Serum Periostin Level and Genetic Polymorphisms Are Associated with Vertebral Fracture in Chinese Postmenopausal Women.

PURPOSES: In order to investigate the association between serum periostin levels and the variation of its encoding gene POSTN and the prevalence of vertebral fractures and bone mineral density (BMD) in Chinese postmenopausal women, an association study was performed. MATERIALS AND METHODS: 385 postmenopausal women were recruited. For participants without a history of vertebral fracture, lateral X-rays of the spine covering the fourth thoracic spine to the fifth lumbar spine were performed to detect any asymptomatic vertebral fractures. Ten tag-single nucleotide polymorphisms (SNP) of POSTN were genotyped. Serum periostin levels, biochemical parameters, and BMD were measured individually. RESULTS: rs9603226 was significantly associated with vertebral fractures. Compared to allele G, the minor allele A carriers of rs9603226 had a 1.722-fold higher prevalence of vertebral fracture (p = 0.037). rs3923854 was significantly associated with the serum periostin level. G/G genotype of rs3923854 had a higher serum periostin level than C/C and C/G (67.26 ± 19.90 ng/mL vs. 54.57 ± 21.44 ng/mL and 54.34 ± 18.23 ng/mL). Furthermore, there was a negative correlation between the serum level of periostin and BMD at trochanter and total hip. CONCLUSION: Our study suggested that genetic variation of POSTN could be a predicting factor for the risk of vertebral fractures. The serum level of periostin could be a potential biochemical parameter for osteoporosis in Chinese postmenopausal women.

LGR4 Gene Polymorphisms Are Associated With Bone and Obesity Phenotypes in Chinese Female Nuclear Families.

Objective: The current study was conducted to determine whether peak bone mineral density (BMD) and obesity phenotypes are associated with certain LGR4 gene polymorphisms found in Chinese nuclear families with female children. Methods: A total of 22 single nucleotide polymorphisms (SNPs) located in and around the LGR4 gene were identified in 1,300 subjects who were members of 390 Chinese nuclear families with female children. Then, BMD readings of the femoral neck, total hip, and lumbar spine as well as measurements of the total lean mass (TLM), total fat mass (TFM), and trunk fat mass were obtained via dual-energy X-ray absorptiometry. The quantitative transmission disequilibrium test was used to analyze the associations between specific SNPs and LGR4 haplotypes and peak BMD as well as between LGR4 haplotypes and TLM, percent lean mass, TFM, percent fat mass, trunk fat mass, and body mass index (BMI). Results: Here, rs7936621 was significantly associated with the BMD values for the total hip and lumbar spine, while rs10835171 and rs6484295 were associated with the trunk fat mass and BMI, respectively. Regarding the haplotypes, we found significant associations between GAA in block 2 and trunk fat mass and BMI, between AGCGT in block 3 and total hip BMD, between TGCTCC in block 5 and femoral neck BMD, and between TACTTC in block 5 and both lumbar spine and femoral neck BMD (all P-values < 0.05). Conclusion: Genetic variations of the LGR4 gene are related to peak BMD, BMI, and trunk fat mass.

Clinical, Biochemical, and Genetic Features of 41 Han Chinese Families With Primary Hypertrophic Osteoarthropathy, and Their Therapeutic Response to Etoricoxib: Results From a Six-Month Prospective Clinical Intervention.

Primary hypertrophic osteoarthropathy (PHO) is a rare inherited disease caused by genetic defects in the prostaglandin metabolism pathway; disturbed prostaglandin E2 (PGE2 ) catabolism resulting in increased PGE2 level is suggested in the pathogenesis. Forty-three Han Chinese patients with PHO were studied and 41 of them were treated. Mutations in the HPGD gene, causing hypertrophic osteoarthropathy, primary, autosomal recessive 1 (PHOAR1; OMIM 259100), were identified in seven patients, and mutations in the SLCO2A1 gene, causing hypertrophic osteoarthropathy, primary, autosomal recessive 2 (PHOAR2; OMIM 614441), were identified in 36 patients. Clinical phenotypes of PHO varied, ranging from mild isolated finger clubbing to severe pachydermia and disabling joint swelling, even within families. Circulating PGE2 metabolism features of PHOAR2 were different from those of PHOAR1. Different frequency and severity of pachydermia between the subgroups were also indicated. A percentage of PHOAR2 patients suffered from gastrointestinal hemorrhage, but this symptom was not observed in the PHOAR1 subgroup. Clinical evidence highlighted the essential role of sex hormones in prostaglandin transporter regulation with respect to PHOAR2 onset, although no significant associations of urinary PGE2 or PGE-M with sex hormones were identified. Treatment with etoricoxib, a selective cyclooxygenase-2 inhibitor, was proved to be beneficial and safe. We detected its notable efficacy in decreasing urinary PGE2 levels in the majority of the enrolled patients during 6 months of intervention; clinical phenotypes assessed, including pachydermia, finger clubbing, and joint swelling, were improved. We found no visible evidence of a positive effect of etoricoxib on periostosis; however, significant links between urinary PGE2 and serum bone turnover markers indicated a potential role of decreased PGE2 in periostosis management. This is the largest reported cohort of subjects genetically diagnosed with PHO. For the first time, we systematically investigated the biochemical and clinical differences between PHOAR1 and PHOAR2, and prospectively showed the positive efficacy and safety of etoricoxib for PHO patients. © 2017 American Society for Bone and Mineral Research.

Association between SNPs and haplotypes in the METTL21C gene and peak bone mineral density and body composition in Chinese male nuclear families.

The methyltransferase-like 21C gene (METTL21C), which is mainly expressed in muscle, can promote the differentiation of myoblasts to myotubes and reduce glucocorticoid-induced apoptosis of osteocytes. The purpose of this study was to explore the association between single nucleotide polymorphisms of METTL21C and peak bone mineral density (BMD), body mass index, total fat mass (TFM), and total lean mass (TLM) in Chinese young men. Fifteen tagging single nucleotide polymorphisms were genotyped, and haplotype blocks were derived in 400 Chinese male nuclear families. The peak BMD of the lumbar and hip, TFM, and TLM were measured by dual-energy X-ray absorptiometry. The association analyses were performed by a quantitative transmission disequilibrium test. Both TLM and TFM had a significant positive effect on peak BMD, but the positive regulation of TLM was stronger than that of TFM. After 1000 permutations, significant within-family associations were found between rs9585961 and lumbar spine BMD and femoral neck BMD, rs9518810 and femoral neck BMD, and rs599976 and body mass index, TFM, and percentage fat mass (all P < 0.05). The association analyses with haplotypes showed that haplotype AG in block 1 was significantly associated with TFM (P = 0.031) and haplotype CAG in block 2 was significantly associated with lumbar spine BMD (P = 0.020). Our study, for the first time, demonstrates that the polymorphisms and haplotypes of METTL21C contribute to the peak BMD and TFM in Chinese males, which suggests that as a quantitative trait locus with potential pleiotropy it may have an influence on osteoporosis and obesity.

Genetically Low Vitamin D Levels, Bone Mineral Density, and Bone Metabolism Markers: a Mendelian Randomisation Study.

Low serum 25-hydroxyvitamin D (25OHD) is associated with osteoporosis and osteoporotic fracture, but it remains uncertain whether these associations are causal. We conducted a Mendelian randomization (MR) study of 1,824 postmenopausal Chinese women to examine whether the detected associations between serum 25OHD and bone mineral density (BMD) and bone metabolism markers were causal. In observational analyses, total serum 25OHD was positively associated with BMD at lumbar spine (P = 0.003), femoral neck (P = 0.006) and total hip (P = 0.005), and was inversely associated with intact parathyroid hormone (PTH) (P = 8.18E-09) and procollagen type 1 N-terminal propeptide (P1NP) (P = 0.020). By contract, the associations of bioavailable and free 25OHD with all tested outcomes were negligible (all P > 0.05). The use of four single nucleotide polymorphisms, GC-rs2282679, NADSYN1-rs12785878, CYP2R1-rs10741657 and CYP24A1-rs6013897, as candidate instrumental variables in MR analyses showed that none of the two stage least squares models provided evidence for associations between serum 25OHD and either BMD or bone metabolism markers (all P > 0.05). We suggest that after controlling for unidentified confounding factors in MR analyses, the associations between genetically low serum 25OHD and BMD and bone metabolism markers are unlikely to be causal.

The efficacy and safety of weekly 35-mg risedronate dosing regimen for Chinese postmenopausal women with osteoporosis or osteopenia: 1-year data.

AIM: Oral risedronate is effective in the treatment of postmenopausal osteoporosis when administered daily, weekly, or monthly. In this 1-year, randomized, double-blind, multicenter study we compared the weekly 35-mg and daily 5-mg risedronate dosing regimens in the treatment of Chinese postmenopausal women with osteoporosis or osteopenia. METHODS: Postmenopausal women with primary osteoporosis or osteopenia were randomly assigned to the weekly group or daily group (n=145 for each) that received oral risedronate 35 mg once a week or 5 mg daily, respectively, for 1 year. The subjects' bone mineral densities (BMDs), bone turnover markers (P1NP and ß-CTX), new vertebral fractures, and adverse events were assessed at baseline and during the treatments. RESULTS: All subjects in the weekly group and 144 subjects in the daily group completed the study. The primary efficacy endpoint after 1 year, ie the mean percent changes in the lumbar spine BMD (95% CI) were 4.87% (3.92% to 5.81%) for the weekly group and 4.35% (3.31% to 5.39%) for the daily group. The incidences of clinical adverse events were 48.3% in the weekly group and 54.2% in the daily group. CONCLUSION: The weekly 35-mg and daily 5-mg risedronate dosing regimens during 1 year of follow-up show similar efficacy in improving BMDs and biochemical markers of bone turnover in Chinese postmenopausal women with osteoporosis or osteopenia. Moreover, the two dosing regimens exhibit similar safety and tolerability.

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.

Association of single nucleotide polymorphism Rs2236518 in PRDM16 gene with BMI in Chinese males.

AIM: PRD1-BF-1-RIZ1 homologous domain containing protein-16 (PRDM16) is a cell-autonomous transcriptional component that stimulates the development of brown fat cells. The aim of this study was to investigate the contribution of genetic variants of PRDM16 to obesity-related phenotype variations in Chinese. METHODS: A total of 3204 subjects (consisting of 400 male-offspring nuclear families, 401 female-offspring nuclear families, and 729 unrelated older males) were recruited. Ten tag single nucleotide polymorphisms (SNPs) within the PRDM16 gene were genotyped using multiplex quantitative real-time PCR by Taqman assay. Body compositions were measured by dual-energy X-ray absorptiometry (DXA). The associations of the SNPs with the obesity-related phenotypes were analyzed using the quantitative transmission disequilibrium test (QTDT), GLM-ANOVA and PLINK statistical methods. RESULTS: Rs2236518 was the only SNP that was associated with BMI in young (aged 20-40 years) males (P=0.011) using QTDT, and in the older men (aged 50-80 years) (P=0.003) using GLM-ANOVA. No significant associations were detected in the females. Nor was a relationship found between any haplotype and obesity-related phenotypes. When PLINK was used, no significant relationship was detected between 10 SNPs and obesity-related phenotypes in any of the studied cohorts. CONCLUSION: Rs2236518 is associated with BMI in the young males (using QTDT), and the older males (using GLM-ANOVA).However, the result is not confirmed using PLINK. The discrepancy needs to be further addressed.

Transforming growth factor-ß1 gene mutations and phenotypes in pediatric patients with Camurati­Engelmann disease.

The aim of the present study was to investigate the clinical characteristics and major causative gene in pediatric patients with Camurati­Engelmann disease (CED). Biochemical and radiographic examinations, bone scintigraphy and genetic analyses were performed in two affected males and their parents. The two patients experienced waddling gait, muscular weakness and growth developmental delay. X-ray radiography revealed typical fusiform thickening of the diaphyseal portions of the long bones. The abnormal uptake of tracer Tc-99m was visualized in the skull and both sides of the upper humeri, ulnas, radii, femurs and tibias using bone scintigraphy. Serum levels of the bone formation marker procollagen type I N-terminal propeptide (PINP) and the bone resorption marker ß­isomerized C-terminal cross-linked telopeptide of type I collagen (ß-CTX) in the 6-year-old patient were significantly increased compared with the normal value range, while only the ß-CTX levels were elevated in the 16-year-old patient. A heterozygous missense mutation p.Arg218Cys in exon 4 of the transforming growth factor ß1 (TGFß1) gene was detected in the two patients, while their parents had normal wild­type genotypes. In conclusion, the p.Arg218Cys mutation was shown to contribute to the clinical phenotypes in two pediatric patients with CED. The results of this study suggest that abnormal bone turnover marker levels, typical radiological findings and mutations in the TGFß1 gene are three important factors in the diagnosis of sporadic CED cases.

The A242T mutation in the low-density lipoprotein receptor-related protein 5 gene in one Chinese family with osteosclerosis.

OBJECTIVE: Osteosclerosis (OMIM: 144750) is a type of autosomal dominant bone disease caused by a mutation in the low-density lipoprotein receptor-related protein 5 (LRP5) gene. The case of a Chinese family with two affected individuals is reported in the present study in order to investigate the clinical characteristics and virulence genes of this sclerosing bone disorder. METHODS: Biochemical and radiographic examinations and bone mineral density (BMD) and genetic analyses were performed in two patients and eight other family members. RESULTS: The 40-year-old proband (II-1) and her 64-year-old mother (I-2) both had chronic lumbodorsal pain, an elongated mandible and torus palatinus in the center of the hard palate. No fractures were observed in any of the family members. Skull, mandibular and pelvic X-rays in each of the two patients revealed thickened cranial plates, an enlarged sella turcica, an elongated mandible and cortical thickening of the long bones. The BMD values of the two patients was significantly higher than the standard age- and sex-matched adult mean reference values. Both patients had higher serum sclerostin levels, while their renal function markers and serum calcium, phosphonium, parathyroid hormone (PTH) and 25(OH)D levels were within the normal ranges. The heterozygous missense mutation p.Ala242Thr in exon 4 of the LRP5 gene was detected in the two patients, while the other family members and 200 healthy donors had normal wild-type genotypes. CONCLUSION: The A242T mutation in the LRP5 gene resulted in a high bone mass phenotype with an elongated mandible and torus palatinus in this osteosclerotic family.

A novel VCP mutation as the cause of atypical IBMPFD in a Chinese family.

INTRODUCTION: Inclusion-body myopathy (IBM) with Paget's disease of bone (PDB) and frontotemporal dementia (FTD), designated as IBMPFD, is a rare, autosomal dominant disorder (MIM 605382). IBMPFD is caused by mutations in the gene that encode valosin-containing protein (VCP). We investigated a Chinese family in which multiple members were diagnosed with PDB and suffered from weakness of the limbs. However, no members of this family were diagnosed with FTD. We made a preliminary diagnosis of PDB, but failed to identify an SQSTM1 mutation in any of the patients. We used whole-exome sequencing to identify the pathogenic gene mutation affecting the Chinese male proband. MATERIALS AND METHODS: Altogether, 254 subjects, including one 56-year-old male proband, four affected, related individuals and additional nine family members from a non-consanguineous Chinese family, and 240 healthy donors were recruited and genomic DNA was extracted. All eight exons and the exon-intron boundaries of the SQSTM1 gene were amplified by polymerase chain reaction (PCR) and directly sequenced in five patients (II13, II4, II5, II8, II9). Using whole-exome sequencing, we identified a novel mutation in VCP as the disease-causing mutation. We confirmed the result by sequencing a 500-bp region of the promoter and the coding region of VCP in all 254 of the participants using Sanger sequencing. RESULTS: No mutation in the SQSTM1 gene was identified in the five patients examined using direct Sanger sequencing. However, through whole-exome sequencing we were able to identify a novel missense mutation in exon 3 of the VCP gene (p.Gly97Glu) in the Chinese male proband. This mutation was confirmed using Sanger sequencing. The proband, four affected individuals and three unaffected individuals carried this mutation. We were able to correctly diagnose the patients with atypical IBMPFD. Structural analysis of the p.Gly97Glu mutation in the VCP protein showed that the affected amino-acid is located in the interface of the protein. This abnormality may therefore interfere with protein function. CONCLUSIONS: This is the first report of a family from China with IBMPFD. A novel VCP mutation was found as the cause of atypical IBMPFD in a Chinese family. Our findings confirm that VCP gene mutations can be a pathogenic cause of IBMPFD.

Susceptibility genes for osteoporotic fracture in postmenopausal Chinese women.

To identify the susceptibility genes for osteoporotic fracture in postmenopausal Chinese women, a two-stage case-control association study using joint analysis was conducted in 1046 patients with nontraumatic vertebra, hip, or distal radius fractures and 2303 healthy controls. First, 113 single-nucleotide polymorphisms (SNPs) in 16 potential osteoporosis candidate genes reported in recent genomewide association studies, meta-analyses studies, large-scale association studies, and functional studies were genotyped in a small-sample-size subgroup consisting of 541 patients with osteoporotic fractures and 554 healthy controls. Variants and haplotypes in SPTBN1, TNFRSF11B, CNR2, LRP4, and ESR1 that have been identified as being associated with osteoporotic fractures were further reanalyzed in the entire case-control group. We identified one SNP in TNFRSF11B (rs3102734), three SNPs in ESR1 (rs9397448, rs2234693, and rs1643821), two SNPs in LRP4 (rs17790156 and rs898604), and four SNPs in SPTBN1 (rs2971886, rs2941583, rs2941584, and rs12475342) were associated with all of the broadly defined osteoporotic fractures. The most significant polymorphism was rs3102734, with increased risk of osteoporotic fractures (odds ratio, 1.35; 95% confidence interval [CI], 1.17-1.55, Bonferroni p = 2.6 × 10(-4) ). Furthermore, rs3102734, rs2941584, rs12475342, rs9397448, rs2234693, and rs898604 exhibited significant allelic, genotypic, and/or haplotypic associations with vertebral fractures. SNPs rs12475342, rs9397448, and rs2234693 showed significant genotypic associations with hip fractures, whereas rs3102734, rs2073617, rs1643821, rs12475342, and rs2971886 exhibited significant genotypic and/or haplotypic associations with distal radius fractures. Accordingly, we suggest that in addition to the clinical risk factors, the variants in TNFRSF11B, SPTBN1, ESR1, and LRP4 are susceptibility genetic loci for osteoporotic fracture in postmenopausal Chinese women.

Lean mass predicts hip geometry and bone mineral density in chinese men and women and age comparisons of body composition.

Previous studies have suggested that changes in hip geometry increase the risk of hip fracture. The aim of this study was to identify whether body composition were associated with hip geometry or bone mineral density (BMD) in a large sample of Chinese people. A total of 2072 subjects aged 20-79 yr (including 700 males and 1372 females) were selected. The following measurements were taken: lumbar spine (L1-4); proximal femur BMD; lean mass (LM); fat mass (FM); and hip geometric parameters, including hip axis length (HAL), cross-sectional moment of inertia (CSMI), cross-sectional area (CSA), neck-shaft angle, and femur strength index (SI) by dual-energy X-ray absorptiometry. FM and LM were positively correlated with HAL, CSMI, and CSA, and negatively correlated with SI in both men and women. Multiple regression analysis showed that leg LM contributions to HAL, CSMI, and CSA variance were 12.6-37.6%. Compared with FM, LM was generally more strongly related to hip geometry and BMD in young and old men and women. Body composition was a good predictor for hip geometry parameter variation and BMD variation.

Thirteen Chinese patients with sporadic Paget's disease of bone: clinical features, SQSTM1 mutation identification, and functional analysis.

To increase awareness of the rarity of Paget's disease of bone (PDB) in the Chinese population, we characterized the clinical manifestations and features of 13 Chinese sporadic PDB patients. The clinical features of our Chinese PDB patients show similarities with cases reported in Western countries. The most common lesion sites were the pelvis, femur, and tibia; the next most common lesion sites were the spine and skull. Most patients had a higher serum alkaline phosphatase (ALP) level. Treatment with bisphosphonates was effective. In addition, we screened for PDB-causing mutations and performed a functional analysis in an attempt to elucidate the molecular pathogenesis of PDB. A total of 216 persons, including 13 sporadic PDB patients, three unaffected relatives of 1 patient, and 200 healthy donors, were recruited. All eight exons and exon-intron boundaries of the SQSTM1 gene were amplified by polymerase chain reaction (PCR) and directly sequenced. We identified a 53-year-old man who harbored a heterozygous T-to-C transversion at position 1250 in exon 8 (1250T > C), which resulted in a methionine-to-threonine (ATG > ACG) substitution at codon 404 (M404T). The M404T mutant SQSTM1 protein exhibited increased NF-κB activation and drove a significantly increased number of osteoclast-like cells (OLCs) that formed in response to RANKL and an increased number of OLC nuclei. This is the first report of an SQSTM1 genetic mutation that contributes to the pathogenesis of PDB in Chinese patients. These results may partially explain the mechanism by which this SQSTM1 mutation contributes to the pathogenesis of sporadic PDB in Chinese patients.

Comparison of the effects of cholecalciferol and calcitriol on calcium metabolism and bone turnover in Chinese postmenopausal women with vitamin D insufficiency.

AIM: To compare the effects of cholecalciferol (800 IU/d) and calcitriol (0.25 µg/d) on calcium metabolism and bone turnover in Chinese postmenopausal women with vitamin D insufficiency. METHODS: One hundred Chinese postmenopausal women aged 63.8±7.0 years and with serum 25-hydroxyvitamin D [25(OH)D] concentration <30 ng/mL were recruited. The subjects were divided into 2 groups based on the age and serum 25(OH)D concentration: 50 subjects (group A) received cholecalciferol (800 IU/d), and 50 subjects (group B) received calcitriol (0.25 µg/d) for 3 months. In addition, all the subjects received Caltrate D (calcium plus 125 IU cholecalciferol) daily in the form of one pill. The markers of calcium metabolism and bone turnover, including the serum levels of calcium, phosphorus, alkaline phosphatase, intact parathyroid hormone, 25(OH)D and ß-CrossLaps of type I collagen containing cross-linked C-telopeptide (ß-CTX), were measured before and after the intervention. RESULTS: After the 3-month intervention, the serum 25(OH)D concentration in group A was significantly increased from 16.01 ± 5.0 to 20.02 ± 4.5 ng/mL, while that in group B had no significant change. The serum calcium levels in both the groups were significantly increased (group A: from 2.36 ± 0.1 to 2.45 ± 0.1 mmol/L; group B: from 2.36 ± 0.1 to 2.44 ± 0.1 mmol/L). The levels of serum intact parathyroid hormone in both the groups were significantly decreased (group A: from 48.56 ± 12.8 to 39.59 ± 12.6 pg/mL; group B: from 53.67 ± 20.0 to 40.32 ± 15.4 pg/mL). The serum levels of ß-CTX in both the groups were also significantly decreased (group A: from 373.93 ± 135.3 to 325.04 ± 149.0 ng/L; group B: from 431.00 ± 137.1 to 371.74 ± 185.0 ng/L). CONCLUSION: We concluded that both cholecalciferol (800 IU/d) and calcitriol (0.25 µg/d) plus Caltrate D modifies the serum calcium and bone turnover markers in Chinese postmenopausal women with vitamin D insufficiency. In addition, cholecalciferol (800 IU/d) significantly increased the serum 25(OH)D concentration.

Contribution of myostatin gene polymorphisms to normal variation in lean mass, fat mass and peak BMD in Chinese male offspring.

AIM: Myostatin gene is a member of the transforming growth factor-ß (TGF-ß) family that negatively regulates skeletal muscle growth. Genetic polymorphisms in Myostatin were found to be associated with the peak bone mineral density (BMD) in Chinese women. The purpose of this study was to investigate whether myostatin played a role in the normal variation in peak BMD, lean mass (LM), and fat mass (FM) of Chinese men. METHODS: Four hundred male-offspring nuclear families of Chinese Han ethnic group were recruited. Anthropometric measurements, including the peak BMD, body LM and FM were measured using dual-energy X-ray absorptiometry (DXA). The single nucleotide polymorphisms (SNPs) studied were tag-SNPs selected by sequencing. Both rs2293284 and +2278GA were genotyped using TaqMan assay, and rs3791783 was genotyped with PCR-restriction fragment length polymorphism (RFLP) analysis. The associations of the SNPs with anthropometric variations were analyzed using the quantitative transmission disequilibrium test (QTDT). RESULTS: Using QTDT to detect within-family associations, neither single SNP nor haplotype was found to be associated with peak BMD at any bone site. However, rs3791783 was found to be significantly associated with fat mass of the trunk (P<0.001). Moreover, for within-family associations, haplotypes AGG, AAA, and TGG were found to be significantly associated with the trunk fat mass (all P<0.001). CONCLUSION: Our results suggest that genetic variation within myostatin may play a role in regulating the variation in fat mass in Chinese males. Additionally, the myostatin gene may be a candidate that determines body fat mass in Chinese men.

Association of ALOX15 gene polymorphisms with obesity-related phenotypes in Chinese nuclear families with male offspring.

AIM: Genetic variation in ALOX12, which encoded human 12-lipoxygenase, was found to be associated with fat mass in young Chinese men. The objective of this study was to investigate the relationship between single nucleotide polymorphisms (SNPs) and haplotypes in the ALOX15 gene and obesity-related phenotypes in Chinese nuclear families with male offspring. METHODS: We recruited 1,296 subjects from 427 nuclear families with male offspring and genotyped five SNPs (rs9894225, rs748694, rs2619112, rs2619118, and rs916055) in the ALOX15 gene locus. The total fat mass (TFM), trunk fat mass (tFM), leg fat mass (LFM) and arm fat mass (AFM) were measured using dual-energy X-ray absorptiometry (DXA). The percentage of fat mass (PFM) was the ratio of TFM and body weight. The association between SNPs and haplotypes of ALOX15 and obesity-related phenotypic variation was measured using quantitative transmission disequilibrium test (QTDT). RESULTS: Using QTDT to measure family-based genetic association, we found that rs916055 had a statistically significant association with PFM (P=0.038), whereas rs916055 had a marginal but statistically insignificant association with tFM (P=0.093). The multiple-parameter 1000 permutations test agreed with the family-based association results: both showed that rs916055 had a statistically significant association with PFM (P=0.033). CONCLUSION: rs916055 in ALOX15 gene was significantly associated with the percentage of fat mass in Chinese nuclear families with male offspring in the family-based association study using QTDT approach.

The virulence gene and clinical phenotypes of osteopetrosis in the Chinese population: six novel mutations of the CLCN7 gene in twelve osteopetrosis families.

Osteopetrosis is a heritable bone disorder resulting from a deficiency of or a functional defect in osteoclasts. We aimed to characterize the molecular defects and clinical manifestations in Chinese patients with osteopetrosis by studying 12 unrelated osteopetrosis families. The entire coding region and adjacent splice sites of the CLCN7, TCIRG1, LRP5 and SOST genes were amplified and directly sequenced. X-rays of hip and lumbar spine, bone mineral density and bone turnover markers were examined simultaneously. Family history and fracture history were collected using a questionnaire. Among 12 unrelated families, 10 families were diagnosed with autosomal dominant osteopetrosis type II (ADOII) with 10 probands and 3 affected subjects. Two individuals in the other two families were diagnosed with uncategorized osteopetrosis because no mutations were detected in any of the four studied genes. Eight mutations, including two reported mutations (R767W and E798FS) and six novel mutations (E313K, A316G, R743W, G741R, W127G and S290F), were detected in the CLCN7 gene from 12 living ADOII patients. Among them, R767W and R743W mutations were two common mutations that were each found in 20% of 10 ADOII probands. In CLCN7-related ADOII patients, long bone fractures and elevated serum CK level were two major clinical phenotypes, especially in patients younger than 18 years. Further functional studies of the above eight mutations in the CLCN7 gene are needed in the future.

Association between low density lipoprotein receptor-related protein 2 gene polymorphisms and bone mineral density variation in Chinese population.

Low density lipoprotein receptor-related protein 2 gene (LRP2) is located next to the genomic region showing suggestive linkage with both hip and wrist bone mineral density (BMD) phenotypes. LRP2 knockout mice showed severe vitamin D deficiency and bone disease, indicating the involvement of LRP2 in the preservation of vitamin D metabolites and delivery of the precursor to the kidney for the generation of 1α,25(OH)(2)D(3). In order to investigate the contribution of LRP2 gene polymorphisms to the variation of BMD in Chinese population, a total of 330 Chinese female-offspring nuclear families with 1088 individuals and 400 Chinese male-offspring nuclear families with 1215 individuals were genotyped at six tagSNPs of the LRP2 gene (rs2389557, rs2544381, rs7600336, rs10210408, rs2075252 and rs4667591). BMD values at the lumbar spine 1-4 (L1-4) and hip sites were measured by DXA. The association between LRP2 polymorphisms and BMD phenotypes was assessed by quantitative transmission disequilibrium tests (QTDTs) in female- and male-offspring nuclear families separately. In the female-offspring nuclear families, rs2075252 and haplotype GA of rs4667591 and rs2075252 were identified in the nominally significant total association with peak BMD at L1-4; however, no significant within-family association was found between peak BMD at the L1-4 and hip sites and six tagSNPs or haplotypes. In male-offspring nuclear families, neither the six tagSNPs nor the haplotypes was in total association or within-family association with the peak BMD variation at the L1-4 and hip sites by QTDT analysis. Our findings suggested that the polymorphisms of LRP2 gene is not a major factor that contributes to the peak BMD variation in Chinese population.