Management of Neonatal Cystic Kidney Disease

Fetal kidney development is a complex and carefully orchestrated process. The proper formation of kidney tissue involves many transcription factors and signaling pathways. Pathogenic variants in the genes that encodethese factors and proteins can result in neonatal cystic kidney disease. Advancements in genomic sequencing have allowed us to identify many of these variants and better understand the genetic underpinnings for an increasing number of presentations of childhood kidney disorders. This review discusses the genes essential in kidney development, particularly those involved in the structure and function of primary cilia, and implications of gene identification for prognostication and management of cystic kidney disorders.

Cystic renal diseases: role of ultrasound. Part II, genetic cystic renal diseases

Kidney cysts are quite common in adults. Though small simple renal cysts in an adult over 30-40 years of age are not too unusual, however, if the same cysts are seen in a child, and especially if there are additional findings, then several diagnostic possibilities may come to mind. The role of ultrasound, together with the help of intravenous contrast agents and Doppler mode, are very critical in describing the morphologic features and follow-up of the complex or multiple and bilateral renal cysts. These sonographic signs are occasionally specific for diagnosis, but in many cases sonographic clues should be evaluated together with the other genetic and clinical data to reach diagnosis.The first part of this pictorial essay included the introduction into the subject and the classification of non-genetic cystic renal diseases. The key features for the non-genetic cystic renal diseases are illustrated. In the second part, eye-catching features of genetic cystic renal diseases are demonstrated.

Compound heterozygous ADAMTS9 variants in Joubert syndrome-related disorders without renal manifestation

BACKGROUND

Ciliopathies are the outcomes of defects of primary cilia structures and functions which cause multisystemic developmental disorders, such as polycystic kidney disease, nephronophthisis, retinitis pigmentosa, Joubert syndrome (JS), and JS-related disorders (JSRD) with additional organ involvement including oral-facial-digital syndrome and so on. They often share common and unexpected phenotypic features.

CASE PRESENTATION

We report a 4-year-old-boy case with compound heterozygous variants of ADAMTS9. Unlike the cases with ADAMTS9 variants in the previous report, which identified that homozygous variants of ADAMTS9 were responsible for nephronophthisis-related ciliopathies in two cases, the current case did not have nephronophthisis nor renal dysfunction, and his clinical features, such as oculomotor apraxia, hypotonia, developmental delay, bifid tongue, and mild hypoplasia of cerebellar vermis indicated JSRD.

CONCLUSIONS

The case suggested a possible association between the clinical presentation of JSRD and ADAMTS9-related disease, and it shows a wide spectrum of ADAMTS9 phenotype.

The Clinical Characteristics and Gene Mutations of Maturity-Onset Diabetes of the Young Type 5 in Sixty-One Patients

AIMS

Maturity-onset diabetes of the young type 5 (MODY5), a rare disease, is very easy to be misdiagnosed as type 2 diabetes. To get better understanding of the disease, we analyzed the clinical characteristics and gene mutations of MODY5.

METHODS

PubMed, Cochrane, the China National Knowledge Infrastructure, and Wanfang were searched with the following search terms: "MODY5" OR "HNF1B maturity-onset diabetes of the young" OR "maturity-onset diabetes of the young type 5" OR "renal cysts and diabetes syndrome". Clinical characteristics and gene mutations of MODY5 were analyzed. The demography, clinical characteristics, and blood indicators of patients were described utilizing simple summary statistics. Variables were analyzed by t-test, Wilcoxon signed rank test, and Fisher exact test. Spearman's correlation analysis was used for bi-variate analysis. All tests were two-sided, and a p-value < 0.05 was considered statistically significant. Statistical analysis was performed using the Statistical Package for the Social Sciences version 26 for Windows (SPSS).

RESULTS

A total of 48 literatures were included in this study, including 61 eligible patients and 4 different mutations. Of the 39 patients with available body weight index, 15 (38.46%) were underweight, 21 (53.85%) were normal weight and 3 (7.69%) were overweight or obese. Of the 38 patients with available family history, 25 (65.79%) reported a family history of diabetes. Of the 34 patients with available age of diabetes diagnosis, the median age of diabetes diagnosis was 16.00 years old and 88.24% (30/34) of patients were under 25 years old when they were first diagnosed with diabetes. Renal cysts were presented in 72.41%, hypomagnesemia in 91.67%, and pancreatic dysplasia in 71.88% of the patients. Patients with hepatocyte nuclear factor 1B (HNF1B) deletion had lower serum magnesium, serum creatinine, and higher eGFR than patients with other gene mutations, and the difference was statistically significant.

CONCLUSIONS

The young onset of diabetes with low or normal BMI, renal cysts, hypomagnesemia, and pancreatic dysplasia should be recommended to genetic testing in order to differentiate MODY5 from other types of diabetes earlier.

Case Report: A case of HNF1B mutation patient with first presentation of diabetic ketosis

BACKGROUND

Maturity-onset diabetes of the young 5 (MODY5), a rare diabetes syndrome of young adults, is associated with variants in hepatocyte nuclear factor 1B (HNF1B) gene.

CASE PRESENTATION

We reported a case of MODY5, which presented with diabetic ketosis, multiple renal cysts, and hypokalemia. In this case, the HNF1B score was estimated as 13 and a heterozygous variant of HNF1B in exon 4 (c.826C>T, p.Arg276*) was identified through Sanger sequencing.

CONCLUSIONS

Multiple renal cysts and youth-onset diabetes are common manifestations in patients with HNF1B mutations, and insufficient insulin secretion may be a potential cause of diabetic ketosis in MODY5.

Using in vivo cerebellar electroporation to study neuronal cell proliferation and differentiation in a Joubert syndrome mouse model

Joubert syndrome (JS) is an autosomal recessive ciliopathy that mainly affects the morphogenesis of the cerebellum and brain stem. To date, mutations in at least 39 genes have been identified in JS; all these gene-encoding proteins are involved in the biogenesis of the primary cilium and centrioles. Recent studies using the mouse model carrying deleted or mutated JS-related genes exhibited cerebellar hypoplasia with a reduction in neurogenesis; however, investigating specific neuronal behaviors during their development in vivo remains challenging. Here, we describe an in vivo cerebellar electroporation technique that can be used to deliver plasmids carrying GFP and/or shRNAs into the major cerebellar cell type, granule neurons, from their progenitor state to their maturation in a spatiotemporal-specific manner. By combining this method with cerebellar immunostaining and EdU incorporation, these approaches enable the investigation of the cell-autonomous effect of JS-related genes in granule neuron progenitors, including the pathogenesis of ectopic neurons and the defects in neuronal differentiation. This approach provides information toward understanding the multifaceted roles of JS-related genes during cerebellar development in vivo.

[Joubert syndrome type 5 caused by a new compound heterozygous mutation in CEP290]

Joubert syndrome (JS) is a recessive neurodegenerative disease characterized by hypotonia, ataxia, psychomotor delay, oculomotor and visual impairments. JS shows clinically variability and genetic heterogeneity. In this article, we report a case of a 14-year-old female patient with JS 5 type associated with a new compound-heterozygous mutation c.2991+1655A>G + c.6604delA (p.Ile2202fs) in CEP290. Clinical and genetic data of JS 5 type can be useful in the diagnosis of disease.

Overexpression of smad7 inhibits the TGF-β/Smad signaling pathway and EMT in NPHP1-defective MDCK cells

BACKGROUND

Nephronophthisis (NPHP) is a kind of ciliopathy. Interstitial fibrosis occurs at the early stage of the disease. TGF-β/Smad is a key signaling pathway in regulating interstitial fibrosis and epithelial-mesenchymal transition (EMT). In this study, we explored the activation of the TGF-β/Smad signaling pathway and EMT in NPHP1-defective MDCK cells to further understand the pathogenesis of NPHP.

METHODS

NPHP1-knockdown (NPHP1^KD) MDCK cells were constructed by recombinant lentiviral short hairpin RNA, and NPHP1-knockout (NPHP1^KO) MDCK cells were constructed by using the CRISPR/Cas9 technique. The morphology and migration ability were observed under a microscope. Western blotting was used to detect the expression of E-cadherin, β-catenin, α-smooth muscle actin (α-SMA), fibroblast-specific protein-1(FSP1), TGF-β1, Smad2, Smad3, p-Smad3, Smad4 and Smad7. The localization of Smad3 was determined by immunofluorescence assay.

RESULTS

NPHP1^KD and NPHP1^KO MDCK cells were spindle-shaped and presented EMT-like changes. E-cadherin and β-catenin expression decreased, while α-SMA and FSP1 expression increased; the TGF-β/Smad signaling pathway was activated, Smad2, Smad3, p-Smad3 and Smad4 expression increased, Smad3 translocated to nuclear and Smad7 expression decreased compared with those in wild type MDCK cells. Overexpression of Smad7 reversed these changes to different degrees.

CONCLUSIONS

Our results indicate that NPHP1 defects induce the activation of the TGF-β/Smad signaling pathway and EMT in MDCK cells. These factors may be implicated in the pathogenesis of interstitial fibrosis in NPHP.

Cystic renal diseases: role of ultrasound. Part I, non-genetic cystic renal diseases

Kidney cysts are quite common in adults.  Though small simple renal cysts in an adult over 30-40 years of age are not too unusual, however, if the same cysts are seen in a child, and especially if there are additional findings, then several diagnostic possibilities may come to mind. The role of ultrasound, together with the help of intravenous contrast agents and Doppler mode, is very critical in describing the morphologic features and follow-up of the complex or multiple and bilateral renal cysts. Sonographic signs are occasionally specific for diagnosis, but in many cases they should be evaluated together with the other genetic and clinical data to reach a diagnosis.The first part of this pictorial essay includes "non-genetic cystic renal diseases" and the second part will include "genetic cystic renal diseases".

Nephronophthisis-Pathobiology and Molecular Pathogenesis of a Rare Kidney Genetic Disease

The exponential rise in our understanding of the aetiology and pathophysiology of genetic cystic kidney diseases can be attributed to the identification of cystogenic genes over the last three decades. The foundation of this was laid by positional cloning strategies which gradually shifted towards next-generation sequencing (NGS) based screenings. This shift has enabled the discovery of novel cystogenic genes at an accelerated pace unlike ever before and, most notably, the past decade has seen the largest increase in identification of the genes which cause nephronophthisis (NPHP). NPHP is a monogenic autosomal recessive cystic kidney disease caused by mutations in a diverse clade of over 26 identified genes and is the most common genetic cause of renal failure in children. NPHP gene types present with some common pathophysiological features alongside a diverse range of extra-renal phenotypes associated with specific syndromic presentations. This review provides a timely update on our knowledge of this disease, including epidemiology, pathophysiology, anatomical and molecular features. We delve into the diversity of the NPHP causing genes and discuss known molecular mechanisms and biochemical pathways that may have possible points of intersection with polycystic kidney disease (the most studied renal cystic pathology). We delineate the pathologies arising from extra-renal complications and co-morbidities and their impact on quality of life. Finally, we discuss the current diagnostic and therapeutic modalities available for disease management, outlining possible avenues of research to improve the prognosis for NPHP patients.

Expanding the Phenotype of the FAM149B1-Related Ciliopathy and Identification of Three Neurogenetic Disorders in a Single Family

Biallelic truncating FAM149B1 variants result in cilia dysfunction and have been reported in four infants with Joubert syndrome and orofaciodigital syndrome type VI, respectively. We report here on three adult siblings, 18 to 40 years of age, homozygous for the known FAM149B1 c.354_357delinsCACTC (p.Gln118Hisfs*20) variant. Detailed clinical examinations were performed including ocular and gait analyses, skeletal- and neuroimaging. All three patients presented with neurological and oculomotor symptoms since birth and mild skeletal dysplasia in infancy resulting in characteristic gait abnormalities. We document mild skeletal dysplasia, abnormal gait with increased hip rotation and increased external foot rotation, ataxia, variable polydactyly, ocular Duane syndrome, progressive ophthalmoplegia, nystagmus, situs inversus of the retinal vessels, olfactory bulb aplasia, and corpus callosal dysgenesis as novel features in FAM149B1-ciliopathy. We show that intellectual disability is mild to moderate and retinal, renal and liver function is normal in these affected adults. Our study thus expands the FAM149B1-related Joubert syndrome to a mainly neurological and skeletal ciliopathy phenotype with predominant oculomotor dysfunction but otherwise stable outcome in adults. Diagnosis of FAM149B1-related disorder was impeded by segregation of multiple neurogenetic disorders in the same family, highlighting the importance of extended clinical and genetic studies in families with complex phenotypes.

SENIOR-LØKEN SYNDROME: A Case Series and Review of the Renoretinal Phenotype and Advances of Molecular Diagnosis

PURPOSE

To report genetic and clinical findings in a case series of 10 patients from eight unrelated families diagnosed with Senior-Løken syndrome.

METHODS

A retrospective study of patients with Senior-Løken syndrome. Data collected included clinical findings electroretinography and ocular imaging. Genetic analysis was based on molecular inversion probes, whole-exome sequencing (WES), and Sanger sequencing.

RESULTS

All patients who underwent electrophysiology (8/10) had widespread photoreceptor degeneration. Genetic analysis revealed two mutations in NPHP1, two mutations in NPHP4, and two mutations in IQCB1 (NPHP5). Five of the six mutations identified in the current study were found in a single family each in our cohort. The IQCB1-p.R461* mutation has been identified in 3 families. Patients harboring mutations in IQCB1 were diagnosed with Leber congenital amaurosis, while patients with NPHP4 and NPHP1 mutations showed early and sector retinitis pigmentosa, respectively. Full-field electroretinography was extinct for 6 of 10 patients, moderately decreased for two, and unavailable for another 2 subjects. Renal involvement was evident in 7/10 patients at the time of diagnosis. Kidney function was normal (based on serum creatinine) in patients younger than 10 years. Mutations in IQCB1 were associated with high hypermetropia, whereas mutations in NPHP4 were associated with high myopia.

CONCLUSION

Patients presenting with infantile inherited retinal degeneration are not universally screened for renal dysfunction. Modern genetic tests can provide molecular diagnosis at an early age and therefore facilitate early diagnosis of renal disease with recommended periodic screening beyond childhood and family planning.

Head titubation and irritability as early symptoms of Joubert syndrome with a homozygous NPHP1 variant

BACKGROUND

Joubert syndrome is an autosomal recessive or X-linked genetic disease with a cerebellar vermis defect or hypoplasia, hypotonia, ocular dyskinesia, and mental retardation. In neonates, respiratory problems such as apnea and tachypnea are notable.

CASE REPORT

We report a patient Joubert syndrome with a homozygous NPHP1 variant, who had head titubation with irritability, including exaggerated jitteriness and a marked Morrow reflex appeared soon after birth without neonatal respiratory problems. These symptoms decreased gradually and disappeared until 1 year.

CONCLUSION

Irritability with head titubation may be an early clinical clue for the clinician to suspect Joubert syndrome.