Homocystinuria due to 5,10-methylenetetrahydrofolate reductase deficiency revealed by stroke in adult siblings

The Association Between No-Reflow and Serum Uric Acid/Albumin Ratio in Patients With Acute Myocardial Infarction Without ST Elevation

This study evaluated the association between no-reflow (NR) and serum uric acid/albumin ratio (UAR) in 360 consecutive patients with non-ST-elevation myocardial infarction (NSTEMI) undergoing primary percutaneous coronary intervention. The study population was divided into two groups as follows: reflow (n = 310) and NR (n = 50) group. The thrombolysis in myocardial infarction (TIMI) flow score was used to describe NR. High UAR (Odds Ratio: 3.495, 95% CI; 1.216-10.048; P < .001) was found to be an independent predictor of NR. Additionally, UAR was positively correlated with the SYNTAX score and neutrophil/lymphocyte ratio; UAR was negatively correlated with left ventricular ejection fraction. The highest cut-off ratio of UAR predicting NR was found to be 1.35 with 68% sensitivity and 66.8% specificity. The area under the curve (AUC) for UAR was .768 (95% CI: .690-.847) after receiver operating characteristic (ROC) curve assessment. The AUC for UAR was found to be higher than for its components: serum uric acid (AUC: .655) and albumin (AUC: .663) (P < .001 for each evaluation).

Identification of a plausible serum uric acid cut-off value as prognostic marker of stroke: the Uric Acid Right for Heart Health (URRAH) study

The Working Group on Uric Acid and Cardiovascular Risk of the Italian Society of Hypertension conceived and designed an ad hoc study aimed at searching for prognostic cut-off values of serum uric acid (SUA) in predicting combined (fatal and non-fatal) cerebrovascular (CBV) events in the whole database. The URic acid Right for heArt Health study is a nationwide, multicenter, observational cohort study involving data on subjects aged 18-95 years recruited on a regional community basis from all the territory of Italy under the patronage of the Italian Society of Hypertension with a mean follow-up period of 120.7 ± 61.8 months. A total of 14,588 subjects were included in the analysis. A prognostic cut-off value of SUA able to discriminate combined CBV events (>4.79 mg/dL or >284.91 µmol/L) was identified by means of receiver operating characteristic curve in the whole database. Multivariate Cox regression analysis adjusted for confounders (age, sex, arterial hypertension, diabetes, chronic kidney disease, smoking habit, ethanol intake, body mass index, low-density lipoprotein cholesterol, and use of diuretics) identified an independent association between SUA and combined CBV events in the whole database (HR 1.249, 95% confidence interval, 1.041-1.497, p = 0.016). The results of the present study confirm that SUA is an independent risk marker for CBV events after adjusting for potential confounding variables, including arterial hypertension, and demonstrate that >4.79 mg/dL is a valid prognostic cut-off value.

Identifying COVID-19 by using spectral analysis of cough recordings: a distinctive classification study

Sound signals from the respiratory system are largely taken as tokens of human health. Early diagnosis of respiratory tract diseases is of great importance because, if delayed, it exerts irreversible effects on human health. The Coronavirus pandemic, which is deeply shaking the world, has revealed the importance of this diagnosis even more. During the pandemic, it has become the focus of researchers to differentiate symptoms from similar diseases such as influenza. Among these symptoms, the difference in cough sound played a distinctive role in research. Clinical data collected under the supervision of doctors in a reliable environment were used as the dataset consisting of 16 subjects suspected of COVID-19 with a specific patient demographic. Using the polymerase chain reaction test, the suspected subjects were divided into two groups as negative and positive. The negative and positive labels represent the patients with non-COVID and with a COVID-19 cough, respectively. Using the 3D plot or waterfall representation of the signal frequency spectrum, the salient features of the cough data are revealed. In this way, COVID-19 can be differentiated from other coughs by applying effective feature extraction and classification techniques. Power spectral density based on short-time Fourier transform and mel-frequency cepstral coefficients (MFCC) were chosen as the efficient feature extraction method. From among the classification techniques, the support vector machine (SVM) algorithm was applied to the processed signals in order to identify and classify COVID-19 cough. In terms of results evaluation, the cough of subjects with COVID-19 was detected with 95.86% classification accuracy thanks to the radial basis function (RBF) kernel function of SVM and the MFCC method. The diagnosis of COVID-19 coughs was performed with 98.6% and 91.7% sensitivity and specificity, respectively.

Uric Acid-to-Albumin Ratio: A Novel Marker for the Extent of Coronary Artery Disease in Patients with Non-ST-Elevated Myocardial Infarction

OBJECTIVE

This research aimed to investigate the predictive value of the uric acid-to-serum albumin ratio (UAR) in establishing the severity and extent of coronary artery disease (CAD) with non-ST segment elevation myocardial infarction (NSTEMI) patients.

METHODS

A total of 402 patients (mean age 63.5 ± 11.6 years) were included in this retrospectively designed study. We compared Synergy between Percutaneous Coronary Intervention with Taxus and Cardiac Surgery Scores (SS) between low (≤22) and intermediate-high (>22) groups. The UAR, the neutrophil-to-lymphocyte ratio (NLR), and the C-reactive protein-to-albumin ratio (CAR) were evaluated and compared.

RESULTS

SS >22 were observed in 30.8% (n = 124) of the patients, and their UAR, NLR, and CAR were significantly higher. Three separate multivariate analysis models performed as the outcome of a reliable correlation between UAR, NLR, CAR, and consequently UAR (OR = 2.08; 95% CI 1.21-3.58; p = 0.008) and CAR (OR = 3.33; 95% CI 1.85-5.9; p < 0.001) reached significance but NLR (OR = 1.26; 95% CI 0.86-1.84; p = 0.20) clinically trended significance (not statistically). Model performance comparisons demonstrated that UAR is a better predictor regarding likelihood ratios (UAR, 60.95; NLR, 57.8; and CAR, 59.0).

CONCLUSION

As a novel inflammatory marker, UAR independently predicted better outcomes than CAR and might be used reliably in prediction of the extent of CAD in NSTEMI patients.

Clinical and molecular characterization of adult patients with late-onset MTHFR deficiency

5,10-Methylenetetrahydrofolate reductase (MTHFR) deficiency usually presents as a severe neonatal disease. This study aimed to characterize natural history, biological and molecular data, and response to treatment of patients with late-onset MTHFR deficiency. The patients were identified through the European Network and Registry for Homocystinuria and Methylation Defects and the Adult group of the French Society for Inherited Metabolic Diseases; data were retrospectively colleted. To identify juvenile to adult-onset forms of the disease, we included patients with a diagnosis established after the age of 10 years. We included 14 patients (median age at diagnosis: 32 years; range: 11-54). At onset (median age: 20 years; range 9-38), they presented with walking difficulties (n = 8), cognitive decline (n = 3) and/or seizures (n = 3), sometimes associated with mild mental retardation (n = 6). During the disease course, symptoms were almost exclusively neurological with cognitive dysfunction (93%), gait disorders (86%), epilepsy (71%), psychiatric symptoms (57%), polyneuropathy (43%), and visual deficit (43%). Mean diagnostic delay was 14 years. Vascular events were observed in 28% and obesity in 36% of the patients. One patient remained asymptomatic at the age of 55 years. Upon treatment, median total homocysteine decreased (from 183 μmol/L, range 69-266, to 90 μmol/L, range 20-142) and symptoms improved (n = 9) or stabilized (n = 4). Missense pathogenic variants in the C-terminal regulatory domain of the protein were over-represented compared to early-onset cases. Residual MTHFR enzymatic activity in skin fibroblasts (n = 4) was rather high (17%-58%). This series of patients with late-onset MTHFR deficiency underlines the still unmet need of a prompt diagnosis of this treatable disease.

Serum uric acid and fatal myocardial infarction: detection of prognostic cut-off values: The URRAH (Uric Acid Right for Heart Health) study

Supplemental Digital Content is available in the text

Objective:

The Working Group on Uric Acid and Cardiovascular Risk of the Italian Society of Hypertension conceived and designed an ad-hoc study aimed at searching for prognostic cut-off values of serum uric acid (SUA) in predicting fatal myocardial infaction (MI) in women and men.

Methods:

The URic acid Right for heArt Health study is a nationwide, multicentre, observational cohort study involving data on individuals aged 18–95 years recruited on a regional community basis from all the territory of Italy under the patronage of the Italian Society of Hypertension with a mean follow-up period of 122.3 ± 66.9 months.

Results:

A total of 23 467 individuals were included in the analysis. Cut-off values of SUA able to discriminate MI status were identified by mean of receiver operating characteristic curves in the whole database (>5.70 mg/dl), in women (>5.26 mg/dl) and in men (>5.49 mg/dl). Multivariate Cox regression analyses adjusted for confounders (age, arterial hypertension, diabetes, chronic kidney disease, smoking habit, ethanol intake, BMI, haematocrit, LDL cholesterol and use of diuretics) identified an independent association between SUA and fatal MI in the whole database (hazard ratio 1.381, 95% confidence intervals, 1.096–1.758, P = 0.006) and in women (hazard ratio 1.514, confidence intervals 1.105–2.075, P < 0.01), but not in men.

Conclusion:

The results of the current study confirm that SUA is an independent risk factor for fatal MI after adjusting for potential confounding variables, and demonstrate that a prognostic cut-off value associated to fatal MI can be identified at least in women.

Asymptomatic hyperuricemia and incident stroke in elderly Chinese patients without comorbidities

BACKGROUND/OBJECTIVES

Hyperuricemia is usually associated with other comorbidities; so it is difficult to distinguish the effects of hyperuricemia from other coexisting comorbidities in patients who suffer a stroke.

SUBJECT/METHODS

Data for this study were collected from the patients of Kangjian Community Health Center of Shanghai. Selected participants ≥65 years of age were available at enrollment (2009-2013). Subjects were excluded if they had hypertension, diabetes mellitus, pre-existing cardiovascular disease, or hyperlipidemia. Further, patients who were overweight or obese, had gout or drug-treated hyperuricemia, or had chronic kidney disease were also excluded. Cox regression was used in order to assess the hazard ratio (HR) for the incidence of stroke events between hyperuricemic and normouricemic patients.

RESULTS

A total of 3243 subjects without comorbidities (70.8 ± 6.0 years) were followed for 35.5 ± 3.0 months. Hyperuricemia conferred increased cumulative incident stroke events (6.9 versus 3.1%, odds ratio [OR] = 2.27, 95% confidence index [CI] 1.52-3.37, p < 0.001). Male and female hyperuricemic subjects also showed a significantly higher incident stroke incidence than normouricemic subjects (6.1 versus 2.7%, OR = 2.34, 95% CI 1.31-4.18, p = 0.003 and 7.6 versus 3.7%, OR = 2.16, 95% CI 1.25-3.72, p = 0.005, respectively). Cox regression showed that hyperuricemia independently predicted incident stroke risk (HR = 2.32, 95%CI 1.56-3.45).

CONCLUSION

Asymptomatic hyperuricemia carried a significant risk of stroke events in Chinese elderly without comorbidities.

Asymptomatic hyperuricemia and coronary artery disease in elderly patients without comorbidities

Because many subjects with hyperuricemia have comorbidities, it can be difficult to differentiate the role of hyperuricemia from that of other comorbidities of coronary artery disease (CAD). Subjects aged ≥ 65 years were enrolled in the study and were available at enrollment and at 5-year follow-up. Subjects were excluded if they were overweight or obese, hypertensive, diabetic, hyperlipidemic, had a pre-existing cardiovascular disease, a history of gout or hyperuricemia on medications, or chronic kidney disease as estimated by a glomerular filtration rate (eGFR) < 60 mL/min per 1.73 m². We used Poisson regression to estimate the hazard ratio (HR) for incident CAD events between hyperuricemic (> 7 mg/dL in men and ≥ 6 mg/dL in women) and normouricemic subjects. A total of 2,142 subjects without comorbidities (mean age of 70.7 ± 5.9 years, 1,194 men) were followed for 57.4 ± 8.9 months. Hyperuricemia was associated with an increased cumulative incidence of incident CAD events (15.0% versus 8.8%, P < 0.001). After adjusting for confounding factors, hyperuricemia independently predicted the risk of incident CAD events (HR=1.71, 95% CI 1.26-2.34). In conclusion, asymptomatic hyperuricemia is a valuable biomarker for predicting the development of incident CAD events.

Guidelines for diagnosis and management of the cobalamin-related remethylation disorders cblC, cblD, cblE, cblF, cblG, cblJ and MTHFR deficiency

BACKGROUND

Remethylation defects are rare inherited disorders in which impaired remethylation of homocysteine to methionine leads to accumulation of homocysteine and perturbation of numerous methylation reactions.

OBJECTIVE

To summarise clinical and biochemical characteristics of these severe disorders and to provide guidelines on diagnosis and management.

DATA SOURCES

Review, evaluation and discussion of the medical literature (Medline, Cochrane databases) by a panel of experts on these rare diseases following the GRADE approach.

KEY RECOMMENDATIONS

We strongly recommend measuring plasma total homocysteine in any patient presenting with the combination of neurological and/or visual and/or haematological symptoms, subacute spinal cord degeneration, atypical haemolytic uraemic syndrome or unexplained vascular thrombosis. We strongly recommend to initiate treatment with parenteral hydroxocobalamin without delay in any suspected remethylation disorder; it significantly improves survival and incidence of severe complications. We strongly recommend betaine treatment in individuals with MTHFR deficiency; it improves the outcome and prevents disease when given early.

Hyperuricemia and coronary heart disease mortality: a meta-analysis of prospective cohort studies

Background

Hyperuricemia may be associated with an increased risk of coronary heart disease (CHD) mortality; however, the results from prospective studies are conflicting. The objective of this study was to assess the association between hyperuricemia and risk of CHD mortality by performing a meta-analysis.

Methods

Pubmed and Embase were searched for relevant prospective cohort studies published until July 2015. Studies were included only if they reported data on CHD mortality related to hyperuricemia in a general population. The pooled adjusted relative risk (RR) was calculated using a random-effects model.

Results

A total of 14 studies involving 341 389 adults were identified. Hyperuricemia was associated with an increased risk of CHD mortality (RR: 1.14; 95 % CI: 1.06–1.23) and all-cause mortality (RR: 1.20; 95 % CI: 1.13–1.28). For each increase of 1 mg/dl of serum uric acid (SUA), the overall risks of CHD and all-cause mortality increased by 20 and 9 %, respectively. According to the gender subgroup analyses, hyperuricemia increased the risk of CHD mortality in women (RR: 1.47; 95 % CI: 1.21–1.73) compared to men (RR: 1.10; 95 % CI: 1.00–1.19). The risk of all-cause mortality was greater in women.

Conclusions

Hyperuricemia may modestly increase the risk of CHD and all-cause mortality. Future research is needed to determine whether urate–lowering therapy has beneficial effects for reducing CHD mortality.

Electronic supplementary material

The online version of this article (doi:10.1186/s12872-016-0379-z) contains supplementary material, which is available to authorized users.

Outcomes of four patients with homocysteine remethylation disorders detected by newborn screening

PURPOSE

We evaluated the clinical outcome in homocysteine remethylation disorders following newborn screening (NBS) and initiation of early specific treatment.

METHODS

Five patients with remethylation disorders were included in this study.

RESULTS

Two asymptomatic patients (one with cblG and one with cblE) were identified by NBS using an approach that combines a postanalytical interpretive tool (available on the Region 4 Stork (R4S) collaborative project website, http://www.clir-r4s.org) and a second-tier test for total homocysteine determination. Both the initial screening and the second-tier test are performed on the same blood spot, with no additional patient contact, resulting in no false-positive outcomes. Two additional patients with methylenetetrahydrofolate reductase deficiency were detected by NBS using low methionine as a marker. Although already symptomatic despite the early diagnosis, the latter two patients greatly improved with treatment and their outcomes are compared with that of another patient with methylenetetrahydrofolate reductase deficiency and significant morbidity who was diagnosed clinically at 3 months of age.

CONCLUSION

Early detection by NBS and timely and specific treatment considerably improve at least short-term outcomes of homocysteine remethylation disorders. When a remethylation disorder is suspected, group-specific treatment could be started prior to the completion of in vitro confirmatory testing because all disorders from this group require similar intervention.

Serum uric acid is an independent predictor for all major forms of cardiovascular death in 28,613 elderly women: a prospective 21-year follow-up study

BACKGROUND

The role of serum uric acid (SUA) as a risk factor for cardiovascular disease (CVD) remains controversial. Little is known about its predictive value for mortality from congestive heart failure (CHF) and stroke, particularly in elderly, post-menopausal women.

METHODS

The relation of SUA to risk of death from total CVD, CHF, stroke and coronary heart disease (CHD) was examined prospectively in a large cohort of 28613 elderly Austrian women (mean age 62.3 years), followed-up for a median of 15.2 years. Adjusted Cox proportional hazards models were calculated to evaluate SUA as an independent predictor for fatal CVD events.

RESULTS

SUA in the highest quartile (>or=5.41 mg/dL) was significantly associated with mortality from total CVD (p<0.0001), showing a clear dose-response relationship; the adjusted hazard ratio (95%CI) in comparison to the lowest SUA quartile was 1.35 (1.20-1.52). In subgroup analyses SUA was independently predictive for deaths from acute and subacute (p<0.0001) and chronic forms (p=0.035) of CHD, yielding adjusted hazard ratios for the highest versus lowest SUA quartile of 1.58 (1.19-2.10) and 1.25 (1.01-1.56), respectively. SUA was further significantly related to fatal CHF (p<0.0001) and stroke (p=0.018); the adjusted hazard ratios for the highest versus lowest SUA quartile were 1.50 (1.04-2.17) and 1.37 (1.09-1.74), respectively.

CONCLUSIONS

These findings, for the first time, demonstrate that SUA is an independent predictor for all major forms of death from CVD including acute, subacute and chronic forms of CHD, CHF and stroke in elderly, post-menopausal women.

Serum uric acid and risk of cardiovascular mortality: a prospective long-term study of 83,683 Austrian men

BACKGROUND

The role of serum uric acid (SUA) as an independent risk factor for cardiovascular disease (CVD) remains controversial, and little is known about its prognostic importance for mortality from congestive heart failure (CHF) and stroke. Few large-scale epidemiologic studies with sufficient follow-up have addressed the association of SUA and CVD mortality in apparently healthy men across a wide age range.

METHODS

A cohort of 83 683 Austrian men (mean age, 41.6 years) was prospectively followed for a median of 13.6 years. We used Cox proportional hazards models adjusted for established risk factors to evaluate SUA as an independent predictor for CVD mortality.

RESULTS

The highest quintile of SUA concentration (>398.81 mumol/L) was significantly related to mortality from CHF (P = 0.03) and stroke (P <0.0001); adjusted hazard ratios (95% confidence interval) for the highest vs lowest quintiles of SUA were 1.51 (1.03-2.22) and 1.59 (1.23-2.04), respectively. SUA was not associated, however, with mortality from acute, subacute, or chronic forms of coronary heart disease (CHD) after adjustment for potential confounding factors (P = 0.12). Age was a significant effect modifier for the relation of SUA to fatal CHF (P = 0.05), with markedly stronger associations found in younger individuals.

CONCLUSIONS

Our study demonstrates for the first time in a large prospective male cohort that SUA is independently related to mortality from CHF and stroke. Although increased SUA is not necessarily a causal risk factor, our results suggest the clinical importance of monitoring and intervention based on the presence of an increased SUA concentration, especially because SUA is routinely measured.

Hereditary spastic paraparesis in adults associated with inborn errors of metabolism: a diagnostic approach

Spastic paraparesis is a general term describing progressive stiffness and weakness in the lower limbs caused by pyramidal tract lesions. This clinical situation is frequently encountered in adult neurology. The diagnostic survey is usually limited to searching for acquired causes (spinal cord compression, inflammatory, metabolic, infectious diseases) and the so-called 'hereditary spastic paraparesis'. Although poorly recognized by neurologists, spastic paraparesis is also one of the multiple presentations of inborn errors of metabolism (IEMs) in children and adults. Pyramidal signs are usually included in a diffuse neurological or systemic clinical picture; however, in some cases spastic paraparesis remains the only symptom for years. Since these metabolic causes are often treatable, it is essential to include them in the general diagnostic approach to spastic paraparesis. Here we review IEMs causing paraparesis in adults.

Serum uric acid level and risk for peripheral arterial disease: analysis of data from the multiple risk factor intervention trial

Although several studies report an association between hyperuricemia and coronary artery disease, little is known about the effect of hyperuricemia and gout on the risk of peripheral arterial disease (PAD). Data on 283 incident clinical cases of PAD during a randomized controlled trial of multiple cardiovascular risk factor intervention are evaluated. The serum uric acid levels among these individuals are compared with those of individuals who did not develop PAD during the study period. Multivariate logistic regression analyses measure the risk of developing PAD associated with higher levels of serum uric acid after adjusting for the effect of traditional vascular risk factors. Age and smoking are independently associated with development of PAD, with odds ratios of 1.08 (95% confidence interval [CI], 1.06-1.09) and 3.83 (95% CI, 2.49-5.91) per year, respectively. Hyperuricemia (serum uric acid level, >7.0 mg/dL) is an independent risk factor, with an odds ratio of 1.23, but the confidence interval of the estimate is wide (95% CI, 0.98-1.54). In this multivariate model, a history of gout was associated with an odds ratio of 1.33 (95% CI, 1.07-1.66). Serum uric acid level is independently associated with a higher (but statistically nonsignificant) risk of PAD. A history of gouty arthritis is an independent and statistically significant predictor of incidence of PAD even after adjustment for the effect of underlying hyperuricemia.

Therapy insight: inborn errors of metabolism in adult neurology--a clinical approach focused on treatable diseases

Inborn errors of metabolism (IEMs) are genetic disorders characterized by dysfunction of an enzyme or other protein involved in cellular metabolism. In most cases, IEMs involve the nervous system. The first clinical symptoms of IEMs usually present in infancy, but in an unknown proportion of cases they can appear in adolescence or adulthood. In this Review, we focus on treatable IEMs, presenting acutely or chronically, that can be diagnosed in an adult neurology department. To make our presentation readily usable by clinicians, the Review is subdivided into eight sections according to the main clinical presentations: emergencies (acute encephalopathies and strokes), movement disorders, peripheral neuropathies, spastic paraparesis, cerebellar ataxia, psychiatric disorders, epilepsy and leukoencephalopathies. Our aim is to present simple guidelines to enable neurologists to avoid overlooking a treatable metabolic disease.

Serum uric acid and cardiovascular disease: recent developments, and where do they leave us?

The relationship between serum uric acid (SUA) and cardiovascular disease has been controversial. Here we review recent literature assessing whether hyperuricemia is an independent risk factor for adverse cardiovascular outcomes. Studies from the past 6 years evaluating the association of SUA with cardiovascular disease were identified through MEDLINE, EMBASE, and Cochrane library searches, bibliography cross-referencing, and review articles. Twenty-one cohort studies in healthy and high-risk patients with cardiovascular disease were identified and reviewed. In studies of high-risk patients, in which more overall events were recorded, 10 of 11 studies were supportive of an independent association. In 10 studies of healthy patients, 6 suggested an independent association of SUA with adverse cardiovascular outcomes. Increasing SUA is likely an independent risk factor for cardiovascular disease in high-risk individuals. However, the magnitude of excess risk attributable to high SUA is likely to be small in healthy individuals. Trials of SUA-lowering therapy in hyperuricemic patients evaluating the effect on cardiovascular outcomes are justified in high-risk patients.

Relations between molecular and biological abnormalities in 11 families from siblings affected with methylenetetrahydrofolate reductase deficiency

Methylenetetrahydrofolate reductase (MTHFR) deficiency is an autosomal recessive disorder resulting in elevated homocysteine levels in plasma and urine. MTHFR catalyses the reduction of methylenetetrahydrofolate to methyltetrahydrofolate, a cofactor for homocysteine remethylation to methionine. MTHFR deficiency may be diagnosed from infancy to adulthood with a broad spectrum of clinical symptoms. A molecular analysis of the MTHFR gene combined with an assessment of MTHFR activity, plasma homocysteine and folate in plasma and red blood cells (RBC), especially methylfolate, was assessed in the members of 11 families from children affected with this disorder. This study was performed to try to define the impact of the mutations found in the MTHFR gene on symptoms and biological abnormalities. A total of 14 mutations were found and 10 of them were identified for the first time. Two were found in two families, two more in two other families and one in three families. The position of the mutation spread all over the gene does not predict the degree of biological abnormalities found in parents or healthy siblings bearing the mutation. Two different mutations located not far apart on the same exon may cause mild or severe abnormalities. The thermolabile variant C677T when expressed in an homozygote state in some parents was associated with lower MTHFR activity, higher homocysteine levels, lower folate levels, mainly methylfolate in RBC than in parents without the mutation; conversely, two or more mutations on the same allele had mild effects when the other allele was normal.

CONCLUSION

Given the heterogeneity of mutations, no one seems preponderant to predict neurological and/or vascular symptoms.

Predictors of stroke mortality in elderly people from the general population. The CArdiovascular STudy in the ELderly

Stroke occurs particularly frequently in elderly people and, being more often disabling than fatal, entails a high social burden. The predictors of stroke mortality have been identified in 3282 subjects aged > or = 65 years, taking part in the CArdiovascular STudy in the ELderly (CASTEL), a population-based study performed in Northeast Italy. Historical and clinical data, blood tests and 14-year fatal events were recorded. Continuous items were divided into quintiles and, for each quintile, adjusted relative risk (RR) with 95% confidence intervals [CI] was derived from multivariate Cox analysis. Age, historical stroke (RR: 5.2; 95% CI: 3.18-8.6) and coronary artery disease (RR: 1.38; CI: 1.18-2.1), atrial fibrillation (RR: 2.40; CI: 1.42-4.0), arterial hypertension (RR: 1.33; CI: 1.15-1.76), systolic blood pressure > or = 163 mmHg (RR: 1.84; CI: 1.20-2.59), pulse pressure > or = 74 mmHg (RR: 1.50; CI: 1.13-2.40), cigarette smoking (RR: 1.60; CI: 1.03-2.47), electrocardiographic left ventricular hypertrophy (RR: 1.72; CI: 1.10-2.61), impaired glucose tolerance (IGT, RR: 1.83; CI: 1.10-3.0), uric acid (UA) > 0.38 mmol/l (RR: 1.61; CI: 1.14-2.10), serum potassium > or = 5 mEq/l (RR: 1.70; CI: 1.24-2.50) and serum sodium < or = 139 mEql/l (RR: 1.34; 1.10-2.10) increased the risk of stroke. In the CASTEL, stroke was the first cardiovascular cause of death. Some independent predictors usually unrelated to stroke mortality (namely pulse pressure, pre-diabetic IGT, UA and blood electrolytes disorders) have been identified.

New disc-based technologies for diagnostic and research applications

The role of genotypic analysis in disease diagnostics and drug response assessment is continually expanding. New genomic discoveries combined with new, novel technologies may provide a greater range of testing capabilities in the near future. We describe the application of nanotechnology, in which DNA microarrays have been placed in a microchannel environment that can be read and analyzed in an optical (CD/DVD) disc drive system. The potential exists to combine molecular and immunological applications together into a rapid, low-cost, high-capacity screening platform. The relevance of this technology is discussed in respect to infectious agent detection, pharmacogenomics, neurogenomics and genetic variations associated with neurologic diseases.

Severe methylenetetrahydrofolate reductase deficiency revealed by a pulmonary embolism in a young adult

Deficiency in methylenetetrahydrofolate reductase (MTHFR), the enzyme involved in the remethylation of homocysteine to methionine using methyltetrahydrofolate as cofactor, induces hyperhomocysteinaemia, homocysteinuria, hypomethioninaemia and low methylfolate levels. Diagnosis usually occurs during infancy because of various neurological abnormalities. We report MTHFR deficiency diagnosed in an adult woman after a pulmonary embolism. Her adult sister, intellectually retarded, suffered from the same disease. Molecular analysis of the MTHFR gene exhibited four different mutations (two missense mutations, one exon skipping and C677T). The impact of these mutations was analysed through the biological abnormalities in the parents and children.

Impact of new mutations in the methylenetetrahydrofolate reductase gene assessed on biochemical phenotypes: a familial study

Methylenetetrahydrofolate reductase (MTHFR) deficiency was identified in two out of four children born from nonconsanguineous parents. One of the affected children exhibited some clinical findings suggesting cystathionine beta-synthase deficiency; MTHFR activity was extremely reduced. In addition, hyperhomocysteinaemia, hypomethioninaemia, low total folate, especially methylfolate in red blood cells, and a reduced methylfolate/total folate ratio were found. Two mutations not yet reported, one on exon 1 of the gene changing an arginine to stop codon and one other on exon 9 changing an arginine to tryptophan were identified in both children in the compound heterozygous state associated with a common polymorphism, 1298A>C, also in the heterozygous state. The mother, homozygous for the mutation on exon 9 and for the polymorphism 1298A>C on exon 7, was clinically and biochemically normal, with normal folate status, mainly methylfolate levels in red blood cells, although MTHFR activity was moderately decreased. The father, heterozygous for the transition arginine to stop codon and for the common polymorphism 677C>T on exon 4, exhibited major biochemical abnormalities, hyperhomocysteinaemia and low methylfolate levels in red blood cells, but was clinically normal. The unaffected children had a biochemical pattern close to that of their mother and were heterozygous for the mutation on exon 9 and also for the two common polymorphisms, 677C>T and 1298A>C. In the affected children, some biochemical abnormalities, including folate status, especially methylfolate levels, were improved with treatment combining methyltetrahydrofolic acid, hydroxocobalamin, pyridoxine and betaine; however, homocysteine concentrations remained high and methionine concentrations were lowered. The father was treated with folic acid, which partially improved biochemical abnormalities. The impact of these mutations is discussed.

Etiology of stroke in children

Although the risk factors for stroke in children are numerous and differ greatly from the causes of stroke in adults, a thorough diagnostic evaluation can identify one or more risk factors in most patients. Cardiac disorders and hemoglobinopathy are the most common causes of ischemic infarction, whereas various congenital anomalies of the blood vessels or defects in coagulation or platelet function are often found in children with intraparenchymal hemorrhage. More than one risk factor is commonly identified, especially in children with dural venous thrombosis. Identification of the underlying risk factors for cerebrovascular disorders in children is important because many of the risk factors can be treated, reducing the risk of subsequent strokes.

Homocysteine and cardiovascular disease: cause or effect?

Both markedly and mildly elevated circulating homocysteine concentrations are associated with increased risk of vascular occlusion. Here we review possible mechanisms that mediate these effects. Inborn errors of homocysteine metabolism result in markedly elevated plasma homocysteine (200-300 micromol/L) and thromboembolic (mainly venous) disease: treatment to lower but not to normalize these concentrations prevents vascular events. Mild homocysteine elevation (>15 micromol/L) occurs in approximately 20-30% of patients with atherosclerotic disease. Usually, this is easily normalized with oral folate and ongoing trials are assessing the effect of folate treatment on outcomes. Although there is evidence of endothelial dysfunction with both markedly and mildly elevated homocysteine concentrations, the elevated homocysteine concentration in atherosclerotic patients is also associated with most standard vascular risk factors, and importantly, with early decline in renal function, which is common in atherosclerosis. Decline in renal function alone causes elevated plasma homocysteine (and cysteine). These observations suggest that mild hyperhomocysteinemia could often be an effect rather than a cause of atherosclerotic disease. Data on the common C677T methylenetetrahydrofolate reductase polymorphism supports this, in that, although homozygosity is a frequent cause of mild hyperhomocysteinemia when plasma folate is below median population concentrations, it appears not to increase cardiovascular risk. Indeed, there is recent evidence suggesting an acute antioxidant effect of folic acid independent of its effect on homocysteine concentrations. This antioxidant mechanism may oppose an oxidant effect of homocysteine and be relevant to treatment of patients with vascular disease, especially those with chronic renal insufficiency. Such patients have moderately elevated plasma homocysteine and greatly increased cardiovascular risk that is largely unexplained.

Methylenetetrahydrofolate reductase deficiency in four siblings: a clinical, biochemical, and molecular study of the family

A diagnosis of methylenetetrahydrofolate reductase (MTHFR) deficiency was made in four sibs at different ages. The first three, including a pair of twins, had retarded psychomotor development, poor social contact, and seizures. Biologically, hyperhomocysteinemia and hypomethioninemia were found associated with low folate levels in serum and red cells, especially undetectable methyltetrahydrofolate in red cells. In the fourth child, prenatal diagnosis was not conclusive because of moderate decrease of enzymatic activity in chorionic villi and trophoblast. The girl was also affected, as shown by hyperhomocysteinemia and low folate levels found several days after birth. A 677C-->T (Ala-->Val) mutation was found in a homozygous state in the four children and in the father. Additionally, a second homozygous mutation, 1081C-->T, changing an arginine to cysteine also was identified in all of the children, whereas the distantly consanguineous parents were heterozygous. This amino acid substitution affecting an arginine residue in a sequence located at the end of catalytic domain seems critical for the function of the enzyme. The difficulty of prenatal diagnosis is discussed given the variability found in enzymatic activity and in the clinical phenotypes.

Homocysteine

Homocysteine is a sulfur-containing amino acid generated through the demethylation of methionine. It is largely catabolized by trans-sulfuration to cysteine, but it may also be remethylated to methionine. Regulation of homocysteine is dependent on nutrient intake, especially folate, vitamins B6 and B12. It is also controlled by individual genetic differences in how vitamins are utilized as cofactors in the reactions controlling homocysteine metabolism. In excess quantities, homocysteine is thought to be thrombophilic and to damage the vascular endothelium. Total plasma homocysteine (tHcy) is now established as a clinical risk factor for coronary artery disease, as well as other arterial and venous occlusive disease in adult populations. These effects are probably related to its role as a teratogen in the pathogenesis of neural tube defects--genetic variants causing hyperhomocysteinemia are associated with both neural tube defects in susceptible pregnancies and with risks for vaso-occlusive disease in later years. Considerable care must be taken in assaying tHcy. Plasma should be separated shortly after collection to avoid artifactual increases due to synthesis by blood cells in vitro. tHcy concentrations must be interpreted in light of the fact that serum albumin, urate, creatinine, and vitamin concentrations may be important analytical covariates. Moreover, concentrations are age- and sex-dependent and are altered by renal function, hormonal status, drug intake, and a variety of other common clinical factors. Why then is homocysteine now of such great clinical and scientific interest? If the homocysteine moiety itself is important in the pathogenesis of vaso-occlusive disease, then simple treatment of hyperhomocysteinemia with vitamins should lead to a significant reduction in disease risk. Such a possibility lies behind the growing momentum to recommend increased supplements of folate and B vitamins to at-risk populations and patient groups today.

Does the polymorphism 677C-T of the 5,10-methylenetetrahydrofolate reductase gene contribute to homocysteine-related vascular disease?

Whether the 677C-T polymorphism of the methylene tetrahydrofolate reductase (MTHFR) gene acts as a risk factor for homocysteine-related vascular disease remains a matter of debate. Testing for the 677C-T nucleotide substitution and assay of plasma homocysteine were carried out simultaneously in 69 controls and 113 vascular disease patients from the Paris area. The variant gene frequency as well as the variant homozygous genotype frequency were very similar in controls and patients. Conversely, plasma homocysteine levels were substantially higher in patients than in controls. A slight interaction between the 677C-T MTHFR polymorphism and homocysteinaemia was observed in the patient group only, while a negative correlation between fasting homocysteine and plasma folate levels was found in all individuals homozygous for the 677C-T MTHFR genotype, irrespective of vascular disease. These data suggest that the 677C-T MTHFR polymorphism is not a major determinant of the vascular disease but contributes to increased plasma homocysteine concentration in conjunction with low plasma folate levels.

Plasma homocysteine levels related to interactions between folate status and methylenetetrahydrofolate reductase: a study in 52 healthy subjects

Hyperhomocysteinemia, a risk factor for vascular disease, is related to vitamin B12, vitamin B6, and especially folate deficiency, or to genetic factors such as mutations in methylenetetrahydrofolate reductase (MTHFR), an enzyme involved in the remethylation pathway of homocysteine to methionine. Recently, a C677 --> T mutation identified in the MTHFR gene was found to be frequently associated with decreased MTHFR activity and an elevated plasma homocysteine concentration. Since hyperhomocysteinemia seems to be determined by both genetic and environmental factors, we studied the interactions between MTHFR (phenotype and genotype) and folate status, including methyltetrahydrofolate (methylTHF), the product of MTHFR, on the homocysteine concentration in 52 healthy subjects, (28 women and 24 men; mean age, 32.7 years). MTHFR activity seems to be dependent on folate status, as shown by a lower activity in folate-deficient subjects and a return to normal values after supplementation with folic acid, and also by a decreased enzymatic activity on phytohemagglutinin (PHA)-stimulated lymphocytes grown in a folic acid-deficient medium. Conversely, the C677 --> T mutation seems to influence folate metabolism. Subjects who were homozygous for this mutation (+/+) had significantly higher plasma homocysteine and lower plasma folate and total and methylfolate levels in red blood cells (RBCs) than heterozygous (+/-) and normal (-/-) subjects. The ratio of RBC methylfolate to RBC total folate was, respectively, 0.27 in +/+, 0.66 in +/-, and 0.71 in -/-. This mutation seems to have an impact on methylTHF generation. These data illustrate the interactions between nutritional and genetic factors.

A methylenetetrahydrofolate reductase gene polymorphism in ischaemic stroke and in carotid artery stenosis

METHODS

A biallelic polymorphism of the methylenetretrahydrofolate reductase (MTHFR) gene, reported to influence the plasma level of homocysteine (Hcy), was investigated for a possible role in influencing the risk of ischaemic cerebrovascular disease (ICVD) and occlusive atherosclerosis in 126 patients with ischaemic stroke and 70 patients with internal carotid artery (ICA) stenosis.

RESULTS

Only minor differences were observed between different groups of patients and control subjects. Although 47% of ICA stenosis patients had increased plasma Hcy, the MTHFR genotype did not correlate with levels of either Hcy, folic acid or vitamin B12. In addition, the MTHFR genotype did not affect Hcy levels, even in the presence of low blood folate.

CONCLUSION

We conclude that this common MTHFR gene polymorphism does not exert a significant influence on the risk of developing ICVD or ICA stenosis, and does not cause the increased level of Hcy observed in ICA stenosis.

Serum uric acid is a strong predictor of stroke in patients with non-insulin-dependent diabetes mellitus

BACKGROUND AND PURPOSE

Patients with non-insulin-dependent diabetes mellitus (NIDDM) are at increased risk for stroke. Hyperuricemia is a common finding in NIDDM, but its significance as an independent risk factor for cardiovascular disease has remained uncertain. Therefore, we investigated serum urate as a predictor of stroke in NIDDM patients free of clinical nephropathy (ie, with a serum creatinine level of < or = 120 micromol/L).

METHODS

In this population-based study, cardiovascular risk factors were determined in 1017 patients (551 men and 466 women) with NIDDM, aged 45 to 64 years at baseline. The patients were followed up for 7 years with respect to stroke events.

RESULTS

During the follow-up period, 31 NIDDM patients (12 men [2.2%] and 19 women [4.1%]) died from stroke and 114 NIDDM patients (55 men [10.0%] and 59 women [12.7%]) had a fatal or nonfatal stroke. The incidence of stroke increased significantly by quartiles of serum uric acid levels (P<.001). High uric acid level (above the median value of > 295 micromol/L) was significantly associated with the risk of fatal and nonfatal stroke by Cox regression analysis (hazard ratio, 1.93 [1.30 to 2.86]; P=.001). This association remained statistically significant even after adjustment for all cardiovascular risk factors (hazard ratio, 1.91 [1.24 to 2.94]; P=.003).

CONCLUSIONS

Our results indicate that hyperuricemia is a strong predictor of stroke events in middle-aged patients with NIDDM independently of other cardiovascular risk factors.

Hyperhomocysteinaemia and associated disease

An elevated plasma homocysteine level may result from various environmental and genetic factors. Herediatary causes of severe hyperhomo-cysteinaemia are very rare and usually lead to disease in childhood or adolescence. Common pathology consists of early atherosclerotic vascular changes, arterioocclusive complications and venous thrombosis. Mildly elevated genetically determined plasma homocysteine levels are observed in 5% of the general population. In the last two decades research has shown mild hyperhomocysteinaemia to be linked to an increased risk of premature atherosclerosis, pregnancies complicated by neural tube defects and early pregnancy loss, and venous thrombosis. Homozygosity for thermolabile MTHFR deficiency has been identified as one important genetic factor, which expression is modified by dietary folate intake. Although mild hyperhomocysteinaemia can easily be treated by vitamin supplementation the beneficial effects of such treatment remains to be shown.

Thermolabile variant of 5,10-methylenetetrahydrofolate reductase associated with low red-cell folates: implications for folate intake recommendations

BACKGROUND

The dietary reference values for folate, as for other nutrients, are targeted to the general and supposedly normal population, not people with special needs, such as those with genetic or metabolic abnormalities or diseases. However, 5-15% of general populations are homozygous for a thermolabile variant of 5,10-methylenetetrahydrofolate reductase (C677T) which causes mild hyperhomocysteinaemia and is positively associated with the development of vascular disease and the risk of neural-tube defects. If tissue-folate status is compromised in large sectors of the population by this or other genetic variants, the present dietary reference values may need to be changed.

METHODS

We identified the C677T genotype and measured red-cell folate concentrations in two groups of healthy women (pregnant, 242, not pregnant, 318). We then analysed the effect of genotype on red-cell folates, which are a reliable marker for tissue folate stores.

FINDINGS

In the pregnant group there were 20 TT homozygotes, 114 wild-type CC homozygotes, and 108 CT heterozygotes. In the non-pregnant group, the numbers were 41, 148, and 129. In both pregnant and non-pregnant groups, red-cell folate was significantly lower among TT homozygous than CC homozygous women (mean 252 [95% CI 202-317] vs 347 [321-372] micrograms/L, p = 0.002 for pregnant women; 284 [250-327] vs 347 [342-372] micrograms/L, p = 0.01 for non-pregnant women). Plasma folate was also significantly lower in TT homozygous than in CC homozygous women in the pregnant group (p = 0.009) but not in the non-pregnant group.

INTERPRETATION

These results suggest that a substantial minority of people in general populations may have increased folate needs. Future studies may show the presence of other common genetic variants that interact with particular nutrients and place doubts on the validity of assuming "normality" for nutrient requirements in any general population.

Hyperhomocysteinaemia and premature coronary artery disease in the Chinese

OBJECTIVES

To examine the prevalence of hyperhomocysteinaemia and compare it with the classic risk factors and vitamin status in Hong Kong Chinese patients with premature atherosclerotic coronary artery disease.

DESIGN

Case-control study.

SETTING

General hospital and community.

SUBJECTS

Forty five patients (39 males) with significant coronary artery disease confirmed by angiography (32 post myocardial infarction) and 23 healthy volunteers (17 male), all aged less than 55 years.

INTERVENTION

Standardised methionine-loading test.

MAIN OUTCOME MEASURES

Coronary artery disease, risk factors.

RESULTS

More patients than controls had fasting hyperhomocysteinaemia (10/45 v 2/23, P = 0.122), post-methionine hyperhomocysteinaemia (17/45 v 1/23, P = 0.008), and an abnormal response to methionine (15/45 v 1/23, P = 0.015). A history of smoking was more frequent in patients (3/23 v 25/45, P = 0.002). Sixteen of 17 patients with hyperhomocysteinaemia but only nine of 28 with normohomocysteinaemia were smokers (P = 0.0002). Fasting plasma cholesterol concentrations (mean (SD)) were higher in hyperhomocysteinaemic patients (6.41 (1.58) mmol/l) than in controls (5.53 (0.90) mmol/l) (P = 0.042). Serum vitamin B-12 was not reduced and serum folate was higher in hyperhomocysteinaemic patients (35 (4) nmol/l) than normohomocysteinaemic patients (26 (9) nmol/l) (P = 0.009).

CONCLUSIONS

Although the prevalence of hyperhomocysteinaemia in Hong Kong Chinese is similar to that in white subjects, hyperhomocysteinaemia is not an independent risk factor for coronary artery disease and is associated with smoking. This may be of some consequence in view of the change to a more Western diet with more animal protein, and therefore methionine, coupled with a high frequency of cigarette smokers in this region. The causes of the hyperhomocysteinaemia are multifactorial but in this pilot study a deficiency of folate and/or vitamin B-12 did not seem to be one of them.

Congenital errors of folate metabolism

Congenital errors of folate metabolism can be related either to defective transport of folate through various cells or to defective intracellular utilization of folate due to some enzyme deficiencies. Defective transport of folate across the intestine and the blood-brain barrier was reported in the condition 'Congenital Malabsorption of Folate'. This disease is characterized by a severe megaloblastic anaemia of early appearance associated with mental retardation. Anaemia is folate-responsive, but neurological symptoms are only poorly improved because of the inability to maintain adequate levels of folate in the CSF. A familial defect of cellular uptake was described in a family with a high frequency of aplastic anaemia or leukaemia. An isolated defect in folate transport into CSF was identified in a patient suffering from a cerebellar syndrome and pyramidal tract dysfunction. Among enzyme deficiencies, some are well documented, others still putative. Methylenetetrahydrofolate reductase deficiency is the most common. The main clinical findings are neurological signs (mental retardation, seizures, rarely schizophrenic syndromes) or vascular disease, without any haematological abnormality. Low levels of folate in serum, red blood cells and CSF associated with homocystinuria are constant. Methionine synthase deficiency is characterized by a megaloblastic anaemia occurring early in life that is more or less folate-responsive and associated with mental retardation. Glutamate formiminotransferase-cyclodeaminase deficiency is responsible for massive excretion of formiminoglutamic acid but megaloblastic anaemia is not constant. The clinical findings are a more or less severe mental or physical retardation. Dihydrofolate reductase deficiency was reported in three children presenting with a megaloblastic anaemia a few days or weeks after birth, which responded to folinic acid. The possible relationship between congenital disorders such as neural tube defects or dihydropteridine reductase deficiency and disturbances of folate metabolism are discussed. Neurological symptoms present in most of these congenital disorders highlight the role of folate in the central nervous system.

Hyperhomocysteinaemia; with reference to its neuroradiological aspects

Severe or even mild hyperhomocysteinaemia can cause a wide range of neurological problems. In recent years its vascular complications, including cerebral stroke, in children and young adults have gained special interest, because hyperhomocysteinaemia is treatable and recurrence of vascular incidents may be preventable. Current knowledge about biochemical mechanisms leading to hyperhomocysteinaemia, the pathogenesis of vascular pathology and neurological disfunction, and the various patterns of cerebral damage are reviewed. The significance of MRI in diagnosis, follow-up and research on hyperhomocysteinaemia is discussed.

Methylenetetrahydrofolate reductase deficiency revealed by a neuropathy in a psychotic adult

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Methylenetetrahydrofolate reductase deficiency: prenatal diagnosis and family studies

Prenatal diagnosis of methylenetetrahydrofolate reductase (MTHFR) deficiency and family studies were performed because of a severely affected first child in this family. The fetus at risk was found to be heterozygous as confirmed by the enzymatic activity assay performed several times after birth. In the father, MTHFR activity was normal in lymphocytes and decreased in fibroblasts, whereas in the asymptomatic mother, the activity was not detectable in fibroblasts and was very low in lymphocytes. The absence of any clinical symptoms in the mother despite a clear MTHFR deficiency and hyperhomocystinemia emphasizes the heterogeneity of this disease.

Symptomatic and asymptomatic methylenetetrahydrofolate reductase deficiency in two adult brothers

We describe two brothers with 5,10-methylene tetrahydrofolate reductase (MTHFR) deficiency. The younger patient first developed limb weakness, incoordination, paresthesiae, and memory lapses at age 15 years, and by his early twenties he was wheelchair bound. His older brother remains asymptomatic at age 37 years. Both had homocystinuria and homocystinemia and low plasma levels of methionine. MTHFR activities in cultured skin fibroblasts of both patients were < 10% control and residual enzyme activities were markedly reduced on heating. The parents had intermediate enzyme activities and the reductase in the father (who had unexplained paraparesis and homocystinemia), but not in the mother, was also thermolabile. Both patients were treated with oral folate and betaine which improved, but did not totally correct, their biochemical abnormality. MTHFR deficiency should be considered in the differential diagnosis of unexplained neurologic disease in adolescents and adults.

Methylenetetrahydrofolate reductase (MR) deficiency: thermolability of residual MR activity, methionine synthase activity, and methylcobalamin levels in cultured fibroblasts

Methylenetetrahydrofolate reductase (MR) deficiency is the most common inborn error of folate metabolism with more than two dozen patients described. The phenotypic spectrum ranges from severe neurological deterioration and early death to asymptomatic adults. Some patients with a severe deficiency of MR have been shown to have thermolabile reductase at 55 degrees C. Since methyltetrahydrofolate, the product of MR, is a methyl donor for methylcobalamin (MeCbl), the cofactor for methionine synthase (MS), we have looked at MeCbl accumulation and MS activity in fibroblasts from 15 patients with MR deficiency. Thermolabile MR was most often but not always seen in later onset disease. MeCbl levels were often lowest in the patients with early onset disease. All but two patients had levels of methionine synthase within the control range.