Shahroud University of Medical siences Shahroud Journal of Medical Sciences 2423-6594 12 3 2026 06 03 Allelic and Genotypic Frequencies and Haplotype Analysis of C677T and A1298C Polymorphisms in the MTHFR Gene in Khuzestan Province, Iran 13 20 eng Mohammad Mahdi Student Research Committees, Dezful University of Medical Sciences, Dezful, Iran.. mohammad119mahdi@gmail.com Ezatollah Ghasemi Student Research Committees, Dezful University of Medical Sciences, Dezful, Iran; Student Research Committees, Dezful University of Medical Sciences, Dezful, Iran.. ezatqassemi@yahoo.com Amir Mashayekhi Student Research Committees, Dezful University of Medical Sciences, Dezful, Iran.. amgenetic@gmail.com 2025 06 02 2025 10 08 Background: The enzyme methylenetetrahydrofolate reductase (MTHFR) is essential for folate metabolism and homocysteine regulation. Genetic polymorphisms in MTHFR vary among populations, and their distribution may influence susceptibility to complex diseases. This research primarily aimed to determine the allelic, genotypic, and haplotypic frequencies of the A1298C and C677T variants of the MTHFR gene in a cohort of healthy individuals from Khuzestan province, Iran. Methods: Peripheral blood samples were collected from 100 unrelated healthy individuals. Genomic DNA was extracted, and genotype determination of A1298C and C677T polymorphisms was performed using the ARMS-PCR technique. Results: For both variants, the heterozygote genotype was the most frequent. 677T allele frequency was 32%, and the 1298C allele frequency was 43%. Analysis of linkage disequilibrium (LD) showed a moderate degree of LD between the C677T and A1298C variants with a weak correlation. Exploratory analyses suggested potential associations between the variants and some medical conditions; however, Results were constrained by the limited sample size, with no significant associations persisting after covariate adjustment. Conclusion: This study provides the first data on allelic, genotypic, and haplotypic frequencies of A1298C and C677T variants in the Khuzestan population. While exploratory analyses hinted at possible disease associations, these results should be interpreted cautiously and warrant confirmation in larger studies. Additionally, the weak LD observed between the two variants suggests they may act independently in contributing to disease susceptibility.