Iron accumulation in the brain and oxidative stress are observed in a number of neurological diseases. Mutations associated with iron dysregulation in the body include the H63D and C282Y HFE missense mutations and transferrin C2 mutation, all of which have been associated with development of neurodegenerative diseases. These genotypes are suspected to cause iron dyshomeostasis, increased oxidative stress, glutamate release, tau phosphorylation, and alterations in inflammatory response1. MRI relaxometry has previously shown alterations in these genotypes, with white matter regions displaying decreased relaxation rate in late myelinating regions. Diffusion tensor metrics were further utilized to investigate the relationship between HFE/transferrin mutations and myelin integrity more precisely. Forty-two cognitively normal healthy Caucasian subjects (22F, 20M) were selected for inclusion in this study design. All subjects were administered a battery of cognitive tests by a neuropsychologist, were determined to be cognitively normal, and did not confounding pre-existing conditions. Blood samples were obtained and genotyped for the H63D and C282Y HFE mutations, as well as the transferrin C2 mutation. Nineteen subjects had wild-type alleles for all genes, while 23 had a combination of the three identified mutant alleles. Those patients with at least one HFE or transferrin mutation were group stratified for comparison to wild-type patients. A 3DT1-weighted scan and diffusion tensor image (70 directions) were collected for each patient, and fractional anisotropy (FA), mean diffusivity (MD), and mode of anisotropy (MO) parametric maps were generated with FSL. All datasets were co-registered to the 3DT1 image, realigned to a template brain, and normalized to an anatomical T1 and FA map template brain using SPM 8. For statistical analysis, the diffusion maps were smoothed with 2.5mm Gaussian kernel and voxel based analysis was performed using a group based method with a cluster size ≥ 100 and p ≤ 0.001 threshold. Voxel-based comparisons between genetically stratified cognitively normal subjects show group-based differences in white matter regions, especially within the corpus collosum and in fasciculi of the frontal lobe (Figs. 1-3). Many of the differences are in white matter areas connecting associative and executive areas of the brain known to myelinate later in development. The reductions in FA and increases in MD are indicative of a loss of white matter integrity as the tissue becomes less structured with proton behavior approaching that of the acellular water compartment. The corpus callosum shows significant FA reductions in the mutant group in areas of communicating fibers between structures supporting high-level cognitive capabilities, with decreases in MO in the same regions. MD is increased in HFE/Tf carriers within frontal white matter that are interhemispherically connected by regions highlighted in the FA and MO comparison.The MRI data presented here demonstrate that cognitively normal H63D/C282Y HFE and transferrin C2 carriers have diffusivity changes in white matter compared to wild-type subjects, without apparent cognitive decline. The regions with increased MD overlap precisely with previous data demonstrating a decrease in relaxation rate in late myelinating frontal white matter. The white matter regions of the corpus collosum in the FA and MO comparisons hemispherically connect those white matter regions outlined in the MD comparison. We hypothesize that the white matter alterations outlined with diffusion metrics are related to metabolic iron changes within late myelinating oligodendrocytes of the frontal lobe. Oligodendrocytes contain the majority of brain iron, as it is required for myelinogenesis, and disruption of white-matter iron homeostasis results in myelination alterations. Changes in myelin are discernable by their effects on proton diffusivity within a voxel, measurable by DTI. The observation that these alterations are located in late-myelinating frontal areas is hypothesized to be related to increased susceptibility within this region of HFE/Tf mutation carriers.