Simplified Diet for nutrition management of phenylketonuria: A survey of U.S. metabolic dietitians.

BACKGROUND: Phenylketonuria (PKU) is an inherited metabolic disorder affecting the conversion of phenylalanine (Phe) to tyrosine. Medical nutrition therapy, consisting of a Phe-restricted diet with medical formula, is the primary treatment for PKU. The Simplified Diet is an approach to PKU nutrition management that allows certain fruits, vegetables, and low-protein foods to be eaten without measuring or tracking, referred to as free/uncounted foods. There is no consensus on how to implement this approach in metabolic centers in the United States (U.S.), and clinical practice varies. AIM: This study describes the clinical experience of metabolic dietitians in U.S.-based metabolic centers related to the use and implementation of the Simplified Diet. METHODS: A survey was developed and sent out to metabolic dietitians to query current clinical practices related to the Simplified Diet. Descriptive statistics were used to analyze responses. RESULTS: Sixty-three dietitians managing ≥5 patients with PKU in U.S.-based metabolic centers responded to the survey. Ninety-eight percent of survey respondents reported using some version of the Simplified Diet in clinical practice. The survey identified areas of strong agreement, including introduction of the Simplified Diet at 6 to 12 months of age. The survey also identified areas of widespread variability, including specific Phe or protein thresholds for free/uncounted foods, and whether or not to set daily quantity limits on these foods. CONCLUSIONS: Significant variability related to implementation of the Simplified Diet exists across U.S.-based metabolic centers. This practice variability may contribute to differences in the patient experience across centers and may indicate a need for development of clinical guidelines.

A Survey of Eating Attitudes and Behaviors in Adolescents and Adults With Phenylalanine Hydroxylase Deficiency.

INTRODUCTION: Phenylalanine hydroxylase deficiency, commonly known as phenylketonuria (PKU), is an inborn error of metabolism that manifests in severe neurological damage when left untreated. Routine newborn screening has made early identification and treatment of affected individuals possible, changing the prognosis of PKU from devastating to excellent. The most effective treatment for PKU involves lifelong dietary restriction of protein, nutrition supplementation via medical foods, and frequent monitoring of amino acid levels in the blood. However, it has been observed that imposing strict medical control over daily dietary habits can lead to destructive attitudes towards eating and body image. This study investigated whether people with PKU are at increased risk of disordered eating behaviors and attitudes. METHODS: Fifteen patients with PKU between the ages of 12 and 35 from the University of Wisconsin (UW) Biochemical Genetics Clinic were surveyed about their metabolic management and eating attitudes and behaviors. RESULTS: While this study was too small to make conclusions of clinical significance, our findings did suggest that patients with poor metabolic control exhibited symptoms of disordered eating at a higher frequency than those with good metabolic control. CONCLUSIONS: There is currently no validated screening tool to evaluate for disordered eating behaviors in individuals with PKU, which makes identifying and treating disordered eating and related conditions difficult. The development of this project emphasized the importance of tailored screening and provider awareness for disordered eating for populations with chronic illnesses.

Newborn Screening for Inherited Metabolic Disorders: Early Identification and Long-Term Care for Patients in the Plain Community, Wisconsin, 2011-2017.

The Plain community is the fastest-growing religious minority in Wisconsin. This community has a high incidence of genetic disorders, many of which are identifiable through newborn screening. We describe efforts by the Wisconsin Newborn Screening Program (WNSP) to improve health care in the Plain community by targeting early identification of, and intervention for, patients with inherited metabolic disorders. WNSP formed partnerships with families and health care providers to increase awareness of screening procedures and the intended benefits of screening, modify testing algorithms to enhance detection, and establish medical homes for patients with confirmed disorders. The estimated number of Plain newborns screened increased by 25.5% during the study period, from 547 in 2011 to 736 in 2017; 122 persons underwent carrier testing, and 143 newborns received second-tier testing. From 2014 to 2017, affected patients received 71 metabolic evaluations in their community medical home without travel to major health centers. This article demonstrates how a comprehensive public health program can help increase screening rates, enhance detection, and establish follow-up care in a hard-to-reach religious community. A key lesson learned was the importance of communication among all stakeholders to develop an effective public health program.

Genotypes of patients with phenylalanine hydroxylase deficiency in the Wisconsin Amish.

In the Plain Community, there is an increased frequency of genetic disorders including phenylalanine hydroxylase (PAH) deficiency. Common pathogenic variants have been observed due to founder effect and closed community. This study obtained genotypes of 12 Plain individuals with PAH deficiency, identified through newborn screen or diagnosed by symptomatic presentation, who are receiving medical care at the University of Wisconsin metabolic clinic. Genotype and phenotypic data were evaluated to characterize genotype-phenotype correlations. Results can inform the need for confirmatory testing for the disorder and provide a better understanding of the biochemical phenotype, which may help with management.