Highly elevated serum total
dolichol (free
dolichol + dolichyl
ester) concentrations have recently been found in two
lysosomal storage diseases,
aspartylglucosaminuria (AGU) and
mannosidosis. The present study demonstrates that the increase of serum
dolichol in AGU patients is caused by an increase of serum free
dolichol. In 15 patients the mean serum level of free
dolichol (227 +/- 16 ng/mL) was 1.9 times higher (p < 0.001) than that in healthy controls (120 +/- 6 ng/mL), while the amounts of
dolichol fatty acid esters were similar in the patients and controls (110 +/- 9 vs. 118 +/- 6 ng/mL). In contrast, 10 patients with
neuronal ceroid-lipofuscinosis (NCL) (three with infantile, four with juvenile, and three with variant late infantile NCL) had significantly (p < 0.01) lower mean serum levels of both free (79 +/- 5 ng/mL) and total (159 +/- 6 ng/mL)
dolichol than age-adjusted healthy controls (free, 100 +/- 6 ng/mL; total, 206 +/- 14 ng/mL). Decreased blood
dolichol has not been reported earlier for any other disease. We conclude that the increased serum free
dolichol in AGU reflects disturbed lysosomal function and that the decreased free and esterified
dolichols in NCLs speak against their presumed primary lysosomal nature.