Prevalencia de mutaciones metilentetrahidrofolato reductasa (MTHFR), protrombina (II G20210G/G20210A) y factor V Leyden en pacientes sometidos a estudio por perfil trombofílico en el Hospital San Vicente de Paúl, Costa Rica, 2017-2018 / Prevalence of mutations Methylentetrahydrofolate reductase (MTHFR), Prothrombin (II G20210G/G20210A) and Leyden V factor in patients undergoing studies by thrombophilic profile. Hospital San Vicente de Paul. Costa Rica, 2017 to 2018

Resumen Introducción: en los últimos años se han descrito alteraciones genéticas asociadas con un mayor o menor riesgo de padecer una enfermedad trombótica. El objetivo del presente estudio es conocer la prevalencia de las mutaciones para la metilentetrahidrofolato reductasa (MTHFR), la protrombina (II G20210G/G20210A) y el factor V Leyden en las muestras de pacientes sometidas a estudio por perfil trombofílico en el Hospital San Vicente de Paúl. Metodología: con la base de datos de muestras referidas del Hospital San Vicente de Paúl, se estudiaron los marcadores de riesgo para trombofilia: MTHFR, Ac Lúpico, mutación del Factor II y Factor V Leyden correspondientes al periodo comprendido entre abril de 2017 a abril de 2018. Resultados: se observó que la frecuencia de la solicitud de estudio por trombofilia era mayor para el sexo femenino, con un 83,7 % del total de análisis, mientras que, para el sexo masculino fue de un 16,3 %. La mutación más prevalente fue la MTHFR, seguida del factor V Leyden, además, ambas se presentaron superiormente en las mujeres. Conclusión: se ha demostrado en varios estudios la asociación de las alteraciones genéticas estudiadas con los eventos trombóticos, por lo tanto, conocer su prevalencia en determinada población es de gran importancia para ayudar al clínico a llegar a un diagnóstico adecuado.

Abstract Introduction: Genetic alterations associated with a higher or lower risk of thrombotic disease have been reported in recent years, the objective of this study is to understand the prevalence of mutations for methylentetrahydrofolate reductase (MTHFR), Mutation for prothrombin (II G20210G/G20210A) and Mutation for factor V Leyden, in the samples of patients undergoing studies by thrombophilic profile, at the Hospital San Vicente de Paul. Methodology: To carry out this study, we use the database of reference samples of the Hospital San Vicente de Paúl for the study of risk markers for thrombophilia: MTHFR, Ac Lúpico, Mutation of Factor II, Factor V Leyden in the period from April 2017 to April 2018. Results: From the analyses requested for thrombophilia study, the frequency in the thrombophilia study request was observed to be higher for female sex, with a frequency of 83.7% of total testing and 16.3% for the male sex. The most prevalent mutation is MTHFR, followed by the Mutation for factor V Leyden, and both mutations occur in greater numbers in women. Conclusion: The association of genetic alterations studied with thrombotic events has been shown in several studies so knowing their prevalence in a given population is of great importance to help the clinic arrive at an appropriate diagnosis.

Efficient Catalysis of Protein Folding by GroEL/ES of the Obligate Chaperonin Substrate MetF.

The cylindrical chaperonin GroEL and its cofactor GroES mediate ATP-dependent protein folding in Escherichia coli by transiently encapsulating non-native substrate in a nano-cage formed by the GroEL ring cavity and the lid-shaped GroES. Mechanistic studies of GroEL/ES with heterologous protein substrates suggested that the chaperonin is inefficient, typically requiring multiple ATP-dependent encapsulation cycles with only a few percent of protein folded per cycle. Here we analyzed the spontaneous and chaperonin-assisted folding of the essential enzyme 5,10-methylenetetrahydrofolate reductase (MetF) of E. coli, an obligate GroEL/ES substrate. We found that MetF, a homotetramer of 33-kDa subunits with (ß/α)8 TIM-barrel fold, populates a kinetically trapped folding intermediate(s) (MetF-I) upon dilution from denaturant that fails to convert to the native state, even in the absence of aggregation. GroEL/ES recognizes MetF-I and catalyzes rapid folding, with ~50% of protein folded in a single round of encapsulation. Analysis by hydrogen/deuterium exchange at peptide resolution showed that the MetF subunit folds to completion in the GroEL/ES nano-cage and binds its cofactor flavin adenine dinucleotide. Rapid folding required the net negative charge character of the wall of the chaperonin cavity. These findings reveal a remarkable capacity of GroEL/ES to catalyze folding of an endogenous substrate protein that would have coevolved with the chaperonin system.

In Vivo Titration of Folate Pathway Enzymes.

How enzymes behave in cells is likely different from how they behave in the test tube. Previous in vitro studies find that osmolytes interact weakly with folate. Removal of the osmolyte from the solvation shell of folate is more difficult than removal of water, which weakens binding of folate to its enzyme partners. To examine if this phenomenon occurs in vivo, osmotic stress titrations were performed with Escherichia coli Two strategies were employed: resistance to an antibacterial drug and complementation of a knockout strain by the appropriate gene cloned into a plasmid that allows tight control of expression levels as well as labeling by a degradation tag. The abilities of the knockout and complemented strains to grow under osmotic stress were compared. Typically, the knockout strain could grow to high osmolalities on supplemented medium, while the complemented strain stopped growing at lower osmolalities on minimal medium. This pattern was observed for an R67 dihydrofolate reductase clone rescuing a ΔfolA strain, for a methylenetetrahydrofolate reductase clone rescuing a ΔmetF strain, and for a serine hydroxymethyltransferase clone rescuing a ΔglyA strain. Additionally, an R67 dihydrofolate reductase clone allowed E. coli DH5α to grow in the presence of trimethoprim until an osmolality of ∼0.81 is reached, while cells in a control titration lacking antibiotic could grow to 1.90 osmol.IMPORTANCEE. coli can survive in drought and flooding conditions and can tolerate large changes in osmolality. However, the cell processes that limit bacterial growth under high osmotic stress conditions are not known. In this study, the dose of four different enzymes in E. coli was decreased by using deletion strains complemented by the gene carried in a tunable plasmid. Under conditions of limiting enzyme concentration (lower than that achieved by chromosomal gene expression), cell growth can be blocked by osmotic stress conditions that are normally tolerated. These observations indicate that E. coli has evolved to deal with variations in its osmotic environment and that normal protein levels are sufficient to buffer the cell from environmental changes. Additional factors involved in the osmotic pressure response may include altered protein concentration/activity levels, weak solute interactions with ligands which can make it more difficult for proteins to bind their substrates/inhibitors/cofactors in vivo, and/or viscosity effects.

Association between 5,10-Methylenetetrahydrofolate Reductase C677T Gene Polymorphism and Risk of Ischemic Stroke: A Meta-analysis.

BACKGROUND: Hyperhomocysteinemia, a condition that is strongly determined by dietary intake of B vitamins, has been suggested to be an independent risk factor for ischemic stroke (IS). To test this hypothesis, we performed a meta-analysis to investigate the associations between 5,10-methylenetetrahydrofolate reductase (MTHFR) C677T gene polymorphism, which plays a critical role in modulating plasma homocysteine concentrations, and IS risk. MATERIALS AND METHODS: We searched case-control studies on the association between MTHFR C677T genetic polymorphism and susceptibility to IS through PubMed, Embase, and Medline databases from January 2000 up to October 2014. The random-effects model was employed because moderate heterogeneity across studies was observed, as assessed by I(2) statistic. Publication bias was estimated using funnel plot and Egger's regression test. RESULTS: A total of 22 case-control studies were included in the current meta-analysis. Significant associations between MTHFR C677T genetic polymorphism and IS were found under the dominant model (pooled odds ratio [OR] = 1.40, 95% confidence interval [CI]: 1.24-1.57), the recessive model (pooled OR = 1.37, 95% CI: 1.16-1.61), and the allele model (pooled OR = 1.29, 95% CI: 1.18-1.42). CONCLUSIONS: The meta-analysis suggests that MTHFR C677T genetic polymorphism is significantly associated with susceptibility to IS, which provides evidence supporting hyperhomocysteinemia as a risk factor for stroke.

The regulation mechanism of yitJ and metF riboswitches.

Riboswitches which function at the transcriptional level are sensitive to cotranscriptional folding. Based on the recently proposed theory of cotranscriptional folding, we developed a transition node approximation method to effectively decrease the conformation space of long RNA chains. Our results indicate that this approximation is reliable for calculating the cotranscriptional folding kinetics of long mRNA chains. We theoretically studied the cotranscriptional folding behavior of the yitJ and metF riboswitches in the absence/presence of S-adenosylmethionine. Although the two S-box riboswitches have similar OFF-state structures and share common features of riboswitches operated at the transcriptional level, their regulation mechanisms are different. The yitJ riboswitch is regulated by a combination of thermodynamic and kinetic mechanisms, while the metF riboswitch is solely kinetically controlled. For the yitJ riboswitch, transcriptional pausing at the U-stretch directly following the terminator decreases the amount of ligand required to trigger the switch. The different regulation mechanisms and binding affinities of the two riboswitches result from the different lengths of the anti-terminator helix, which in yitJ is short and only disrupts helix P1 of the riboswitch aptamer, but in metF is long and breaks both the helices P1 and P4.

Flavin-dependent enzymes in cancer prevention.

Statistical studies have demonstrated that various agents may reduce the risk of cancer's development. One of them is activity of flavin-dependent enzymes such as flavin-containing monooxygenase (FMO)(GS-OX1), FAD-dependent 5,10-methylenetetrahydrofolate reductase and flavin-dependent monoamine oxidase. In the last decade, many papers concerning their structure, reaction mechanism and role in the cancer prevention were published. In our work, we provide a more in-depth analysis of flavin-dependent enzymes and their contribution to the cancer prevention. We present the actual knowledge about the glucosinolate synthesized by flavin-containing monooxygenase (FMO)(GS-OX1) and its role in cancer prevention, discuss the influence of mutations in FAD-dependent 5,10-methylenetetrahydrofolate reductase on the cancer risk, and describe FAD as an important cofactor for the demethylation of histons. We also present our views on the role of riboflavin supplements in the prevention against cancer.

NdgR, a common transcriptional activator for methionine and leucine biosynthesis in Streptomyces coelicolor.

We show here that NdgR, a known transcriptional activator of isopropylmalate dehydratase in actinomycetes, may have other targets in the cell. An in-frame deletion mutant of ndgR showed unexpectedly poor growth in defined minimal medium even in the presence of leucine. To our surprise, it was supplementation of cysteine and methionine that corrected the growth. Based on this, we propose that NdgR induces cysteine-methionine biosynthesis. Direct involvement of NdgR in the very last steps of methionine synthesis with methionine synthase (metH) and 5,10-methylenetetrahydrofolate reductase (metF) was examined. From a pulldown assay, it was seen that NdgR was enriched from crude cell lysates with a strong affinity to metH and metF upstream sequences. Direct physical interaction of NdgR with these targets was further examined with a gel mobility shift assay. ndgR, leuC, metH, and metF were inducible in M145 cells upon nutrient downshift from rich to minimal medium but were not induced in the ndgR knockout mutant. Taking these observations together, NdgR-dependent metH-metF expression would account for the abnormal growth phenotype of the ndgR mutant although there may be additional NdgR-dependent genes in the Cys-Met metabolic pathways. As the first transcriptional factor reported for regulating Cys-Met metabolism in Streptomyces, NdgR links two disparate amino acid families, branched-chain amino acids (BCAAs) and sulfur amino acids, at the transcriptional level. Considering that Cys-Met metabolism is connected to mycothiol and one-carbon metabolism, NdgR may have broad physiological impacts.

Polymorphic variants of genes involved in homocysteine metabolism in celiac disease.

Celiac disease (CD) is a polygenic chronic enteropathy conferring an increased risk for various nutrient deficiency states. Hyperhomocysteinemia is a frequent finding in CD and may be related to the development of venous thrombosis, cardiovascular disease, and stroke in untreated CD patients. Recently, a possible excess in the frequency of the MTHFR c.677C>T (rs1801133) gene variant in CD patients was reported. The purpose of this study was to determine if there exist differences in the distribution of polymorphic variants of genes involved in homocysteine/methyl group metabolism between CD patients and the general population. A set of 10 gene polymorphisms (MTHFR rs1801133, MTR rs1805087, MTHFD1 rs2236225, MTRR rs1801394, CBS 844ins68, BHMT1 rs7356530 and rs3733890, BHMT2 rs526264 and rs625879, and TCN2 rs1801198) was tested in 134 patients with CD and 160 matched healthy controls. The frequency of the MTR rs1805087 GG genotype in CD patients was lower than in controls (0.01 and 0.06, respectively), although statistical significance was not achieved (P = 0.06). For the other analyzed polymorphisms, there was no evidence of difference in both allelic and genotypic distribution between cases and controls. The exhaustive Multifactor Dimensionality Reduction analysis revealed no combination of interactive polymorphisms predicting the incidence of CD. In contrast to the well-documented clinical observations of increased risks of vascular disease in patients with longstanding untreated CD, in our group of patients no significant association with CD was found for all tested polymorphic variants of genes involved in homocysteine metabolism. These findings should be replicated in studies with a larger sample size.

Plasma homocysteine and MTHFRC677T polymorphism as risk factors for incident dementia.

BACKGROUND: Elevated total plasma homocysteine (tHcy) has been associated with increased risk of dementia. The C677T polymorphism of the 5,10-methylenetetrahydrofolate reductase gene (MTHFR) increases tHcy and provides a means of studying the association between tHcy and dementia while not being as susceptible to the common biases and confounding of observational studies. The authors designed this longitudinal study to determine if high tHcy and the MTHFR C677T polymorphism increase the risk of incident dementia among older men. METHODS: The authors studied 4227 men aged 70-89 years from the Health in Men Study cohort and established the diagnosis of dementia (International Classification of Diseases-10th edition) using morbidity and mortality records. Information on tHcy, MTHFR gene status, lifestyle and clinical variables were obtained using postal and face-to-face assessments. RESULTS: 230 men (5.4%) developed dementia during the mean follow-up period of 5.8 ± 1.6 years (range 0.1-8.2 years). The hazard of dementia increased with a doubling of tHcy concentration (adjusted HR 1.48, 95% CI 1.10 to 2.00) and was higher in men with tHcy >15 µmol/l (adjusted HR 1.36 95% CI 1.03 to 1.81, p=0.032). Men with the TT genotype had a HR of dementia of 1.25 (95% CI 0.81 to 1.92). CONCLUSIONS: The results of this prospective study are consistent with a causal link between high tHcy and incident dementia, but the study lacked power to determine an effect of the MTHFR genotype.

DNA methylation and cognitive functioning in healthy older adults.

Long-term supplementation with folic acid may improve cognitive performance in older individuals. The relationship between folate status and cognitive performance might be mediated by changes in methylation capacity, as methylation reactions are important for normal functioning of the brain. Although aberrant DNA methylation has been implicated in neurodevelopmental disorders, the relationship between DNA methylation status and non-pathological cognitive functioning in human subjects has not yet been investigated. The present study investigated the associations between global DNA methylation and key domains of cognitive functioning in healthy older adults. Global DNA methylation, defined as the percentage of methylated cytosine to total cytosine, was measured in leucocytes by liquid chromatography-MS/MS, in 215 men and women, aged 50-70 years, who participated in the Folic Acid and Carotid Intima-Media Thickness (FACIT) study (clinical trial registration number NCT00110604). Cognitive performance was assessed by means of the Visual Verbal Word Learning Task, the Stroop Colour-Word Interference Test, the Concept Shifting Test, the Letter-Digit Substitution Test and the Verbal Fluency Test. Using hierarchical linear regression analyses adjusted for age, sex, level of education, alcohol consumption, smoking status, physical activity, erythrocyte folate concentration and 5,10-methylenetetrahydrofolate reductase 677 C â†’ T genotype, we found that global DNA methylation was not related to cognitive performance on any of the domains measured. The present study results do not support the hypothesis that global DNA methylation, as measured in leucocytes, might be associated with cognitive functioning in healthy older individuals.

Associations among objectively measured physical activity, fasting plasma homocysteine concentration, and MTHFR C677T genotype.

Elevated fasting plasma homocysteine (Hcy) level is a vascular disease risk factor. Plasma Hcy is affected by 5,10-methylenetetrahydofolate reductase (MTHFR) genotype and dietary folate intake. This cross-sectional study in 434 Japanese adults examined the associations among objectively measured physical activity (PA), plasma Hcy adjusting for dietary folate intake, and MTHFR C677T genotype. Daily PA was measured by triaxial accelerometry and all subjects completed a questionnaire about their dietary habits. Plasma Hcy and MTHFR C677T genotype were determined. Plasma Hcy in subjects with the TT genotype was significantly higher than in those with CC or CT genotype (p < 0.001). Plasma Hcy was significantly different between ≥ 200 (7.6 ± 0.2 nmol/mL) and <200 µg/day (8.3 ± 0.3 nmol/mL) folate intake groups (p = 0.003). There were no differences in plasma Hcy adjusting for age, sex, and folate intake between groups according to PA category in all subjects. However, there were significant interactions between time spent in light PA (p = 0.003), vigorous PA (p = 0.001), or inactivity (p = 0.004), and MTHFR genotype. In only the TT genotype, shorter time spent in light PA was associated with higher plasma Hcy than a longer time spent in light PA (11.5 ± 3.3 nmol/mL vs. 8.5 ± 3.3 nmol/mL, p < 0.001), and longer time spent in vigorous PA and inactivity were associated with higher plasma Hcy (11.8 ± 3.3 nmol/mL vs. 8.4 ± 3.2 nmol/mL, 11.6 ± 3.3 nmol/mL vs. 8.4 ± 3.3 nmol/mL, respectively, p < 0.001). In conclusion, light and vigorous PA were associated with plasma Hcy only in the TT genotype, but there were no such associations in all genotypes.

Folate and choline metabolism gene variants and development of uterine cervical carcinoma.

OBJECTIVE: It has been reported that aberrant DNA methylation can be associated with HPV infection and cervical tumorigenesis. The aim of this study was to evaluate the possibility that polymorphic variants of genes that may affect DNA methylation status are associated with the risk of cervical cancer in the Polish population. DESIGN AND METHOD: Employing PCR-RFLPs and HRM analyses, we examined the prevalence of BHMT Arg239Gln (rs3733890), MTR Asp919Gly (rs1805087), MTHFR Ala222Val (rs1801133), MTHFD1 Arg653Gln (rs2236225) and MTRR Ile22Met (rs1801394) genotypes and alleles in patients with advanced cervical cancer (n=124) and controls (n=168). RESULTS: The odds ratio (OR) for BHMT Gln/Gln genotype was 0.433 (95% CI=0.1780-1.054; p=0.0602). The OR for patients having the BHMT Arg/Gln or Gln/Gln genotypes was 0.579 (95% CI=0.3622-0.924; p=0.0216). We also observed a significantly higher frequency of the BHMT 239Gln allele in controls than in patients, p=0.0165. The genotype and allele frequencies of the MTR Asp919Gly, MTHFR Ala222Val, MTHFD1 Arg653Gln and MTRR Ile22Met gene variants did not display statistical differences between patients with cervical cancer and controls. We also did not find a significant association between the distribution of any genotypes or alleles and cancer characteristics. CONCLUSION: Our results might suggest the protective role of the BHMT 239Gln variant in cervical cancer incidence.

Genotyping of two single nucleotide polymorphisms in 5,10-methylenetetrahydrofolate reductase by multiplex polymerase chain reaction and capillary electrophoresis.

Two single nucleotide polymorphisms (SNPs) of 5,10-methylenetetrahydrofolate reductase (MTHFR) gene, A1298C and C677T, were widely considered to be related with various neoplasia disorders. We established a simple and effective capillary electrophoresis (CE) method for detection of two SNPs in MTHFR gene simultaneously. DNA samples were amplified by multiplex PCR with universal fluorescence-labeled primer and analyzed by single-strand conformation polymorphism (SSCP)-CE method. The CE method was performed using 1.5% hydroxyethyl cellulose in 1× TBE buffer containing 1M urea. The PCR products after SSCP procedure were electrokinetically injected at -10 kV, 30s. Separation voltage was -6 kV and the temperature was set at 20°C. The optimal SSCP-CE method was applied to detect two polymorphisms in MTHFR gene of acute lymphoblastic leukemia (ALL) and attention-deficit/hyperactivity disorder (ADHD) patients. Genotyping results were evaluated in terms of relationships between outcomes for ADHD patients after ALL chemotherapy and ALL disease. The SSCP-CE method and multiplex PCR with universal fluorescence primer were used as the fast technique for screening two SNPs in MTHFR gene, A1298C and C677T. The genotyping data were coincident with DNA sequencing. This SSCP-CE method was found feasible for detecting mutation of MTHFR gene in populations.

Impact of MTHFR gene C677T polymorphism on Bcl-2 gene methylation and protein expression in colorectal cancer.

OBJECTIVE: To investigate the impact of MTHFR C677T polymorphism on Bcl-2 gene promoter CpG island (CGI) methylation and Bcl-2 protein expression. MATERIAL AND METHODS: MTHFR polymorphisms of 86 sporadic colorectal cancer (CRC) patients and 100 healthy volunteers were analyzed by PCR-based restriction fragment length polymorphism, and Bcl-2 promoter CGI methylation in 86 CRC tissues and 86 paired nonneoplastic adjacent tissues was determined by methylation-specific PCR. Bcl-2 oncoprotein expression in 70 CRC tissues and paired nonneoplastic adjacent tissues was detected by immunohistochemistry. RESULTS: The frequency of MTHFR 677 T allele and combined variant genotypes (677CT + TT) in CRC patients was significantly higher than that in healthy controls (p = 0.023 and p = 0.035, respectively), and there is a significant association between 677TT or 677(CT + TT) genotypes and CRC (OR = 2.534, p = 0.045 and OR = 1.888, p = 0.035, respectively). The frequency of methylated Bcl-2 promoter CGI in tumor tissues was significantly lower than that in nonneoplastic adjacent tissues (p = 0.014). The frequency of methylated Bcl-2 promoter CGI in CRC tissues of the individuals with CC genotype was significantly higher than that of those with CT/TT genotypes (p = 0.018), there was significant distribution difference of C and T alleles between individuals with methylated and unmethylated Bcl-2 promoter CGI in colorectal cancer tissues (p = 0.023). Bcl-2 promoter hypomethylation was significantly correlated with Bcl-2 oncoprotein expression in colorectal cancer tissues (r = 0.558, p < 0.001). CONCLUSION: Bcl-2 promoter is hypomethylated in colorectal cancer tissue, and there is a significant correlation between MTHFR 677 TT or CT/TT genotypes and CRC or Bcl-2 promoter CGI methylation/oncoprotein expression in CRC.

The significance of 1793G>A polymorphism in MTHFR gene in women with first trimester recurrent miscarriages.

BACKGROUND: Recurrent miscarriages (RM) are significant social and clinical problem. One of suggested reason of RM is hyperhomocysteinemia. Polymorphic genes involved in homocysteine and folate metabolism, including 5,10-methylenetetrahydrofolate reductase (MTHFR) gene, are considered as an important risk factors for homocysteine accumulation and modulator of RM susceptibility. Therefore the aim of this study was to evaluate the frequency of MTHFR polymorphisms (677C>T, 1298A>C, and 1793G>A) in women with recurrent miscarriages. MATERIAL AND METHODS: We have analyzed 104 Polish women with a history of 3 or more unexplained recurrent miscarriages in the first pregnancy trimester (6-13 gestation week). The control group consisted of 169 women without obstetrical complication, any history of miscarriage and with at least one live birth in anamnesis. The investigated polymorphisms were determined by PCR/RFLP methods. RESULTS: For MTHFR 1793G>A polymorphism we have observed significant overrepresentation of heterozygotic GA genotypes in RM group (15.38% vs. 4.14% in the controls, OR=4.21, p=0.003). For 677C>T and 1298A>C we have shown lack of significant association with RM. Nevertheless, such significant association was observed if more than one mutated MTHFR variant was present in one patient. CONCLUSIONS: Our research indicate the possible role of MTHFR 1793G>A polymorphism in pathogenesis of RM. The noticed tendency to more frequent occurrence of haplotypes of MTHFR gene including two or three mutated alleles showed the possibility of summarized amplification of these variants effect influencing RM susceptibility.

Evidence for a genetic basis for altitude illness: 2010 update.

Altitude illness refers to a group of environmentally mediated pathophysiologies. Many people will suffer acute mountain sickness shortly after rapidly ascending to a moderately hypoxic environment, and an unfortunate few will develop potentially fatal conditions such as high altitude pulmonary edema or high altitude cerebral edema. Some individuals seem to be predisposed to developing altitude illness, suggesting an innate contribution to susceptibility. The implication that there are altitude-sensitive and altitude-tolerant individuals has stimulated much research into the contribution of a genetic background to the efficacy of altitude acclimatization. Although the effect of altitude attained and rate of ascent on the etiology of altitude illness is well known, there are only tantalizing, but rapidly accumulating, clues to the genes that may be involved. In 2006, we reviewed what was then known about the genetics of altitude illness. This article updates that review and attempts to tabulate all the available genetic data pertaining to these conditions. To date, 58 genes have been investigated for a role in altitude illness. Of these, 17 have shown some association with the susceptibility to, or the severity of, these conditions, although in many cases the effect size is small or variable. Caution is recommended when evaluating the genes for which no association was detected, because a number of the investigations reviewed in this article were insufficiently powered to detect small effects. No study has demonstrated a clear-cut altitude illness gene, but the accumulating data are consistent with a polygenic condition with a strong environmental component. The genes that have shown an association affect a variety of biological pathways, suggesting that either multiple systems are involved in altitude pathophysiology or that gene-gene interactions play a role. Although numerous studies have been performed to investigate specific genes, few have looked for evidence of heritability or familial transmission, or for epidemiological patterns that would be consistent with genetically influenced conditions. Future trends, such as genome-wide association studies and epigenetic analysis, should lead to enhanced understanding of the complex interactions within the genome and between the genome and hypoxic environments that contribute to an individual's capacity to acclimatize rapidly and effectively to altitude.

Serum adiponectin is associated with homocysteine in elderly men and women, and with 5,10-methylenetetrahydrofolate reductase (MTHFR) in a sex-dependent manner.

Plasma homocysteine associates positively with cardiovascular disease. C-to-T substitution at base 677 of the 5,10-methylenetetrahydrofolate reductase (MTHFR) gene associates with increased plasma homocysteine. The association of adiponectin with cardiovascular disease is unclear. This study of survivors of a 30-year cohort of the Jewish Israeli population, 310 men and 273 women (mean age, 70.5 ± 7.0 years for both), investigated the relationship between adiponectin and homocysteine, and between adiponectin and the MTHFR C677T genotype. Serum adiponectin associated positively with total homocysteine in both men (r = 0.27, P < .001) and women (r = 0.22, P < .001). In women, the TT MTHFR genotype associated with lower median adiponectin levels, 8.98 mg/L, compared with 9.88 and 10.57 mg/L for TC and CC, respectively (P = .05; CC vs TT, P = .01). In men, the trend was opposite, but not statistically significant: 7.90, 7.03, and 6.88 mg/L for TT, TC, and CC genotypes, respectively (P = .5). This study demonstrated a positive association between homocysteine and adiponectin in both elderly men and women and a statistically significant association between adiponectin and MTHFR C677T genotypes in women only.

Genetic effects on carotid intima-media thickness: systematic assessment and meta-analyses of candidate gene polymorphisms studied in more than 5000 subjects.

BACKGROUND: Carotid intima-media thickness (CIMT) is highly heritable and associated with stroke and myocardial infarction, making it a promising quantitative intermediate phenotype for genetic studies of vascular disease. There have been many CIMT candidate gene association studies, but no systematic review to identify consistent, reliable findings. METHODS AND RESULTS: We comprehensively sought all published studies of association between CIMT and any genetic polymorphism. We obtained additional unpublished data and performed meta-analyses for the 5 most commonly studied genes (studied in at least 2 studies in a total of >5000 subjects). We used a 3-step meta-analysis method: meta-analysis of variance; genetic model selection; and random effects meta-analysis of the mean CIMT difference between genotypes. We performed subgroup analyses to investigate effects of ethnicity, vascular risk status, and study size. We accounted for potential reporting bias by assessing qualitatively the possible effects of including unavailable data. Polymorphisms in 3 of the 5 genes (apolipoprotein E, angiotensin I converting enzyme, and 5,10-methylenetetrahydrofolate reductase) had an apparent association with CIMT, but for all these, we found evidence of small study bias. Apolipoprotein E epsilon2/epsilon3/epsilon4 was the only polymorphism with a persistent, statistically significant but modest association when we restricted analysis to larger studies (>1000 subjects). CONCLUSIONS: Of the most extensively studied polymorphisms, apolipoprotein E epsilon2/epsilon3/epsilon4 is the only one so far with a convincing association with CIMT. Larger studies than have generally been performed so far may be needed to confirm the associations identified in future genome-wide association studies, and to investigate modification of effect according to characteristics such as ethnicity and vascular risk status.

Quantification of key folate forms in serum using stable-isotope dilution ultra performance liquid chromatography-tandem mass spectrometry.

Folates act as essential coenzymes in many biological pathways. Alteration in folate form distribution might have biological significance, especially in relation to certain genetic polymorphisms. We developed a stable-isotope dilution ultra performance liquid chromatography-mass spectrometry (UPLC-MS/MS) method for quantification of the folate forms 5-methyltetrahydrofolate (5-methylTHF), 5-formylTHF, 5,10-methenylTHF, THF, and folic acid in serum. After extraction using an ion exchange and mixed mode solid-phase, samples were separated and detected using an UPLC-MS/MS system. The quantification limits were between 0.17nmol/L (5-formylTHF) and 1.79nmol/L (THF), and the assay was linear up to 100nmol/L (5-methylTHF) and 10nmol/L (5-formylTHF, 5,10-methenylTHF, THF, and folic acid). The intraassay CVs for 5-methylTHF and 5-formylTHF were 2.0% and 7.2%, respectively. Mean recoveries were between 82.3% for THF and 110.8% for 5,10-methenylTHF. Concentrations of total folate measured by the new method showed a strong correlation with those measured by an immunologic assay (r=0.939; p<0.001). The mean total folate from 32 apparently healthy subjects was 18.09nmol/L, of which 87.23% was 5-methylTHF. Concentrations of homocysteine showed a better correlation to the total folate measured by the new method compared to that obtained by an immunologic assay. We also confirmed that MTHFR polymorphism has a significant effect on folate distribution in this small population of non-supplemented subjects.