Catechol-o-methyltransferase gene polymorphism is associated with skeletal muscle properties in older women alone and together with physical activity

Association of regular aerobic exercises and neuromuscular junction variants with incidence of frailty: an analysis of the Chinese Longitudinal Health and Longevity Survey

BACKGROUND

Candidate genes of neuromuscular junction (NMJ) pathway increased risk of frailty, but the extent and whether can be offset by exercises was unclear. The aim of this study was to investigate the association between aerobic exercises and incident frailty regardless of NMJ pathway-related genetic risk.

METHODS

A cohort study on participants from Chinese Longitudinal Healthy Longevity Survey was conducted from 2008 to 2011. A total of 7006 participants (mean age of 80.6 ± 10.3 years) without frailty at baseline were interviewed to record aerobic exercise status, and 4053 individuals among them submitted saliva samples. NMJ pathway-related genes were genotyped and weighted genetic risk scores were constructed.

RESULTS

During a median follow-up of 3.1 years (19 634 person-years), there were 1345 cases (19.2%) of incident frailty. Persistent aerobic exercises were associated with a 26% lesser frailty risk [adjusted hazard ratio (HR) = 0.74, 95% confidence interval (CI) = 0.64-0.85]. This association was stronger in a subgroup of 1552 longevous participants (age between 90 and 111 years, adjusted HR = 0.72, 95% CI = 0.60-0.87). High genetic risk was associated with a 35% increased risk of frailty (adjusted HR = 1.35, 95% CI = 1.16-1.58). Of the participants with high genetic risk and no persistent aerobic exercises, there was a 59% increased risk of frailty (adjusted HR = 1.59, 95% CI = 1.20-2.09). HRs for the risk of frailty increased from the low genetic risk with persistent aerobic exercise to high genetic risk without persistent aerobic exercise (P trend <0.001).

CONCLUSIONS

Both aerobic exercises and NMJ pathway-related genetic risk were significantly associated with frailty. Persistent aerobic exercises can partly offset NMJ pathway-related genetic risk to frailty in elderly people.

TimeMeter assesses temporal gene expression similarity and identifies differentially progressing genes

Comparative time series transcriptome analysis is a powerful tool to study development, evolution, aging, disease progression and cancer prognosis. We develop TimeMeter, a statistical method and tool to assess temporal gene expression similarity, and identify differentially progressing genes where one pattern is more temporally advanced than the other. We apply TimeMeter to several datasets, and show that TimeMeter is capable of characterizing complicated temporal gene expression associations. Interestingly, we find: (i) the measurement of differential progression provides a novel feature in addition to pattern similarity that can characterize early developmental divergence between two species; (ii) genes exhibiting similar temporal patterns between human and mouse during neural differentiation are under strong negative (purifying) selection during evolution; (iii) analysis of genes with similar temporal patterns in mouse digit regeneration and axolotl blastema differentiation reveals common gene groups for appendage regeneration with potential implications in regenerative medicine.

Validity and Reliability of a Single Question for Leisure-Time Physical Activity Assessment in Middle-Aged Women

PURPOSE

To investigate the validity and test-retest reliability of a single seven-level scale physical activity assessment question (SR-PA L7) and its three-level categorization (SR-PA C3).

METHODS

The associations of SR-PA L7 and C3 with accelerometer-measured leisure-time physical activity (ACC-LTPA) and with the results of four different physical performance tests (6-min walk [n = 733], knee extension [n = 695], vertical jump [n = 731], and grip force [n = 780]) were investigated among women aged 47-55 years participating in the Estrogenic Regulation of Muscle Apoptosis study (n = 795). The reliability was studied using Spearman correlations with 4-month test-retest period (n = 152).

RESULTS

SR-PA L7 and C3 had low correlations with ACC-LTPA (rs = .105-.337). SR-PA L7, SR-PA C3, and ACC-LTPA explained comparable but small amount of variance of the physical performance test results. The reliability analysis provided moderate agreement (rs = .707 and .622 for SR-PA L7 and C3, respectively).

CONCLUSIONS

SR-PA L7 and C3 demonstrated limited validity and reasonable repeatability.

Parallelism in eco-morphology and gene expression despite variable evolutionary and genomic backgrounds in a Holarctic fish

Understanding the extent to which ecological divergence is repeatable is essential for predicting responses of biodiversity to environmental change. Here we test the predictability of evolution, from genotype to phenotype, by studying parallel evolution in a salmonid fish, Arctic charr (Salvelinus alpinus), across eleven replicate sympatric ecotype pairs (benthivorous-planktivorous and planktivorous-piscivorous) and two evolutionary lineages. We found considerable variability in eco-morphological divergence, with several traits related to foraging (eye diameter, pectoral fin length) being highly parallel even across lineages. This suggests repeated and predictable adaptation to environment. Consistent with ancestral genetic variation, hundreds of loci were associated with ecotype divergence within lineages of which eight were shared across lineages. This shared genetic variation was maintained despite variation in evolutionary histories, ranging from postglacial divergence in sympatry (ca. 10-15kya) to pre-glacial divergence (ca. 20-40kya) with postglacial secondary contact. Transcriptome-wide gene expression (44,102 genes) was highly parallel across replicates, involved biological processes characteristic of ecotype morphology and physiology, and revealed parallelism at the level of regulatory networks. This expression divergence was not only plastic but in part genetically controlled by parallel cis-eQTL. Lastly, we found that the magnitude of phenotypic divergence was largely correlated with the genetic differentiation and gene expression divergence. In contrast, the direction of phenotypic change was mostly determined by the interplay of adaptive genetic variation, gene expression, and ecosystem size. Ecosystem size further explained variation in putatively adaptive, ecotype-associated genomic patterns within and across lineages, highlighting the role of environmental variation and stochasticity in parallel evolution. Together, our findings demonstrate the parallel evolution of eco-morphology and gene expression within and across evolutionary lineages, which is controlled by the interplay of environmental stochasticity and evolutionary contingencies, largely overcoming variable evolutionary histories and genomic backgrounds.

Prevalence and association of single nucleotide polymorphisms with sarcopenia in older women depends on definition

The prevalence of sarcopenia depends on the definition used. There are, however, consistent sarcopenic characteristics, including a low muscle mass and muscle strength. Few studies have investigated the relationship between sarcopenia and genotype. A cross-sectional study was conducted with 307 community-dwelling ≥60-year-old women in South Cheshire, UK. Handgrip strength was assessed with a handgrip dynamometer and skeletal muscle mass was estimated using bioelectrical impedance. DNA was extracted from saliva (∼38%) or blood (∼62%) and 24 single-nucleotide polymorphisms (SNPs) were genotyped. Three established sarcopenia definitions - %Skeletal Muscle Mass (%SMM), Skeletal Muscle Mass Index (SMI) and European Working Group on Sarcopenia in Older People (EWGSOP) - were used to assess sarcopenia prevalence. Binary logistic regression with age as covariate was used to identify SNPs associated with sarcopenia. The prevalence of sarcopenia was: %SMM 14.7%, SMI 60.6% and EWGSOP 1.3%. Four SNPs were associated with the %SMM and SMI definitions of sarcopenia; FTO rs9939609, ESR1 rs4870044, NOS3 rs1799983 and TRHR rs7832552. The first three were associated with the %SMM definition, and TRHR rs7832552 with the SMI definition, but none were common to both sarcopenia definitions. The gene variants associated with sarcopenia may help proper counselling and interventions to prevent individuals from developing sarcopenia.

The significance of polymorphism and expression of oestrogen metabolism-related genes in Chinese women with premature ovarian insufficiency

The aim of this study was to investigate whether polymorphism and expression of CYP17, CYP1A1, COMT and SULT1A1 affected the risk of idiopathic primary ovarian insufficiency (POI) in Chinese women. DNA sequencing and real-time PCR were used to detect these genes in 132 cases of idiopathic POI and 132 normal women. A significant increase in the C allele of CYP17 (rs743572) polymorphism was observed in women with POI compared with controls (P_FDR = 0.046). A significant decrease was observed in the C allele of CYP1A1 (rs4646903) in women with POI compared with controls (P_FDR = 0.004). The A allele of COMT (rs4680) polymorphism was more frequent in women with POI compared with controls (P_FDR = 0.029). The genotypic frequency of SULT1A1 (rs9282861) was not significantly different between the two groups. For the relative expression of CYP17 and COMT were statistically significant (both P_FDR = 0.066), with false discovery rate controlled at 0.1. No significant difference was observed in the RNA levels of CYP1A1 and SULT1A1 between the two groups. The frequency of expression of the CYP17 T/C variant tended to be higher and the A allele of COMT polymorphism together with down-regulation of its mRNA expression may be more frequent in Chinese women with idiopathic POI.

Influence of dopamine polymorphisms on the risk for anorexia nervosa and associated psychopathological features

Dopamine neuronal functions make polymorphisms in dopaminergic pathways good candidates for playing a relevant role in anorexia nervosa (AN) and related psychopathological features. We have analyzed the effect of 8 polymorphisms in genes coding for dopamine receptors (DRD2, DRD3, and DRD4), transporters (DAT1) and metabolizing enzymes (COMT) in 78 women with AN and 186 control subjects. Associated psychopathological characteristics in patients with AN were assessed by the Eating Disorders Inventory Test-2 and SCL-90R self-reported questionnaires. The DRD4 variable number of tandem repeats (VNTR) 7R/7R and DRD4 -616CC genotypes were significantly associated with a greater risk for AN (odds ratio, 3.83; confidence interval, 1.05-13.98; P = 0.04; and odds ratio, 1.74; confidence interval, 1.01-2.97; P = 0.03, respectively). The analysis of physiological parameters in the patients with AN revealed that the short allele of a 120-base pair tandem repeat in the promoter region of the DRD4 gene was associated with higher weight (48.35 ± 6.79 vs 43.95 ± 5.78 kg; Bonferroni, P < 0.05), whereas the DRD4 -521TT genotype was associated with significantly higher body mass index (17.29 ± 2.25 vs 18.13 ± 2.41 kg/m2; Bonferroni, P < 0.05). The DRD4 C-616G and DAT1 VNTR polymorphisms correlated with several psychopathological features in patients with AN. Carriers of the mutant homozygous genotypes scored higher in all but one of the Eating Disorders Inventory Test-2 subscales. After correction for multiple testing, differences in Asceticism scores between DAT1 VNTR genotypes, as well as differences in Drive for Thinness and Body Dissatisfaction between C-616G genotypes remained significant (P < 0.05). The results show that certain genetic alterations in the dopamine pathways are able to modify the risk for AN as well as modulate psychopathological features that are often coupled to this disorder.

Genetic markers of bone and joint health and physical capability in older adults: the HALCyon programme

BACKGROUND

Good bone and joint health is essential for the physical tasks of daily living and poorer indicators of physical capability in older adults have been associated with increased mortality rates. Genetic variants of indicators of bone and joint health may be associated with measures of physical capability.

METHODS

As part of the Healthy Ageing across the Life Course (HALCyon) programme, men and women aged between 52 and 90+ years from six UK cohorts were genotyped for a polymorphism associated with serum calcium (rs1801725, CASR), two polymorphisms associated with bone mineral density (BMD) (rs2941740, ESR1 and rs9594759, RANKL) and one associated with osteoarthritis risk rs3815148 (COG5). Meta-analysis was used to pool within-study effects of the associations between each of the polymorphisms and measures of physical capability: grip strength, timed walk or get up and go, chair rises and standing balance.

RESULTS

Few important associations were observed among the several tests. We found that carriers of the serum calcium-raising allele had poorer grip strength compared with non-carriers (pooled p=0.05, n=11,239) after adjusting for age and sex. Inconsistent results were observed for the two variants associated with BMD and we found no evidence for an association between rs3815148 (COG5) and any of the physical capability measures.

CONCLUSION

Our findings suggest elevated serum calcium levels may lead to lower grip strength, though this requires further replication. Our results do not provide evidence for a substantial influence of these variants in ESR1, RANKL and COG5 on physical capability in older adults.

Handgrip strength at midlife and familial longevity : The Leiden Longevity Study

Low handgrip strength has been linked with premature mortality in diverse samples of middle-aged and elderly subjects. The value of handgrip strength as marker of "exceptional" human longevity has not been previously explored. We postulated that the genetic influence on extreme survival might also be involved in the muscular strength determination pathway. Therefore, the objective of this study was to assess the muscle strength in a sample of middle-aged adults who are genetically enriched for exceptional survival and comparing them to a control group. We included 336 offspring of the nonagenarian from the Leiden Longevity Study who were enriched for heritable exceptional longevity, and 336 of their partners were used as controls. The Leiden Longevity study was a prospective follow up study of long-living siblings pairs together with their offspring and their partners. Handgrip strength was used as a proxy for overall muscle strength. No significant difference in handgrip strength was seen between the offspring of the nonagenarian and their partners after adjustment for potential confounders including body compositions, sum score of comorbidities, medication use, smoking and alcohol history. The main determinants of midlife handgrip strength were age, gender, total body percentage fat and relative appendicular lean mass. Although midlife handgrip strength has previously been shown to be an important prognostic indicator of survival, it is not a marker of exceptional familial longevity in middle-aged adults. This finding suggests that genetic component of susceptibility to extreme survival is likely to be separate from that of muscular strength.

The genetic pleiotropy of musculoskeletal aging

Musculoskeletal aging is detrimental to multiple bodily functions and starts early, probably in the fourth decade of an individual's life. Sarcopenia is a health problem that is expected to only increase as a greater portion of the population lives longer; prevalence of the related musculoskeletal diseases is similarly expected to increase. Unraveling the biological and biomechanical associations and molecular mechanisms underlying these diseases represents a formidable challenge. There are two major problems making disentangling the biological complexity of musculoskeletal aging difficult: (a) it is a systemic, rather than "compartmental," problem, which should be approached accordingly, and (b) the aging per se is neither well defined nor reliably measurable. A unique challenge of studying any age-related condition is a need of distinguishing between the "norm" and "pathology," which are interwoven throughout the aging organism. We argue that detecting genes with pleiotropic functions in musculoskeletal aging is needed to provide insights into the potential biological mechanisms underlying inter-individual differences insusceptibility to the musculoskeletal diseases. However, exploring pleiotropic relationships among the system's components is challenging both methodologically and conceptually. We aimed to focus on genetic aspects of the cross-talk between muscle and its "neighboring" tissues and organs (tendon, bone, and cartilage), and to explore the role of genetics to find the new molecular links between skeletal muscle and other parts of the "musculoskeleton." Identification of significant genetic variants underlying the musculoskeletal system's aging is now possible more than ever due to the currently available advanced genomic technologies. In summary, a "holistic" genetic approach is needed to study the systems's normal functioning and the disease predisposition in order to improve musculoskeletal health.

Genetics of muscle strength and power: polygenic profile similarity limits skeletal muscle performance

Environmental and genetic factors influence muscle function, resulting in large variations in phenotype between individuals. Multiple genetic variants (polygenic in nature) are thought to influence exercise-related phenotypes, yet how the relevant polymorphisms combine to influence muscular strength in individuals and populations is unclear. In this analysis, 22 genetic polymorphisms were identified in the literature that have been associated with muscular strength and power phenotypes. Using typical genotype frequencies, the probability of any given individual possessing an "optimal" polygenic profile was calculated as 0.0003% for the world population. Future identification of additional polymorphisms associated with muscular strength phenotypes would most likely reduce that probability even further. To examine the genetic potential for muscular strength within a human population, a "total genotype score" was generated for each individual within a hypothetical population of one million. The population expressed high similarity in polygenic profile with no individual differing by more than seven genotypes from a typical profile. Therefore, skeletal muscle strength potential within humans appears to be limited by polygenic profile similarity. Future research should aim to replicate more genotype-phenotype associations for muscular strength, because only five common genetic polymorphisms identified to date have positive replicated findings.

Factors affecting short-term precision of musculoskeletal measures using peripheral quantitative computed tomography (pQCT)

Few studies have investigated factors influencing the precision of peripheral quantitative computed tomography (pQCT) measures. This study found time between repeat scans and subject anthropometric characteristics to influence short-term precision of pQCT-derived measures in the lower leg. These findings have implications for both investigators and clinicians utilizing pQCT outcomes.

INTRODUCTION

Peripheral quantitative computed tomography (pQCT) is increasingly being used to investigate musculoskeletal changes associated with age, disease and/or intervention. Precision of pQCT measures is of paramount importance in this endeavor. This study aimed to establish the short-term precision of pQCT-derived musculoskeletal measures of the lower leg and investigate factors influencing this precision.

METHODS

Thirty healthy subjects had a series of six pQCT scans of the lower leg (66% of tibial length proximal from its distal end) performed on two separate days by two different testers. The influences of different testers, time between repeat scans, and subject anthropometric characteristics on precision were explored.

RESULTS

Overall precision error (root mean square) increased from bone (<1%) to muscle (<1.5%) to fat (3%). The two testers were equally precise in performing pQCT measures; however, precision error increased when repeat scans were repeated 1 week apart as opposed to on the same day. Subject anthropometric characteristics influenced precision errors with the general finding being that an increase in subject size was associated with less precise pQCT measures.

CONCLUSIONS

pQCT is a relatively precise technique for the assessment of bone and muscle, but precision is influenced by time between repeat scans and subject anthropometric characteristics. Investigators and clinicians need to be aware of these factors influencing pQCT outcomes as they may influence statistical power in clinical studies and the characterization of change in individual patients.

Locomotor adaptation and aftereffects in patients with reduced somatosensory input due to peripheral neuropathy

We studied 12 peripheral neuropathy patients (PNP) and 13 age-matched controls with the "broken escalator" paradigm to see how somatosensory loss affects gait adaptation and the release and recovery ("braking") of the forward trunk overshoot observed during this locomotor aftereffect. Trunk displacement, foot contact signals, and leg electromyograms (EMGs) were recorded while subjects walked onto a stationary sled (BEFORE trials), onto the moving sled (MOVING or adaptation trials), and again onto the stationary sled (AFTER trials). PNP were unsteady during the MOVING trials, but this progressively improved, indicating some adaptation. During the after trials, 77% of control subjects displayed a trunk overshoot aftereffect but over half of the PNP (58%) did not. The PNP without a trunk aftereffect adapted to the MOVING trials by increasing distance traveled; subsequently this was expressed as increased distance traveled during the aftereffect rather than as a trunk overshoot. This clear separation in consequent aftereffects was not seen in the normal controls suggesting that, as a result of somatosensory loss, some PNP use distinctive strategies to negotiate the moving sled, in turn resulting in a distinct aftereffects. In addition, PNP displayed earlier than normal anticipatory leg EMG activity during the first after trial. Although proprioceptive inputs are not critical for the emergence or termination of the aftereffect, somatosensory loss induces profound changes in motor adaptation and anticipation. Our study has found individual differences in adaptive motor performance, indicative that PNP adopt different feed-forward gait compensatory strategies in response to peripheral sensory loss.