Interferon Gamma,but not Calcitriol Improves the Osteopetrotic Phenotypes in ADO2 Mice

ADO2 is a heritable osteosclerotic disorder that usually results from heterozygous missense dominant negative mutations in the chloride channel 7 gene (CLCN7). ADO2 is characterized by a wide range of features and severity, including multiple fractures, impaired vision due to secondary bony overgrowth and/or the lack of the optical canal enlargement with growth, and osteonecrosis/osteomyelitis. The disease is presently incurable, although anecdotal evidence suggests that calcitriol and interferon gamma‐1b (IFN‐G) may have some beneficial effects. To identify the role of these drugs for the treatment of ADO2, we utilized a knock‐in (G213R mutation in Clcn7) ADO2 mouse model that resembles the human disease. Six‐week‐old ADO2 heterozygous mice were administered vehicle (PBS) or calcitriol or IFN‐G 5 times per week for 8 weeks. We determined bone phenotypes using DXA and μCT, and analyzed serum biochemistry and bone resorption markers. ADO2 mice treated with all doses of IFN‐G significantly (p<0.05) attenuated the increase of whole body aBMD and distal femur BV/TV gain in both male and female compared to the vehicle group. In contrast, mice treated with low and medium doses of calcitriol showed a trend of higher aBMD and BV/TV whereas high dose calcitriol significantly (p<0.05) increased bone mass compared to the vehicle group. The calcium and phosphorus levels did not differ between vehicle and IFN‐G or calcitriol treated mice; however, we detected significantly (p<0.05) elevated levels of CTX/TRAP5b ratio in IFN‐G treated mice. Our findings indicate that while IFN‐G at all doses substantially improved the osteopetrotic phenotypes in ADO2 heterozygous mice, calcitriol treatment at any dose did not improve the phenotype and at high dose further increased bone mass. Thus, use of high dose calcitriol therapy in ADO2 patients merits serious reconsideration. Importantly, our data support the prospect of a clinical trial of IFN‐G in ADO2 patients.     

Chloride channel 7 (ClCN7) gene mutations and autosomal dominant osteopetrosis, type II.

ADO2 is an uncommon sclerosing bone disorder with incomplete penetrance and variable expressivity. Positional candidate studies were performed to identify the gene responsible for ADO2. In 11 of 12 kindreds, five different missense mutations were identified in the ClCN7 gene, indicating the genetic basis and possible dominant negative mechanism for ADO2. INTRODUCTION: Autosomal dominant osteopetrosis, type II (ADO2) is an uncommon sclerosing bone disorder with a distinct radiographic appearance and unique clinical characteristics. We present the results from our genetic studies designed to identify the ADO2 gene through a positional candidate approach. METHODS: Having identified 12 families with ADO2, we initially performed linkage studies in our seven largest kindreds and observed a summed maximum LOD score of 15.91 at marker D16S521 on chromosome 16p13.3. Critical meiotic recombination events further narrowed the putative gene region to a 7.6-cM area, which contains the candidate genes ATP6L and chloride channel 7 (ClCN7). We screened affected individuals from each ADO2 family for mutations in these genes using direct sequencing. Identified mutations were subsequently confirmed through direct sequencing or restriction fragment length polymorphism analysis. We then calculated the overall disease penetrance rate after all available at-risk family members were assessed for ClCN7 gene mutations. RESULTS: No ATP6L mutations were identified in affected subjects. Subsequently, as CICN7 gene mutations were being reported, we identified two novel (L213F, R762L) and three known (G215R, R286W, R767W) missense mutations in 11 kindreds. In our large sample, disease penetrance was 66% (62 clinically affected individuals/94 subjects with the gene mutation). To date, nine different mutations have been discovered in the ClCN7 gene in 22 of 23 ADO2 families studied. CONCLUSIONS: We conclude that mutations in the CICN7 gene are responsible for ADO2 and that genetic heterogeneity is unlikely to exist in this disorder. Based on the preponderance of missense mutations and the knowledge that chloride channels probably function as dimers, it seems that heterozygous ClCN7 gene mutations may cause ADO2 through a dominant negative mechanism.     

Identification of the CLCN7 gene mutations in two Chinese families with autosomal dominant osteopetrosis (type II)

Here we report the identification of two different mutations in chloride channel 7 gene in two unrelated patients with autosomal dominant osteopetrosis type II. We determined that one patient (a 32-year-old woman) carried a heterozygous gene for a R767W mutation in exon 24, and another patient (a 17-year-old boy) carried a heterozygous gene for a novel frameshift mutation (Glu798FS) in exon 25. Recent studies have reported loss-of-function mutations in the chloride channel 7 (CLCN7) gene as a cause of autosomal dominant osteopetrosis type II (ADO-II). The identification of gene mutations in Chinese with ADO has not been reported previously. In this study, we identified mutations of the CLCN7 gene in two unrelated Chinese families with ADO-II. Two probands with ADO-II were diagnosed based on their bone characteristics on X-rays and their laboratory results. All 25 exons of the CLCN7 gene, including the exon–intron boundaries, were sequenced. We found in family 1 that the proband (a 32-year-old woman) was heterozygous for a CLCN7 mutation. The nonsynonymous mutation consisted of a heterozygous C/T transition at codon 2327 in exon 24, which resulted in an arginine (CGG)-to tryptophan (TGG) substitution at position 767 (R767W). The same heterozygous mutation (C/T) was determined in her father and son, who were asymptomatic with normal skeleton radiography. In family 2, we found that the proband (a 17-year-old boy) carried a novel frameshift mutation (Glu798FS) resulting from a G insertion between codon 60 and codon 61 in exon 25. The heterozygous –/G insertion is predicted to elongate the peptide of CLCN7 by 120 amino acids after position 797 amino acids. Similarly, some individuals of this family carried the same heterozygous mutation, but they are all asymptomatic. Furthermore, the R767W and Glu798FS mutations were not found in 100 unrelated controls. Our present findings suggest that the novel Glu798FS mutation in exon 25 and R767W in exon 24 in the CLCN7 gene were responsible for ADO-II in these Chinese patients.     

Tripod-shaped Syndactyly in Apert Syndrome with FGFR2 p.P253R Mutation

Apert syndrome is a rare acrocephalosyndactyly (craniosynostosis) syndrome characterized by craniofacial dysmorphism and syndactyly of the hands and feet. It is caused by FGFR2 mutations and inherited in an autosomal dominant manner. This article describes a novel clinical variant of Apert syndrome having bilateral symmetrical tripod-shaped syndactyly in hands with milder craniofacial features in a sporadic case, along with a mutation in the fibroblast growth factor receptor 2 ( FGFR2 ) gene. The patient had shown craniosynostosis, dysmorphic face, ocular hypertelorism, marked depression of the nasal bridge, long philtrum, and low set ears. Direct resequencing of the FGFR2 gene through Sanger’s method identified a heterozygous missense mutation; FGFR2c.758C>G (FGFR2p.P253R) in the exon-7 of the gene.     

一例Ⅱ型常染色体显性骨硬化症患者CLCN7基因突变分析

目的探讨1例Ⅱ型常染色体显性遗传骨硬化症(autosomal dominant osteopetrosis,ADO)患者的氯离子通道7基因(chloride channel 7,CLCN7)的突变情况。方法纳入1例骨硬化青年女性患者。采用骨密度检测、X线成像等临床手段对其临床表现进行分析;并对患者及其父亲的CLCN7基因进行外显子测序,从正常人DNA样本库中随机挑选50个样本进行CLCN7基因外显子测序来对比分析测序结果。结果X线片显示椎体骨密度增加,成“夹心饼”样;髋部和股骨骨密度增加,盆骨出现“骨中骨”现象。骨密度结果显示腰椎1-4 Z值为13,股骨颈Z值为7.8,全髋Z值为10,患者骨骼呈骨硬化表现,测序结果显示9号外显子上发生错义突变(纯合突变),导致c.746C>T(p.Pro249Leu);其父亲和50个对照样本均无此突变。结论此患者为CLCN7基因c.746C>T(p.Pro249Leu)纯合错义突变的ADOⅡ型常染色体显性骨硬化症。     

A newly discovered mutation in PICK1 in a human with globozoospermia

Globozoospermia is a human infertility syndrome caused by spermatogenesis defects （OMIM 102530）. Acrosome plays an important role at the site of sperm-zonapellucida binding during the fertilization process. Thus, malformation of the acrosome is the most prominent feature seen in globozoospermia. Disruption of several mouse genes, including Gopc （Golgi-associated PDZ and coiled-coil motif containing protein）, Hrb （HIV-I Rev binding protein）, Csnk2α2 （casein kinase 2, α prime polypeptide） and Pick1 （protein interacting with C kinase 1）, results in a phenotype similar to globozoospermia in humans, which suggests their potential role in the disease. However, no mutations with a clear link to globozoospermia have been identified in these genes in humans. In this study, we screened the candidate genes men- tioned above in three globozoospermia type I patients and discovered a homozygous missense mutation （G198A） in exon 13 of the PICK1 gene in a Chinese family. The family member affected by this homozygous missense mutation showed a complete lack of acrosome. Using the candidate gene screening strategy, our study is the first to identify an autosomal recessive genetic mutation in PICK1 that was responsible for globozoospermia in humans.     

ClC-7 expression levels critically regulate bone turnover,but not gastric acid secretion

Mutations in the 2Cl⁻/1H⁺-exchanger ClC-7 impair osteoclast function and cause different types of osteoclast-rich osteopetrosis. However, it is unknown to what extent ClC-7 function has to be reduced to become rate-limiting for bone resorption. In osteoclasts from osteopetrosis patients expression of the mutated ClC-7 protein did not correlate with disease severity and resorption impairment. Therefore, a series of transgenic mice expressing ClC-7 in osteoclasts at different levels was generated. Crossing of these mice with Clcn7^−/− mutants rescued the osteopetrotic phenotype to variable degrees. One resulting double transgenic line mimicked human autosomal dominant osteopetrosis. The trabecular bone of these mice showed a reduction of osteoblast numbers, osteoid, and osteoblast marker gene expression indicative of reduced osteoblast function. In osteoclasts from these mutants ClC-7 expression levels were 20 to 30% of wildtype levels. These reduced levels not only impaired resorptive activity, but also increased numbers, size and nucleus numbers of osteoclasts differentiated in vitro. Although ClC-7 was expressed in the stomach and PTH levels were high in Clcn7^−/− mutants loss of ClC-7 did not entail a relevant elevation of gastric pH. In conclusion, we show that in our model a reduction of ClC-7 function by approximately 70% is sufficient to increase bone mass, but does not necessarily enhance bone formation. ClC-7 does not appear to be crucially involved in gastric acid secretion, which explains the absence of an osteopetrorickets phenotype in CLCN7-related osteopetrosis.     

Hereditary leiomyomatosis and renal cell cancer (HLRCC): Case series and review of the literature

BackgroundHereditary leiomyomatosis and renal cell cancer (HLRCC) is an autosomal dominant syndrome caused by heterozygous pathogenic germline variants in the fumarate hydratase (FH) gene. It is characterized by cutaneous and uterine leiomyomas and an increased risk of developing renal cell carcinoma (RCC). HLRCC-related RCC tends to be aggressive. To date, only a few publications have described HLRCC-related RCC, and the clinical, morphological and molecular aspects of HLRCC-related RCC need to be further studied.MethodsWe retrospectively analyzed the clinical and pathological data of 3 patients with HLRCC recently diagnosed. Immunohistochemistry and Whole-exome sequencing was performed on 3 patients. The function of the DNA variant was predicted in silico.ResultsWe reported 3 patients from unrelated Chinese families, with HLRCC-related RCC and identified 3 different germline FH mutations (2 missense and 1 nonsense). A novel missense mutation of FH gene (c.454A>G, p.N152D) was predicted to be probably pathogenic and deleterious by multiple protein function predicting software. This study indicated that the novel mutation may be responsible for the occurrence of HLRCC-related RCC. 100% (2/2) female RCC patients had uterine fibroids. No cutaneous manifestations were identified.ConclusionWe indicate that germline screening should be encouraged in early-onset patients. Clinicopathological data, such as family history and immunohistochemical results can provide valuable clinical information for the differential diagnosis of HLRCC-associated RCC in advance.     

A case of nephrogenic diabetes insipidus with a novel missense mutation in the <Emphasis Type="BoldItalic">AVPR2</Emphasis> gene

We describe a pediatric case of nephrogenic diabetes insipidus (NDI) with a novel missense mutation in the arginine vasopressin receptor 2 (AVPR2) gene. The patient, a 3-year-old boy, had polyuria (4357 ml/day, 7230 ml/m²/day) and polydipsia. Water deprivation testing demonstrated no decrease of urine volume, and urinary volume did not respond to subcutaneous injection of 0.1 U/kg pitressin. Molecular genetic analysis demonstrated that the patient had an AVPR2 missense mutation involving substitution of phenylalanine for tyrosine at position 205 (Y205F). It was also found that the patient’s mother was heterozygous for this Y205F mutation. Analysis of the intermolecular interaction of the Tyr-205 hydrogen group by molecular modeling showed that Tyr-205 was located in transmembrane domain (TM) 5, and that its hydroxy group formed a hydrogen bond with Leu-169 main-chain =O located in TM 4. The mutation of Tyr-205 to phenylalanine would cause loss of this hydrogen bond and decrease or change the interaction between these TM coils, thus affecting the ability of AVP to bind to the receptor. According to this molecular model of AVPR2, the Y205F mutation would cause nephrogenic diabetes insipidus.     

Two novel mutations of <Emphasis Type="Italic">CLCN7</Emphasis> gene in Chinese families with autosomal dominant osteopetrosis (type II)

Autosomal dominant osteopetrosis type II (ADO-II) is a heritable bone disorder characterized by osteosclerosis, predominantly involving the spine (vertebral end-plate thickening, or rugger-jersey spine), the pelvis (“bone-within-bone” structures) and the skull base. Chloride channel 7 (CLCN7) has been reported to be the causative gene. In this study, we aimed to identify the pathogenic mutation in four Chinese families with ADO-II. All 25 exons of the CLCN7 gene, including the exon–intron boundaries, were amplified and sequenced directly in four probands from the Chinese families with ADO-II. The mutation site was then identified in other family members and 250 healthy controls. In family 1, a known missense mutation c.296A>G in exon 4 of CLCN7 was identified in the proband, resulting in a tyrosine (UAU) to cysteine (UGU) substitution at p.99 (Y99C); the mutation was also identified in his affected father. In family 2, a novel missense mutation c.865G>C in exon 10 was identified in the proband, resulting in a valine (GUC) to leucine (CUC) substitution at p.289 (V289L); the mutation was also identified in her healthy mother and sister. In family 3, a novel missense mutation c.1625C>T in exon 17 of CLCN7 was identified in the proband, resulting in an alanine (GCG) to valine (GUG) substitution at p.542 (A542V); the mutation was also identified in her father. In family 4, a hot spot, R767W (c.2299C>T, CGG>TGG), in exon 24 was found in the proband which once again proved the susceptibility of the site or the similar genetic background in different races. Moreover, two novel mutations, V289L and A542V, occurred at a highly conserved position, found by a comparison of the protein sequences from eight vertebrates, and were predicted to have a pathogenic effect by PolyPhen-2 software, which showed “probably damaging” with a score of approximately 1. These mutation sites were not identified in 250 healthy controls. Our present findings suggest that the novel missense mutations V289L and A542V in the CLCN7 gene were responsible for ADO-II in the two Chinese families.     

Novel SOST gene mutation in a sclerosteosis patient and her parents

IntroductionSclerosteosis (OMIM 269500) is a rare autosomal recessive condition characterized by increased bone density associated with syndactyly. It is linked to a genetic defect in the SOST gene coding for sclerostin. So far, six different loss-of-function mutations in SOST have been reported in patients with sclerosteosis. Our objective was to sequence and identify mutation in the SOST and LRP5 genes which are known to be causal for craniotubular hyperostosis in a patient from India.Patient and methodsA 22 year old woman presented with typical features of sclerosteosis in form of progressive visual and hearing loss, syndactyly and radiographs revealing increased density of bone. Genomic sequencing of the SOST gene as well as exons 2, 3 and 4 of the LRP5 gene was performed.ResultsWe identified a novel homozygous mutation in the ^SOST gene, characterized as one nucleotide insertion resulting in a frame shift mutation and loss of functional sclerostin. Her parents were also found to have a similar but heterozygous mutation in the ^SOST gene.ConclusionA novel frame shift mutation in the ^SOST gene causing loss of functional sclerostin was identified in a patient with sclerosteosis and her parents.     

An association study of HFE gene mutation with idiopathic male infertility in the Chinese Han population

Mutations in the haemochromatosis gene (HFE) influence iron status in the general population of Northern Europe, and excess iron is associated with the impairment of spermatogenesis. The aim of this study is to investigate the association between three mutations (C282Y, H63D and S65C) in the HFE gene with idiopathic male infertility in the Chinese Han population. Two groups of Chinese men were recruited: 444 infertile men (including 169 with idiopathic azoospermia) and 423 controls with proven fertility. The HFE gene was detected using polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) technique. The experimental results demonstrated that no C282Y or S65C mutations were detected. Idiopathic male infertility was not significantly associated with heterozygous H63D mutation (odds ratio=0.801, 95% confidence interval=0.452–1.421, χ²=0.577, P=0.448). The H63D mutation frequency did not correlate significantly with the serum luteinizing hormone (LH), follicle-stimulating hormone (FSH) and testosterone (T) levels in infertile men (P=0.896, P=0.404 and P=0.05, respectively). Our data suggest that the HFE H63D mutation is not associated with idiopathic male reproductive dysfunction.     

Hereditary vitamin D–resistant rickets (HVDRR) owing to a heterozygous mutation in the vitamin D receptor

Hereditary vitamin D–resistant rickets (HVDRR) is a rare autosomal recessive disease caused by mutations in the vitamin D receptor (VDR). Patients exhibit severe rickets and hypocalcemia. Heterozygous parents and siblings appear normal and exhibit no symptoms of the disease. We analyzed the VDR gene of a young girl who exhibited the clinical features of HVDRR without alopecia. The patient had clinical and radiographic features of rickets, hypocalcemia, and elevated serum concentrations of 1,25‐dihydroxyvitamin D [1,25(OH)₂D]. A single heterozygous missense mutation was found in the VDR gene that substituted glutamic acid with alanine at amino acid 420 (E420A). Sequencing of the girl's VDR cDNAs showed that the f/M1 allele contained the E420A mutation, whereas the F/M4 allele was completely normal. The girl's father, who was also heterozygous for the E420A mutation on the f/M1 allele, exhibited minor symptoms of vitamin D resistance. In contrast, the mother had no signs of the disease and had no mutations in her VDR gene. Both the girl and the father's skin fibroblasts showed resistance to 1,25(OH)₂D₃ by their severely reduced induction of CYP24A1 gene expression. In transactivation assays, the E420A mutant VDR showed dominant‐negative activity towards the wild‐type VDR. This is the first report that we are aware of describing a patient with HVDRR caused by a single heterozygous missense mutation in the VDR gene. The E420A mutant appears to act in a dominant‐negative fashion, silencing the wild‐type VDR and resulting in an attenuated response to 1,25(OH)₂D₃. © 2011 American Society for Bone and Mineral Research     

Identification of a novel AGXT gene mutation in primary hyperoxaluria after kidney transplantation failure

Primary hyperoxaluria is a genetic disorder in glyoxylate metabolism that leads to systemic overproduction of oxalate. Functional deficiency of alanine-glyoxylate aminotransferase in this disease leads to recurrent nephrolithiasis, nephrocalcinosis, systemic oxalosis, and kidney failure. The aim of this study was to determine the molecular etiology of kidney transplant loss in a young Tunisian individual. We present a young man with end-stage renal disease who received a kidney allograft and experienced early graft failure. There were no improvement in kidney function; he required hemodialysis and graft biopsy revealed calcium oxalate crystals, which raised suspicion of primary hyperoxaluria. Genetic study in the AGXT gene by PCR direct sequencing identified three missense changes in heterozygote state: the p. Gly190Arg mutation next to two other novels not previously described. The classification of the deleterious effect of the missense changes was developed using the summered results of four different mutation assessment algorithms, SIFT, PolyPhen, Mutation Taster, and Align-GVGD. This system classified the changes as polymorphism in one and as mutation in other. The patient was compound heterozygous mutations. Structural analysis showed that the novel mutation, p.Pro28Ser mutation, affects near the dimerization interface of AGT and positioned on binding site instead of the inhibitor, amino-oxyacetic acid (AOA).With the novel AGXT mutation, the mutational spectrum of this gene continues to broaden in our population. The diagnosis of PH1 was not recognized until after renal transplant with fatal consequences, which led us to confirm the importance of screening before planning for kidney transplantation in population with a relatively high frequency of AGXT mutation carriers.     

Dosage Effect of a Phex Mutation in a Murine Model of X-Linked Hypophosphatemia

X-linked hypophosphatemia (XLH) is caused by mutations in the PHEX gene, which increase circulating levels of the phosphaturic hormone, fibroblast growth factor 23 (FGF23). Because XLH is a dominant disease, one mutant allele is sufficient for manifestation of the disease. However, the dosage effect of a PHEX mutation in XLH is not completely understood. To examine the effect of Phex genotypes, we compared serum biochemistries and skeletal measures between all five possible genotypes of a new murine model of XLH (Phex ^K496X or Phex ^Jrt ). Compared to sex-matched littermate controls, all Phex mutant mice had hypophosphatemia, mild hypocalcemia, and increased parathyroid hormone and alkaline phosphatase levels. Furthermore, mutant mice had markedly elevated serum Fgf23 levels due to increased Fgf23 expression and reduced cleavage of Fgf23. Although females with a homozygous Phex mutation were slightly more hypocalcemic and hypophosphatemic than heterozygous females, the two groups had comparable intact Fgf23 levels. Similarly, there was no difference in intact Fgf23 or phosphorus concentrations between hemizygous males and heterozygous females. Compared to heterozygous females, homozygous counterparts were significantly smaller and had shorter femurs with reduced bone mineral density, suggesting the existence of dosage effect in the skeletal phenotype of XLH. However, overall phenotypic trends in regards to mineral ion homeostasis were mostly unaffected by the presence of one or two mutant Phex allele(s). The lack of a gene dosage effect on circulating Fgf23 (and thus phosphorus) levels suggests that a Phex mutation may create the lower set point for extracellular phosphate concentrations.     

Caspase-3 gene deletion prolongs survival in polycystic kidney disease

Pan-caspase inhibition reduces tubular apoptosis and proliferation and slows progression of disease in a rat model of polycystic kidney disease (PKD). It is unknown, however, which specific caspases are involved in PKD progression. Because caspase-3 is a major mediator of apoptosis, its role in autosomal recessive PKD was determined. Mice with caspase-3 gene deletion were crossed with mice harboring the congenital polycystic kidney (cpk) mutation to generate double-mutant mice. cpk;casp3^−/− mice lived nearly 4 times longer than littermate control cpk mice (mean survival of 117 d versus 32 d, P < 0.01), and cpk;casp3^+/− mice lived slightly longer than controls (mean survival of 56 d). In addition, the kidney weight, relative to body weight, was significantly lower in the cpk;casp3^−/− mice than in the cpk and cpk;casp3^+/− mice. Despite deletion of caspase-3, however, apoptosis occurred and cysts formed; therefore, the alternative pathways of apoptosis in cystic kidneys were investigated. Caspase-7 was up-regulated and the anti-apoptotic protein Bcl-2 was down-regulated in cpk, cpk;casp3^+/−, and cpk;casp3^−/− mice compared with wild-type controls. In summary, homozygous deletion of caspase-3 markedly prolongs survival of cpk mice, but a caspase-7-mediated pathway may compensate for the deficiency of functional caspase-3. These findings suggest that pan-caspase inhibition may have a greater therapeutic effect than selective caspase inhibition in PKD.Inherited polycystic kidney disease (PKD) is one of the leading causes of end-stage kidney disease requiring dialysis and kidney transplantation in children and adults.¹ Inherited PKD includes both autosomal dominant and autosomal recessive forms. Autosomal dominant polycystic kidney disease (ADPKD) results from mutations in one of two genes, PKD1 or PKD2. The prevalence of ADPKD varies between 1 in 400 and 1 in 1000, thus making it one of the most common hereditary diseases in the United States. ADPKD progresses to end-stage renal disease (ESRD) over a period of decades in 50% to 75% of affected people. Autosomal recessive polycystic kidney disease (ARPKD) results from a mutation in a single gene, PKHD1. ARPKD is less common, affecting about 1 in 20,000 live births and results in ESRD in childhood.²The congenital polycystic kidney (cpk) mouse is the most extensively characterized mouse model of PKD.² The inheritance, cyst localization in the kidney, and severity of kidney disease in the cpk mouse resembles ARPKD. Cys1, the cpk gene, encodes a cilia-associated protein called cystin that is disrupted in the cpk mouse.³ Increased apoptosis in polycystic kidneys has been described in cpk mice^4–8 as well as in human and other rat and mouse models of PKD.⁹ In support of a deleterious effect of apoptosis in PKD, we have recently demonstrated that pan-caspase inhibition reduces tubular apoptosis and proliferation and slows disease progression in the Han:SPRD rat model of PKD.¹⁰ The effect of caspase or apoptosis inhibition in other rat and mouse models of PKD is not known. Caspase-3 is the major mediator of apoptosis (i.e., the so-called “executioner” caspase) and caspase-1 is a pro-inflammatory caspase. However, the effect of inhibition of a specific caspase on PKD is not known. We tested the hypothesis that specific inhibition of caspase-3 would prolong life and reduce cyst formation in PKD.In the present study, we developed cpk mice that were either heterozygous or homozygous for caspase-3 deletion to determine the effect of specific caspase-3 deletion on the development of PKD.     

A partial loss-of-function variant in GNRNR gene in a Chinese cohort with idiopathic hypogonadotropic hypogonadism

BackgroundIdiopathic hypogonadotropic hypogonadism (IHH) is a rare genetic disease attributed to the disorder of hypothalamic-pituitary-gonadal axis. Mutations in the GNRHR gene are one of the most common genetic causes of IHH. Herein, we aimed to investigate GNRHR variants in a Chinese cohort with IHH, and to characterize them at the molecular level.MethodsA total of 153 IHH patients were recruited, and variants were detected using a tailored next-generation sequencing panel. GNRHR rare sequencing variant (RSV) was verified using Sanger sequencing. Phenotypic features and therapeutic outcomes of patients were followed up. In order to examine the pathogenicity of the GNRHR RSV, we performed conservative analysis, crystal structure prediction, expression analysis as well as the assessment of ERK1/2 activation and IP3/Ca²⁺ response.ResultsThe same heterozygous RSV (p.R240Q) in GNRHR was identified in four sporadic IHH patients. These patients exhibited different severity of testicular development and hormone profile. hCG treatment was effective in improving gonadal development, serum testosterone, and semen quality. The GNRHR RSV has no effect on the expression of mRNA and protein, whereas damaged ERK1/2 activation and inositol triphosphate/calcium signaling.ConclusionsThe study expands GNRHR mutation spectrum in IHH patients, and reveals that the GNRHR RSV is a partial loss-of-function mutation. Although this heterozygous RSV may not have a significant influence on the pathogenesis of IHH, but its homozygous/ compound status should be paid attention in this research field.