The condition requires the strict restriction of protein consumption in its natural state. Noncompliance seriously affects the cognitive and motor health of patients
A research team led by Júlio César Rocha, a researcher at CINTESIS – Center for Health Technology and Services Research, has just started a study that aims to assess the nutritional status of patients suffering from a rare genetic disease: phenylketonuria. This condition, also known as PKU, is characterized by the deficiency of an enzyme produced in the liver, necessary to process phenylalanine – an essential amino acid, present in almost all foods, but more in those richest in protein (such as meat, fish, eggs and dairy products).
The project, entitled TNSPKU – Trends in nutritional status of patients with Phenylketonuria, is being developed at the University Hospital Center of Porto and in partnership with the Faculty of Nutrition and Food Sciences of the University of Porto (FCNAUP) and the Birmingham Children’s Hospital from United Kingdom, with the support of Biomarin Pharmaceutical.
Excessive levels of phenylalanine in the bloodstream become toxic, compromising the normal functioning of the brain. Among the problems that may arise from non-adherence to treatment for phenylketonuria are delayed psychomotor development, cognitive deficit (which may be severe), microcephaly, hyperactivity, convulsions, among others.
“The pillar of treatment is a diet low in protein and phenylalanine, which must be implemented rigorously, from birth and for life,” explains the CINTESIS researcher. To ensure adequate protein supply for growth and development, these patients must consume special protein substitutes that provide mostly amino acids (other than phenylalanine) along with other important nutrients. “At the same time, special products that are very low in phenylalanine and rich in carbohydrates and lipids are also provided by the Portuguese State in a co-payment system, guaranteeing an adequate energy supply”, adds Júlio César Rocha.
Despite their importance for the health of patients with phenylketonuria, protein substitutes and special hypoproteic foods contribute to a dietary pattern often high in carbohydrates and lipids, so their consumption may increase the risk of developing overweight and obesity in these patients.
The objective of this study, explains Júlio César Rocha, who is also a Nutritionist at the University Hospital Center of Porto, is “to evaluate the prevalence of overweight and obesity, and to assess the prevalence of the metabolic syndrome in this group of people, which has such a specific dietary pattern”. In addition, the team aims to evaluate the effect of sapropterin (so far, the only drug available on the market for the treatment of phenylketonuria) in the risk of overweight and obesity in these patients.
“In all, 94 patients will participate in the study and more than 760 nutritional status evaluations of these patients, recorded over the last 10 years, will be analyzed,” explains the specialist. The team will collect the data regarding anthropometric measures, body composition, blood pressure, nutritional intake and biochemical analyzes.
In addition, researchers will compare the records of two different groups: one group will include patients who exclusively follow dietary treatment and the other group will count patients who cumulatively take sapropterin. “The idea is to be able, in the end, to verify the existence of possible differences between these two groups, regarding their nutritional state of health”, clarifies the CINTESIS researcher.
It is estimated that more than 300 Portuguese live with phenylketonuria. Since 1979, the disease has been diagnosed in the first days of the child’s life through the neonatal heel prick test. The early diagnosis of this pathology allows the treatment to be started immediately, limiting the negative impact of this disease on the central nervous system.