A recent research study investigating MTHFR polymorphisms and vitamin B12 deficiency found a statistically significant correlation between patients carrying MTHFR C677T homozygous and heterozygous variance and lower haemoglobin value and lower platelet count. And the MTHFR A1298C homozygous and heterozygous variance and lower haemoglobin. Among patients with homozygous for MTHFR C677T, the incidence of gastropathy was 62.5%.
Interestingly both polymorphisms were associated with a haematologic manifestation of vitamin B12 deficiency. They conclude that in individuals already prone to Vitamin deficiency, reduced MTHFR enzyme function leads to a metabolic imbalance exacerbating anemia.