If followed over time, CTH values in the splenium of the corpus callosum peaked between 5–10 years of age in ALD patients as compared to controls and while splenium of the corpus callosum rCTH was not significantly affected by age in our control cohort, we found a decrease with ageing in hemizygotes (Fig. 3). The gene discussed is CTH; the disease is X-linked adrenoleukodystrophy.