The MTHFR C677T polymorphism influences the efficacy of folic acid supplementation on the nerve conduction studies in patients with diabetic polyneuropathy; A randomized, double blind, placebo-controlled study

Among patients with diabetic polyneuropathy, the status of folic acid, homocysteine, and nerve conduction studies (NCS) variations has been associated with methylenetetrahydrofolate reductase (MTHFR) gene polymorphisms. The objective of the present study is to assess B9 vitamin supplementation associated with MTHRF C677T polymorphism can be effective on NCS variations in patients. This study is a randomized, double‑blind, placebo‑controlled study. Patients were randomly allocated to either intervention (1 mg of folic acid, n = 40) or placebo (n = 40) groups based on parallel group design. Blood samples were taken to determine the serum levels of folic acid and homocysteine. The NCS data were collected for the assessment of diabetic neuropathy. Genotyping was performed for C677T polymorphism of the MTHFR gene. Four months after intervention, patients significantly observed change of serum folic acid and homocysteine levels based on C677T genotypes in the MTHFR gene. The amplitude of sensory peroneal nerve between intervention and placebo groups with CC genotype was significantly different (2.8 ± 1.6 vs. 1.9 ± 1.1). However, peak latency and amplitude of sensory sural nerve between CC (3.8 ± 1.8 vs. 4.0 ± 1.5 for peak latency and 3.5 ± 1.0 vs. 2.5 ± 1.0 for amplitude; and CT + TT genotypes (3.7 ± 1.7 vs. 3.9 ± 1.3 for peak latency and 3.2 ± 1.0 vs. 2.3 ± 1.1 for amplitude) were significant. Furthermore, significant difference for variables of motor tibial nerve and motor peroneal nerve amplitude was observed in different groups of MTHFR C677T genotypes (5.4 ± 2.9 vs. 4.6 ± 3.2 for onset‑latency of tibial nerve between CC genotype; 4.8 ± 2.8 vs. 4.6 ± 3.2 for onset‑latency of tibial nerve between CT + TT genotype; 0.6 ± 0.2 vs. 0.3 ± 0.1 for amplitude of tibial nerve between CC genotype; 0.5 ± 0.3 vs. 0.3 ± 0.2 for amplitude of tibial nerve between CT + TT genotype; 26.0 ± 13.3 vs. 23.2 ± 13.4 for velocity of tibial nerve between CC genotype; 26.0 ± 13.7 vs. 23.1 ± 9.6 for velocity of tibial nerve between CT + TT genotype; 1.6 ± 1.0 vs. 0.9 ± 0.7 for amplitude of peroneal nerve between CC genotype; 1.4 ± 0.7 vs. 0.9 ± 0.5 for amplitude of peroneal nerve between CT + TT genotype). The study determined that MTHFR C677T polymorphism effects the efficacy of folic acid supplementation on serum folic acid, homocysteine levels and some NCS parameters in diabetic polyneuropathy patients.