Oxysterol changes along with cholesterol and vitamin D changes in adult phenylketonuric patients diagnosed by newborn mass-screening

Phenylketonuria (PKU) possibly leads to hypocholesterolemia and lowered vitamin D (VD) status. Metabolism of oxysterols linking with those of cholesterol and VD has never been examined in PKU.Blood oxysterols along with blood phenylalanine, lipids and VD were examined for 33 PKU adults aged 21-38 years and 20 age-matched healthy controls.Total- and low-density cholesterols, and 25-hydroxy VD(3) were decreased significantly in the PKU group (cholesterols, 10% decrease; 25-hydroxy VD(3) 35% decrease vs. the control group). 24S-hydroxycholesterol (24S-OHC) eliminating brain cholesterol, and 27-OHC and 7α-hydroxycholesterol (7α-OHC) representing peripheral and hepatic cholesterol elimination, respectively, were significantly decreased in PKU group: 24S-OHC, 25% decrease, p.01; 27-OHC and 7α-OHC, 35-40% decrease, p.001. 7β-Hydroxycholesterol (7β-OHC) reflecting oxidative stress was increased significantly in PKU group (p.05). 7α-OHC and 27-OHC levels in PKU group always showed similar values, regardless of other parameters while the 24S-OHC and 7β-OHC levels decreased and increased, respectively, showing significant correlations with phenylalanine level (p.005). 27-OHC level showed a significant positive correlation with the 25-hydroxy VD(3) level in this group (p.001).Blood oxysterol changes predominate over blood cholesterol changes and influence on VD status in adult PKU patients.