Establishment of bovine expanded potential stem cells.

Embryonic stem cells (ESCs) and induced pluripotent stem cells have the potential to differentiate to all cell types of an adult individual and are useful for studying development and for translational research. However, extrapolation of mouse and human ESC knowledge to deriving stable ESC lines of domestic ungulates and large livestock species has been challenging. In contrast to ESCs that are usually established from the blastocyst, mouse expanded potential stem cells (EPSCs) are derived from four-cell and eight-cell embryos. We have recently used the EPSC approach and established stem cells from porcine and human preimplantation embryos. EPSCs are molecularly similar across species and have broader developmental potential to generate embryonic and extraembryonic cell lineages. We further explore the EPSC technology for mammalian species refractory to the standard ESC approaches and report here the successful establishment of bovine EPSCs (bEPSCs) from preimplantation embryos of both wild-type and somatic cell nuclear transfer. bEPSCs express high levels of pluripotency genes, propagate robustly in feeder-free culture, and are genetically stable in long-term culture. bEPSCs have enriched transcriptomic features of early preimplantation embryos and differentiate in vitro to cells of the three somatic germ layers and, in chimeras, contribute to both the embryonic (fetal) and extraembryonic cell lineages. Importantly, precise gene editing is efficiently achieved in bEPSCs, and genetically modified bEPSCs can be used as donors in somatic cell nuclear transfer. bEPSCs therefore hold the potential to substantially advance biotechnology and agriculture.

An Nphp1 knockout mouse model targeting exon 2-20 demonstrates characteristic phenotypes of human nephronophthisis.

Nephronophthisis (NPH) is the most prevalent monogenetic disorder leading to end-stage renal failure (ESRD) in childhood. Mutations in Nphp1, encoding a cilia-localized protein, account for the majority of NPH cases. Despite its identification many years ago, Nphp1 deletions targeting exon 4 or exon 20 have not reproduced the histological features of human NPH in murine models. In this study, we deleted exon 2-20 of Nphp1 by CRISPR/Cas9 gene editing to create a near-total knockout (KO) mouse model (Nphp1del2-20/del2-20). Nphp1del2-20/del2-20 mice faithfully reproduced the renal and extrarenal phenotypes associated with human NPH, including renal cyst development, tubular basement membrane thickening, retinal degeneration and abnormal spermatogenesis. Importantly, Nphp1 re-expression using an adenoviral-associated-virus-9 vector could partially rescue both renal and retinal phenotypes in Nphp1del2-20/del2-20 mice. Our results reported the first relevant Nphp1 mouse model with renal phenotypes for human disease. It will be a valuable model for future studies of Nphp1 function and to develop novel treatments for this common childhood disease.

Reducing GEF-H1 Expression Inhibits Renal Cyst Formation, Inflammation, and Fibrosis via RhoA Signaling in Nephronophthisis.

Nephronophthisis (NPHP) is the most prevalent monogenic disease leading to end-stage renal failure in childhood. RhoA activation is involved in NPHP pathogenesis. This study explored the role of the RhoA activator guanine nucleotide exchange factor (GEF)-H1 in NPHP pathogenesis. We analyzed the expression and distribution of GEF-H1 in NPHP1 knockout (NPHP1KO) mice using Western blotting and immunofluorescence, followed by GEF-H1 knockdown. Immunofluorescence and renal histology were used to examine the cysts, inflammation, and fibrosis. A RhoA GTPase activation assay and Western blotting were used to detect the expression of downstream GTP-RhoA and p-MLC2, respectively. In NPHP1 knockdown (NPHP1KD) human kidney proximal tubular cells (HK2 cells), we detected the expressions of E-cadherin and α-smooth muscle actin (α-SMA). In vivo, increased expression and redistribution of GEF-H1, and higher levels of GTP-RhoA and p-MLC2 in renal tissue of NPHP1KO mice were observed, together with renal cysts, fibrosis, and inflammation. These changes were alleviated by GEF-H1 knockdown. In vitro, the expression of GEF-H1 and activation of RhoA were also increased, with increased expression of α-SMA and decreased E-cadherin. GEF-H1 knockdown reversed these changes in NPHP1KD HK2 cells. Thus, the GEF-H1/RhoA/MLC2 axis is activated in NPHP1 defects and may play a pivotal role in NPHP pathogenesis.

[Analysis of SALL1 gene variant in a boy with Townes-Brocks syndrome without anal atresia].

OBJECTIVE: To explore the genetic basis for a child presented with renal failure and multi-cystic dysplastic kidney without anal atresia. METHODS: Peripheral blood sample of the child and his parents were collected and subjected to whole exome sequencing. Candidate variant was verified by Sanger sequencing. RESULTS: The 40-day-old infant had presented with vomiting brown matter in a 7 days neonate and was transferred for kidney failure. Clinical examination has discovered renal failure, polycystic renal dysplasia, congenital hypothyroidism, bilateral thumb polydactyly, sensorineural hearing loss and preauricular dermatophyte. Genetic testing revealed that he has harbored a previously unreported c.824delT, p.L275Yfs*10 frameshift variant of SALL1 gene, which was confirmed by Sanger sequencing as de novo. CONCLUSION: The patient was diagnosed with Townes-Brocks syndrome due to the novel de novo variant of SALL1 gene. Townes-Brocks syndrome without anal atresia is rare. Above finding has also enriched the mutational spectrum of the SALL1 gene.

Overexpression of smad7 inhibits the TGF-ß/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-ß/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-ß/Smad signaling pathway and EMT in NPHP1-defective MDCK cells to further understand the pathogenesis of NPHP. METHODS: NPHP1-knockdown (NPHP1KD) MDCK cells were constructed by recombinant lentiviral short hairpin RNA, and NPHP1-knockout (NPHP1KO) 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, ß-catenin, α-smooth muscle actin (α-SMA), fibroblast-specific protein-1(FSP1), TGF-ß1, Smad2, Smad3, p-Smad3, Smad4 and Smad7. The localization of Smad3 was determined by immunofluorescence assay. RESULTS: NPHP1KD and NPHP1KO MDCK cells were spindle-shaped and presented EMT-like changes. E-cadherin and ß-catenin expression decreased, while α-SMA and FSP1 expression increased; the TGF-ß/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-ß/Smad signaling pathway and EMT in MDCK cells. These factors may be implicated in the pathogenesis of interstitial fibrosis in NPHP.

COQ2 mutation associated isolated nephropathy in two siblings from a Chinese pedigree.

BACKGROUD: Coenzyme Q10 (CoQ10) is involved in the biosynthesis of adenosine triphosphate (ATP), and is most abundant in the mitochondrial membrane. The primary CoQ10 deficiency caused by COQ2 defect is mostly manifested as encephalopathy, encephalopathy with nephropathy, and rarely as an isolated nephrotic syndrome. METHODS: Clinical and pathological data and peripheral blood samples of 2 siblings with steroid-resistant nephrotic syndrome (SRNS) and their family members of a Chinese pedigree were collected. DNA was extracted and subjected to next-generation sequencing of target genes of hereditary nephropathy. RESULTS: Compound heterozygous mutations of COQ2 (c.1058A > G, p.Y353C, paternal and c.973A > G, p.T325A, maternal)were identified in both siblings of the pedigree. Mutation of p.Y353C was novel. The proband was a girl, who presented with SRNS at the age of 7 months. CoQ10 was administered after the gene sequencing results came out. Proteinuria decreased gradually to 1+, occasionally negative. The child was normal in growth and intelligence. She is now 4 years old. The second patient was her elder brother. He was found to have SRNS at the age of 2 years old. Renal pathology indicated focal segmental glomerulosclerosis (FSGS). Electronic microcopy revealed that a large quantity of mitochondria with normal contour was accumulated within the podocytes. Both patients were in normal intelligence without convulsion. CONCLUSION: The 2 cases harboring COQ2compound heterozygous mutations presented with isolated SRNS, with a renal pathology of FSGS and a large quantity of mitochondria with normal contour accumulated within the podocytes. CoQ10 was efficacy in eliminating proteinuria.

Transplantation for infantile nephronophthisis with loss-of-function mutation in NPHP3: Lesson from a case.

The choice of KT only or CLKT for infantile NPHP with mild liver fibrosis is understudied. A 5-year-old girl was transferred to our center for KT due to ESRD. Her primary disease was infantile NPHP with compound heterozygous NPHP3 mutations: c.458A>C(p.Q153P)/missense mutation and c.2032A>T(p. K678X)/nonsense mutation. The patient had elevated liver enzymes and biopsy-proven liver fibrosis. As liver synthesis was acceptable, only KT was performed. However, liver fibrosis progressed at 1.5 years after transplantation, manifested with portal hypertension and hypersplenism. Common causes for portal hypertension were excluded, and the progression was attributed to NPHP. AMR attacked allograft at about 2 years post-transplant. To solve both the liver and the kidney problems, CLKT was performed. Her liver and kidney function recovered initially, but she unfortunately died of pneumonia and subsequent intracranial hemorrhage two weeks later. Nonsense mutation in NPHP3 gene may be correlated with rapid progression of liver disease in infantile NPHP. More studies are required to determine the role of CLKT in these cases; however, combined transplantation may improve long-term graft and patient survival.

WT1 mutation-associated nephropathy: a single-center experience
.

This study explored Wilms' tumor 1 (WT1) mutations in children with, or suspected of having, steroid-resistant nephrotic syndrome (SRNS), referred to or treated in our hospital in the past 6 years as well as the correlation between genotype and phenotype in WT1 mutation-associated nephropathy in Chinese patients. In total, 76 patients participated in the study. WT1 mutations were identified in 15 patients, 5 of whom harbored splice-site mutations in intron 9. Four of these 5 patients exhibited early onset of nephropathy and rapid deterioration of renal function. Missense mutations were detected in 8 patients, 4 of whom harbored hot-site mutations and had early-onset proteinuria. Of these 4 patients, rapid progression to end-stage renal disease was only observed in 1. Nonsense mutations were identified in 2 patients; both had a large number of immature glomeruli in the kidney cortex. Calcineurin inhibitors (CNI) were administered in 8 patients. Two patients with missense mutations and 1 patient with a nonsense mutation achieved complete remission. Two patients with missense mutations and 2 with splice-site mutations showed an improvement. One patient with a splice-site mutation showed no changes. In conclusion, a high WT1 mutation rate was observed in this group of SRNS patients. Patients with splice-site mutations experienced a rapid disease progression, and patients harboring nonsense mutations showed a prominent glomerular developmental delay. CNI therapy was effective in patients with WT1 missense mutations and nonsense mutations.
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Association of single-nucleotide polymorphism in the FKBP5 gene with response to steroids in pediatric patients with primary nephrotic syndrome
.

AIM: This study aimed to assess the association of single-nucleotide polymorphism (SNP) of FKBP5 with response to steroids in children with primary nephrotic syndrome (NS). MATERIALS AND METHODS: A total of 66 primary NS patients (cases) and 68 healthy individuals (controls) were enrolled in this study. The FKBP5 polymorphism rs4713916 (T/C) was analyzed by polymerase chain reaction (PCR) and sequencing after amplification of regions that potentially contain the SNP. The frequency of the FKBP5 (rs4713916) SNP as well as its relationship with response to steroids was investigated. RESULTS: The frequencies of the "TT" genotype starkly differed between the cases and controls (p = 0.024). The TT genotype showed overtly different frequency in the steroid-dependent NS group compared with controls (p = 0.041). CONCLUSION: The current data indicate that assessment of FKBP5 mutations could provide a basis for the identification of primary NS patients more likely to be efficiently treated with steroids.
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[Clinical and pathological features and the misdiagnosis of childhood Alport syndrome: a retrospective analysis of 91 cases].

OBJECTIVE: To explore the clinical and pathological features and the diagnosis of childhood Alport syndrome (AS). METHODS: A retrospective analysis was performed on clinical data of 91 children with AS. RESULTS: Hematuria was observed in all 91 patients, of whom 86 were accompanied with proteinuria. Sixty-one children with X-Linked AS (XL-AS) had positive family history. Renal biopsy was performed on 82 children. Mild to moderate mesangial proliferation was observed in 74 cases. Small amounts of immune complexes deposits in the glomerular mesangial area were observed in 48 cases. Glomerular basement membrane (GBM) attenuation, thickening and layering were observed in 53 cases by electron microscopy (EM). In 63 cases receiving renal tissue type IV collagen α3 and α5 chain immunofluorescence detection, 58 were diagnosed with AS, including 53 cases of XL-AS and 5 cases of autosomal recessive AS. In 91 cases of AS, 58 were diagnosed as AS by renal tissue type IV collagen α3 and α5 chain immunofluorescence, 21 were diagnosed by EM, one was diagnosed by skin biopsy, and 12 were diagnosed by gene detection. Six novel mutations of COL4A5 gene were found. Forty-five cases were misdiagnosed before the diagnosis of AS. Forty-one of the 45 cases received steroids and/or immunosuppressant therapy. CONCLUSIONS: The clinical manifestations and pathological changes are not specific in children with AS, resulting in a higher rate of misdiagnosis. Typical lesions of GBM under EM are only observed in a part of patients. There is a high novel mutation rate of COL4A5 in the detected AS children.

Dent Disease in Chinese Children and Findings from Heterozygous Mothers: Phenotypic Heterogeneity, Fetal Growth, and 10 Novel Mutations.

OBJECTIVE: To characterize the phenotypes of Dent disease in Chinese children and their heterozygous mothers and to establish genetic diagnoses. STUDY DESIGN: Using a modified protocol, we screened 1288 individuals with proteinuria. A diagnosis of Dent disease was established in 19 boys from 16 families by the presence of loss of function/deleterious mutations in CLCN5 or OCRL1. We also analyzed 16 available patients' mothers and examined their pregnancy records. RESULTS: We detected 14 loss of function/deleterious mutations of CLCN5 in 15 boys and 2 mutations of OCRL1 in 4 boys. Of the patients, 16 of 19 had been wrongly diagnosed with other diseases and 11 of 19 had incorrect or unnecessary treatment. None of the patients, but 6 of 14 mothers, had nephrocalcinosis or nephrolithiasis at diagnosis. Of the patients, 8 of 14 with Dent disease 1 were large for gestational age (>90th percentile); 8 of 15 (53.3%) had rickets. We also present predicted structural changes for 4 mutant proteins. CONCLUSIONS: Pediatric Dent disease often is misdiagnosed; genetic testing achieves a correct diagnosis. Nephrocalcinosis or nephrolithiasis may not be sensitive diagnostic criteria. We identified 10 novel mutations in CLCN5 and OCRL1. The possibility that altered CLCN5 function could affect fetal growth and a possible link between a high rate of rickets and low calcium intake are discussed.

Twenty-eight-year review of childhood renal diseases from renal biopsy data: A single centre in China.

AIM: The aim of the present study was to investigate the clinicopathologic characteristics of biopsy-proven childhood renal diseases and to compare the trends and changes during two different time intervals between 1984 and 2011 at the First Affiliated Hospital of Sun Yat-sen University in China. METHODS: We retrospectively analyzed kidney biopsy data from children with renal diseases and compared the data during two time intervals, namely 1984-1997 and 1998-2011. RESULTS: A total of 1313 children were enrolled in the present study. There were 921 children with primary glomerular disease (PGD) and 312 children with secondary glomerular disease (SGD), accounting for 70.1% and 23.8% of participants, respectively. The major clinical manifestation of PGD was nephrotic syndrome (NS), which accounted for 31.2% of cases, while the main aetiology of SGD was lupus nephritis (40.7%). The main biopsy patterns of PGD were IgA nephritis (27.6%), minimal change disease (24.0%), and mesangial proliferative glomerulonephritis (16.9%). PGD was the major class of disease in both time intervals, but the ratio of PGD decreased over time, while the ratio of SGD and other glomerular diseases increased. PGD was also the major class of disease in each age group; however, the incidence of PGD decreased with increasing age. CONCLUSION: The incidence patterns of paediatric renal diseases changed over the 28-year period of this study. Our results show that different renal diseases characterize different age intervals. Furthermore, there are several associations between clinical presentation and biopsy features in childhood renal disease.

High mutation rate of NPHP3 in 18 Chinese infantile nephronophthisis patients.

AIM: The present study was designed to explore mutations of NPHP2 and NPHP3 and clinical features in 18 Chinese infantile nephronophthisis (NPHP) patients. METHODS: Patients were subjected to screen for mutations in both NPHP2 and NPHP3, and clinical data were collected. RESULTS: Eighteen patients from 17 families were included in this study. Eight of 17 (47.1%) patients detected were identified to have mutations in NPHP3, but none had a mutation in NPHP2. Of the patients with NPHP3 mutations, four had compound heterozygous mutations, and the other four harboured single heterozygous mutations. Ten of the NPHP3 mutations were novel. Low molecular weight proteinuria was observed in all 16 detected patients. Renal histology were available in seven children, five patients showed infantile type NPHP features, and the other two patients from the same family showed juvenile type NPHP features. Liver involvement was observed in all patients with NPHP3 mutations and congenital heart disease in two patients harbouring NPHP3 mutation of c.2369 T > C (p.L790P). CONCLUSIONS: In this group of infantile NPHP patients, mutations of NPHP3 were prevalent, whereas mutation of NPHP2 was absent. Genotype to phenotype correlations were observed in patients with NPHP3 mutations and all patients with NPHP3 mutations showed renal-hepatic phenotype.

SP6 controls human cytotrophoblast fate decisions and trophoblast stem cell establishment by targeting MSX2 regulatory elements.

The commitment and differentiation of human placental progenitor cytotrophoblast (CT) cells are crucial for a successful pregnancy, but the underlying mechanism remains poorly understood. Here, we identified the transcription factor (TF), specificity protein 6 (SP6), as a human species-specific trophoblast lineage TF expressed in human placental CT cells. Using pluripotent stem cells as a model, we demonstrated that SP6 controls CT generation and the establishment of trophoblast stem cells (TSCs) and identified msh homeobox 2 (MSX2) as the downstream effector in these events. Mechanistically, we showed that SP6 interacts with histone acetyltransferase P300 to alter the landscape of H3K27ac at targeted regulatory elements, thereby favoring transcriptional activation and facilitating CT cell fate decisions and TSC maintenance. Our results established SP6 as a regulator of the human trophoblast lineage and implied its role in placental development and the pathogenies of placental diseases.

Clinical features and mutation of NPHP5 in two Chinese siblings with Senior-Løken syndrome.

Senior-Løken syndrome is a rare syndromic form of nephronophthisis that is associated with retinal dystrophy. Presently, seven genes (NPHP1-6 and NPHP10) have been associated with Senior-Løken syndrome. NPHP5 mutations are known to cause classical Senior-Løken syndrome. Here, we report two sisters (II-4, II-5) from a Chinese Han ethnic family who presented with classical Senior-Løken syndrome. Both affected sisters exhibited Leber's congenital amaurosis and juvenile nephronophthisis that progressed to end-stage renal disease by the age of 16 years and 9 months in patient II-4 and 12 years and 9 months in patient II-5. Sequence analysis showed a homozygous truncated mutation in NPHP5, c.1090C>T (p.R364X), in the patient II-4. This mutation is predicted to introduce a new open reading frame that results in the truncation of the C-terminal 235 amino acids of nephrocystin-5 and its consequent loss of function. Both parents carried a single heterozygous mutation in the same position, and no homozygous deletion of NPHP1 was found in this pedigree.

Identification of renal cyst cells of type I Nephronophthisis by single-nucleus RNA sequencing.

Background: Nephronophthisis (NPH) is the most common genetic cause of end-stage renal disease (ESRD) in childhood, and NPHP1 is the major pathogenic gene. Cyst formation at the corticomedullary junction is a pathological feature of NPH, but the mechanism underlying cystogenesis is not well understood. The isolation and identification of cystic cell subpopulation could help to identify their origins and provide vital clues to the mechanisms underlying cystogenesis in NPH. Methods: Single-nucleus RNA sequencing (snRNA-seq) was performed to produce an atlas of NPHP1 renal cells. Kidney samples were collected from WT (Nphp1 +/+) mice and NPHP1 (Nphp1 del2-20/del2-20) model mice. Results: A comprehensive atlas of the renal cellular landscape in NPHP1 was generated, consisting of 14 basic renal cell types as well as a subpopulation of DCT cells that was overrepresented in NPHP1 kidneys compared to WT kidneys. GO analysis revealed significant downregulation of genes associated with tubular development and kidney morphogenesis in this subpopulation. Furthermore, the reconstruction of differentiation trajectories of individual cells within this subpopulation confirmed that a specific group of cells in NPHP1 mice become arrested at an early stage of differentiation and proliferate to form cysts. We demonstrate that Niban1 is a specific molecular marker of cystic cells in both mice and human NPHP1. Conclusion: In summary, we report a novel subpopulation of DCT cells, marked by Niban1, that are classified as cystic cells in the NPHP1 mice kidney. These results offer fresh insights into the cellular and molecular basis of cystogenesis in NPH.

Psychological research of the children with chronic kidney disease and their guardians during the COVID-19 pandemic.

Background: There is great mental stress due to the coronavirus disease 2019 (COVID-19) pandemic. However, there are no detailed psychological studies of the children with chronic kidney disease (CKD) and their guardians during the COVID-19 pandemic. Objective: This study explores the psychological pressure on children with CKD and their guardians. Methods: An online survey was conducted at 20 of the largest pediatric nephropathy departments in China, including the Rutter Parent Questionnaire, Self-rating Anxiety Scale (SAS), and Self-rating Depression Scale (SDS). Overall, 885 children (589 children with CKD associated with 296 children of the control group) completed the survey together with their guardians. Results: There was no statistical difference between CKD children and control children regarding their Rutter behavior scores and abnormal behaviors. Nevertheless, the abnormal behavior of children might aggravate the anxiety and depression of guardians in both CKD and control groups (p < 0.05). We confirmed that the anxiety and depression of guardians in the CKD group were both significantly higher than those in the control group (p < 0.05). The guardians in the CKD group with lower annual income were more likely to experience anxiety (p < 0.05). Furthermore, the guardians whose children were older than 11 years old might be more anxious than those who were 6-11 years old. Besides, the guardians in the CKD group who watched the news for 30-60 min daily were less likely to have depression than those who watched < 10 min (p < 0.05). The subgroup results showed that the gender, the time of watching the news, the annual income of guardians, and children's age might be the most critical factors influencing guardians' psychological burden. Conclusion: The guardians in the CKD group have more severe anxiety and depression during the pandemic. The children's abnormal behavior, adolescents' pressure, low household income, and the panic about the pandemic may be the main reasons for the anxiety and depression of guardians.

The Clinical and Genetic Features in Chinese Children With Steroid-Resistant or Early-Onset Nephrotic Syndrome: A Multicenter Cohort Study.

Steroid-resistant nephrotic syndrome (SRNS) is one of the major causes of end-stage kidney disease (ESKD) in children and young adults. For approximately 30% of children with SRNS results from a genetic cause. In this study, genotype-phenotype correlations in a cohort of 283 pediatric patients with SRNS or early-onset NS (nephrotic syndrome presenting within the first year of life) from 23 major pediatric nephrology centers in China were analyzed. All patients were performed with next-generation sequencing and Sanger sequencing. The overall mutation detection rate was 37.5% (106 of 283 patients). WT1 was the most frequently detected mutation, followed by NPHS1, NPHS2, and ADCK4, and these four major causative genes (WT1, NPHS1, NPHS2, and ADCK4) account for 73.6% of patients with monogenic SRNS. Thirteen of 106 individuals (12.3%) carried mutations in ADCK4 that function within the coenzyme Q10 biosynthesis pathway. In the higher frequently ADCK4-related SRNS, two mutations, c.737G>A (p.S246N) and c.748G>C (p.D250H), were the most prevalent. Our study provides not only definitive diagnosis but also facilitate available targeted treatment for SRNS, and prediction of prognosis and renal outcome. Our indications for genetic testing are patients with FSGS, initial SRNS, cases of positive family history or those with extra-renal manifestations.

Novel mutation of TCIRG1 and clinical pictures of two infantile malignant osteopetrosis patients.

Infantile malignant osteopetrosis (IMO) (OMIM 259700) is a lethal autosomal recessive disease. The underlying gene in most IMO patients is TCIRG1. This codes for the TCIRG1 protein involved in the cellular proton pump, which is highly expressed on surfaces of osteoclasts. We have characterized a family comprising two affected siblings born to healthy parents. The sister and her younger brother both presented classical X-ray images of IMO at 17 h and 16 weeks, respectively, after birth, and both died after the appearance of fever and flu-like symptoms months later. Radiographs revealed normal bone density in both parents. Mutation detection of the TCIRG1 gene was performed in the boy and the parents. The novel mutation c.242delC (p.Pro81ArgfsX85) and the known mutation c.1114C>T (p.Gln372X) were both identified in the boy. Both mutations are predicted to introduce premature stop codons, with deletion of 666 amino acids from the C terminus of the TCIRG1 protein of one allele and 459 from the other. Both mutations involve loss of part or the whole of the ATPase V0-complex domain of the protein. The father carries the c.242delC (p.Pro81ArgfsX85) mutation and the mother the c.1114C>T (p.Gln372X). Our findings provide new data for pre- and post-natal genetic diagnosis and identification of heterozygous carriers of the disease.

Clinical pictures and novel mutations of WT1-associated Denys-Drash syndrome in two Chinese children.

Denys-Drash syndrome (DDS) is characterized by early onset of nephropathy, genitalia malformation, and Wilms' tumor, where WT1 is the gene that is mutated in most patients. We report two de novo mutations in WT1 found in two Chinese DDS children. Patient 1 was a boy with complete DDS who was presented with progressive nephropathy, unilateral Wilms' tumor, bilateral cryptorchidism, and renal histology showing diffuse mesangial sclerosis (DMS). When the patient was 24 months old, a liver ultrasound showed multiple nodules, and the patient died of pneumonia 1 month later. The de novo novel mutation, c.1130A>T (p.His377Leu), was identified; the mutation replaces histidine with leucine in the zinc finger (Znf) structure and is predicted to change the local spatial structure of the protein. Patient 2 had 46 XX with incomplete DDS and presented with normal genitalia, proteinuria, unilateral Wilms' tumor with renal pedicle lymph node metastasis, and renal histology showing DMS. Her renal function remains normal after 48 months. A de novo mutation, c.1168C>T (p.Arg390Term), was identified; it truncates 60 amino acids at the C terminus, and it is predicted to result in loss of the DNA-binding capacities of the WT1 protein.