Effects of AMPD1 gene C34T polymorphism on cardiac index, blood pressure and prognosis in patients with cardiovascular diseases: a meta-analysis

Inborn Errors of Purine Salvage and Catabolism

Cellular purine nucleotides derive mainly from de novo synthesis or nucleic acid turnover and, only marginally, from dietary intake. They are subjected to catabolism, eventually forming uric acid in humans, while bases and nucleosides may be converted back to nucleotides through the salvage pathways. Inborn errors of the purine salvage pathway and catabolism have been described by several researchers and are usually referred to as rare diseases. Since purine compounds play a fundamental role, it is not surprising that their dysmetabolism is accompanied by devastating symptoms. Nevertheless, some of these manifestations are unexpected and, so far, have no explanation or therapy. Herein, we describe several known inborn errors of purine metabolism, highlighting their unexplained pathological aspects. Our intent is to offer new points of view on this topic and suggest diagnostic tools that may possibly indicate to clinicians that the inborn errors of purine metabolism may not be very rare diseases after all.

Genetic Profile in Genes Associated with Sports Injuries in Elite Endurance Athletes

Injuries are a complex trait that can stem from the interaction of several genes. The aim of this research was to examine the relationship between muscle performance-related genes and overuse injury risk in elite endurance athletes, and to examine the feasibility of determining a total genotype score that significantly correlates with injury. A cohort of 100 elite endurance athletes (50 male and 50 female) was selected. AMPD1 (rs17602729), ACE (rs4646994), ACTN3 (rs1815739), CKM (rs8111989) and MLCK ([rs2849757] and [rs2700352]) polymorphisms were genotyped by using real-time polymerase chain reaction (real time-PCR). Injury characteristics during the athletic season were classified following the Consensus Statement for injuries evaluation. The mean total genotype score (TGS) in non-injured athletes (68.263±13.197 arbitrary units [a.u.]) was different from that of injured athletes (50.037±17.293 a.u., p<0.001). The distribution of allelic frequencies in the AMPD1 polymorphism was also different between non-injured and injured athletes (p<0.001). There was a TGS cut-off point (59.085 a.u.) to discriminate non-injured from injured athletes with an odds ratio of 7.400 (95% CI 2.548-21.495, p<0.001). TGS analysis appears to correlate with elite endurance athletes at higher risk for injury. Further study may help to develop this as one potential tool to help predict injury risk in this population.

Genetic profile in genes associated with muscle injuries and injury etiology in professional soccer players

Many causes define injuries in professional soccer players. In recent years, the study of genetics in association with injuries has been of great interest. The purpose of this study was to examine the relationship between muscle injury-related genes, injury risk and injury etiology in professional soccer players. In a cross-sectional cohort study, one hundred and twenty-two male professional football players were recruited. AMPD1 (rs17602729), ACE (rs4646994), ACTN3 (rs1815739), CKM (rs8111989) and MLCK (rs2849757 and rs2700352) polymorphisms were genotyped by using Single Nucleotide Primer Extension (SNPE). The combined influence of the six polymorphisms studied was calculated using a total genotype score (TGS). A genotype score (GS) of 2 was assigned to the “protective” genotype for injuries, a GS of 1 was assigned to the heterozygous genotype while a GS of 0 was assigned to the “worst” genotype. Injury characteristics and etiology during the 2021/2022 season were classified following a Consensus Statement for injuries recording. The distribution of allelic frequencies in the AMPD1 and MLCK c.37885C&gt;A polymorphisms were different between non-injured and injured soccer players (p &lt; 0.001 and p = 0.003, respectively). The mean total genotype score (TGS) in non-injured soccer players (57.18 ± 14.43 arbitrary units [a.u.]) was different from that of injured soccer players (51.71 ± 12.82 a.u., p = 0.034). There was a TGS cut-off point (45.83 a.u.) to discriminate non-injured from injured soccer players. Players with a TGS beyond this cut-off had an odds ratio of 1.91 (95%CI: 1.14–2.91; p = 0.022) to suffer an injury when compared with players with lower TGS. In conclusion, TGS analysis in muscle injury-related genes presented a relationship with professional soccer players at increased risk of injury. Future studies will help to develop this TGS as a potential tool to predict injury risk and perform prevention methodology in this cohort of football players.

Genotype scores in energy and iron-metabolising genes are higher in elite endurance athletes than in nonathlete controls

Information about the association of energy and iron-metabolising genes with endurance performance is scarce. The objective of this investigation was to compare the frequencies of polymorphic variations of genes involved in energy generation and iron metabolism in elite endurance athletes versus nonathlete controls. Genotype frequencies in 123 male elite endurance athletes (75 professional road cyclists and 48 elite endurance runners) and 122 male nonathlete participants were compared by assessing 4 genetic polymorphisms: AMPD1 c.34C/T (rs17602729), PPARGC1A c.1444G/A (rs8192678) HFE_H63D c.187C/G (rs1799945) and HFE_C282Y c.845G/A (rs1800562). A weighted genotype score (w-TGS; from 0 to 100 arbitrary units (a.u.)) was calculated by assigning a corresponding weight to each polymorphism. In the nonathlete population, the mean w-TGS value was lower (39.962 ± 14.654 a.u.) than in the group of elite endurance athletes (53.344 ± 17.053 a.u). The binary logistic regression analysis showed that participants with a w-TGS > 38.975 a.u had an odds ratio of 1.481 (95% confidence interval: 1.244-1.762; p < 0.001) for achieving elite athlete status. The genotypic distribution of polymorphic variations involved in energy generation and iron metabolism was different in elite endurance athletes vs. controls. Thus, an optimal genetic profile in these genes might contribute to physical endurance in athlete status. Novelty Genetic profile in energy generation and iron-metabolising genes in elite endurance athletes is different than that of nonathletes. There is an implication of an "optimal" genetic profile in the selected genes favouring endurance sporting performance.

Association of long noncoding RNA H19 polymorphisms with the susceptibility and clinical features of ischemic stroke in southern Chinese Han population

Stroke is the leading cause of death in China. Previous studies have demonstrated that long noncoding RNAs play important roles in ischemic stroke (IS). This study aimed to investigate long noncoding RNA H19 (lncRNA H19) expression in IS cases and the association between lncRNA H19 variants and IS risk and IS-related risk factors. A total of 550 IS cases and 550 controls were recruited for this study. LncRNA H19 expression was detected using quantitative real-time polymerase chain reaction. Genotyping was conducted by the Sequenom MassARRAY technology. LncRNA H19 level in peripheral blood of IS cases was significantly upregulated compared with healthy controls (P = 0.046). No significant association was observed between lncRNA H19 rs217727 and rs4929984 polymorphisms with IS risk in all genetic models, and rs217727-rs4929984 haplotypes are not associated with IS susceptibility. Further meta-analysis also implied that the rs217727 and rs4929984 polymorphisms were not associated with IS in Chinese population. However, rs4929984 is significantly associated with the diastolic blood pressure level of IS patients (additive model: P_adj = 0.007; dominant model: P_adj = 0.013), whereas rs217727 is associated with international normalized ratio (additive model: P_adj = 0.019; recessive model: P_adj = 0.004), prothrombin time activity level (additive model: P_adj = 0.026; recessive model: P_adj = 0.004), and homocysteine level (recessive model: P_adj = 0.048) in patients with IS. Our findings suggest that lncRNA H19 level may affect the occurrence of IS, and lncRNA H19 variants may influence blood pressure, coagulation function, and homocysteine metabolism of patients with IS in the southern Chinese Han population.

Shortage of Cellular ATP as a Cause of Diseases and Strategies to Enhance ATP

Germline mutations in cellular-energy associated genes have been shown to lead to various monogenic disorders. Notably, mitochondrial disorders often impact skeletal muscle, brain, liver, heart, and kidneys, which are the body’s top energy-consuming organs. However, energy-related dysfunctions have not been widely seen as causes of common diseases, although evidence points to such a link for certain disorders. During acute energy consumption, like extreme exercise, cells increase the favorability of the adenylate kinase reaction 2-ADP -> ATP+AMP by AMP deaminase degrading AMP to IMP, which further degrades to inosine and then to purines hypoxanthine -> xanthine -> urate. Thus, increased blood urate levels may act as a barometer of extreme energy consumption. AMP deaminase deficient subjects experience some negative effects like decreased muscle power output, but also positive effects such as decreased diabetes and improved prognosis for chronic heart failure patients. That may reflect decreased energy consumption from maintaining the pool of IMP for salvage to AMP and then ATP, since de novo IMP synthesis requires burning seven ATPs. Similarly, beneficial effects have been seen in heart, skeletal muscle, or brain after treatment with allopurinol or febuxostat to inhibit xanthine oxidoreductase, which catalyzes hypoxanthine -> xanthine and xanthine -> urate reactions. Some disorders of those organs may reflect dysfunction in energy-consumption/production, and the observed beneficial effects related to reinforcement of ATP re-synthesis due to increased hypoxanthine levels in the blood and tissues. Recent clinical studies indicated that treatment with xanthine oxidoreductase inhibitors plus inosine had the strongest impact for increasing the pool of salvageable purines and leading to increased ATP levels in humans, thereby suggesting that this combination is more beneficial than a xanthine oxidoreductase inhibitor alone to treat disorders with ATP deficiency.

Identification of Two Novel Single Nucleotide Polymorphisms in the Promoter Region of the Pig AMP Deaminase 1 Gene Associated with Carcass Traits

The AMP deaminase 1 (AMPD1) gene plays an important role in purine nucleotide interconversion and energy metabolism. In this study, two novel single nucleotide polymorphisms (SNPs) (g.-626 G > A and g.-566 A>G) were detected in the proximal promoter region of the AMPD1 gene. The Chinese indigenous pig breeds (Meishan and Tongcheng) had higher frequencies of the G and A alleles than Western meat-type breeds (Landrace and Large White) at the g.-626 G > A and g.-566 A>G loci. The transcriptional activity of the AMPD1 promoter carrying the haplotype H1 (A^-626G^-566) was significantly (p < 0.05) higher than that of the haplotype H2 (G^-626A^-566). In addition, pigs with the haplotype combination H1H1 had significantly (p < 0.05) higher mRNA expression levels of the AMPD1 gene than those with haplotype combinations H1H2 and H2H2 in two different skeletal muscles. Association analyses revealed that the pigs with the haplotype combination H1H1 had significantly higher lean meat percentage values but lower average backfat thickness (ABT, cm), buttock fat thickness (cm), and thorax-waist fat thickness (cm) values than the pigs with the haplotype combinations H1H2 and H2H2. These findings demonstrate that the two novel SNPs in the promoter region of the AMPD1 gene have significant associations with pig fat deposition traits.

Expression of serum AMPD1 in thyroid carcinoma and its clinical significance

This study investigated the expression of adenosine monophosphate deaminase 1 (AMPD1) in serum of patients with papillary thyroid carcinoma (PTC) and its clinical significance. The expression levels of AMPD1 mRNA in serum of 157 patients with PTC and 100 normal controls were detected by real-time fluorescent quantitative polymerase chain reaction (PCR), and the relationships between expression level of AMPD1 in serum of PTC patients and clinicopathological factors as well as prognosis were analyzed. The results of real-time fluorescent quantitative PCR showed that the expression of AMPD1 mRNA in serum of PTC patients was lower than that in normal human serum (P<0.01). The expression of AMPD1 in serum of PTC patients was not significantly different from the clinicopathological features such as sex, age, lymph node metastasis and the number of lesions (P>0.05); there were distinct differences between its expression and tumor-node-metastasis (TNM) staging and tumor diameter (P<0.05). The single factor Cox analysis revealed that sex, age, number of lesions, TNM staging and the occurrence of lymph node metastasis were significantly correlated with the prognosis of patients (P<0.05). Multivariate Cox analysis showed that TNM staging hazard ratio (HR)=2.93, 95% confidence interval (CI): 1.52-7.04, P=0.015 was an independent prognostic factor in PTC patients. Survival analysis indicated that there was a statistically significant difference in the 5-year overall survival rate between patients with high expression of AMPD1 and those with low expression (P=0.007). In conclusion, the expression of AMPD1 in serum of patients with PTC is closely related to the malignant evolution of PTC and clinical prognosis of patients. AMPD1 is expected to become an important molecule in judging the clinical prognosis of PTC patients, and may become a new target for molecular targeted therapy of PTC.

Effects of AMPD1 common mutation on the metabolic-chronotropic relationship: Insights from patients with myoadenylate deaminase deficiency

PURPOSE

Current evidence indicates that the common AMPD1 gene variant is associated with improved survival in patients with advanced heart failure. Whilst adenosine has been recognized to mediate the cardioprotective effect of C34T AMPD1, the precise pathophysiologic mechanism involved remains undefined to date. To address this issue, we used cardio-pulmonary exercise testing data (CPX) from subjects with myoadenylate deaminase (MAD) defects.

METHODS

From 2009 to 2013, all the patients referred in our laboratory to perform a metabolic exercise testing, i.e. a CPX with measurements of muscle metabolites in plasma during and after exercise testing, were prospectively enrolled. Subjects that also underwent an open muscle biopsy for diagnosis purpose were finally included. The metabolic-chronotropic response was assessed by calculating the slope of the linear relationship between the percent heart rate reserve and the percent metabolic reserve throughout exercise. MAD activity was measured using the Fishbein's technique in muscle biopsy sample. The common AMPD1 mutation was genotyped and the AMPD1 gene was sequenced to screen rare variants from blood DNA.

RESULTS

Sixty-seven patients were included in the study; 5 had complete MAD deficiency, 11 had partial MAD deficiency, and 51 had normal MAD activity. Compared with normal MAD activity subjects, MAD deficient subjects appeared to have a lower-than-expected metabolic-chronotopic response during exercise. The metabolic-chronotropic relationship is more closely correlated with MAD activity in skeletal muscle (Rs = 0.57, p = 5.93E-7, Spearman correlation) than the presence of the common AMPD1 gene variant (Rs = 0.34, p = 0.005). Age-predicted O2 pulse ratio is significantly increased in MAD deficient subjects, indicating a greater efficiency of the cardiovascular system to deliver O2 (p < 0.01, Scheffé's post hoc test).

CONCLUSION

The metabolic-chronotropic response is decreased in skeletal muscle MAD deficiency, suggesting a biological mechanism by which AMPD1 gene exerts cardiac effect.