Discovery of unique CYP716C oxidase involved in pentacyclic triterpene biosynthesis from Camptotheca acuminata.

Dozens of triterpenes have been isolated from Camptotheca acuminata, however, triterpene metabolism in this plant remains poorly understood. The common C28 carboxy located in the oleanane-type and ursane-type triterpenes indicates the existence of a functionally active triterpene, C28 oxidase, in this plant. Thorough mining and screening of the CYP716 genes were initiated using the multi-omics database for C. acuminata. Two CYP716A (CYP716A394 and CYP716A395) and three CYP716C (CYP716C80-CYP716C82) were identified based on conserved domain analyses and hierarchical cluster analyses. CYP716 microsomal proteins were prepared and their enzymatic activities were evaluated in vitro. The CYP716 classified into the CYP716C subfamily displays ß-amyrin oxidation activity, and CYP716A displays α-amyrin and lupeol oxidation activity, based on gas chromatography-mass spectrometry analyses. The oxidation products were determined based on their mass and nuclear magnetic resonance spectrums. The optimum reaction conditions and kinetic parameters for CYP716C were determined, and functions were verified in Nicotiana benthaminana. Relative quantitative analyses revealed that these CYP716C genes were enriched in the leaves of C. acuminata plantlets after 60 d. These results indicate that CYP716C plays a dominant role in oleanane-type triterpene metabolism in the leaves of C. acuminata via a substrate-specific manner, and CYP716A is responsible for ursane- and lupane-type triterpene metabolism in fruit. This study provides valuable insights into the unique CYP716C-mediated oxidation step of pentacyclic triterpene biosynthesis in C. acuminata.

[Study on the changes of cartilage metabolites in patients with knee osteoarthritis before and after fibula osteotomy].

OBJECTIVE: To explore changes of C-terminal cleavage epitope of type Ⅱ collagen 3/4 fragment in cartilage metabolism (Col2-3/4Clong mono or C2C), carboxyl-terminal telopeptide of type Ⅱ collagen (CTX-Ⅱ) and knee joint function before and after osteotomy of fibula in patients with knee osteoarthritis. METHODS: From January 2019 to March 2020, 65 patients with knee osteoarthritis who underwent fibular osteotomy treatment accompanied with medial pain were selected, including 25 males and 40 females, aged from 44 to 70 years old with an average of (56.20±10.05) years old;25 patients were gradeⅠ, 19 patients with gradeⅡ, 17 patients with grade Ⅲ, and 4 patients with grade Ⅳ according to Kellgren-Lawrence grading. The content of CTX-Ⅱ and C2C in knee joint fluid, serum interleukin 1ß ( IL-1ß), tumor necrosis factor-α (TNF-α) before osteotomy and 6 months after osteotomy were detected. Visual analogue scale(VAS) was used to evaluate degree of pain relief, American Knee Society Score (KSS) and Hospital for Special Surgery (HSS) were applied to evaluate recovery of knee joint function. RESULTS: Sixty-five patients were followed up from 6 to 18 months with an average of(12.4±3.6) months. VAS, KSS and HSS score at 6 months after osteotomy were better than that of before osteotomy(P<0.05). Serum IL-1ß, TNF-α and content of CTX-Ⅱand C2C of knee joint fluid at 6 months after osteotomy were lower than those before osteotomy(P<0.05). CONCLUSION: Fibula osteotomy could relieve pain of knee osteoarthritis, maintain balance of joint stress, reduce organism inflammatory response, improve cartilage metabolism, reduce decomposition of articular cartilage, and reduce level of CTX-Ⅱand C2C, which is benefit for regeneration of articular cartilage and promote recovery of knee joint function.

Nonlinear associations between environmental factors and lipid levels in middle-aged and elderly population in China: A national cross-sectional study.

BACKGROUND: Blood lipid is an important factor affecting cardiovascular disease in middle-aged and elderly people. At present, the associations between environmental factors and blood lipid level in elderly people has been controversial, and the nonlinear effect of their relationship is lack of research. METHODS: This study used data from a national cross-sectional survey of blood lipid levels in 13,354 subjects and data from environmental monitoring sites. Logistic regression was used to measure the relationship between the basic characteristics of the study population and blood lipid levels. After controlling the confounding factors, the nonlinear associations between environmental factors and blood lipid levels of middle-aged and elderly people in different geographical regions were studied by random forest model. RESULTS: The risk of dyslipidemia is significantly higher in middle-aged women, obese people, elderly people, and urban people. Smoking and alcohol consumption increase the risk. The associations between environmental factors and lipid levels of middle-aged and elderly people are nonlinear, the correlation effect between air pollutants and blood lipid level is mainly shown in northern China, and the correlation between meteorological factors and blood lipid level is more obvious in southern China. CONCLUSIONS: This study shows that the associations between environmental factors and lipid levels in middle-aged and elderly population are nonlinear and have regional differences. Therefore it should be considered in optimizing the allocation of public health resources and preventing and controlling environmental exposure of middle-aged and elderly population.

Five novel NF1 gene pathogenic variants in 10 different Chinese families with neurofibromatosis type 1.

BACKGROUND: Neurofibromatosis type 1 (NF1) is an autosomal dominant disorder with equal sex incidence that is characterized by neurofibromas, café-au-lait macules, axillary freckling, optic pathway tumor, distinctive osseous lesion, and iris Lisch nodules. Inactivating variants in the NF1 gene have been identified to be correlated with NF1. This tumor suppressor gene is located at 17q11.2. METHODS: Ten affected NF1 probands and their available relatives from 10 unrelated Chinese families with neurofibromatosis type 1 were clinically studied. All of these probands mainly complained of osseous lesions. PCR was used to analyze and sequence the variants. We collected both laboratory and radiological information. RESULTS: We detected five novel pathogenic variants including two de novo variants in these 10 families: one missense variant, p.Cys709Arg(c.2125T>C), in exon 18 and four frameshift variants: p.Leu1459Profs*2(c.4436dupT) in exon 34; p.Lys99Argfs*4(c.296delA) in exon 4; p.Leu762Cysfs*2(c.2283delA) in exon 19; and p.Leu1522Ilefs*53(c.4562_4563dupAT) in exon 34. CONCLUSION: Novel pathogenic variants in the NF1 gene in these families correlated with the phenotype and genotype and explained the clinical manifestations of these patients. The results help us to understand the genetic basis of patients with neurofibromatosis type 1 in China. Our study expands the pathogenic variant spectrum of the NF1 gene and may be helpful in genetic counseling and prenatal genetic diagnosis.

Fibroblast Growth Factor 21 Is Associated With Bone Mineral Density, but not With Bone Turnover Markers and Fractures in Chinese Postmenopausal Women.

Fibroblast growth factor 21 (FGF21) is a member of the endocrine FGF subfamily and an important metabolic regulator that has multiple beneficial effects on glucose homeostasis and lipid metabolism. However, it was unclear whether FGF21 would induce bone defects in humans. This study evaluated the associations of FGF21 levels, bone mineral density (BMD), osteoporotic fracture, and bone turnover marks (BTMs) in postmenopausal women. A total of 1342 postmenopausal Chinese Han women (511 cases of fragility fracture in the case group and 831 cases in nonfragility fracture group) were enrolled. Serum FGF21 concentration was measured by ELISA (Quantikine), serum calcium (Ca), phosphate (P), alkaline phosphatase, 25-hydroxyvitamin D, parathyroid hormone, ß-crosslinked C-telopeptide of type l collagen, were measured using an automated Roche electro-chemiluminescence system. BMD was measured using dual-energy X-ray absorptiometry. The association with age, BMD, 25-hydroxyvitamin D, parathyroid hormone, ß-crosslinked C-telopeptide of type l collagen, and FGF21 levels were also evaluated in postmenopausal women. In nonfracture group and fragility fracture group, postmenopausal women's FGF21 level was 226.57pg/mL (149.11-354.43 pg/mL) and 219.43pg/mL (147.21-323.74 pg/mL), respectively. There is no significant difference in serum FGF21 levels between the fragility fracture group and the nonfracture group (p = 0.160). There was a significant statistical difference in BMD between the fragility fracture group and the nonfracture group (p = 0.000). In multiple linear regression analysis, FGF21 levels were significantly positive associated with lumbar BMD in postmenopausal women (L1-4, p = 0.007), independent of other factors, especially in fragility fracture group (L1-4, p = 0.001). In addition, a significant positive association was also observed between serum FGF21 levels and age in postmenopausal women (p < 0.05). We reveal a positive correlation between serum FGF21 concentrations with lumbar BMD in Chinese Han postmenopausal women. No significant correlations are present between serum FGF21 and bone turnover marks or serum FGF21 and fragility fracture in our study.

The Spatial Distribution Characteristics of the Tumor Biomarker Alpha-fetoprotein: A Cross-section Study.

OBJECTIVES: This study aims to explore the spatial characteristics of the alpha-fetoprotein (AFP) reference value in healthy Chinese adults, and its relationship to geographical location. METHODS: A total of 9396 AFP reference values were collected from patients in 96 administrative units. A correlation analysis and support vector machine (SVM) were employed to extract dependent geographical factors and predict the reference values in the entire country, respectively. A geostatistics analysis was developed to reveal the spatial characteristics of the value. RESULTS: Under the long-term influence of geographical environment, AFP reference values show spatial autocorrelation and regional variation. The values are higher in western and northern areas than in eastern and southern areas of China. CONCLUSIONS: The AFP reference values show regional differences, and this difference should be considered in clinical practice.

Whole-Exome Sequencing Identifies Novel Recurrent Somatic Mutations in Sporadic Parathyroid Adenomas.

Primary hyperparathyroidism is commonly caused by excess production of parathyroid hormone from sporadic parathyroid adenomas. However, the genetic architecture of sporadic primary hyperparathyroidism remains largely uncharacterized, especially in the Chinese population. To identify genetic abnormalities that may be involved in the etiology of sporadic parathyroid adenomas and to determine the mutation frequency of previously identified genes in the Chinese population, we performed whole-exome sequencing of 22 blood-tumor pairs from sporadic parathyroid adenomas. The most important finding is the recurrently mutated gene, ASXL3, which has never been reported in parathyroid tumors before. Moreover, we identified two different somatic mutations in the CDC73 gene and one somatic mutation in the EZH2 gene. The Y54X mutation in the CDC73 gene was previously identified in parathyroid carcinomas, which proved that parathyroid adenomas and carcinomas might possess similar molecular signatures. No mutations in the MEN1 or CCND1 genes were observed in our study. Thus, our data provide insights into the genetic pathogenesis of sporadic parathyroid adenomas and are valuable for the development of diagnostic and therapeutic approaches for sporadic primary hyperparathyroidism.

Targeted resequencing of phosphorus metabolism­related genes in 86 patients with hypophosphatemic rickets/osteomalacia.

Hypophosphatemic rickets/osteomalacia is characterized by defective renal phosphate reabsorption and abnormal bone mineralization. Hypophosphatemic rickets/osteomalacia consists of inherited and acquired forms, many of which have unknown aetiology. In the present study, next­generation sequencing­based resequencing was used on samples from Chinese subjects with hypophosphatemic rickets/osteomalacia, aiming to detect the spectrum of pathogenic genes in these patients. A total of 86 hypophosphatemic rickets/osteomalacia patients (ranging from 3 to 70 years old) were recruited. Patients with tumour­induced osteomalacia (TIO), renal tubular acidosis, renal osteodystrophy, and adefovir­induced Fanconi syndrome were excluded. Targeted massively parallel resequencing of 196 candidate genes for hypophosphatemic rickets/osteomalacia was performed in the 86 affected unrelated individuals (cases) and in 100 unrelated healthy controls to identify new genes and mutations in known genes that cause hypophosphatemic rickets/osteomalacia. The results identified seven phosphate­regulating gene with homologies to endopeptidases on the X chromosome (PHEX) mutations (of which two were novel) and one novel dentin matrix protein 1 (DMP1) mutation in eight patients. Following targeted exome sequencing data analysis, 14 candidate disease­related gene loci were selected, two of which were of most concern regarding disease severity. Further validation of the present results is warranted, with additional sequencing projects and functional tests. To our knowledge, the present study is the largest cohort of cases with hypophosphatemic rickets/osteomalacia to undergo targeted resequencing. The diagnosis and understanding of the molecular aetiologies of these disorders will be improved by this fast and efficient approach.

Novel mutations of TCIRG1 cause a malignant and mild phenotype of autosomal recessive osteopetrosis (ARO) in four Chinese families.

Human autosomal recessive osteopetrosis (ARO), also known as infantile malignant osteopetrosis, is a rare genetic bone disorder that often causes death. Mutations in T-cell immune regulator 1 (TCIRG1) are a frequent cause of human ARO. Six additional genes (TNFSF11, TNFRSF11A, CLCN7, OSTM1, SNX10, PLEKHM1) were also found to be associated with human ARO. In order to expand the mutation spectrum and clinical diversity for a better understanding of the ARO phenotype and to further investigate the clinical characteristics of benign subjects with ARO, we here report five individuals with ARO from four unrelated Chinese families. X-ray examination was conducted and bone turnover markers were assayed. The gene of T-cell immune regulator 1 (TCIRG1) was screened and analyzed. Monocyte-induced osteoclasts were prepared and their resorption ability was studied in vitro. We identified five novel mutations (c.66delC, c.1020+1_1020+5dup, c.2181C>A, c.2236+6T>G, c.692delA) in these patients. Four patients displayed a malignant phenotype, three of them died, and one who received bone marrow transplantation survived. The remaining one, a 24-year-old male from a consanguineous family, was diagnosed based on radiological findings but presented no neurological or hematological defects. He was homozygous for c.2236+6T>G in intron 18; this mutation influenced the splicing process. An in vitro functional study of this novel splicing defect showed no resorption pits on dentine slices. TCIRG1-dependent osteopetrosis with a mild clinical course was observed for the first time in Chinese population. The present findings add to the wide range of phenotypes of Chinese patients with TCIRG1-dependent ARO and enrich the database of TCIRG1 mutations.

Reports of 17 Chinese patients with tumor-induced osteomalacia.

Tumor-induced osteomalacia (TIO) is a rare acquired form of hypophosphatemic osteomalacia, which is usually attributed to the overproduction of fibroblast growth factor 23 (FGF-23) by benign mesenchymal neoplasms. Localization and thereafter surgical resection of tumors lead to a cure. The present study aimed to investigate the clinical data, diagnostic methods, and follow-up after tumor resection at one medical center in Shanghai to characterize the profile of this rare disorder and to share our successful experience in diagnosis and treatment. Twenty-three patients with adult-onset hypophosphatemia osteomalacia seen in Shanghai Sixth People's Hospital from 2009 to 2014 and 95 normal individuals were enrolled. After taking a medical history and performing a physical examination, we analyzed the laboratory results (including the serum FGF-23 levels) and localized the tumors by 18F-fluorodeoxyglucose positron emission tomography and computed tomography (18F-FDG PET/CT), 99mTc-octreotide (99mTc-OCT) scintigraphy, and magnetic resonance imaging (MRI). On the basis of the results of laboratory tests and imaging findings, tumor resection was conducted in 17 patients with a certain diagnosis of TIO. The results demonstrated that the 17 patients (nine men and eight women, average age 46.6 ± 12.9 years) had TIO. FGF-23 level was elevated in 94.1 % of patients (16 of 17 patients) . Serum phosphorus level decreased in 100 % of patients. 18F-FDG PET/CT revealed five tumors, 99mTc-OCT scintigraphy revealed two tumors, physical examination revealed nine tumors, and MRI revealed one tumor, among which 58.8 % of the causative tumors (10 of 17 tumors) were located in the lower extremities. After tumor resection, serum phosphorus levels normalized in 100 % of patients (all 17 patients) in 4-21 days and FGF-23 levels decreased in 90 % of patients (nine of ten patients). We found 64.7 % of the tumors (11 of 17 tumors) were phosphaturic mesenchymal tumors or a phosphaturic mesenchymal tumor mixed connective tissue variant. Measurement of serum phosphorus and FGF-23 levels in patients with suspected TIO is of paramount importance for diagnosing of TIO. 18F-FDG PET/CT, 99mTc-OCT scintigraphy, and physical examination play a considerable role in revealing TIO-associated tumors. TIO-associated tumors were more frequently located in the lower extremities than in other places; thus, the lower extremities need to be carefully checked. Complete surgical resection results in normalization of parameters in laboratory tests and relief of symptoms of TIO patients.

Associations of Serum Osteocalcin and Polymorphisms of the Osteocalcin Gene with Bone Mineral Density in Postmenopausal and Elderly Chinese Women.

BACKGROUND: The aims of this study were: (1) to evaluate the association of serum osteocalcin with bone mineral density (BMD) and markers of bone metabolism in postmenopausal and elderly Chinese women, and (2) to observe the relationships of single-nucleotide polymorphisms (SNPs) in and around the osteocalcin gene with osteocalcin and BMD. METHODS: A cross-sectional study was conducted with 725 postmenopausal Chinese women. Five SNPs (rs1543294, rs1800247, rs759330, rs2842880, and rs933489) of the osteocalcin gene were genotyped. Serum osteocalcin and intact parathyroid hormone (PTH), 25-hydroxyvitamin D [25(OH)D], and type I collagen containing cross-linked C-telopeptide (ß-CTX) were measured. The BMD of the lumbar spine and proximal femur was measured by dual-energy X-ray absorptiometry. RESULTS: Osteocalcin was positively correlated with serum phosphorus (p = 0.001), alkaline phosphatase (ALP; p < 0.001), PTH (p = 0.002) and ß-CTX (p < 0.001), and negatively correlated with BMD at the lumbar spine (p < 0.001) and total hip (p = 0.002). No significant association was obtained between the SNPs, haplotypes of the osteocalcin gene, and BMD or osteocalcin. CONCLUSION: Our results suggest that osteocalcin was positively correlated with serum phosphorus, ALP, PTH, and ß-CTX, but negatively correlated with BMD at the lumbar spine and total hip. Common genetic variants of the osteocalcin gene may not be a major contributor to variations in serum osteocalcin or BMD in postmenopausal and elderly Chinese women.

Osteomalacia induced by long-term low-dose adefovir dipivoxil: Clinical characteristics and genetic predictors.

CONTEXT: Adefovir dipivoxil (ADV) was an important cause of adult-onset hypophosphatemic osteomalacia. However, its clinical characteristics and mechanisms have not been well defined. OBJECTIVE: The objective of the study was to summarize the clinical characteristics of ADV-induced osteomalacia and to explore the association between ADV-associated tubulopathy and polymorphisms in genes encoding drug transporters. DESIGN, SETTING, PATIENTS, AND MAIN OUTCOME MEASURE: Seventy-six affected patients were clinically studied. The SLC22A6 and ABCC2 genes were screened and compared with healthy people from the HapMap. RESULTS: Hypophosphatemia, high serum alkaline phosphatase (ALP) levels, hypouricemia, nondiabetic glycosuria, proteinuria, metabolic acidosis and high bone turnover markers were the main metabolic characteristics. Fractures and pseudofractures occurred in 39 patients. Stopping ADV administration, supplementing calcitriol and calcium was effective during the follow-up period. Single SNP analysis revealed a higher percentage of the G/A genotype at c.2934 in exon 22 of the ABCC2 gene (rs3740070) in patients than in healthy people (12% [7 of 58 patients] vs. 0% [0 of 45 patients]; P=0.017), while there was no subject with homozygosity for the A allele at c.2934. CONCLUSIONS: ADV can be nephrotoxic at a conventional dosage. The G/A genotype at c.2934 of the ABCC2 gene may be a predictor of patients at greater risk for developing ADV-associated tubulopathy. Larger case-control studies are needed to further verify this finding.

Identification of two novel mutations in the COMP gene in six families with pseudoachondroplasia.

Pseudoachondroplasia (PSACH; MIM no. 177170) is an autosomal dominant osteochondrodysplasia characterized by short­limb short stature, brachydactyly and early­onset osteoarthropathy. Typically, at approximately two years of age, the rate of growth falls below the standard growth curve, causing a moderately severe form of disproportionate short­limb short stature. The current study described the clinical and radiographic observations of six Chinese patients with PSACH, and identified two de novo novel missense mutations [p.Asp326Asn (c.976G>A) and c.1585A>G (p.Thr529Ala)] in cartilage oligomeric matrix protein (COMP) in the patients. The current study expanded the mutation spectrum of the COMP gene, and contributes to the understanding of phenotype/genotype of COMP­associated diseases.

OPG, RANKL, and RANK gene polymorphisms and the bone mineral density response to alendronate therapy in postmenopausal Chinese women with osteoporosis or osteopenia.

OBJECTIVE: The aim of the study was to explore the association between OPG, RANKL, and RANK gene variations and the bone mineral density (BMD) response to alendronate therapy in postmenopausal Chinese women with osteoporosis or osteopenia. MATERIALS AND METHODS: In the present study, 40 single-nucleotide polymorphisms (SNPs) in the OPG, RANKL, and RANK genes were genotyped in 501 postmenopausal Chinese women with osteoporosis or osteopenia who were given alendronate (70 mg weekly) orally for 1 year. The BMD at the lumbar spine 1-4 (L1-L4), femoral neck, and total hip was measured. RESULTS: A total of 442 patients completed 1 year of alendronate therapy. The rs7239261 SNP of the RANK gene was significantly associated with baseline L1-L4 BMD (P=0.0004) after correction for age and BMI. Participants with the SNP A allele (C/A and A/A) had a higher BMD than those with the C/C genotype (C/A vs. C/C, P=0.001; A/A vs. C/C, P=0.025). Haplotypes AG of rs7239261-rs12969154, GG of rs3826619-rs11877530, and CACG of rs1805034-rs8083511-rs17069895-rs7231887 in the RANK gene were genetic protective factors toward a higher baseline L1-L4 BMD. No association was observed between any SNP or haplotype of the OPG, RANKL, and RANK genes and the response of BMD to alendronate therapy. CONCLUSION: The RANK gene might contribute to genetic variability in L1-L4 BMD in postmenopausal Chinese women with osteoporosis or osteopenia. No evidence of an association between any SNP or haplotype of the OPG, RANKL, and RANK genes and the response of BMD to alendronate therapy was found in postmenopausal Chinese women with osteoporosis or osteopenia.

Two novel mutations of CLCN7 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.

Identification of two novel mutations in the PHEX gene in Chinese patients with hypophosphatemic rickets/osteomalacia.

OBJECTIVE: X-linked dominant hypophosphatemia (XLH) is the most prevalent form of inherited rickets/osteomalacia in humans. The aim of this study was to identify PHEX gene mutations and describe the clinical features observed in 6 unrelated Chinese families and 3 sporadic patients with hypophosphatemic rickets/osteomalacia. METHODS: For this study, 45 individuals from 9 unrelated families of Chinese Han ethnicity (including 16 patients and 29 normal phenotype subjects), and 250 healthy donors were recruited. All 22 exons and exon-intron boundaries of the PHEX gene were amplified by polymerase chain reaction (PCR) and directly sequenced. RESULTS: The PHEX mutations were detected in 6 familial and 3 sporadic hypophosphatemic rickets/osteomalacia. Altogether, 2 novel mutations were detected: 1 missense mutation c.1183G>C in exon 11, resulting in p.Gly395Arg and 1 missense mutation c.1751A>C in exon 17, resulting in p.His584Pro. No mutations were found in the 250 healthy controls. CONCLUSIONS: Our study increases knowledge of the PHEX gene mutation types and clinical phenotypes found in Chinese patients with XLH, which is important for understanding the genetic basis of XLH. The molecular diagnosis of a PHEX genetic mutation is of great importance for confirming the clinical diagnosis of XLH, conducting genetic counseling, and facilitating prenatal intervention, especially in the case of sporadic patients.

Identification of a novel mutation in the CLCN5 gene in a Chinese family with Dent-1 disease.

Dent disease comprises a group of X-linked recessive inherited renal tubular disorders, the symptoms of which include low-molecular-weight proteinuria (LMWP), hypercalciuria, nephrocalcinosis, and progressive renal failure. We sought to characterize the clinical manifestations and to identify the mutations associated with this disease in Chinese patients. In total, 155 DNA samples were collected from one affected individual, four of his family members, and 150 healthy donors. All 12 exons and the exon-intron boundaries of the CLCN5 gene were amplified and directly sequenced in this Chinese family. The proband demonstrated osteomalacia, which had resulted in more than 10 fractures, LMWP, and renal failure. A single base 'G' deletion at nucleotide 246 (c. 246delG) was identified in exon 5 of the CLCN5 gene in this patient, resulting in a frame shift mutation (fsX) that changed the Threonine (Thr) residue in position 83 to Proline (Pro). The proband's mother was found to be a carrier of this mutation. The present study suggests that a novel frameshift mutation (c. 246delG) in exon 5 of the CLCN5 gene is responsible for Dent disease in this case. Our findings also expand the known spectrum of CLCN5 mutations.

Two novel mutations in the SLCO2A1 gene in a Chinese patient with primary hypertrophic osteoarthropathy.

Primary hypertrophic osteoarthropathy (PHO) is a rare monogenetic disease characterized by digital clubbing, periostosis and pachydermia. Mutations in the 15-hydroxy-prostaglandin dehydrogenase (HPGD) gene and solute carrier organic anion transporter family member 2A1 (SLCO2A1) gene have been shown to be associated with PHO. Here, we described clinical characteristics in a Chinese patient with PHO, and identified two novel mutations in SLCO2A1: a heterozygous guanine-to-thymidine transition at the invariant -1 position of the acceptor site of intron 2 (c.235-1G>T) and a heterozygous missense mutation p.Pro219Leu (c.656C>T) in exon 5.

Mutation screening for the EXT1 and EXT2 genes in Chinese patients with multiple osteochondromas.

BACKGROUND AND AIMS: Multiple osteochondromas (MO), an autosomal dominant skeletal disease, is characterized by the presence of multiple cartilage-capped bone tumors (exostoses). Two genes with mutations that are most commonly associated with MO have been identified as EXT1 and EXT2, which are Exostosin-1 and Exostosin-2. In this study, a variety of EXT1 and EXT2 gene mutations were identified in ten Chinese families with MO. METHODS: We investigated ten unrelated Chinese families involving a total of 46 patients who exhibited typical features of MO. The coding exons of EXT1 and EXT2 were sequenced after PCR amplification in ten probands. Radiological investigation was conducted simultaneously. RESULTS: Nine mutations were identified, five in EXT1 and four in EXT2, of which three were de novo mutations and six were novel mutations. One proband carried mutations in both EXT1 and EXT2 simultaneously, and three probands, including one sporadic case and two familial cases, had no detectable mutations. CONCLUSIONS: Our findings are useful for extending the mutational spectrum in EXT1 and EXT2 and understanding the genetic basis of MO in Chinese patients.

Identification of one novel mutation in the C-propeptide of COL2A1 in a Chinese family with spondyloperipheral dysplasia.

Spondyloperipheral dysplasia (SPD; OMIM 271700) is an autosomal dominant connective tissue disorder characterized by vertebral body abnormalities (platyspondyly, end-plate indentations), hip dysplasia and brachydactyly type E. Here, we identified a novel truncating mutation (p.Lys1444AsnfsX27) in the C-propeptide of type II collagen in an affected Chinese individual with SPD. Our findings will provide clues to the phenotype-genotype relations and may assist not only in the clinical diagnosis of SPD but also in the interpretation of genetic information used for prenatal diagnosis and genetic counseling.