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PubMed2026

Personalised Nutraceutical Treatment Guided by MTHFR Genotype in Mental Health: A Retrospective Cohort Study.

BACKGROUND & AIMS: One-carbon metabolism plays a central role in neurotransmitter synthesis, methylation capacity, and neurobiological resilience. Variants in the methylenetetrahydrofolate reductase (MTHFR) gene can reduce enzymatic activity, affecting folate- and methionine-cycle functions and potentially influencing biological pathways relevant to mood and anxiety disorders. Personalised nutraceutical treatment strategies, particularly those addressing methylation capacity through targeted B-vitamin, folate, and adjunctive metabolic interventions are increasingly implemented in integrative clinical practice, yet evidence regarding their clinical outcomes remains limited. METHODS: We conducted a retrospective cohort study of 50 adults attending an integrative general practice clinic for anxiety and/or depression. All received personalised nutraceutical treatment informed by clinical assessment, laboratory testing and, for 37/50 patients, MTHFR genotyping. Psychological distress was measured using the Kessler-10 (K10) scale at baseline and approximately three months later. Secondary analyses evaluated whether outcomes differed by MTHFR genotype, whether specific supplements (e.g., L-methylfolate and SAMe) were associated with greater improvement, whether biomarker changes correlated with symptom change, and the safety/tolerability profile. RESULTS: Across the full cohort, mean K10 scores significantly decreased by four points over the treatment period, with 72% of patients showing clinical improvement. Reductions in psychological distress were seen across all MTHFR genotypes, including individuals with homozygous variant genotypes. Supplement-specific analyses showed improvement among those receiving methylfolate or SAMe, although the differences were not statistically significant. Following nutraceutical treatment, biomarker analyses demonstrated significant increases in serum vitamin B12 and modest reductions in homocysteine, but biomarker shifts did not correlate strongly with K10 change. No serious adverse events or clinically significant abnormalities in liver or renal function were identified. CONCLUSIONS: In this real-world primary care cohort, personalised nutraceutical treatment, grounded in one-carbon metabolism support and applied alongside usual care, was associated with clinically meaningful reductions in psychological distress. Outcomes were comparable across MTHFR genotypes when treatments were appropriately tailored, suggesting that genotype and biomarker-informed nutraceutical strategies may mitigate potential metabolic disadvantages. These findings support further controlled research into precision nutraceutical psychiatry for anxiety and depression. Secondary analyses of genotype subgroup, specific supplements, and biomarker-outcome associations are reported alongside Benjamini-Hochberg FDR-adjusted p-values and should be interpreted as hypothesis-generating.

Humans↗

PubMed2026

Case Report: Persistent isolated hyperhomocysteinemia in an adolescent with celiac disease and homozygous MTHFR c.665C>T polymorphism: a multifactorial disturbance of one-carbon metabolism.

UNLABELLED: Hyperhomocysteinemia in adolescence typically prompts investigation for classical inborn errors of sulfur amino acid metabolism, including cystathionine β-synthase deficiency and cobalamin-dependent remethylation disorders. However, persistent elevations may also arise from interactions between common genetic polymorphisms and acquired nutritional conditions that alter one-carbon metabolism. CASE PRESENTATION: We report an 18-year-old male with type 1 diabetes mellitus, celiac disease on a strict gluten-free diet, congenital unilateral sensorineural hearing loss, and persistent isolated hyperhomocysteinemia. At age 16, he presented with an acute visual field disturbance and right occipital cortical MRI changes suggestive of ischemia. Plasma homocysteine was persistently between 50 and 65 μmol/L.Extensive metabolic and genetic investigations, including targeted gene panels, whole-exome and research whole-genome sequencing, mitochondrial DNA sequencing, mitochondrial complex activities in fibroblasts, and fibroblast complementation, excluded classical homocystinuria and remethylation defects. Sequential trials of pyridoxine, hydroxocobalamin, and high-dose betaine produced modest or transient improvement. Re-analysis of exome data showed homozygosity for the common MTHFR c.665C>T (p.Ala222Val) variant. Family testing revealed that his father (TT) and mother (CT) had normal homocysteine (10.9 and 10.4 μmol/L), indicating that MTHFR TT alone is insufficient to cause a biochemical phenotype and functions as a susceptibility factor. Combined oral methylfolate (1,000 µg daily) and vitamin B12 (cyanocobalamin 1,000 µg daily) reduced homocysteine from 66 to 24.6 μmol/L in 8 weeks. CONCLUSION: This case illustrates multifactorial hyperhomocysteinemia arising from interactions between celiac disease-related micronutrient vulnerability and reduced MTHFR activity. Recognition of gene-nutrient interactions is important when classical metabolic disorders are excluded and may guide targeted therapy.

MTHFR polymorphism↗

PubMed1991

Thermolabile methylenetetrahydrofolate reductase: an inherited risk factor for coronary artery disease.

Severe methylenetetrahydrofolate reductase (MTHFR) deficiency with less than 2% of normal enzyme activity is characterized by neurological abnormalities, atherosclerotic changes, and thromboembolism. We have discovered a "new" variant of MTHFR deficiency which is characterized by the absence of neurological abnormalities, an enzyme activity of about 50% of the normal value, and distinctive thermolability under specific conditions of heat inactivation. In this study, lymphocyte MTHFR specific activities in the thermolabile variant and control groups were 5.58 +/- 0.91 and 10.33 +/- 2.89 nmol formaldehyde formed/mg protein/h, respectively. The difference was significant (P less than .01). However, there was overlap among the individual values from the two groups. On the other hand, residual MTHFR activity after heat inactivation was 11.2 +/- 1.43% in the thermolabile variant and 36.3 +/- 5.18% in the controls. There was no overlap. Enzyme studies in 10 subjects with thermolabile MTHFR and their family members support the hypothesis that thermolabile MTHFR is inherited as an autosomal recessive trait. To elucidate the association of thermolabile MTHFR with the development of coronary artery disease, we determined the thermostability of lymphocyte MTHFR in 212 patients with proven coronary artery disease and in 202 controls without clinical evidence of atherosclerotic vascular disease. Thermolabile MTHFR was found in 36 (17.0%) cardiac patients and 10 (5.0%) controls. The difference in incidence between the two groups was statistically significant (P less than .01). The average age at onset of clinical coronary artery disease in 36 patients with thermolabile MTHFR was 57.3 +/- 7.6 years (35-72 years). The mean total plasma homocysteine concentration in patients with thermolabile MTHFR was 13.19 +/- 5.32 nmol/ml and was significantly different from the normal mean of 8.50 +/- 2.80 nmol/ml (P less than .05). There was no association between thermolabile MTHFR and other major risk factors. We conclude that thermolabile MTHFR is a variant(s) of MTHFR deficiency which is inherited as an autosomal recessive trait. In addition, it is positively associated with the development of coronary artery disease. Determination of in vitro thermostability of lymphocyte MTHFR is a reliable method for identifying subjects with this abnormality.

Adolescent↗

PubMed2026

Methylenetetrahydrofolate Reductase C677T and A1298C Polymorphisms are Not Associated With Recurrent Aphthous Stomatitis: A Case-Control Study.

OBJECTIVES: Methylenetetrahydrofolate reductase (MTHFR) polymorphisms have been investigated as potential genetic factors associated with recurrent aphthous stomatitis (RAS). This study investigated whether MTHFR C677T and A1298C polymorphisms, as well as circulating homocysteine, folate, and vitamin B12 levels, are associated with RAS. MATERIALS AND METHODS: In this prospective case-control study, 55 patients with clinically diagnosed RAS and 55 age- and sex-matched controls were enrolled. MTHFR C677T and A1298C genotyping was performed by polymerase chain reaction on genomic DNA extracted from EDTA blood samples. Plasma homocysteine was measured by chemiluminescent immunoassay, while serum folate and vitamin B12 were assessed by electrochemiluminescence. In patients with RAS, number of ulcers, clinical subtype, episode frequency, healing time, and pain intensity were recorded. Associations were analysed using χ² tests and ANOVA, with statistical significance set at P < .05. RESULTS: No significant differences were found between RAS and non-RAS groups in the distribution of MTHFR C677T or A1298C genotypes. Mean homocysteine, folate, and vitamin B12 levels, as well as their categorical distributions, were also comparable between groups (all P > .05). Within the RAS group, episode frequency was significantly associated with homocysteine and folate serological levels, whereas no significant associations were observed between MTHFR genotypes and the clinical variables assessed. CONCLUSIONS: In this cohort, MTHFR C677T and A1298C polymorphisms were not associated with RAS occurrence. However, homocysteine and folate serological levels were associated with selected indicators of disease course, suggesting that metabolic factors may contribute to RAS phenotype in a subset of patients. CLINICAL RELEVANCE: Although MTHFR polymorphisms do not appear to be directly associated with RAS onset, assessment of homocysteine and folate serological levels may help identify patients with a more severe or recurrent clinical course and support a more individualized approach.

Humans↗

PubMed1991

Intermediate hyperhomocysteinemia resulting from compound heterozygosity of methylenetetrahydrofolate reductase mutations.

Four subjects with thermolabile methylenetetrahydrofolate reductase (MTHFR) were discovered among 16 "obligate" heterozygotes for severe MTHFR deficiency and their family members. All four subjects had less than 25% of normal mean MTHFR specific activity in lymphocyte extracts. Three of them with normal serum folate and cyanocobalamin had intermediate hyperhomocysteinemia, and one with high serum folate and cyanocobalamin had no excessive accumulation of serum homocysteine. The biochemical features in these four subjects are distinguishable from subjects homozygous for the thermolabile MTHFR, whose specific activity is approximately 50% of the normal mean, and from heterozygotes for severe MTHFR deficiency, in whom the enzyme is thermostable and has a specific activity of about 50% of the normal mean. We propose that these four subjects are genetic compounds of the allele for the severe mutation and the allele for thermolabile mutation of the MTHFR gene. It is postulated that subjects with this genetic compound are more susceptible to the development of intermediate hyperhomocysteinemia despite normal folate and B12 levels. Nonetheless, hyperhomocysteinemia due to this compound heterozygosity is correctable by oral folic acid therapy.

Adolescent↗

PubMed1992

Increased neurotoxicity of arsenic in methylenetetrahydrofolate reductase deficiency.

A 16-year-old girl from Surinam presented with mental deterioration and severe paraparesis with areflexia and bilateral Babinski signs. Laboratory examination showed a hyperhomocysteinemia that was caused by 5,10-methylene-tetrahydrofolate reductase (MTHFR) deficiency. In addition, urine samples contained large amounts of arsenic. An open bag with the pesticide copper acetate arsenite was found to be the source of exposure. In remethylation defects such as MTHFR deficiency, the concentration of methyldonors is severely reduced. As arsenic is detoxified by methylation, we suggest that the MTHFR deficiency in this girl might explain the fact that of all family members exposed to arsenic, only she developed severe clinical signs and symptoms of arsenic poisoning.

Adolescent↗

PubMed1988

Thermolabile methylenetetrahydrofolate reductase in patients with coronary artery disease.

Thermostability of lymphocyte methylenetetrahydrofolate reductase (MTHFR) was determined in 21 patients aged less than 50 years with proven coronary artery disease, and in 21 age- and sex-matched controls without clinical evidence of vascular disease. The mean +/- SD of residual activity after heat inactivation at 46 degrees C for five minutes was 37.6% +/- 5.6% in the controls. In contrast, patients with coronary artery disease could be divided into two subgroups. Fifteen of them had 38.1 +/- 5.9% residual activity which was similar to that of the controls. In six of them the mean +/- SD residual activity after heat inactivation was 13.6% +/- 5.1% which was below 2 SD of the normal mean. These observations suggested that thermolabile MTHFR was associated with development of coronary artery disease.

Adult↗

PubMed2026

One-carbon metabolism and chemotherapy-induced toxicities in patients with stage II-III colorectal cancer: a prospective cohort study.

BACKGROUND: One-carbon metabolism (OCM) is a target of the chemotherapeutic agent capecitabine. OBJECTIVES: We investigated OCM biomarker concentrations in relation to capecitabine-induced toxicities in patients with stage II-III colorectal cancer. METHODS: Within a prospective cohort, 297 patients receiving adjuvant capecitabine-based chemotherapy were included. Pretreatment plasma concentrations of the OCM biomarkers folate, vitamin B2, vitamin B6, vitamin B12, total homocysteine, methionine, serine, and glycine were determined. We also investigated whether associations differed according to methylenetetrahydrofolate reductase (MTHFR) C677T genotypes. Chemotherapy-induced toxicities were defined as toxicity-induced modifications of capecitabine treatment. To allow for inspection of shapes of the associations, restricted cubic splines and Cox proportional hazards models were used to calculate hazard ratios (HRs) and 95% confidence intervals (CIs) adjusted for age and sex. RESULTS: In total, 156 (53%) patients experienced toxicity-induced modifications of capecitabine treatment. Folate was not associated with toxicities in the overall population. Higher folate concentrations were associated with a lower risk of toxicities in patients with MTHFR C677T CT/TT genotype (HRperdoubling: 0.75; 95% CI: 0.57, 0.98) but not in patients with CC genotype (HRperdoubling: 1.17; 95% CI: 0.84, 1.63). Higher concentrations of vitamin B2 were associated with a lower risk of toxicities (HRperdoubling: 0.81; 95% CI: 0.67, 0.99), whereas higher glycine concentrations were associated with a higher risk of toxicities (HRperdoubling: 1.87; 95% CI: 1.18, 2.94). The association between vitamin B6 and vitamin B12 and toxicities appeared nonlinear. Homocysteine, methionine, and serine were not associated with toxicities. CONCLUSIONS: Future studies investigating whether nutrition-guided optimization of OCM biomarkers will result in improved treatment tolerance are warranted.

Humans↗

PubMed2026

Characterization of DPYD pharmacogenetic variation in Mexican patients with gastrointestinal malignancies.

PURPOSE: Fluoropyrimidines are among the most widely used chemotherapeutic agents for gastrointestinal malignancies, but interindividual variability in dihydropyrimidine dehydrogenase (DPD) activity, encoded by DPYD, can lead to severe or lethal toxicities. Most pharmacogenetic data on DPYD originates from European populations, limiting the applicability of current guidelines in admixed groups. METHODS: We evaluated DPYD pharmacogenetic variation and its association with fluoropyrimidine-related adverse events in Mexican patients with gastrointestinal cancers. Adverse events were prospectively assessed using CTCAE v5.0. Genotyping was performed with the Illumina Global Screening Array and analyzed using PLINK and R. RESULTS: A total of 208 patients were enrolled, and 192 samples passed genotyping quality control; 156 patients received fluoropyrimidines. Only three patients (1.5%) carried actionable DPYD variants (rs3918290, rs67376798 and rs75017182), yielding allele frequencies of 0.26%, approximately ten-fold lower than those reported in European cohorts. Genome-wide analyses did not reveal significant genotype-phenotype associations, though suggestive variants in SDK1, ZPBP, and FGF12 were observed. Pharmacodynamic analyses identified frequent variation in TYMS rs2847153 and MTHFR rs1801133, both previously associated with fluoropyrimidine toxicity. Overall, patients exhibited a predominantly Native Mexican ancestry (56.5%), which may explain the markedly low frequency of actionable DPYD alleles commonly found in European populations. CONCLUSIONS: These findings highlight the limited representation of admixed populations in pharmacogenetic research and underscore the need for population-specific data to inform safe and equitable fluoropyrimidine dosing.

Humans↗

PubMed2026

Genomic, transcriptomic, and molecular predictors of response to neoadjuvant therapy in locally advanced rectal cancer: a narrative review.

Total neoadjuvant therapy (TNT) has emerged as a key treatment paradigm for locally advanced rectal cancer, reducing distant metastasis rates and facilitating organ preservation in selected patients. However, treatment response remains heterogeneous, highlighting the need for biomarkers that can guide treatment selection and optimise outcomes. This narrative review synthesises the current evidence regarding tumour-intrinsic genomic biomarkers associated with response to neoadjuvant therapy, encompassing somatic mutations, germline polymorphisms, gene expression profiles, mismatch repair (MMR) status, protein expression, epigenetic markers, and circulating tumour-derived biomarkers across conventional chemoradiotherapy (CRT) and TNT paradigms. Across the reviewed literature, individual somatic mutations, including KRAS, TP53, and BRAF, demonstrated limited reproducibility as predictive biomarkers, although KRAS mutations were recurrently associated with lower pathological complete response (pCR) rates in CRT-era cohorts. Germline polymorphisms in DNA repair (XRCC1) and folate metabolism (MTHFR) genes showed inconsistent associations with treatment response. In contrast, transcriptomic biomarkers demonstrated greater biological coherence, with proliferative, epithelial-mesenchymal transition, and metabolic signatures frequently associated with treatment resistance, while multi-gene classifiers generally outperformed single-gene markers. Among currently available tumour-intrinsic biomarkers, MMR deficiency was the most consistently reported biomarker associated with reduced response to fluoropyrimidine-based regimens, including TNT, although TNT-specific evidence remains comparatively limited. Dynamic circulating tumour DNA (ctDNA) monitoring, particularly ctDNA clearance during or after therapy, was consistently associated with pathological response and long-term oncologic outcomes across reviewed studies, whereas baseline ctDNA levels showed limited predictive value. Overall, the reviewed literature suggests that biomarker research in rectal cancer has evolved from single-gene analyses towards pathway-level and dynamic biomarkers. The integration of transcriptomic signatures, MMR status, and dynamic ctDNA monitoring may represent a promising strategy for personalising neoadjuvant therapy, improving patient selection for organ-preserving approaches, and enhancing oncologic outcomes in locally advanced rectal cancer. Nevertheless, the evidence base remains heterogeneous, and further prospective validation, assay standardisation, and evaluation within contemporary TNT cohorts are required before these biomarkers can be routinely incorporated into clinical decision-making.

Humans↗

PubMed2025

Exploring precision medicine by utilizing individual genetic information for the management of Alzheimer's disease.

Alzheimer's Disease (AD) represents a formidable challenge in neurology, characterized by progressive neurodegeneration and cognitive decline. Traditional therapeutic approaches have failed to deliver significant outcomes, underscoring the need for innovative paradigms such as precision medicine. The review explores integrating genomic, biomarker-driven, and individualized therapeutic strategies to tackle AD. It examines the role of key genetic factors, including APOE and MTHFR polymorphisms, in influencing disease susceptibility and treatment responses. Advances in biomarker technologies, such as blood-based and imaging biomarkers, are highlighted for their potential in early diagnosis and patient stratification. Additionally, the review underscores the importance of tailoring interventions across different stages of AD, incorporating lifestyle modifications and emerging tools like artificial intelligence & recent patented technologies. Precision medicine offers a transformative pathway, aiming to deliver personalized, effective care that addresses the complex and multifactorial nature of AD. The paradigm shift promises improved clinical outcomes and enhanced patient quality of life.

Humans↗