ABSTRACT
Introducción: la fenilcetonuria (PKU) es el error congénito del metabolismo de las proteínas más frecuente. El tratamiento dietético consiste en un plan de alimentación con una ingesta de proteínas naturales restringida, un sustituto proteico libre o de bajo contenido en fenilalanina (Phe) y el aporte de alimentos muy bajos en proteínas. El objetivo principal de este trabajo fue investigar si es posible aumentar la ingesta de proteína natural (PN) que se indica a los pacientes con PKU manteniendo los dosajes de Phe en sangre en rangos de seguridad. Materiales y método: se buscaron en 6 bases de datos electrónicas artículos publicados. Se identificaron un total de 154 artículos de Pub Med por intervalo de años desde 1999 a 2020. Se eligieron 15 artículos que se adaptaron a los criterios de inclusión y exclusión y respondían al objeto de estudio de esta revisión bibliográfica. Resultados: hay varios factores que pueden influenciar la estimación de la tolerancia de Phe como la severidad del fenotipo del paciente, la edad, el rango de seguridad de Phe en sangre, la prescripción de Phe y la adherencia al sustituto proteico. Si los niveles de Phe en sangre se mantienen en forma constante dentro del rango adecuado y por un período determinado, se debería considerar un incremento de la ingesta de Phe. El aumento de la ingesta de PN deberá ser realizado de manera controlada, individual y evaluando en forma constante el impacto en los dosajes de Phe en sangre. Conclusión: optimizar la ingesta de PN ofrece una mejora en la calidad de vida de pacientes con PKU, facilita la capacidad del paciente para socializar y contribuye a una mejor adherencia a la dieta(AU).
Introduction: phenylketonuria (PKU) is the most frequent inborn error of protein metabolism. The dietary treatment consists of a diet with a restricted natural protein intake, a free or low phenylalanine (Phe) protein substitute, and the intake of low protein food. The main objective of this work is to analyze if it is possible to increase the natural protein (NP) intake prescribed to PKU patients while maintaining blood Phe dosages within safe range. Materials and method: studies published were searched in 6 electronic data- basis. A total of 154 Pub Med articles were identified by range of years from 1999 to 2020. Fifteen articles which met the inclusion and exclusion criteria and responded to the objective of this bibliographic review were chosen. Results: several factors may influence Phe tolerance, such as severity of the patient´s phenotype, age, blood Phe safe range, Phe prescription and adherence to protein substitute. If Phe blood levels remain constantly within safe range and for a certain period, an increase of Phe intake should be considered. Increase of NP intake must be carried out in a controlled manner, individually and constantly evaluating blood Phe levels. Conclusion: optimizing NP intake offers the PKU patient an improvement in quality of life, facilitates the patient´s ability to socialize and contributes to a better adherence to the diet(AU).
Subject(s)
Phenylketonurias , Phenylketonurias/diet therapy , Proteins , Eating , MetabolismABSTRACT
Abstract Phenylketonuria (PKU, OMIM 261600) is predominantly caused by mutations in the PAH gene. One hundred and three Argentine PKU patients were studied by Sanger sequencing; 101 were completely characterized (90.3% were compound heterozygotes). Fifty-four different pathogenic variants were identified. Mutations were distributed all along the PAH gene but concentrated in exon 7 (26%), 12 (12%), 11 (10%), and 6 (10%). 77% were missense, and 77% affected the enzyme catalytic domain, nine mutations accounted for 57% of 179 studied alleles: p.Arg261Gln (Allele frequency(AF):10.6%), c.1066-11G>A (AF:9,5%), p.Arg408Trp (AF:8,3%), p.Tyr414Cys (AF:5,5%), p.Ala403Val, p.Val388Met, and p.Arg158Gln (AF: 5% each), p.Leu48Ser, and p.Ile65Thr (AF:4% each). The predicted phenotype was assigned by Guldberg´s arbitrary value (AV) and compared with the clinical phenotype based in tolerance to Phe intake. 29.1% (n:30) were hyperphenylalaninemias, 18.5% (n:19) mild-PKU, 27.2% (n:28) moderate-PKU and 25.2 % (n:26) classical-PKU. Genotype/phenotype correlation was statistically significant (p<0.001) Overall concordance was 62,5%: 93.3% in hyperphenylalaninemia, 64.7% in mild-PKU and 65.4% in classical patients. The moderate-PKU showed a weak concordance (17%) with milder AV prediction than clinical assessment. 74% of discordant moderate patients harbored p.Arg261Gln, and p.Val388Met. Our cohort is highly heterogeneous, with predominant Mediterranean influence (mainly Spanish), but with differences with other Latin-American countries.