Acromegaly management in the Nordic countries: A Delphi consensus survey.

OBJECTIVE: Acromegaly is associated with increased morbidity and mortality if left untreated. The therapeutic options include surgery, medical treatment, and radiotherapy. Several guidelines and recommendations on treatment algorithms and follow-up exist. However, not all recommendations are strictly evidence-based. To evaluate consensus on the treatment and follow-up of patients with acromegaly in the Nordic countries. METHODS: A Delphi process was used to map the landscape of acromegaly management in Denmark, Sweden, Norway, Finland, and Iceland. An expert panel developed 37 statements on the treatment and follow-up of patients with acromegaly. Dedicated endocrinologists (n = 47) from the Nordic countries were invited to rate their extent of agreement with the statements, using a Likert-type scale (1-7). Consensus was defined as ≥80% of panelists rating their agreement as ≥5 or ≤3 on the Likert-type scale. RESULTS: Consensus was reached in 41% (15/37) of the statements. Panelists agreed that pituitary surgery remains first line treatment. There was general agreement to recommend first-generation somatostatin analog (SSA) treatment after failed surgery and to consider repeat surgery. In addition, there was agreement to recommend combination therapy with first-generation SSA and pegvisomant as second- or third-line treatment. In more than 50% of the statements, consensus was not achieved. Considerable disagreement existed regarding pegvisomant monotherapy, and treatment with pasireotide and dopamine agonists. CONCLUSION: This consensus exploration study on the management of patients with acromegaly in the Nordic countries revealed a relatively large degree of disagreement among experts, which mirrors the complexity of the disease and the shortage of evidence-based data.

Genetic Screening of WNT4 and WNT5B in Two Populations with Deviating Bone Mineral Densities.

A role for WNT4 and WNT5B in bone metabolism was indicated by genome-wide association studies (GWAS) and a Wnt4 knockout mouse model. The aim of this study was therefore to replicate and further investigate the causality between genetic variation in WNT4 and WNT5B and deviating bone mineral density (BMD) values. A WNT4 and WNT5B mutation screening was performed in patients with craniotubular hyperostosis using Sanger sequencing. Here, no putative causal mutations were detected. Moreover, a high and low BMD cohort was selected from the Odense Androgen Study population for re-sequencing. In WNT4 we detected four variants (three rare, one common), while in WNT5B we detected five variants (two rare, three common). For the common variants, no significant difference in genotype frequencies between the high and low BMD cohorts was observed. The SNPs associated with the GWAS were genotyped in these cohorts, but again no significant difference in genotype frequencies was observed. Despite the findings of the GWAS, we were not able to replicate or further verify the genetic association of polymorphisms in WNT4 and WNT5B with BMD. In order to do so, the intronic regions of both genes could be investigated more thoroughly in more extended populations (or extremes) with greater power. Future genetic and functional studies toward adjacent genes of WNT4 and WNT5B can also be interesting to figure out whether the signal from GWAS could possibly be attributed to genetic variation in these genes.

The relationship between health-related quality of life, obesity and testosterone levels in older men.

BACKGROUND: quality of life evaluated by Short-Form 36 (SF-36) is decreased in obesity and hypogonadism, but the importance of regional fat mass is unknown. In the present study, we evaluated associations between SF-36, regional fat deposits and bioavailable testosterone (BioT) in ageing men. METHODS: a population-based cross-sectional study in older men. Data included SF-36 questionnaires with the dimensions such as physical function, role limitations physical, bodily pain, general health, vitality, social function, role limitations emotional and mental health. Furthermore, waist, lean body mass (measured by dual X-ray absorptiometry), visceral adipose tissue and subcutaneous adipose tissue (SAT) (measured by magnetic resonance imaging) and BioT were established. RESULTS: five hundred and ninety-eight men aged 60-74 years were included. The SF-36 dimensions such as physical function, general health, vitality and role limitations functional were inversely associated with waist and SAT and positively associated with BioT. In multiple regression analysis, waist was the body composition measure with the strongest association with SF-36 dimension scores. CONCLUSION: SF-36 dimension scores were more closely associated with central obesity than with BioT. CLINICAL TRIAL REGISTRATION NUMBER: www.clinicaltrials.gov, NCT00155961.

Variation in the Kozak sequence of WNT16 results in an increased translation and is associated with osteoporosis related parameters.

The importance of WNT16 in the regulation of bone metabolism was recently confirmed by several genome-wide association studies and by a Wnt16 (Wnt16(-/-)) knockout mouse model. The aim of this study was thus to replicate and further elucidate the effect of common genetic variation in WNT16 on osteoporosis related parameters. Hereto, we performed a WNT16 candidate gene association study in a population of healthy Caucasian men from the Odense Androgen Study (OAS). Using HapMap, five tagSNPs and one multimarker test were selected for genotyping to cover most of the common genetic variation in and around WNT16 (MAF>5%). This study confirmed previously reported associations for rs3801387 and rs2707466 with bone mineral density (BMD) at several sites. Furthermore, we additionally demonstrated that rs2908007 is strongly associated with BMD at several sites in the young, elderly and complete OAS population. The observed effect of these three associated SNPs on the respective phenotypes is comparable and we can conclude that the presence of the minor allele results in an increase in BMD. Additionally, we performed re-sequencing of WNT16 on two cohorts selected from the young OAS cohort, based on their extreme BMD values. On this basis, rs55710688 was selected for an in vitro translation experiment since it is located in the Kozak sequence of WNT16a. We observed an increased translation efficiency and thus a higher amount of WNT16a for the Kozak sequence that was significantly more prevalent in the high BMD cohort. This observation is in line with the results of the Wnt16(-/-) mice. Finally, a WNT luciferase reporter assay was performed and showed no activation of the ß-catenin dependent pathway by Wnt16. We did detect a dose-dependent inhibitory effect of Wnt16 on WNT1 activation of this canonical WNT pathway. Increased translation of WNT16 can thus lead to an increased inhibitory action of WNT16 on canonical WNT signaling. This statement is in contrast with the known activating effect of canonical WNT signaling on bone formation and suggests a stimulatory effect on bone metabolism via noncanonical WNT signaling. More research is required to not only confirm this hypothesis, but also to further elucidate the role of non-canonical WNT pathways in bone metabolism and the general mechanisms of interplay between the different WNT signaling pathways.

A common LRP4 haplotype is associated with bone mineral density and hip geometry in men-data from the Odense Androgen Study (OAS).

Osteoporosis is a common disease characterized by an increased susceptibility to fracture. It is a complex disorder resulting from the interaction of several polymorphisms in different genes and environmental factors. Since we recently reported a role for low density lipoprotein-related protein (LRP)-4 in monogenic disorders with bone overgrowth, we now wanted to evaluate whether genetic variation in the LRP4 gene has an effect on the susceptibility to osteoporosis in a population based cohort from the Odense Androgen Study. We chose to genotype four common (minor allele frequency (MAF)≥0.05) and non-synonymous coding polymorphisms located in the extracellular region of the LRP4 protein: rs3816614 (A/g), rs2306029 (G/a), rs2306033 (C/t) and rs6485702 (G/a) (large and small characters indicate major and minor alleles, respectively). Bone mineral density (BMD) measurements of the hip, the spine and whole body as well as different hip geometry parameters were available for a total of 1404 Danish men from two age groups ([20-29 years]: n=804; [60-74 years]: n=600). Using linear regression analysis adjusted for age, height and weight, we found significant associations between both rs2306029 and rs6485702 and BMD at all sites except the lumbar spine. The most significant association was found with whole body BMD (p=4.7×10(-5)). In addition, we found these two polymorphisms to be associated with different geometry parameters especially of the femoral shaft. Analysis of the two associated SNPs in the separate age groups demonstrated that most associations are only present in the youngest group of Danish men. In the group of elderly men, one Bonferroni corrected association between whole body BMD and rs6485702 was found to be significant. Subsequently, all polymorphisms were included in haplotype analyses using the PLINK software (v1.07). After adjusting for age, height and weight, two out of five common haplotypes (MAF≥0.01) were found to be of particular interest in the regulation of hip and whole body BMD (AGCG, AACA). Additional analysis suggested that these latter associations are driven by the association of rs6485702. We suggest, based on these results and the localisation of the variant in the third ß-propeller domain of LRP4, that the variant has possibly a functional effect. Hereby, we conclude that common variation in the LRP4 gene determines hip and whole body BMD and thus confirm previous results from different GWAs. In addition, our data proves an additional role for LRP4 in regulating hip structure. Finally, interaction analysis for LRP4 with SOST and LRP5 showed interaction with LRP5 for femoral shaft geometry.

Genetic association study of WNT10B polymorphisms with BMD and adiposity parameters in Danish and Belgian males.

Because of the importance of the Wnt pathway in the development and maintenance of both adipose and bone tissue, we wanted to evaluate the involvement of WNT10B, a Wnt pathway activator, in adipogenesis and osteoblastogenesis in humans. Genetic association between WNT10B polymorphisms and adiposity parameters as well as bone mineral density (BMD) measurements was analysed in two independent populations. The first is a population of 1,228 Danish men (702 aged 20-29 years; 532 aged 60-74 years) from the Odense Androgen Study (OAS), which was designed as a cross-sectional, population-based study. The second population, called SIBLOS, includes 922 Belgian men (34 ± 5 years old) and contains siblings selected from over 500 families. Four tagSNPs (rs833840, rs833841, rs10875902 and rs4018511) that capture variation of ten SNPs (MAF > 5 %) in a 15.2 kb region spanning the WNT10B gene and its flanking regions were genotyped. Although no association with body mass index was found, we found all tagSNPs to be associated with BMD parameters (BMD whole body, total hip and femoral neck) and height in the OAS population. The association of rs10875902 was most prominent (nominal p = 0.012) and confirmed a previously shown negative effect on BMD. No significant associations were observed in the SIBLOS population. In the present study, no association between WNT10B polymorphisms and adiposity parameters was found. However, our results clearly illustrate a role for WNT10B variants in determining human BMD. The effect of WNT10B polymorphisms on height should be evaluated in additional populations.

Resistin polymorphisms show associations with obesity, but not with bone parameters in men: results from the Odense Androgen Study.

Resistin is an obesity-related adipokine which has also been implicated in bone metabolism. Therefore, we designed a study to investigate the possible role of resistin gene variation in both obesity and bone mineral density. We included 1,155 individuals from the Odense Androgen Study (663 young subjects and 492 older subjects), a population-based, prospective, observational study on the inter-relationship between endocrine status, body composition, muscle function, and bone metabolism in men, in an association study with resistin (RETN) polymorphisms. Three RETN variants (rs1862513, rs3745367 and rs3745369) were genotyped with TaqMan Pre-Designed Genotyping assays. Linear regression was performed to investigate the possible association of these variants with several obesity- and bone-related parameters. After genotyping 1,155 Danish men, 663 young subjects and 492 older subjects, we found that rs3745367 was associated with several obesity-related measures in both the young and elderly cohort. Rs3745369 was only associated with obesity-phenotypes in the elderly cohort. When studying the combined cohorts, we could confirm the associations of rs3745367 with several obesity-related parameters. We were unable to identify any association between RETN polymorphisms and bone-related measurements. Together, these results illustrate resistin's role in the development of obesity. Rs3745367 gives the most consistent results in the current study and these should be confirmed in other populations. Research into its possible functional effect might also be required. A role for RETN variants in determining bone mineral density seems unlikely from our results.

Single nucleotide polymorphisms in sFRP4 are associated with bone and body composition related parameters in Danish but not in Belgian men.

The senescence accelerated mouse P6 (SAMP6) has a low bone mass and has previously shown to be a good model for senile osteoporosis in humans. In addition to a reduced bone mass, SAMP6 mice are obese and have hyperlipidemia. Using positional cloning and expression studies, an increased expression of sfrp4 was found in these mice. SFRP4 is a modulator of the Wnt signalling pathway. This pathway has been previously shown to be involved in regulating bone mass. Additional evidence that sFRP4 has an influence on BMD was delivered by linkage and association studies mostly performed in Asian populations. Based on these data we decided to perform an association study between common variants in sFRP4, BMD, hip geometry parameters and body composition parameters in a population consisting of 1383 Danish men (783 aged 20-29 years; 600 aged 60-74 years). Afterwards we tried to replicate the significant results in a population of 994 Belgian men. In the Danish population we found 6 SNPs associated with BMD at the hip and/or femoral neck. Furthermore, all 6 SNPs were associated with several hip geometry parameters. The homozygous presence of the minor allele resulted for all SNPs (except rs4720265) in a decrease in bone density and bone strength. Finally, we observed in the Danish population age specific associations with height and fat mass. In the Belgian population we tried to replicate the results of three SNPs with BMD and body composition parameters. Unfortunately, we were not able to replicate the results found in the Danish cohort but we found one SNP (rs2598116) associated with height. In conclusion, genetic variation in sFRP4 has an influence on hip fracture risk, percentage body fat and height in a Danish male population. However, we were unable to replicate these results in an independent Belgian population.

Association study of common variants in the sFRP1 gene region and parameters of bone strength and body composition in two independent healthy Caucasian male cohorts.

Bone mineral density (BMD) and bone strength are predictive parameters for the development of osteoporosis and related fracture later in life. Although it is well known that BMD and bone strength have a high heritability, not much of the variation is already explained. Mice models showed that sFRP1 has an influence on bone formation. Therefore this study aimed to investigate the effect of common genetic variation on BMD and bone strength in Caucasian men of different ages. Using HapMap we selected 13 tagSNPs which tag most common genetic variation in and around sFRP1 and we genotyped these SNPs in the young cohort of the Odense Androgen Study (OAS). The OAS includes a total of 1383 Danish men from two different age groups ([20-29 years]: N=783; [60-74 years]: N=600) and is well characterised. The subjects were phenotyped for BMD at several sites, and additionally for body composition and hip geometry parameters. Based on the results of the young cohort we selected three SNPs for further analysis in the complete OAS population. To conclude we tried to replicate the results of two SNPs in an independent population of 994 Belgian men. We found a strong association for rs9694405 with BMI as well in both cohorts separately as in the whole OAS population. Further we found rs4736965 associated with several hip geometry parameters in the same population. However we were not able to replicate those results in the Belgian population. At last we found in the OAS population age specific effects for rs10106678 with whole body BMD and waist to hip ratio.

Association study of polymorphisms in the SOST gene region and parameters of bone strength and body composition in both young and elderly men: data from the Odense Androgen Study.

By means of different genetic association studies the SOST gene, encoding sclerostin, has repeatedly been suggested to regulate bone mineral density (BMD) and osteoporosis susceptibility. This study aimed at a further understanding of the importance of two previously studied single-nucleotide polymorphisms in the SOST gene, rs10534024 (SRP3) and rs9902563 (SRP9), in the Odense Androgen Study (OAS) cohort. This cohort includes a total of 1,383 Danish men from two different age groups, 20-29 years (n = 783) and 60-74 years (n = 600), and is well characterized. Subjects were phenotyped for BMD at several sites and additionally for body composition and hip geometric parameters. In a combined analysis of the young and the elderly OAS, no associations were found for SRP3 either with BMD or with hip geometry. Instead, we found that this polymorphism had a relatively large effect on weight (-1.149 kg) and body mass index (-0.389 kg/m(2)) (P = 0.021 and 0.006 under a codominant model). For SRP9, a significant association was found for femoral neck BMD (+0.020 g/cm(2), P = 0.020) and a trend toward significance for hip geometry (buckling ratio of the narrow neck) but only when considering a recessive effect of the minor allele (C). No age-specific effects were found for either of the two SNPs. In summary, we are the first to find interesting associations between SRP3 and body composition. For SRP9, we replicated a site-specific association with femoral neck BMD. In addition, we report a novel association for this polymorphism with hip geometry.