B. Niaspan administration reduces the percentage of myelin outfoldings (red asterisks) in Mtmr2-/- sciatic nerves without affecting the number of myelinated fibers as assessed by semithin section analysis at P75, n= 8 mice per genotype, results are mean ± SEM, p=0.0093, two-tailed Mann Whitney U test, representative of three independent experiments. Niaspan treatment does not alter myelin thickness in WT or Mtmr2-/- mice as assessed by g-ratio analysis (WT saline-treated, 0.67 ± 0.003, 2014 fibers; Mtmr2-/- Niaspan-treated, 0.67 ± 0.007, 1924 fibers; Mtmr2-/- saline-treated, 0.68 ± 0.003, 2244 fibers; n=4 animals per condition). 