Methylenetetrahydrofolate Reductase Mutation Research Articles

A retrospective study of the factors associated with hypercoagulability in the pediatric patients at a tertiary care children’s hospital*

The objective of this study was to determine the risk factors of hypercoagulability in children. We explored the interaction of multiple risk factors with the incidence of thrombosis. Our hypothesis was that as the number of risk factors for thrombosis increased the actual incidence of thrombosis would also increase. Retrospective review from 2003 through 2006 based on a search using two electronic medical record databases. Pediatric Tertiary Care Children's Hospital. Two hundred twenty-six patients were identified and analyzed. Search terms included factor V Leiden polymerase chain reaction, prothrombin gene 20210A mutation, methylene tetrahydrofolate reductase mutation, antithrombin III, and protein C and S levels. Clinical data were compiled for regression analysis. The presence of one risk factor was not significant. Two risk factors increased the risk of thrombosis (p = 0.005; OR 3.128). Three or more risk factors further increased the risk of thrombosis (p = 0.003; OR 4.861). Older age (>11 yrs) was protective against thrombosis (p = 0.007; OR 0.995), and the presence of a central venous catheter when analyzed against accumulating risk factors showed a higher risk than that found during the regression analysis (p = 0.001; OR 3.638). The population at our institution is reflective of the previously reported standards for the genetic predispositions toward thrombosis. Although older age is associated with a lower incidence of thrombosis, the presence of a central venous access device is detrimental. Accumulation of factors results in an increased risk of thrombosis. This article suggests that when inserting a central venous access device, consideration of a hypercoagulation workup should occur. Those with any two or more risk factors, genetic or acquired, and the comorbidity of a CVL may warrant consideration for the institution of anticoagulation with an agent like low molecular weight heparin.

Polymorphisms in methylenetetrahydrofolate reductase and pregnancy outcomes after in vitro fertilization

OBJECTIVE: Studies on potential factors influential in recurrent pregnancy loss have suggested a possible association with inherited thrombophilias. Dysfunction of methylenetetrahydrofolate reductase (MTHFR) due to polymorphic genotypes may lead to elevated homocysteine levels, a condition that has been associated with increased risk of thrombotic events. The role of thrombophilia in recurrent early pregnancy loss is still uncertain and a controversial subject of contemporary research interest. In particular little is known regarding the effect of MTHFR polymorphisms on implantation. We sought to determine the potential relationship of different MTHFR genotypes with pregnancy outcomes from in vitro fertilization. The main objective was to determine whether MTHFR mutations have any effect on pregnancy rates. DESIGN: A retrospective cohort analysis of all patients who underwent in vitro fertilization at a private infertility office from January 2006 to December 2007 was performed. MATERIALS AND METHODS: IRB approval was obtained to perform a retrospective cohort analysis of all patients who underwent in vitro fertilization at a private infertility office from January 2006 to December 2007 was performed. Additional outcomes studied included detection of a gestational sac on ultrasound, ovulation induction and embryo characteristics, pregnancy loss, and live birth rates. One-way analysis of variance (ANOVA), Student's t-test and multivariate regression analysis were done using Stata10 adjusting for potential confounders. Chi-square and Fisher's exact statistic were used where appropriate. RESULTS: A total of 216 patients undergoing IVF and tested for MTHFR were identified in this cohort with 7.4% diagnosed with RPL. In our cohort among those with the diagnosis of RPL, the most common MTHFR genotype was heterozygous A1298C (6 of 16 patients with diagnosis of RPL). MTHFR wild type had an achieved pregnancy rate of 66% per cycle and having any polymorphism resulted in an achieved pregnancy rate of 73% per cycle overall (p=0.33). No difference was seen when stratified by each genotype. CONCLUSIONS: Polymorphisms in MTHFR do not appear to affect pregnancy rates following IVF as determined by a detectable serum β-hCG.

Mutations in cystathionine β‐synthase or methylenetetrahydrofolate reductase gene increaseN‐homocysteinylated protein levels in humans

Severely elevated plasma homocysteine (Hcy) levels observed in genetic disorders of Hcy metabolism are associated with pathologies in multiple organs and lead to premature death due to vascular complications. In addition to elevating plasma Hcy, mutations in cystathionine beta-synthase (CBS) or methylenetetrahydrofolate reductase (MTHFR) gene lead to markedly elevated levels of circulating Hcy-thiolactone. The thiooester chemistry of Hcy-thiolactone underlies its ability to form isopeptide bonds with protein lysine residues (N-Hcy-protein), which may impair or alter the protein's function. However, it was not known whether genetic deficiencies in Hcy metabolism affect N-Hcy-protein levels in humans. Here we show that plasma N-Hcy-protein levels are significantly elevated in CBS- and MTHFR-deficient patients. We also show that CBS-deficient patients have significantly elevated plasma levels of prothrombotic N-Hcy-fibrinogen. These results provide a possible explanation for increased atherothrombosis observed in CBS-deficient patients.

The Impact of Prothrombotic Mutations on Factor Consumption in Adult Patients with Severe Hemophilia

About 10% of patients with severe hemophilia exhibit a milder clinical phenotype with less frequent bleeds. Among many other factors, coinheritance of prothrombotic mutations have been proposed to act as modulators of clinical severity in severe hemophilia. We conducted a study to evaluate the impact of 3 prothrombotic mutations (factor V Leiden, factor II, and methylenetetrahydrofolate reductase mutations) on clinical phenotype of patients with severe hemophilia in our institution. For this purpose we compared the average annual factor concentrate consumption between carriers and noncarriers of prothrombotic mutations. A total of 38 hemophilia A and B patients with factor levels less than 1 were recruited between October 2006 and October 2007. Prothrombotic mutations were detected in venous blood using polymerase chain reaction amplification technique. Eighteen patients (47%) carried no prothrombotic mutations. The remaining 20 patients (53%) were found to be carriers of either 1 or 2 mutations. Median age in both carrier and the non-carrier groups was 27 years. None of the patients in either group gave a history of thromboembolic event. Median annual factor concentrate consumptions in carriers and noncarriers were 610 +/- 530 units/kg and 770 +/- 670 units/kg, respectively (P = .203). Our results demonstrated no significant difference in annual factor concentrate consumption between carriers and noncarriers of prothrombotic mutations. Considering that average annual factor consumption is a surrogate indicator of clinical phenotype, we concluded that coinheritance of prothrombotic mutations was not associated with occurrence of different clinical phenotypes in severe hemophilia.

Pharmacogenetics of Nitrous Oxide

Pharmacogenetics of Nitrous Oxide

Hyperhomocysteinemia Due to Pernicious Anemia Leading to Pulmonary Thromboembolism in a Heterozygous Mutation Carrier

Pulmonary thromboembolism is a life-threatening condition resulting mostly from lower extremity deep-vein or pelvic-vein thrombosis. A 46-year-old woman was admitted to hospital with pain on the right side of the chest and hemoptysis. On laboratory analysis, D-dimer level was elevated. Computed tomographic pulmonary angiography revealed intravascular filling defects due to thrombi in right lower lobe pulmonary segmental arteries. Screening for thrombophilic states was normal except for heterozygous mutations of both prothrombin and methylene tetrahydrofolate reductase (MTHFR 677) genes. Homocysteine level was high, and vitamin B12 level and serum ferritin level were reduced. Serum antiparietal antibody was positive, and therefore, pernicious anemia was diagnosed along with iron-deficiency anemia. After the diagnoses were established, enoxaparin followed by warfarin was started in addition to oral vitamin B12, pyridoxine, thiamine, folic acid, and ferroglycine sulfate supplementation. At the end of 8 weeks of the replacement therapy, vitamin B12, folate, and homocysteine levels and red cell volume were found to be normal, with complete resolution of the thrombus confirmed by repeat computed tomographic pulmonary angiography. We conclude that hyperhomocysteinemia due to vitamin B12 deficiency associated with pernicious anemia might have decreased the threshold for thrombosis. In addition, the presence of heterozygous prothrombin and methylene tetrahydrofolate reductase mutations might serve as synergistic cofactors triggering pulmonary thromboembolism.

Percutaneous closure of patent foramen ovale: technical success and clinical outcomes of an infrequently-performed procedure

Objective: Procedural volume is thought to be a surrogate for quality, but this may not hold true for less frequently performed procedures. At most institutions, patent foramen ovale (PFO) closurewill be performed infrequently as long as conservative indications for it are followed. We analyzed the safety and efficacy of infrequently performed PFO closure procedures. Methods: Fifty-two patients with cryptogenic stroke or transient ischemic attack undergoing PFO closure from June 2001 to December 2005 were analyzed for technical success and clinical outcomes. All patients had transesophageal echocardiography before PFO closure. CardioSEAL (NMT Medical, Boston, MA), Amplatzer (AGA Medical Corporation, Minneapolis, MN), or CardiaStar (Cardia, Inc, Burnsville, MN) devices were used. Patients were discharged on aspirin, clopidogrel or (at the discretion of the neurologist), coumadin for 6 months. Possible late neurologic events were evaluated by a neurologist. Echocardiograms were obtained at 6 months and telephone follow-up was performed at an average of 28±10 months post procedure. Results: The study population was young (mean age, 45 years) and included 25 men (48%). Presentation was stroke in 66%. Comorbidities included diabetes (25%), hypertension (54%), hypercholesterolemia (59%), and mildmoderate aortic atherosclerosis in 28 (54%). Hypercoagulability disorders included methylenetetrahydrofolate reductase mutation in 27 (52%), all with normal homocysteine, low protein S in 2 (4%), and cardiolipin antibodies in 6 (12%). Seventeen patients (33%) had atrial septal aneurysms. Balloonstretched PFO size ranged from 6 to 25 mm. Deployment success was 100%; mild residual shunting persisted in 19 (37%). Mean length of stay was 1 day. Predischarge complications included bleeding in 4 patients and arrhythmia in 3 patients. At 28 months of follow-up, 4 patients reported spells of uncertain etiology, and 1 had paroxysmal atrial fibrillation. There were no transient ischemic attacks or strokes. One patient died of renal failure and sepsis unrelated to PFO closure. Conclusions: Low-volume PFO closure (15 per year) can be performed safely and effectively in a moderate-volume interventional laboratory with good short-term and long-term clinical results.

The Association Between Common C677T Mutation in Methylenetetrahydrofolate Reductase Gene and the Risk of Venous Thrombosis in an Iranian Population

Background: Venous thrombosis is a multicausal disease involving acquired and genetic factors. The prevalence of methylenetetrahydrofolate reductase (MTHFR) C677T genotypes and its association with venous thrombosis is not established in the Iranian population. In this study we investigated a possible association between fasting hyperhomocysteinemia and C677T mutation in the MTHFR gene with venous thrombosis. Materials and Methods: We studied 200 venous thrombotic patients and 100 healthy controls, of similar age and sex. Mutation analysis was carried out by PCR-RFLP, and the homocysteine level was measured by EIA. Results: No significant differences in the frequency of C677T genotypes were observed between patients and controls (P=0.2). The frequency of the T allele was 21% and 27.2% in controls and patients, respectively (odds ratio, 1.27; 95% CI, 0.83–1.94, P=0.15). Fasting homocysteine level was significantly higher in patients than controls (P=0.001). Conclusions: We concluded that hyperhomocysteinemia, but not MTHFR C677T mutation, is a significant risk factor for venous thrombosis in the Iranian population, and measuring the level of homocysteine is less expensive and more useful than the genetic test for the MTHFR mutation.

Polymorphism of the 5,10-Methylenetetrahydrofolate Reductase (MTHFR) Gene and Microsatellite Instability (MSI) in Mucinous Colorectal Cancer

Purpose: Generally, a mucinous carcinoma (Muc) of the colon show higher rates of microsatellite instability (MSI) than a non-mucinous carcinoma (non-Muc). Mutated methylenetetrahydrofolate reductase (MTHFR) brings about low enzyme activity, which may reduce genomic DNA methylation. These processes may be critical for the oncogenic transformation of human cells. We compared the relationship of MSI and MTHFR polymorphism in Muc to that in non-Muc. Methods: From March 2003 to August 2007, genomic DNA was isolated from whole blood and tissue specimens of 285 colorectal cancer patients (Muc: 31 cases, non-Muc: 254 cases) and 448 normal control patients. These were subjected to MSI analysis and MTHFR genotyping by using PCR-based restriction fragment length polymorphism analyses. Results: MSI was significantly more frequent in the Muc group (40.7%) than in the non- Muc group (14.8%). The frequencies of polymorphism of MTHFR 677C＞T were CC (31.5%), CT (57%), and TT (11.5%) in the patient group and 32.4%, 53.1%, and 14.5% in the control group. In the Muc group, the frequencies of polymorphism of MTHFR 677C＞T were CC (36%), CT (56%), TT (8%), and in the non-Muc group, they were 31.1%, 57%, and 11.9%. The frequencies of polymorphism of MTHFR 1298A＞C were AA (73%), AC (21.3%), and CC (5.7%) in the patient group and 69.6%, 28.6%, and 1.8% in the control group. In the Muc group, the frequencies of polymorphism of MTHFR 1298A＞C were AA (50%), AC (30%), and CC (20%), and in the non-Muc group, they were 76%, 20.3%, and 3.7%. The Muc group showed higher frequencies of the CC variant than the non-Muc group (P-value=0.018). No relation between MSI and MTHFR polymorphisms were seen in any comparison of the Muc and the non-Muc groups. Conclusions: The Muc group showed higher rates of MSI than the non-Muc group, but no definite difference between the Muc and the non-Muc groups was noted in the case of polymorphism of MTHFR 677C＞T. However, the TT-type variant showed slightly lower frequencies in the Muc group than in the non-Muc group. On the contrary, the Muc group showed a higher rate of the CC variant in polymorphism of MTHFR 1298A＞C. These inconsistent results seem to be due to the small size of the Muc group, so further study is needed.

Multifactorial Thrombophilia in a Pregnancy: A Case Report

Thrombophilias are inherited or acquired conditions that predispose individuals to thromboembolism. Thrombophilic disorders increase obstetric complications, such as early pregnancy loss, fetal growth retardation, placental abruption, and preeclampsia. Recurrent pregnancy loss affects 1% to 3% of women of reproductive age, and a large proportion of these losses remain unexplained. Thrombophilic defects were found in 49% to 65% of women with pregnancy complications compared with 18% to 22% of women with normal pregnancies, suggesting a 3- to 8-fold increase in risk. We report a case of a pregnant woman who had a history of recurrent pregnancy losses that was complicated with protein S deficiency, factor V Leiden mutation, methylene tetrahydrofolate reductase mutation, and antiphospholipid syndrome in her pregnancy.

Diffuse Multicystic Encephalomalacia in a Preterm Baby Due to Homozygous Methylenetetrahydrofolate Reductase 677 C→T Mutation

Methylenetetrahydrofolate reductase catalyzes the formation of 5-methyltetrahydrofolate from 5,10-methylentetrahydrofolate and produces folate for the methylation of homocysteine to methionine. Due to insufficient conversion of homocysteine to methionine, plasma homocysteine levels increase in methylenetetrahydrofolate reductase deficiency. Homocysteine is an amino acid that contains a neurotoxic sulfur molecule and can induce neuronal apoptosis. Methylenetetrahydrofolate reductase deficiency is 1 of the etiological factors that causes neurological symptoms and signs in the newborn and childhood period. Here, we report a premature baby with prenatal onset diffuse multicystic encephalomalacia and cerebellar atrophy due to homozygous methylenetetrahydrofolate reductase mutation.

The Diagnostic Dilemma: Dual Presentations of Clinical Mucosal Bleeding and Venous Thrombosis Associated with the Presence of Thrombophilia Markers and Mild Reduction in von Willebrand Factor

A prothrombotic and hemorrhagic state can separately manifest in one patient and can potentially cause several diagnostic problems. We report an intriguing case as an example of a potential hemostasis-based diagnostic dilemma. A 29-year-old female patient presented with a personal history of menorrhagia and other mucosal bleeding and renal ovarian thrombosis. Previous investigations had uncovered several diagnostic anomalies, including von Willebrand disease (VWD), factor V Leiden (FVL), antiphospholipid syndrome, and thrombocytopaenia. Previous therapy in this patient included heparin and warfarin for the thrombosis and desmopressin acetate (DDAVP) and antifibrinolytic therapy for surgical management. Subsequent laboratory testing with fresh samples consistently confirmed an equivocal (borderline normal/abnormal) level of von Willebrand factor (VWF) and FVL with activated protein C resistance (APCR). A patient sample, differentially labeled according to the tests being performed, was later distributed for blind testing to participants within several modules of the RCPA Quality Assurance Program (QAP). Most participants reported a low level of VWF consistent with possible mild Type 1 VWD, and most (but not all) reported a positive finding for APCR. All participants correctly reported the sample as heterozygous for the FVL mutation, negative for the Prothrombin gene mutation G20210A, and heterozygous for the methylenetetrahydrofolate reductase (MTHFR) mutation C677T. Interestingly, a significant number of laboratories performing Protein S testing using clot-based procedures also identified a false Protein S deficiency. In conclusion, this exercise showed how, either depending on the clinical review and specific laboratory investigation and tests performed, a pro-bleeding diagnosis (of either VWD or thrombocytopenia) or pro-thrombophilia risk (Antiphospholipid Syndrome or FVL/APCR or false Protein S deficiency) could potentially and differentially arise in the one patient.

Methylenetetrahydrofolate Reductase TT Genotype as a Predictor of Cardiovascular Risk in Hypertensive Adolescents

Methylenetetrahydrofolate reductase (MTHFR) is associated with homocysteine level. In deficit of MTHFR, cardiovascular risk is increased with hyperhomocysteinemia and hypomethionemia. Mutation of the MTHFR gene is associated with the risk for premature cardiovascular diseases. However, the association between MTHFR mutation and cardiovascular risk is still controversial. The purposes of this study were to determine whether MTHFR genotype is associated with cardiovascular risks in hypertensive adolescents and to investigate the association between MTHFR genotype and carotid intima-media thickness (IMT). Forty-three hypertensive adolescents were included in this study. Serum lipid levels, insulin, vitamin B(12), folate, renin, aldosterone, angiotensin converting enzyme, and homocysteine levels were evaluated. The carotid IMT and diameter were estimated by ultrasound. Brachial-ankle pulse wave velocity was also measured. Polymerase chain reaction was conducted to amplify genomic DNA fragment containing C677T position of the MTHFR gene. The height, weight, body mass index, obesity index, arm circumference, fat mass, and fat distribution were significantly greater in patients with C677T mutation. The C677T mutation group showed significantly greater carotid IMT, higher homocysteine, and lower folic acid levels than the normal genotype group. Interpretation of MTHFR genotype might be useful in predicting the development of premature coronary artery disease in hypertensive adolescents.

Physical activity is inversely associated with total homocysteine levels, independent of C677T MTHFR genotype and plasma B vitamins.

The homocysteine level is considered to be a product of genetic and lifestyle interactions, mainly mutated methylenetetrahydrofolate reductase (MTHFR) and the intake of folate, vitamin B12 and pyridoxine, and their blood levels. Physical activity has been associated with lower homocysteine levels in some population studies, especially among elderly subjects. To further elucidate the observed association between homocysteine and physical activity, while accounting for the effect of the MTHFR C677T genotype, and of plasma levels of folate and B12 vitamins, a cross-sectional study of 620 males and females, aged 70.5 +/- 6.8 years, was carried out. Information on lifestyle habits was collected and laboratory examinations of 12-h fasting total plasma homocysteine, folate, and vitamin B12, as well as DNA analysis for MTHFR C677T variant, were performed. Median total homocysteine values were 11.4 micromol/l for males and 9.4 for females; p < 0.001. Smoking and ethnic origin were not found to be associated with homocysteine levels. Physically active subjects had significantly lower total homocysteine levels when adjusted for sex (p = 0.01). Significant inverse correlations were found between body mass index, plasma folate, B12 and homocysteine levels. Homocysteine levels of the CC, CT and TT genotypes were 9.7, 10.6 and 10.2 mumol/l, respectively (p = 0.002, controlling for sex). In a multiple linear regression model, a sedentary lifestyle increased homocysteine levels by 7% as compared to an active one (p = 0.03) controlling for sex, age, body mass index, folate, vitamin B12, and C677T genotype, all of which were also found to be significantly associated with homocysteine levels. Any level of physical activity was found to be independently associated with lower homocysteine levels in an elderly population, controlling for MTHFR genotype, plasma B-vitamins, age, sex, smoking and BMI. This study emphasizes the importance of maintaining a physically active lifestyle in the elderly.

Thrombophilic risk factors among 16 Lebanese patients with cerebral venous and sinus thrombosis

Cerebral venous and sinus thrombosis (CVST) is a multifaceted disorder. The frequency of inherited and acquired thrombophilia among 16 CVST patients was evaluated. The mean age of the patients was 22.9 years. Five out of the 16 CVST patients (31.2%) showed the G1691A mutation of factor V. The frequency of the C677T methylenetetrahydrofolate reductase (MTHFR) genotype was 50% (8/16) in patients (2 of them were homozygous). Four of the patients (25%) had both factor V Leiden and MTHFR mutation. Three of the patients had positive antiphospholipid antibodies. At the time of CVST, 2 female patients were taking oral contraceptive pills. Four patients were known to have malignancies. Despite the limitation of the sample size, we identified an inherited coagulopathy at high rate in our patients. Combined inherited thrombophilia was also present in 25% of patients. This finding supports the impression of a multifactorial process leading to CVST in Lebanese patients.

Pelvic Varicosities and Inferior Vena Cava

Large pelvic varicosities and an absence of the inferior vena cava below the renal veins were identified in pregnancy. A young woman with a history of hemitruncus repair in infancy was noted to have large pelvic varicosities on a transvaginal ultrasonogram in early pregnancy. Magnetic resonance imaging confirmed these findings. Her protein S activity was mildly depressed, and an methylene tetrahydrofolate reductase mutation was present with normal fasting homocysteine levels. Despite concerns regarding the presence of these varicosities and potential thrombotic and hemorrhagic complications, a spontaneous vaginal delivery was achieved. Large pelvic varicosities may be present in women with congenital heart disease. Although these women are at risk for complications, vaginal delivery may be safely achieved.

Genetic prothrombotic mutations are common in neonates but are not associated with umbilical catheter-associated thrombosis

To evaluate the prevalence of hereditary prothrombotic mutations, and their effect on the incidence and severity of umbilical arterial or venous catheter (UAC or UVC)-associated thrombosis. All neonates with a UAC or UVC were studied prospectively for the presence, severity and timing of thrombosis with duplex Doppler ultrasound scan. Genetic testing for factor V Leiden (FVL), prothrombin mutation (PTm) and methylene-tetrahydrofolate reductase (MTHFR) mutations was performed using PCR and restriction fragment length polymorphism assays. Umbilical catheter (UC)-associated thrombosis developed in 16/53 (31%) neonates; 23% of UACs and 22% of UVCs were associated with thrombosis. The prevalence of a significant prothrombotic mutation was present in 10/51 (20%) of infants: FVL (8%), MTHFR667 homozygosity (10%), MTHFR1298 homozygosity (2%) and PTm (0%). There was no increase in the risk of UC-associated thrombus in patients carrying these prothrombotic mutations; our study had the power to detect a 2.5-fold increased risk of thrombosis for any of these significant mutations. In addition, MTHFR667 heterozygosity was found in 41% of infants and MTHFR1298 heterozygosity in 52% and also were not associated with increased risk of UC-associated thrombus. The risk of MTHFR double heterozygosity (db het) was 14%, the risk of a significant or db het was 17/51 (33%) and the risk of any mutation was 90%. Prothrombotic genetic mutations are common in our Neonatal Intensive Care Unit population but do not appear to increase the risk of UC-associated thrombosis.

Two Cousins With Neonatal Stroke, PAI-1 4G Variant and MTHFR A1298C Mutation

The authors describe 2 female cousins with neonatal stroke. One was heterozygous for the plasminogen activator inhibitor-1 4G variant and compound heterozygous for the A1298C and C677T methylenetetrahydrofolate reductase mutations. Her cousin was homozygous for the plasminogen activator inhibitor-1 4G variant and heterozygous for the methylenetetrahydrofolate reductase A1298C and factor V Leiden mutations.

Intermediate hyperhomocysteinaemia and compound heterozygosity for the common variant c.677C&gt;T and a MTHFR gene mutation

Methylenetetrahydrofolate reductase (MTHFR) is a key enzyme in the regulation of plasma homocysteine levels. MTHFR deficiency, an autosomal recessive disorder, results in homocystinuria and hypomethioninaemia and presents with highly variable symptoms affecting many organs but predominantly the central nervous system. The common polymorphism of the MTHFR gene, c.677C>T, a known risk factor for elevated plasma homocysteine levels, occurs frequently in the caucasian population. In this study we investigated three subjects with moderate hyperhomocysteinaemia (total plasma homocysteine 72 micromol/L in case 1 and 90 micromol/L in case 3, total non-protein-bound homocysteine 144-186 micromol/L in case 2) but different clinical presentation with no symptoms in case 1, muscle weakness at 17 years of age in case 2, and syncopes and cerebral convulsions at 18 years of age in case 3. Each subject was compound heterozygous for the c.677C>T polymorphism and a novel mutation of the MTHFR gene (case 1: c.883G>A [p.D291N]; case 2: c.1552_c.1553delGA [p.E514fsX536]; case 3: c.616C>T [p.P202S]). Moderately decreased fibroblast MTHFR activity was associated with severely reduced affinity for NADPH and increased sensitivity to inhibition by S-adenosylmethionine (AdoMet) in case 2, and with mild FAD responsiveness in case 3. In case 1, fibroblast MTHFR activity was normal but the sensitivity to inhibition by AdoMet was slightly reduced. This study indicates that the sequence alteration c.677C>T combined with severe MTHFR mutations in compound heterozygous state may lead to moderate biochemical and clinical abnormalities exceeding those attributed to the c.677TT genotype and might require in addition to folate substitution further therapy to normalize homocysteine levels.

Livedoid vasculopathy and hypercoagulability in a patient with primary Sjögren's syndrome

A 31-year-old woman presented with a 5-year history of painful ulcerations, palpable purpura, porcelain-white atrophic scars of the malleolar region and dorsal aspect of the feet, livedo reticularis on the limbs, arthralgia, xerophthalmia, and xerostomia. Skin biopsy revealed vessel wall hyalinization and thrombosis of the microvasculature with a very scarce dermal inflammatory infiltrate. Biopsy of the oral mucosa showed mononuclear infiltration of an intralobular duct of a salivary gland. Laboratory studies, including autoantibodies and inflammation markers, were normal, except for a positive rheumatoid factor. Coagulation screening revealed C677T methylenetetrahydrofolate reductase (MTHFR) mutation, with a normal serum homocysteine. The patient was treated with oral methylprednisolone (32 mg/day with progressive reduction) and enoxaparin (20 mg/day subcutaneously), with complete ulcer healing within 4 months. Livedoid vasculitis or vasculopathy has not been referred to previously in association with Sjögren's syndrome, but may be associated with other autoimmune disorders and anomalies of coagulation, namely factor V Leiden mutation, protein C deficiency, and MTHFR mutation, associated or not with hyperhomocysteinemia, a condition that seems to confer an increased risk of recurrent arterial and venous thrombosis. We stress the importance of anticoagulant therapy for ulcer healing and for the prevention of other thrombotic events.