Use of sapropterin in Mexican patients with yperphenylalaninemia

Hyperphenylalaninemia is caused by deficient enzyme activity of phenylalanine hydroxylase. It was one of the first genetic disorders susceptible to treatment with a natural protein restricted diet for life. While this treatment has proven effective in preventing mental retardation, eliminating certain foods from the diet entails the risk of nutritional deficiencies. For these reasons, new non-nutritional therapeutic strategies have been developed. One is the administration of sapropterin dihydrochloride, the synthetic form of tetrahydrobiopterin (BH4), which is the natural cofactor of phenylalanine hydroxylase, whose purpose is to reduce blood phenylalanine levels. We studied 6 patients with confirmed diagnosis of hyperphenylalaninemia or phenylketonuria. Sapropterin dihydrochloride was administered for 28 days and the intake of phenylalanine was calculated in each patient. To evaluate the response to sapropterin phenylalanine blood levels were measured at zero, eight and 24 hours and on days seven, 14, 21 and 28. The 24-hours recall was used to establish the intake of phenylalanine before and during the study. A positive response was determined as a reduction of phenylalanine blood levels ≥30% Four of the six patients responded positively to sapropterin dihydrochloride. The aim of this paper is to present the experience with sapropterin dihydrochloride in a group of Mexican patients with hyperphenylalaninemia.