CTH and X-linked adrenoleukodystrophy: We examined 10 asymptomatic ALD subjects (hemizygotes) and found higher values of CTH in whole white matter when compared to age and sex-matched controls (3.20 ± 0.44 s versus 1.83 ± 0.15 s; unpaired samples t-test, P < 0.01, Fig. 2A).