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Tumor-induced osteomalacia (TIO) is a rare paraneoplastic syndrome caused by mesenchymal tumors that secrete fibroblast growth factor 23 (FGF23). Patients present with progressive bone pain, muscle weakness, and fragility fractures. TIO is characterized by hypophosphatemia, excess renal phosphate excretion, and low/inappropriately normal 1,25-dihydroxyvitamin D (1,25(OH)2D) levels. Rarity and enigmatic clinical presentation of TIO contribute to limited awareness among the medical community. Accordingly, appropriate diagnostic tests may not be requested, leading to delayed diagnosis and poorer patient outcomes. We have developed a global guidance document to improve the knowledge of TIO in the medical community, enabling the recognition of patients with TIO and appropriate referral. We provide recommendations aiding diagnosis, referral, and treatment, helping promote a global standard of patient management. We reviewed the literature and conducted a three-round Delphi survey of TIO experts. Statements were drafted based on published evidence and expert opinions (≥70% consensus required for final recommendations). Serum phosphate should be measured in patients presenting with chronic muscle pain or weakness, fragility fractures, or bone pain. Physical examination should establish features of myopathy and identify masses that could be causative tumors. Priority laboratory evaluations should include urine/serum phosphate and creatinine to assess renal tubular reabsorption of phosphate and TmP/GFR, alkaline phosphatase, parathyroid hormone, 25-hydroxyvitamin D, 1,25(OH)2D, and FGF23. Patients with the clinical/biochemical suspicion of TIO should be referred to a specialist for diagnosis confirmation, and functional imaging should be used to localize causative tumor(s). Recommended treatment is tumor resection or, with unresectable/unidentifiable tumors, phosphate salts plus active vitamin D, or burosumab.

Background Progressive pseudorheumatoid dysplasia (PPRD) is a rare genetic disease with autosomal recessive inheritance. There was a lack of genotype–phenotype correlation data from the Chinese population. This study aimed to identify the genotype and phenotype characteristics of Chinese PPRD patients and to conduct a genotype–phenotype analysis of Chinese PPRD patients. Methods Genetic analysis was performed for suspected PPRD patients from Peking Union Medical College Hospital. Medical records were collected from the electronic medical record system and patient-held portable health records. Published Chinese PPRD cases were gathered from both international and Chinese local databases. We collected demographic information, genetic variants, clinical manifestations, and imaging characteristics for further analysis. Results We included 105 Chinese PPRD patients in the current study. Thirty-three variants, including nine novels and five hotspot variants, were identified, with 26/33 (79%) variants exclusively seen in the Chinese population. Chinese PPRD patients share a phenotype similar to that in international reports. Joint involvement may progress with age (R2 = 0.2541). Long bone shortening and severe deformities occur in three patients with biallelic null variants, of which at least one variant is located in exon 2. Among hotspot variants, c.624dupA (p.C209Mfs*21) were associated with later onset and more involved joints. Elbow joints were more likely to be affected in patients carrying c.624dupA (p.C209Mfs*21) and c.866dupA (p.S209Efs*13). Shoulder joints are more likely to be involved in patients with biallelic null variants (P = 0.027). Conclusions Chinese PPRD patients share a unique mutation spectrum. Among the five hotspot variants, c.624dupA is associated with later onset of disease, more extensive joint involvement, and a tendency to affect elbow joints. Biallelic null variants with at least one variant in exon 2 could be a likely cause of long bone shortening and severe deformities.

Autoimmune polyendocrine syndrome type 1 (APS-1) is a rare inherited autoimmune disease, characterized by a classic triad, including chronic mucocutaneous candidiasis, primary adrenocortical insufficiency and hypoparathyroidism. The present study investigated phenotypes and pathogenic variants in a Chinese woman with non-classical APS-1. Disease-associated variants in a patient with APS-1 were identified via targeted next generation sequencing and the variant was confirmed via Sanger sequencing. Serum levels of calcium, phosphorus, parathyroid hormone (PTH), follicle-stimulating hormone (FSH), luteinizing hormone (LH), estradiol and urinary levels of calcium were measured. Blood count assays and bone marrow morphology were investigated. The patient was a 32-year-old woman who had suffered from typical carpopedal spasms since she was 7 years old. She developed syncope, primary amenorrhea, intermittent diarrhea and general fatigue in subsequent years. Hypocalcemia, hyperphosphatemia, low levels of PTH and estradiol, elevated levels of FSH and LH, and absence of erythroblasts were observed, which indicated hypoparathyroidism, primary ovarian insufficiency and pure red cell aplasia. A novel heterozygous missense variant (NM_000383.2: c.623G>T, NP_000374.1: p.Gly208Val) in exon 5 of autoimmune regulator and a reported variant (NM_000383.2: c.371C>T, NP_000374.1: p.Pro124Leu) in exon 3 were detected, of which the c.623G>T variant may be a pathogenic variation that induces APS-1. Under a regular follow-up and therapeutic adjustment of calcium, calcitriol, hormone replacement therapy and methylprednisolone, the endocrine function and clinical symptoms of the patient were notably improved. The results of the present study expand the known genetic and phenotypical spectra of APS-1.

Summary Zoledronic acid (ZOL) is a therapy inhibiting bone resorption. In this study, generic ZOL (Yigu®) showed its clinical efficacy consistency with original ZOL (Aclasta®) in Chinese postmenopausal women with osteoporosis. This study provides a practical basis for the application of Yigu® in Chinese population. Introduction Yigu® has been approved its bioequivalence to Aclasta®. However, the clinical efficacy and safety of Yigu® have not been evaluated yet. Here, we compared the effectiveness and safety between Yigu® and Aclasta® in Chinese postmenopausal women with osteoporosis and assessed the efficacy of intravenous infusion of ZOL. Methods This was a randomized open-label, active-controlled study in postmenopausal women with osteoporosis of 14 clinical centers in China. Postmenopausal women with osteoporosis were recruited and randomized to receive a single infusion of 5 mg Yigu® or Aclasta®. The primary endpoint was the percentage change in bone mineral density (BMD) at lumbar spine after 12 months of treatment and was assessed for equivalence. The secondary endpoint was the percentage change in BMD at proximal femur after 12 months. Additional secondary endpoints were percentage changes in BMD at the above sites after 6 months of treatment and changes in bone turnover biomarkers during ZOL treatment. Safety was also evaluated and compared between two groups. Results A total of 458 postmenopausal women with osteoporosis were enrolled (n = 227, Yigu®; n = 231, Aclasta®). The mean percentage change in the BMD had no statistical difference at the lumbar spine (5.32% vs 5.18%), total hip (2.72% vs 2.83%), and femoral neck (2.37% vs 2.81%) between Yigu® and Aclasta® groups after 12 months of treatment. The mean difference of BMD change at the lumbar spine after 12 months between two groups was 0.15% (95% CI: − 0.71 to 1.00, equivalence margin: − 1.5%, 1.5%), demonstrating the treatments were equivalent. Meanwhile, the decreases in the P1NP and β-CTX showed no difference between two groups after 14 days and 6 and 12 months of treatment. As regards the whole sample, BMD significantly increased after 12 months of treatment. Also, serum C-terminal telopeptide of type 1 collagen (β-CTX) and procollagen 1 N-terminal peptide (P1NP) significantly decreased at each visit period. The overall adverse events were comparable and quite well between two groups. Conclusion Intravenous infusion of zoledronic acid achieved the potent anti-resorptive effects which led to significant increase in BMD of Chinese postmenopausal women with osteoporosis. Yigu® was equivalent to Aclasta® with respect to efficacy and safety.

Background Primary hypertrophic osteoarthropathy (PHO) is a rare disease related to HPGD and SLCO2A1 gene mutation. Gastrointestinal involvement of PHO is even rarer with unknown pathogenesis. Clinical features of GI complication in PHO mimics other auto-immune based bowel entities, such as inflammatory bowel diseases and cryptogenic multifocal ulcerous stenosing enteritis (CMUSE). We aimed to analyze the clinical, genetic, radiological and pathological features of Chinese patients with PHO and determine the difference between PHO patients presenting with and without GI involvement. Methods We reported two PHO cases with gastrointestinal involvement and reviewed all the studies of PHO in Chinese population published from January 1, 2000, to April 30, 2018. Clinical and genetic presentations of PHO in Chinese patients were analyzed. We compared the characteristics of those patients with gastrointestinal involvement against those without. Results The two patients were both males with complete-form PHO for more than 10 years. GI related symptoms included diarrhea, chronic gastrointestinal hemorrhage, incomplete intestinal obstruction, anemia, and edema, which were unresponsive to etoricoxib treatment. Radiological examinations revealed segmental intestinal stenosis and thickened intestinal wall. Endoscopic findings included multiple ulcers and mucosal inflammation. Both patients had mutations of SLCO2A1 according to sequence analysis. The surgical pathology revealed chronic inflammation involving the intestinal mucosa and submucosa, similar to histological changes in CMUSE. According to the systemic review of 158 Chinese patients with PHO, 17.2% had gastrointestinal involvement, including peptic ulcer, gastric polyps, hypertrophic gastritis, and segmental intestinal stenosis. Patients with gastrointestinal involvement were more likely to have anemia (40.0% vs. 4.5%, P P = 0.003), and myelofibrosis (19.0% vs. 0.9%, P = 0.002) than those without. Most patients with gastrointestinal complication had SLCO2A1 mutation (86.7%, 13 /15). Conclusions Digestive tract involvement is uncommon in patients with PHO and often presents with anemia, and hypoalbuminemia resulted from intestinal inflammation. The intestinal pathologic characteristics are distinct from Crohn’s disease but similar to CMUSE. Mutations in SLCO2A1 might be the pathogenic cause of GI involvement of PHO. NSAIDs may not be effective for PHO patients with gastrointestinal complications.

At least 15 candidate genes have been implicated in hypoparathyroidism (HP). However, comprehensive screening of causative genes for HP is lacking. Here, we investigated the genotype spectrum in a large group of Chinese patients with childhood onset HP. A total of 173 patients with childhood onset HP were analyzed using targeted next-generation sequencing (NGS), including 15 candidate genes combined with multiplex ligation-dependent probe amplification (MLPA) of the TBX1 gene. Twenty-seven pathogenic or likely pathogenic mutations in five genes (TBX1, AIRE, GATA3, FAM111A, and CASR) including 13 novel variants in 23 patients, and 12 variants of uncertain clinical significance in five genes (GATA3, CASR, FAM111A, GCM2, and PTH) in 11 patients, were identified by NGS. Additionally, an entire gene deletion of TBX1 in 25 patients was found by TBX1-MLPA. Combined with clinical data, 26 (15.0%) cases of DiGeorge syndrome (OMIM #188400), nine (5.2%) autoimmune polyglandular syndrome type 1 (OMIM #240300), eight (4.6%) autosomal dominant hypocalcemia type 1 (OMIM #601198), four (2.3%) hypoparathyroidism-deafness-renal dysplasia syndrome (OMIM #146255), and one (0.6%) Kenny-Caffey syndrome type 2 (OMIM #127000) were verified. Among them, 16 of 26 (61.5%) DiGeorge syndrome cases were undiagnosed due to the lack of obvious clinical clues before genetic testing. The onset age of patients with mutations (median [interquartile range], 2.8 [0.1, 9.6] years) was significantly earlier than those without mutations (13.0 [8.8, 15.0] years) (p

Osteoporosis in men has been neglected despite its association with disability and mortality. We evaluated the effect of bisphosphonates (BPs) on bone mineral density (BMD) and bone turnover biomarkers of osteoporotic men with different androgen levels.This case-control study included 136 osteoporotic men who were divided into normal group (n = 75) and hypogonadism group (n = 61) (patients treated with testosterone were excluded) according to their serum testosterone levels (cutoff value, 350 ng/dL). BMD, serum testosterone, total alkaline phosphatase, and cross-linked C-telopeptide of type I collagen were detected. The relationship between testosterone levels and BMD at baseline was evaluated. All patients were treated with BPs for 2 years. We compared the effects of BPs on BMD and bone turnover biomarkers between the 2 groups.At baseline, there were no significant differences in BMD and bone turnover biomarkers between the 2 groups. Testosterone levels were positively correlated with BMD in the hypogonadism group. After treatment, the lumbar BMD increased by 7.65% ± 1.54% and 7.47% ± 1.88% in normal and hypogonadism groups, respectively (both P.01 vs baseline) and hip BMD increased without significant differences between the 2 groups. Serum cross-linked C-telopeptide of type I collagen and alkaline phosphatase levels decreased without significant differences between the 2 groups (all P.01 vs baseline).Testosterone level is positively correlated with BMD in men with hypogonadism. In osteoporotic men, BPs significantly increase spine and hip BMD and decrease bone resorption. The efficacy of BPs is similar in men with or without hypogonadism.

Hyperplastic callus (HPC) is the most conspicuous features of osteogenesis imperfecta (OI) type V, of which accurate diagnosis and treatment are facing challenges. We investigate the clinical features, and impact factors of HPC in OI type V patients. In this retrospective single-center study, a total of 21 patients with type V OI confirmed by IFITM5 mutation were included. Radiological characteristics of bone were evaluated by X-rays, dual-energy X-ray absorptiometry, and computed tomography scan. Bone biopsy specimens were performed and stained by routine hematoxylin-eosin. The effects of bisphosphonates on HPC were investigated. Eleven patients (52.3%) had HPCs at 19 skeletal sites, 11 of which affected the femur. Three patients developed four (21.1%) HPCs after fractures, and 15 (78.9%) HPCs occurred in absence of bone fracture. The progress of HPCs was variable, of which most HPCs enlarged in the initial phase and remained stable, and only one HPC dwindled in size. One patient had a rapidly growing mass on the right humerus, and biopsy showed irregular trabeculae of woven bone and immature bone and cartilage in the loose and edematous collagenous network without signs of tumor. Bisphosphonates treatment had no significant effects on HPC of OI patients. HPC is the specific characteristic of OI type V patients, and its location, shape, size, and progression are variable, and the femur is the most frequently involved site. It is very important to make a diagnosis of HPC through detecting IFITM5 mutation and completing pathological diagnosis if necessary. The treatment of HPC is worth further exploration.

Background Osteogenesis imperfecta (OI) is a phenotypically and genetically heterogeneous bone disease characterized by bone fragility and recurrent fractures. X‐linked inherited OI with mutation in PLS3 is so rare that its genotype–phenotype characteristics are not available. Methods We designed a novel targeted next‐generation sequencing (NGS) panel with the candidate genes of OI to detect pathogenic mutations and confirmed them by Sanger sequencing. The phenotypes of the patients were also investigated. Results The proband, a 12‐year‐old boy from a nonconsanguineous family, experienced multiple fractures of long bones and vertebrae and had low bone mineral density (BMD Z‐score of −3.2 to −2.0). His younger brother also had extremity fractures. A novel frameshift mutation (c.1106_1107insGAAA; p.Phe369Leufs*5) in exon 10 of PLS3 was identified in the two patients, which was inherited from their mother who had normal BMD. Blue sclerae were the only extraskeletal symptom in all affected individuals. Zoledronic acid was beneficial for increasing BMD and reshaping the compressed vertebral bodies of the proband. Conclusion We first identify a novel mutation in PLS3 that led to rare X‐linked OI and provide practical information for the diagnosis and treatment of this disease., A novel frameshift mutation was identified to cause X‐linked osteogenesis imperfecta (OI) in this study. Clinical hallmarks of the extremely rare disease were recurrent fractures. Bisphosphonates (BPs) were effective for these patients. Our findings may provide helpful information for clinical diagnosis and management of X‐linked OI.

We identified a novel large fragment deletion from intron 9 to 3’UTR in PLS3 (E10-E16del) in one Chinese boy with X-linked early-onset osteoporosis and vertebral fractures, which expanded the pathogenic spectrum of X-linked early-onset osteoporosis. Treatment with zoledronic acid was beneficial for increasing BMD and reshaping the vertebral bodies of this patient. X-linked early-onset osteoporosis is a rare disease, which is characterized by low bone mineral density (BMD), vertebral compression fractures (VCFs), and/or long bone fractures. We aimed to detect the phenotype and the underlying pathogenic mutation of X-linked early-onset osteoporosis in a boy from a nonconsanguineous Chinese family. We investigated the pathogenic mutation of the patient with X-linked early-onset osteoporosis by targeted next-generation sequencing and confirmed it by Sanger sequencing. We also observed the effects of zoledronic acid on fracture frequency and BMD of the patient. Low BMD and multiple VCFs were the main phenotypes of X-linked early-onset osteoporosis. We identified a total of 12,229 bp deletion in PLS3, involving intron 9 to the 3’UTR (E10-E16 del). This large fragment deletion might be mediated by Alu repeats and microhomology of 26 bp at each breakpoint junction. Zoledronic acid treatment could significantly increase the Z-score of BMD and reshape the compressed vertebral bodies. We identified a large fragment deletion mutation in PLS3 for the first time and elucidated the possible mechanism of the deletion, which led to X-linked early-onset osteoporosis and multiple vertebral fractures. Our findings would enrich the etiology spectrum of this rare disease.

Fibrous dysplasia (FD) is a rare disorder characterized by pain, deformity, and pathologic fractures. McCune-Albright syndrome (MAS) includes a combination of FD, hyperfunctional endocrinopathy, and/or café-au-lait pigmentation. Surgery is generally ineffective in treating FD. This study aimed to evaluate the efficacy and safety of bisphosphonates (BPs) and compare the efficacy of different BPs in FD patients.In this retrospective clinical study, laboratory and clinical findings of 22 polyostotic FD cases all associated with MAS were recorded before and after therapy with BPs.Within the first year of therapy with BPs, the level of alkaline phosphatase (ALP) decreased by 30.3% of baseline in the alendronate cases and by 22.7 ± 16.9% and 34.1 ± 26.3% in the pamidronate (PAM) (n = 10) and zoledronic acid (ZA) (n = 11) groups, respectively. There was no significant difference ( P = .256) between the PAM and ZA groups in the rate of change in ALP levels. Bone pain was alleviated in 64% of the cases. Number of affected bones was positively correlated with baseline serum ALP levels ( r = 0.533; P = .011), which was the only significant factor affecting efficacy of BPs. BP treatment was safe and caused no obvious impairment on children's linear growth.Our results suggest that BPs may suppress high bone turnover to partially control the activity of the disease and are well tolerated in most patients. ZA has similar effects as PAM in controlling disease activity.ALP = alkaline phosphatase; β-CTX = C-terminal telopeptide of type I collagen; BP = bisphosphonate; BTM = bone turnover marker; FD = fibrous dysplasia; MAS = McCune-Albright syndrome; ONJ = osteonecrosis of the jaw; PAM = pamidronate; PFD = polyostotic fibrous dysplasia; ULN = upper limit of normal; ZA = zoledronic acid.

Key points The inheritance of two defective alleles of SLC4A4, the gene that encodes the widely-expressed electrogenic sodium bicarbonate cotransporter NBCe1, results in the bicarbonate-wasting disease proximal renal tubular acidosis (pRTA). In the present study, we report the first case of compound-heterozygous inheritance of pRTA (p.Arg510His/p.Gln913Arg) in an individual with low blood pH, blindness and neurological signs that resemble transient ischaemic attacks. We employ fluorescence microscopy on non-polarized (human embryonic kidney) and polarized (Madin–Darby canine kidney) renal cell lines and electrophysiology on Xenopus oocytes to characterize the mutant transporters (R510H and Q913R). Both mutant transporters exhibit enhanced intracellular retention in renal cells, an observation that probably explains the HCO3− transport deficit in the individual. Both mutants retain a close-to-normal per molecule Na+/HCO3− cotransport activity in Xenopus oocytes, suggesting that they are suitable candidates for folding-correction therapy. However, Q913R expression is uniquely associated with a depolarizing, HCO3− independent, Cl−-conductance in oocytes that could have pathological consequences if expressed in the cells of patients. Abstract Proximal renal tubular acidosis (pRTA) is a rare, recessively-inherited disease characterized by abnormally acidic blood, blindness, as well as below average height and weight. pRTA is typically associated with homozygous mutation of the solute carrier 4 family gene SLC4A4. SLC4A4 encodes the electrogenic sodium bicarbonate cotransporter NBCe1, a membrane protein that acts to maintain intracellular and plasma pH. We present the first description of a case of compound-heterozygous inheritance of pRTA. The individual has inherited two mutations in NBCe1: p.Arg510His (R510H) and p.Gln913Arg (Q913R), one from each parent. In addition to the usual features of pRTA, the patient exhibits unusual signs, such as muscle spasms and fever. We have recreated these mutant transporters for expression in model systems. We find that both of the mutant proteins exhibit substantial intracellular retention when expressed in mammalian renal cell lines. When expressed in Xenopus oocytes, we find that the R510H and Q913R-mutant NBCe1 molecules exhibit apparently normal Na+/HCO3− cotransport activity but that Q913R is associated with an unusual HCO3− independent anion-leak. We conclude that a reduced accumulation of NBCe1 protein in the basolateral membrane of proximal-tubule epithelia is the most probable cause of pRTA in this case. We further note that the Q913R-associated anion-leak could itself be pathogenic if expressed in the plasma membrane of mammalian cells, compromising the benefit of strategies aiming to enhance mutant NBCe1 accumulation in the plasma membrane.

The carbonic anhydrase II (CAII) deficiency syndrome is a rare autosomal recessive osteopetrosis with renal tubular acidosis (RTA) and cerebral calcifications (MIM259730). CAII deficiency syndrome is caused by mutations in the gene CAII, which encodes the enzyme carbonic anhydrase II. CAII mutations are rarely reported in the Asian population. Here, we described two unrelated CAII deficiency families of Chinese Han origin with clinical and genetic analysis. Altogether, 106 subjects, including 2 probands, 4 unaffected family members from two non-consanguineous Chinese families, and 100 healthy controls were recruited. All seven exons and the exon-intron boundaries of the CAII gene were amplified and directly sequenced. Reverse transcription PCR (RT-PCR) was used to study the effect of splice site mutation. All clinical and biochemical parameters of the probands were collected. Two novel mutations of CAII gene were identified by mutational analysis: A nonsense mutation in exon 4 (c.T381C p.Y127X) in both families; a splice mutation at the splice donor site of intron 3 (c.350+2T>C, IVS3+2T>C) in one family. The splice-site mutation causes exon 3 skipping in patient's mRNA resulting in an in-frame deletion and a novel premature stop codon. These mutations were predicted to result in a loss of function of CAII. This is the first report of CAII deficiency syndrome in Chinese population. Our findings extent the spectrum of CAII mutations observed in patients with CAII deficiency syndrome.

OBJECTIVE: To study the clinical features of two families with distal renal tubular acidosis (dRTA) and mutations in the pathogenic gene SLC4A1. METHODS: Family investigation, medical history collection, and measurement of biochemical parameters were performed to analyze the clinical phenotype and genetic characteristics of dRTA. Direct sequencing was used to detect SLC4A1 gene mutations. RESULTS: Three patients in these two families (two of them were mother and son) were diagnosed with dRTA with typical clinical features, including short stature, metabolic acidosis, alkaline urine, hypokalemia, and nephrocalcinosis. SLC4A1 gene analysis showed that all the three patients had a pathogenic missense mutation R589H (c.1766G > A). The child in family 1 had a de novo mutation of SLC4A1, and the child in family 2 had an SLC4A1 gene mutation inherited from the mother, which met the characteristic of autosomal dominant inheritance. CONCLUSIONS: This study reports the R589H mutation in SLC4A1 gene in families with hereditary dRTA for the first time in China. Clinical physicians should perform gene detection for patients suspected of hereditary dRTA to improve the diagnosis and treatment of this disease.

Aim: To investigate the association between LRP5 gene polymorphisms and response to alendronate in Chinese osteoporotic women. Materials & methods: Six hundred and thirty nine Chinese postmenopausal women with osteopenia or osteoporosis were included and received alendronate treatment. The A1330V polymorphism of LRP5 was investigated. Bone mineral density (BMD) and bone turnover markers (ALP and β-isomerized carboxy-telopeptide of type I collagen [β-CTX]) were measured before and after treatment. The correlation of LRP5 polymorphisms with changes in BMD and bone turnover biomarkers were analyzed after treatment. Results: After 12 months of treatment, participants with CC and CT genotypes had a larger increase in lumbar spine BMD and a larger decrease in serum β-CTX and ALP levels than those with TT genotype (all p < 0.001). No significant genotype–treatment interaction was found in hip BMD. Conclusion: The A1330V polymorphism of LRP5 is possibly correlated with response to alendronate treatment in Chinese women with osteoporosis, and the TT genotype could possibly predict a weak response to alendronate. Original submitted 31 October 2013; Revision submitted 13 January 2014

Osteogenesis imperfecta (OI) is a group of inherited disorders characterized by recurrent fragile fractures. Serpin peptidase inhibitor, clade F, member 1 (SERPINF1) is known to cause a distinct, extremely rare autosomal recessive form of type VI OI. Here we report, for the first time, the detection of SERPINF1 mutations in Chinese OI patients. We designed a novel targeted next-generation sequencing panel of OI-related genes to identify pathogenic mutations, which were confirmed with Sanger sequencing and by co-segregation analysis. We also investigated the phenotypes of OI patients by evaluating bone mineral density, radiological fractures, serum bone turnover markers, and pigment epithelium-derived factor (PEDF) concentration. Six patients with moderate-to-severe bone fragility, significantly low bone mineral density, and severe deformities of the extremities were recruited from five unrelated families for this study. Six pathogenic mutations in SERPINF1 gene were identified, five of which were novel: (1) a homozygous in-frame insertion in exon 3 (c.271_279dup, p.Ala91_Ser93dup); (2) compound heterozygous mutations in intron 3 (c.283 + 1G > T, splicing site) and exon 5 (c.498_499delCA, p.Arg167SerfsX35, frameshift); (3) a homozygous frameshift mutation in exon 8 (c.1202_1203delCA, p.Thr401ArgfsX); (4) compound heterozygous missense mutation (c.184G > A, p.Gly62Ser) and in-frame insertion (c.271_279dup, p.Ala91_Ser93dup) in exon 3; and (5) a heterozygous nonsense mutation in exon 4 (c.397C>T + ?, p.Gln133X + ?). Serum PEDF levels were barely detectable in almost all subjects. We identified five novel mutations in SERPINF1 and confirmed the diagnostic value of serum PEDF level for the first time in Chinese patients with the extremely rare OI type VI.

The inheritance of two defective alleles of SLC4A4, the gene that encodes the widely-expressed electrogenic sodium bicarbonate cotransporter NBCe1, results in the bicarbonate-wasting disease proximal renal tubular acidosis (pRTA). In the present study, we report the first case of compound-heterozygous inheritance of pRTA (p.Arg510His/p.Gln913Arg) in an individual with low blood pH, blindness and neurological signs that resemble transient ischaemic attacks. We employ fluorescence microscopy on non-polarized (human embryonic kidney) and polarized (Madin-Darby canine kidney) renal cell lines and electrophysiology on Xenopus oocytes to characterize the mutant transporters (R510H and Q913R). Both mutant transporters exhibit enhanced intracellular retention in renal cells, an observation that probably explains the HCOProximal renal tubular acidosis (pRTA) is a rare, recessively-inherited disease characterized by abnormally acidic blood, blindness, as well as below average height and weight. pRTA is typically associated with homozygous mutation of the solute carrier 4 family gene SLC4A4. SLC4A4 encodes the electrogenic sodium bicarbonate cotransporter NBCe1, a membrane protein that acts to maintain intracellular and plasma pH. We present the first description of a case of compound-heterozygous inheritance of pRTA. The individual has inherited two mutations in NBCe1: p.Arg510His (R510H) and p.Gln913Arg (Q913R), one from each parent. In addition to the usual features of pRTA, the patient exhibits unusual signs, such as muscle spasms and fever. We have recreated these mutant transporters for expression in model systems. We find that both of the mutant proteins exhibit substantial intracellular retention when expressed in mammalian renal cell lines. When expressed in Xenopus oocytes, we find that the R510H and Q913R-mutant NBCe1 molecules exhibit apparently normal Na

Osteoporosis is a disease of disequilibrium between bone formation and bone loss, and vitamin D is one of the key hormones in the regulation of bone metabolism, the major role of which is to provide the proper micro-environment for bone mineralization. Vitamin D deficiency which has been defined by most experts as circulating 25-hydroxyvitamin D levels of less than 20 ng/mL (50 nmol/L) is widespread all over the world. As shown by the results of recent studies, vitamin D deficiency could increase the risk of low bone mineral density or osteoporosis, muscle disorders, falls, and as a matter of course, fractures due to both osteoporosis and falls. Long-term supplementation of vitamin D and calcium are good prevention measures for osteoporosis, falls and fractures. At the same time, they are essential components of osteoporosis management. Many studies show that sufficient vitamin D intake could increase bone mass, and decrease the risk of falls and fractures.

A normal reference value of parathyroid hormone (PTH) was established for the first time in a large sample of healthy Chinese subjects by completely excluding interference of vitamin D deficiency. A high PTH level correlated significantly with an elevated bone turnover and a reduced bone mineral density (BMD). The aims of this study are to establish a normal reference value for serum PTH and to evaluate the effect of parathyroid gland status on bone turnover and BMD. Our cross-sectional study included 1436 healthy individuals from 5 different Chinese cities. Concentrations of serum PTH, 25-hydroxyvitamin D (25OHD), procollagen I N-terminal peptide (P1NP, a bone formation marker), and carboxyl-terminal telopeptide of type I collagen (β-CTX, a bone resorption marker) were measured by electrochemiluminescence immunoassay. BMD was measured by dual-energy X-ray absorptiometry. The relation of PTH concentration to age, gender, height, and weight was examined. Reference values of PTH were established for all subjects and for subjects categorized by serum 25OHD concentrations. Correlations of PTH levels with bone turnover biomarkers and BMD were statistically analyzed. Reference values of PTH were 8.84–69.95 pg/mL in all the subjects and 7.48–60.73 and 5.83–56.78 pg/mL in the subjects with serum 25OHD concentrations of ≥20 and ≥30 ng/mL, respectively. Serum PTH showed a negative linear correlation with 25OHD, and the breakpoint was 18.21 ng/mL, below which the PTH level rapidly increased. The increase in PTH levels with age showed a positive linear correlation with P1NP and β-CTX concentrations and a negative linear correlation with BMD at the lumbar spines and the femoral neck. A reference value of PTH was established in a large sample of healthy Chinese subjects according to 25OHD status, gender, and age. A high PTH level correlated significantly with an elevated bone turnover and a reduced BMD.

Osteopetrosis is a group of genetic bone disorders. Mutations in the chloride channel 7 gene (CLCN7) lead to chloride channel defect, which results in autosomal dominant osteopetrosis type II (ADO-II), autosomal recessive osteopetrosis (ARO), and intermediate autosomal recessive osteopetrosis (IARO). In the present study, we identified seven novel mutations of the CLCN7 gene and reported the first case of IARO with compound heterozygous mutation in Chinese population. Osteopetrosis is a heritable bone disorder due to the deficiency of or function defect in osteoclasts. Mutations in the CLCN7 lead to chloride channel defects, which result in osteopetrosis with diverse severity ranging from asymptomatic or relatively mild symptoms in ADO-II to the very severe phenotype in ARO. Heterozygous mutations in CLCN7 are associated to ADO-II, while homozygous and compound heterozygous mutations in CLCN7 may result in ARO and IARO. To date, a total of 24 mutations in CLCN7 were identified in ADO-II, and only 3 mutations were identified in IARO. In the present study, we reported seven unrelated ADO-II patients and one IARO patient from Chinese population and elucidated the characteristics of CLCN7 gene mutations in these patients. All 25 CLCN7 exons and exon-intron boundaries from genomic DNA were amplified and sequenced in eight affected individuals suffering from ADO-II/IARO. The clinical, biochemical, and radiographic analysis were evaluated to compare the differences between ADO-II and IARO both in genotype and phenotype. The results showed that there were seven novel CLCN7 mutations identified in these ADO-II/IARO patients, including six heterozygous missense mutations (p.L224R, p.S290Y, p.R326G, p.G347R, p.S473N, and p.L564P) and a novel splice mutation (p.K691FS). The compound heterozygous mutations (p.L224R and p.K691FS) were firstly observed in one IARO patient. The present study would enrich the database of CLCN7 mutations and improve our understanding of this heritable bone disorder.

Pycnodysostosis is a rare autosomal recessive skeletal dysplasia characterized by short stature, osteosclerosis, acro-osteolysis, frequent fractures, and skull deformities. Mutation in the gene encoding cathepsin K (CTSK), which is a lysosomal cysteine protease, has been found to be responsible for this disease. Here we reported a consanguineous Chinese family with 1 affected individual demonstrating autosomal recessive pycnodysostosis with recurrent kidney stone, a new clinical manifestation which has not been reported in patients of pycnodysostosis before. To identify the pathogenic mutation, we evaluated the patient clinically, biochemically, and radiographically. To screen for mutations in the CTSK gene of the patient and his family members, all of its exons and exon-intron junctions were PCR amplified from genomic DNA and sequenced. Sequence analysis of the patient's CTSK gene revealed homozygosity for a missense mutation (c.746T>C) in exon 6, which leads to amino change (p.Ile249Thr) in the mature CTSK protein. This mutation was firstly reported by Michela Donnarumma and his colleagues in 2007 in a Spanish family. Our study strengthens the role of this particular mutation in the pathogenesis of pycnodysostosis.

To explore the clinico-genetic characteristics and protein status of parathyroid carcinoma (PC) diagnosed at Peking Union Medical College Hospital from January 1980 to December 2012.Genomic DNA was extracted from peripheral blood lymphocytes and paraffin-embedded tissue for analysis. The mutations of CDC73 gene were detected by direct sequencing. And the expression of parafibromin in tumor tissues was evaluated by immunohistochemical analysis.Twenty-four PC patients were recruited. The mean ages at the diagnosis of PHPT and PC were 42.2 and 42.6 years respectively. The serum calcium at the diagnosis of PHPT was 3.78 mmol/L, serum phosphorus 0.65 mmol/L and the median increment of serum parathyroid hormone (PTH) level 20.0. The recurrent rate was 76.2% during a 5-year follow-up.Genetic analysis identified 11 mutations of CDC73 gene (45.8%), among which c.34_35 insCT, c.626_629 delAACA, c.260_261 delGA, c.570 delG, c.40 CT and IVS3+1 GA were novel mutation first identified in our cohort. Nine of them had germline mutations. All tissue samples from normal parathyroid displayed strong positive immunostaining of parafibromin. Complete (55%, 11/20) or partial (45%, 9/20) loss of parafibromin expression was observed in PC tissues. The age at the diagnosis of PHPT, serum calcium, serum phosphorus, PTH, alkaline phosphatase (ALP), bone involvement rate, kidney stone/calcification rate, recurrent rate, metastatic rate and immunostaining level showed no significant difference between the patients with and without CDC73 mutation.In Chinese population, CDC73 mutation and complete/partial loss of immunohistochemical staining for parafibromin occur frequently in PC. Therefore it may be useful in the subset of tumors with equivocal histological examination.

To explore the clinical and genetic characteristics of a Chinese boy with infantile hypophosphatasia.The clinical data of the boy was carefully collected. The laboratory and radiographic examination were taken in the case. Sequencing for all the twelve ALPL exons and the flanking exon-intron junctions was performed in the proband and his parents with their genomic DNA.Two mutations were found with one missense mutation c.814CT (p. R272C) in the proband and his father and the other deletion mutation c.1101_1103 delCTC (p.S368del) in the proband and his mother. The proband was manifested as a compound heterozygotes of the two mutations. The mutations were not detected in fifty normal controls.The result suggests that the compound heterozygous mutation in ALPL is responsible for infantile hypophosphatasia in the Chinese family.

To compare the accuracy of whole body diffusion weighted magnetic resonance imaging (WB-DWI) with that of somatostatin receptor scintigraphy (SRS) in the detection and localization of the lesions in patients with oncogenic osteomalacia (OOM).Totally 6 patients with clinically suspected oncogenic osteomalacia were enrolled. All of them underwent WB-DWI and SRS within 2 weeks to evaluate the possible presence of tumors that lead to osteomalacia. Surgical and pathological findings were considered as the gold standard. The sensitivity, specificity, and accuracy were calculated.Pathology confirmed the diagnosis of two soft tissue tumors (including 1 angiolipoma and 1 mesenchymal tumor) and one bone tumor of malignant neurofibroma. The sensitivity, specificity, and accuracy in the identification of lesions in patients with oncogenic osteomalacia were 33.33%, 100%, 66.67% for WB-DWI and 33.33%, 66.67%, 50% for SRS (P0.05).For adult patients with osteomalacia, WB-DWI and SRS can provide mutually supportive data and be used for identifying potential oncogenic osteomalacia.

It is widely recognized that the diagnosis of parathyroid carcinoma (PC) is often difficult because of the overlap of characteristics between malignant and benign parathyroid tumors, especially at an early stage. Our study aimed to investigate the differential expression of Ki-67, galectin-3, fragile histidine triad (FHIT) gene, and parafibromin in PC, parathyroid adenoma (PA), parathyroid hyperplasia (PH), and normal parathyroid (NP) tissues; then to assess these expression values for use in differential diagnosis of malignant and benign parathyroid tumors.Data of 15 cases with PC, 19 PAs, and 8 PHs were retrospectively analyzed for their clinical characteristics. The expression of Ki-67, galectin-3, FHIT, and parafibromin were detected via immunohistochemistry in the above-mentioned specimens and 6 NPs as control.Complete loss of parafibromin expression was seen in 9 of 15 (60%) carcinomas, and all normal parathyroid tissues and parathyroid benign tumors stained positive for parafibromin except for one (4%) adenoma. Galectin-3 staining was positive in 11 of 15 (73%) carcinomas, 5 of 19 (26%) adenomas, 1 of 8 (12%) hyperplasias, and 0 of 6 normal tissues. The Ki-67 proliferative index was high in 4 of 15 (27%) carcinomas, 1 of 19 (5%) adenomas, and none of the hyperplasia or normal tissues. FHIT expression did not differ appreciably among the tumor types. The combination of overexpression of galectin-3 or loss of parafibromin increased sensitivity for PC to 87%, while the specificity of both positive galectin-3 and positive Ki-67 could reach 100%.These data suggested that loss of parafibromin and overexpression of galectin-3 and Ki-67 might help to distinguish parathyroid carcinoma from other parathyroid tumors. And the combination of two or three of these markers might produce better sensitivity and/or specificity for the diagnosis of parathyroid carcinoma.

Autosomal recessive polycystic kidney disease (ARPKD) is a rare inherited disease, which is a disorder with multiple organ involvement, mainly the kidney and liver. It is caused by mutations in the PKHD1 gene. Here, we reported the clinical characteristics of a case with ARPKD and analyze the genetic features of this patient as well as of his father using targeted exome sequencing and Sanger sequencing.Genomic DNA was extracted from peripheral blood leukocytes obtained from a patient with ARPKD. The mutations were identified using exome sequencing and confirmed by Sanger sequencing.The patient was diagnosed as ARPKD based on ultrasonography and abdominal computed tomography which showed polycystic changes, multiple calcinosis of both kidneys, and multiple dilated bile ducts of the liver. Compound heterozygous PKHD1 gene mutations A979G and G5935A, which lead to substitution of an asparagine for an aspartate at amino acid 327 (N327D) and a glycine for an arginine at amino acid 1979 (G1979R) respectively, were identified using targeted exome sequencing and confirmed by Sanger sequencing for the patient. In addition, the father of the patient was identified to be a carrier of heterozygous A979G mutation of this gene.We identified that the compound heterozygous PKHD1 gene mutations are the molecular basis of the patient with ARPKD. Targeted exome sequencing is suitable for genetic diagnosis of single-gene inherited diseases like ARPKD in which the pathogenic gene is a large.

To investigate the clinical features and treatment protocol and prognosis for the hypophosphataemic osteomalacia related to adefovir dipivoxil.Analysis was made upon a case of patient with chronic hepatitis B developed hypophosphataemic osteomalacia after administration of adefovir dipivoxil. Literature review was carried out to survey the global prevalence of hypophosphataemic osteomalacia after administration of adefovir dipivoxil among patients with chronic hepatitis B.The clinical symptoms started paralleling to the time taking adefovir dipivoxil, and alleviated after the patient withdrawn adefovir dipivoxil 10 weeks and was given phosphorus. Meanwhile, serum inorganic phosphorus recovered to normal (0.98 mmol/L), which lowest level was 0.77 mmol/L. Systematic review of the literature showed that hyperphosphaturia related to adefovir dipivoxil was dose-dependent, time-dependent and reversible. All reported cases of hypophosphataemic osteomalacia secondary to adefovir dipivoxil (10 mg/d) were from Asian population.Adefovir dipivoxil induced hypophosphataemic osteomalacia is rarely seen in clinical practice. Those patients with chronic hepatitis B who take adefovir dipivoxil, no matter dosages, should take periodical examinations including blood calcium and serum inorganic phosphorus to monitor whether hypophosphataemic osteomalacia occurs. Other anti-virus drugs could be used when it happens.

Osteogenesis imperfecta (OI) is a rare bone disease and its effective treatment is relatively deficient. We tried to assess the effects of new bisphosphonate, ibandronate on children with OI.In this open-label, prospective, controlled study, 30 children with OI were enrolled. They received either infusions of ibandronate (2 mg) in every three months or oral calcitriol 0.25 µg daily for 24 months. All patients took 500 mg calcium plus 200 U vitamin D daily together. The endpoints were the change of annual new fracture rate (observed by case history and X ray films of spine), bone mineral density (BMD, measured by dual energy X-ray absortiometry), serum concentration of carboxy-telopeptide cross-links of type I collagen (CTX, bone resorption marker) and alkaline phosphatase (ALP, bone formation marker) during the follow-up.After the cyclic infusions of ibandronate, the annual new fracture rate was significantly decreased from 1.9 to 0.13 time, obviously lower than that of calcitriol group, which decreased from 1.8 to 1.0 time after the treatment (P0.001). The significant increase of BMD at the lumbar spine, femoral neck, trochanter, total hip was found in the group of ibandronate by 59.0%, 42.0%, 47.5% and 36.6% in time dependent manner (compared with the baseline, P0.001). The increase of BMD in ibandronate group was greater than that of calcitriol group (P0.001). The concentrations of ALP and CTX were obviously decreased in ibandronate group, and the reduction of CTX was more significant than that of ALP (P0.001). The tolerance of the children to ibandronate was quite well. Mild fever and muscle pain were found in 9 cases within 1 - 3 days after the first infusion of ibandronate, which could relieve after 1 - 2 days without special management.The benefits of cyclic infusions of ibandronate to children with OI are significant because ibandronate could significantly reduce annual bone fracture rate, increase lumbar and hip BMD, preserve vertebral morphometry of patients through inhibition of bone resorption.

To analyse hyperinsulinemia in Bartter syndrome.Twenty-three cases of Bartter syndrome [age (27 ± 9) years; fasting serum potassium (2.8 ± 0.5) mmol/L], 20 patients of aldosterone-producing adenoma [APA, age (45 ± 11)years, fasting serum potassium (3.0 ± 0.4) mmol/L], 20 patients of idiopathic hyperaldosteronism [IHA, age (51 ± 11) years, fasting serum potassium (3.4 ± 0.2) mmol/L] were diagnosed in Peking Union Medical College Hospital from September 2003 to May 2008. All patients underwent 3-hours oral glucose tolerance test (3hOGTT), postural stimulation test and calculated HOMA-insulin resistance (HOMA-IR) and HOMA-insulin sensitivity (HOMA-IS) by Homeostasis model.The insulin area under curve[(229.0 ± 162.4) mIU×L(-1)×h] was significantly higher than APA group [(121.2 ± 81.1) mIU×L(-1)×h, P0.05] and were similar to the aged-matched patients with IHA [(227.7 ± 158.6) mIU×L(-1)×h]. But HOMA-IR in Bartter group were similar to APA group (1.96 ± 1.14 vs 1.41 ± 0.91), and HOMA-IR in APA group was lower than IHA group (1.96 ± 1.14 vs 2.40 ± 1.60, P0.05). There was no deference in HOMA-IS among three groups, but APA group had lower level. In all three groups, the peak of insulin secretion was delayed.Bartter syndrome patients commonly present with hyperinsulinemia.