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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↗

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↗

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↗

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↗

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↗