Circulating Inhibitory Factor 1 levels in adult patients with Prader-Willi syndrome

Objectives: Prader-Willi syndrome (PWS) is a rare genetic syndrome characterized by hyperphagia and early development of morbid obesity. Cardiovascular disease (CVD) and metabolic syndrome (MetS) are major comorbidities in these patients leading to premature death. Inhibitory factor 1 (IF₁) works as a regulatory protein, inhibiting the ATP hydrolase activity of mitochondrial ATP synthase and likely playing a role in lipid metabolism. We aimed to assay IF₁ in adult patients with PWS evaluating any relationship with clinical, genetic and biochemical parameters.

Methods: We recruited 35 adult patients with genetically confirmed PWS.

Results: IF₁ serum concentration displayed a normal distribution with an average value of 70.7 ± 22.6 pg/mL, a median value of 66.1 pg/mL. It was above the reference range only in one patient. All parameters were compared from both sides of IF₁ median without displaying any significant differences. Patients with normal or low HDL-cholesterol did not present any difference as regards IF₁ levels, which were not different between patients with and without MetS. Non-esterified fatty acids (NEFA) serum levels (r=0.623; p<0.001) showed a statistically significant correlation with IF₁. Cholesterol and its fractions did not present any correlation with IF_1.

Conclusions: In this study we do not confirm that HDL-cholesterol and IF₁ are correlated, but we show that in adult PWS patients, NEFA are correlated with serum IF_1. This protein could play a role to some extent in determining the complex metabolic alterations in PWS patients.