Sapropterin treatment does not enhance the health-related quality of life of patients with phenylketonuria and their parents

The struggle that is phenylketonuria: What do the patients and caregivers suffer from

To assess stress levels and life hardships of patients with phenylketonuria and their parents. Between January 2020 and June 2020, 156 patients with PKU and their parents who arrived for regular examinations were included. Parents were asked to complete the parenting stress index, Zarit Burden Scale, and the Strengths and Difficulties Questionnaire (SDQ), and children over the age of 11 were asked to fill the Rosenberg Self-Esteem Scale, the State-Trait Anxiety Inventory, and the SDQ. We found a significant negative correlation between the Rosenberg Self-Esteem Scale and age at diagnosis (r = -0.27, P = .035), mother's age (r = -0.33, P = .009), and father's age (r = -0.38, P = .004). There was a significant positive correlation between the State-Trait Anxiety Inventory and patient's age (r = 0.36, P = .006), mother's age (r = 0.29, P = .031) and father's age (r = 0.38, P = .024). In the child form of the SDQ, emotional problems were significantly positively correlated with serum phenylalanine (Phe) levels at diagnosis (r = 0.35, P = .036), total points were significantly positively correlated with serum Phe levels at clinical examination (r = -0.34, P = .004), and social problems were significantly negatively correlated with the father's age (r = -0.34, P = .047). We found a significant positive correlation between the Zarit Burden Scale and number of siblings (r = 0.195, P = .023). In the parent form of the SDQ, emotional problems were significantly positively correlated with patient age (r = 0.217, P = .032), peer problems were significantly positively correlated with age at diagnosis (r = 0.211, P = .037), behavioral problems (r = 0.203, P = .045), and attention deficit and hyperactivity (r = 0.203, P = .045) were significantly positively correlated with serum Phe levels at diagnosis. Phenylketonuria is difficult to cope with both for the patients and their parents because of diet obligation, high expenditures for the formulas required for the diet, requirement of regular clinical examinations, and possible development of mental disability and psychiatric disorders. Patients and their families should be psychologically evaluated and support should be provided if needed.

The treatment of biochemical genetic diseases: From substrate reduction to nucleic acid therapies

Newborn screening (NBS) began a revolution in the management of biochemical genetic diseases, greatly increasing the number of patients for whom dietary therapy would be beneficial in preventing complications in phenylketonuria as well as in a few similar disorders. The advent of next generation sequencing and expansion of NBS have markedly increased the number of biochemical genetic diseases as well as the number of patients identified each year. With the avalanche of new and proposed therapies, a second wave of options for the treatment of biochemical genetic disorders has emerged. These therapies range from simple substrate reduction to enzyme replacement, and now ex vivo gene therapy with autologous cell transplantation. In some instances, it may be optimal to introduce nucleic acid therapy during the prenatal period to avoid fetopathy. However, as with any new therapy, complications may occur. It is important for physicians and other caregivers, along with ethicists, to determine what new therapies might be beneficial to the patient, and which therapies have to be avoided for those individuals who have less severe problems and for which standard treatments are available. The purpose of this review is to discuss the "Standard" treatment plans that have been in place for many years and to identify the newest and upcoming therapies, to assist the physician and other healthcare workers in making the right decisions regarding the initiation of both the "Standard" and new therapies. We have utilized several diseases to illustrate the applications of these different modalities and discussed for which disorders they may be suitable. The future is bright, but optimal care of the patient, including and especially the newborn infant, requires a deep knowledge of the disease process and careful consideration of the necessary treatment plan, not just based on the different genetic defects but also with regards to different variants within a gene itself.

Professional activity, gender and disease-related emotions: The impact on parents' experiences in caring for children with phenylketonuria

Introduction

Clinical management of rare diseases often fails to acknowledge the challenges faced by caregivers. Whilst management of phenylketonuria (PKU) may not be considered as dire as other conditions, most studies primarily concentrate on clinical issues, dietary adherence, or the quality of life of the PKU patients, leaving caregivers in the background. The aim of the study was to evaluate the psychosocial effects of PKU on family caregivers.

Methods

Between October 30th, 2022 and February 28th, 2023, we collected data from caregivers of children with PKU using an anonymous, self-administered, computer-assisted online questionnaire. The survey was distributed among to patients during their regular visits to five Polish PKU treatment centers.

Results

A total of 159 Polish caregivers of children with PKU completed the survey. This research shows that while women caregivers were more likely to be unemployed due to their responsibilities for childcare (50.3% compared to 0% for men), and men caregivers were more likely to be employed full-time (93.8% compared to 40.6% for women), the former reported higher emotional engagement in caregiving (88.1% vs 56.3% respectively). Significantly, unemployed mothers reported higher levels of loneliness, helplessness, and emotional control problems, and lacked psychological/emotional support more often than employed mothers. This research also shows a statistically significant positive correlation between mothers' education level and financial situation (p < 0.05) and education level and professional activity (p < 0.01). Additionally, a significant positive correlation was found between perceived financial situation and feeling of happiness (p < 0.001), and between financial situation and professional activity (p < 0.001). Finally, a significant positive correlation was observed between feeling of happiness and professional activity (p < 0.05).

Conclusions

According to our findings, there is a link between subjective happiness, financial situation, and professional activity among female caregivers. The relationship between these factors goes beyond just the income earned from work. The results of our study imply that there could even be a therapeutic advantage for working mothers. It is crucial to recognize the emotional difficulties that employed mothers may experience while taking care of a child with PKU, and to provide them with the necessary assistance and resources to meet their needs. Additionally, our results may provide a foundation for redefining the support system for caregivers in Poland.

Phenylalanine hydroxylase deficiency treatment and management: A systematic evidence review of the American College of Medical Genetics and Genomics (ACMG)

PURPOSE

Elevated serum phenylalanine (Phe) levels due to biallelic pathogenic variants in phenylalanine hydroxylase (PAH) may cause neurodevelopmental disorders or birth defects from maternal phenylketonuria. New Phe reduction treatments have been approved in the last decade, but uncertainty on the optimal lifespan goal Phe levels for patients with PAH deficiency remains.

METHODS

We searched Medline and Embase for evidence of treatment concerning PAH deficiency up to September 28, 2021. Risk of bias was evaluated based on study design. Random-effects meta-analyses were performed to compare IQ, gestational outcomes, and offspring outcomes based on Phe ≤ 360 μmol/L vs > 360 μmol/L and reported as odds ratio and 95% CI. Remaining results were narratively synthesized.

RESULTS

A total of 350 studies were included. Risk of bias was moderate. Lower Phe was consistently associated with better outcomes. Achieving Phe ≤ 360 μmol/L before conception substantially lowered the risk of negative effect to offspring in pregnant individuals (odds ratio = 0.07, 95% CI = 0.04-0.14; P < .0001). Adverse events due to pharmacologic treatment were common, but medication reduced Phe levels, enabling dietary liberalization.

CONCLUSIONS

Reduction of Phe levels to ≤360 μmol/L through diet or medication represents effective interventions to treat PAH deficiency.

Impact on Diet Quality and Burden of Care in Sapropterin Dihydrochloride Use in Children with Phenylketonuria: A 6 Month Follow-Up Report

INTRODUCTION

In phenylketonuria (PKU) changes in dietary patterns and behaviors in sapropterin-responsive populations have not been widely reported. We aimed to assess changes in food quality, mental health and burden of care in a paediatric PKU sapropterin-responsive cohort.

METHODS

In an observational, longitudinal study, patient questionnaires on food frequency, neophobia, anxiety and depression, impact on family and burden of care were applied at baseline, 3 and 6-months post successful sapropterin-responsiveness testing (defined as a 30% reduction in blood phenylalanine levels).

RESULTS

17 children (10.8 ± 4.2 years) completed 6-months follow-up. Patients body mass index (BMI) z-scores remained unchanged after sapropterin initiation. Blood phenylalanine was stable. Natural protein increased (p < 0.001) and protein substitute intake decreased (p = 0.002). There were increases in regular cow's milk (p = 0.001), meat/fish, eggs (p = 0.005), bread (p = 0.01) and pasta (p = 0.011) intakes but special low-protein foods intake decreased. Anxiety (p = 0.016) and depression (p = 0.022) decreased in caregivers. The impact-on-family, familial-social impact (p = 0.002) and personal strain (p = 0.001) lessened. After sapropterin, caregivers spent less time on PKU tasks, the majority ate meals outside the home more regularly and fewer caregivers had to deny food choices to their children.

CONCLUSION

There were significant positive changes in food patterns, behaviors and burden of care in children with PKU and their families after 6-months on sapropterin treatment.

Suitability and Allocation of Protein-Containing Foods According to Protein Tolerance in PKU: A 2022 UK National Consensus

Introduction: There is little practical guidance about suitable food choices for higher natural protein tolerances in patients with phenylketonuria (PKU). This is particularly important to consider with the introduction of adjunct pharmaceutical treatments that may improve protein tolerance. Aim: To develop a set of guidelines for the introduction of higher protein foods into the diets of patients with PKU who tolerate >10 g/day of protein. Methods: In January 2022, a 26-item food group questionnaire, listing a range of foods containing protein from 5 to >20 g/100 g, was sent to all British Inherited Metabolic Disease Group (BIMDG) dietitians (n = 80; 26 Inherited Metabolic Disease [IMD] centres). They were asked to consider within their IMD dietetic team when they would recommend introducing each of the 26 protein-containing food groups into a patient’s diet who tolerated >10 g to 60 g/day of protein. The patient protein tolerance for each food group that received the majority vote from IMD dietetic teams was chosen as its tolerance threshold for introduction. A virtual meeting was held using Delphi methodology in March 2022 to discuss and agree final consensus. Results: Responses were received from dietitians from 22/26 IMD centres (85%) (11 paediatric, 11 adult). For patients tolerating protein ≥15 g/day, the following foods were agreed for inclusion: gluten-free pastas, gluten-free flours, regular bread, cheese spreads, soft cheese, and lentils in brine; for protein tolerance ≥20 g/day: nuts, hard cheeses, regular flours, meat/fish, and plant-based alternative products (containing 5−10 g/100 g protein), regular pasta, seeds, eggs, dried legumes, and yeast extract spreads were added; for protein tolerance ≥30 g/day: meat/fish and plant-based alternative products (containing >10−20 g/100 g protein) were added; and for protein tolerance ≥40 g/day: meat/fish and plant-based alternatives (containing >20 g/100 g protein) were added. Conclusion: This UK consensus by IMD dietitians from 22 UK centres describes for the first time the suitability and allocation of higher protein foods according to individual patient protein tolerance. It provides valuable guidance for health professionals to enable them to standardize practice and give rational advice to patients.

Dietary Liberalization in Tetrahydrobiopterin-Treated PKU Patients: Does It Improve Outcomes?

PURPOSE

this systematic review aimed to assess the effects of dietary liberalization following tetrahydrobiopterin (BH4) treatment on anthropometric measurements, nutritional biomarkers, quality of life, bone density, mental health and psychosocial functioning, and burden of care in PKU patients.

METHODS

the PubMed, Cochrane, and Embase databases were searched on 7 April 2022. We included studies that reported on the aforementioned domains before and after dietary liberalization as a result of BH4 treatment in PKU patients. Exclusion criteria were: studies written in a language other than English; studies that only included data of a BH4 loading test; insufficient data for the parameters of interest; and wrong publication type. Both within-subject and between-subject analyses were assessed, and meta-analyses were performed if possible.

RESULTS

twelve studies containing 14 cohorts and 228 patients were included. Single studies reported few significant differences. Two out of fifteen primary meta-analyses were significant; BMI was higher in BH4-treated patients versus controls (p = 0.02; standardized mean difference (SMD) (95% confidence interval (CI)) = -0.37 (-0.67, -0.06)), and blood cholesterol concentrations increased after starting BH4 treatment (p = 0.01; SMD (CI) = -0.70 (-1.26, -0.15)).

CONCLUSION

there is no clear evidence that dietary liberalization after BH4 treatment has a positive effect on anthropometric measurements, nutritional biomarkers, or quality of life. No studies could be included for bone density, mental health and psychosocial functioning, and burden of care.

Health Related Quality of Life of Caregivers of Children and Adolescents With Phenylketonuria: A Systematic Review

Introduction. Caregivers of children with chronic illness are at risk of having impairment in their quality of life (QOL). We systematically reviewed the available literature related to the Health Related Quality Of Life (HRQOL) of caregivers of children with Phenylketonuria (PKU). Methods. We comprehensively searched in electronic databases including Scopus, Science Direct, CINAHL, Medline, PubMed, Google scholar, and ProQuest. The search criteria included studies with samples more than one, children suffering from PKU, exploring parents or primary caregiver’s HRQOL, published from 2010 to 2020, full article available for download and published in English. Eight studies including 5 cross sectional studies, 1 open label trial, and 2 surveys were systematically reviewed. Results. Seven out of 8 studies have established a negative correlation between PKU and parent’s HRQOL in at least 1 of the domains. In one study, the HRQOL of parents is higher than their population norms. Conclusion. Most of the caregivers had poor to moderate HRQOL. More studies are required to explore HRQOL of caregivers of children with PKU using similar tools and outcome measures addressing all the domains of HRQOL in order to have more clarity on the impact of PKU on caregiver’s HRQOL. Interventional studies might help in improving the HRQOL of caregivers.

Phenylketonuria

Phenylketonuria (PKU; also known as phenylalanine hydroxylase (PAH) deficiency) is an autosomal recessive disorder of phenylalanine metabolism, in which especially high phenylalanine concentrations cause brain dysfunction. If untreated, this brain dysfunction results in severe intellectual disability, epilepsy and behavioural problems. The prevalence varies worldwide, with an average of about 1:10,000 newborns. Early diagnosis is based on newborn screening, and if treatment is started early and continued, intelligence is within normal limits with, on average, some suboptimal neurocognitive function. Dietary restriction of phenylalanine has been the mainstay of treatment for over 60 years and has been highly successful, although outcomes are still suboptimal and patients can find the treatment difficult to adhere to. Pharmacological treatments are available, such as tetrahydrobiopterin, which is effective in only a minority of patients (usually those with milder PKU), and pegylated phenylalanine ammonia lyase, which requires daily subcutaneous injections and causes adverse immune responses. Given the drawbacks of these approaches, other treatments are in development, such as mRNA and gene therapy. Even though PAH deficiency is the most common defect of amino acid metabolism in humans, brain dysfunction in individuals with PKU is still not well understood and further research is needed to facilitate development of pathophysiology-driven treatments.

Protein Substitute Requirements of Patients with Phenylketonuria on BH4 Treatment: A Systematic Review and Meta-Analysis

The traditional treatment for phenylketonuria (PKU) is a phenylalanine (Phe)-restricted diet, supplemented with a Phe-free/low-Phe protein substitute. Pharmaceutical treatment with synthetic tetrahydrobiopterin (BH4), an enzyme cofactor, allows a patient subgroup to relax their diet. However, dietary protocols guiding the adjustments of protein equivalent intake from protein substitute with BH4 treatment are lacking. We systematically reviewed protein substitute usage with long-term BH4 therapy. Electronic databases were searched for articles published between January 2000 and March 2020. Eighteen studies (306 PKU patients) were eligible. Meta-analyses demonstrated a significant increase in Phe and natural protein intakes and a significant decrease in protein equivalent intake from protein substitute with cofactor therapy. Protein substitute could be discontinued in 51% of responsive patients, but was still required in 49%, despite improvement in Phe tolerance. Normal growth was maintained, but micronutrient deficiency was observed with BH4 treatment. A systematic protocol to increase natural protein intake while reducing protein substitute dose should be followed to ensure protein and micronutrient requirements are met and sustained. We propose recommendations to guide healthcare professionals when adjusting dietary prescriptions of PKU patients on BH4. Studies investigating new therapeutic options in PKU should systematically collect data on protein substitute and natural protein intakes, as well as other nutritional factors.

Benzene Derivatives from Ink Lead to False Positive Results in Neonatal Hyperphenylalaninemia Screening with Ninhydrin Fluorometric Method

Ninhydrin-based fluorometric quantification of phenylalanine is one of the most widely used methods for hyperphenylalaninemia (HPA) screening in neonates due to its high sensitivity, high accuracy, and low cost. Here we report an increase of false positive cases in neonatal HPA screening with this method, caused by contamination of blood specimen collection devices during the printing process. Through multiple steps of verification, the contaminants were identified from ink circles printed on the collection devices to indicate the positions and sizes of blood drops. Blood specimens from HPA-negative persons collected on these contaminated collection devices showed positive results in the fluorometric tests, but negative results in tandem mass spectroscopy (MS/MS) experiments. Contaminants on the collection devices could be extracted by 80% ethanol and showed an absorption peak around 245 nm, suggesting that these contaminants may contain benzene derivatives with similar structure to phenylalanine. High-performance liquid chromatography (HPLC) analysis of the ethanol extracts from contaminated collection devices identified two prominent peaks specifically from the devices. Methyl-2-benzoylbenzoate (MBB, CAS#606-28-0) was found as one of the major chemicals from contaminated collection devices. This report aims to remind colleagues in the field of this potential contamination and call for tighter regulation and quality control of specimen collection devices.

Patient and observer reported outcome measures to evaluate health-related quality of life in inherited metabolic diseases: a scoping review

Background

Health-related Quality of Life (HrQoL) is a multidimensional measure, which has gained clinical and social relevance. Implementation of a patient-centred approach to both clinical research and care settings, has increased the recognition of patient and/or observer reported outcome measures (PROMs or ObsROMs) as informative and reliable tools for HrQoL assessment. Inherited Metabolic Diseases (IMDs) are a group of heterogeneous conditions with phenotypes ranging from mild to severe and mostly lacking effective therapies. Consequently, HrQoL evaluation is particularly relevant.

Objectives

We aimed to: (1) identify patient and/or caregiver-reported HrQoL instruments used among IMDs; (2) identify the main results of the application of each HrQoL tool and (3) evaluate the main limitations of HrQoL instruments and study design/methodology in IMDs.

Methods

A scoping review was conducted using methods outlined by Arksey and O’Malley. Additionally, we critically analysed each article to identify the HrQoL study drawbacks.

Results

Of the 1954 studies identified, 131 addressed HrQoL of IMDs patients using PROMs and/or ObsROMs, both in observational or interventional studies. In total, we identified 32 HrQoL instruments destined to self- or proxy-completion; only 2% were disease-specific. Multiple tools (both generic and disease-specific) proved to be responsive to changes in HrQoL; the SF-36 and PedsQL questionnaires were the most frequently used in the adult and pediatric populations, respectively. Furthermore, proxy data often demonstrated to be a reliable approach complementing self-reported HrQoL scores. Nevertheless, numerous limitations were identified especially due to the rarity of these conditions.

Conclusions

HrQoL is still not frequently assessed in IMDs. However, our results show successful examples of the use of patient-reported HrQoL instruments in this field. The importance of HrQoL measurement for clinical research and therapy development, incites to further research in HrQoL PROMs’ and ObsROMs’ creation and validation in IMDs.

Electronic supplementary material

The online version of this article (10.1186/s13023-018-0953-9) contains supplementary material, which is available to authorized users.

An Introduction to Pharmacotherapy for Inborn Errors of Metabolism

Inborn errors of metabolism comprise a wide array of diseases and complications in the pediatric patient. The rarity of these disorders limits the ability to conduct and review robust literature regarding the disease states, mechanisms of dysfunction, treatments, and outcomes. Often, treatment plans will be based on the pathophysiology associated with the disorder and theoretical agents that may be involved in the metabolic process. Medication therapies usually consist of natural or herbal products. Established efficacious pediatric doses for these products are difficult to find in tertiary resources, and adverse effects are routinely limited to single case reports. This review article attempts to summarize some of the more common inborn errors of metabolism in a manner that is applicable to pharmacists who will provide care for these patients.

The impact of metabolic control and tetrahydrobiopterin treatment on health related quality of life of patients with early-treated phenylketonuria: A PKU-COBESO study

The aim of this study was to examine Health-Related Quality of Life (HRQoL) of patients with Phenylketonuria (PKU) in three different age groups and to investigate the impact of metabolic control and tetrahydrobiopterin (BH4) treatment on HRQoL of these patients. Participants were 90 early-treated patients aged 7 to 40 years (M = 21.0, SD = 10.1) and 109 controls aged 7 to 40.8 years (M = 19.4, SD = 8.6). HRQoL was assessed with the (generic) TNO-AZL questionnaires. Overall, good HRQoL was reported for children below 12 years of age, although they were judged to be less autonomic than their healthy counterparts. Adolescents aged 12-15 years showed poorer HRQoL in the domain "cognitive functioning" compared to controls. For adults ≥16 years, poorer age-controlled HRQoL was found for the domains cognition, depressive moods, and anger, with a further trend for the domain "pain". With respect to metabolic control, only for adult PKU-patients robust associations were observed, indicating poorer functioning, most notably in the domains cognition, sleep, pain, sexuality and anger, with higher historical and concurrent Phe-levels. With respect to BH4-use, effects on HRQoL were again only observed for adult PKU-patients. After controlling for age and historical Phe-levels, small but significant differences in favor of adult BH4-users compared to non-users were observed for HRQoL-categories happiness, anger, and social functioning. Together, these results show that, particularly for adult PKU-patients, HRQoL-problems are evident and that many of these problems are related to (history of) metabolic control. Beneficial effects of BH4-use appear to be limited to those associated with relief from the practical burdens related to the strict dietary treatment regimen, i.e. general mood and sociability, whereas metabolic control is more strongly related to basic physical and cognitive functioning.

Extended Experience of Lower Dose Sapropterin in Irish Adults with Mild Phenylketonuria

Adherence to dietary and treatment recommendations is a long-standing concern for adults and adolescents with PKU and treating clinicians. In about 20-30% of PKU patients, Phe levels may be controlled by tetrahydrobiopterin (BH4) therapy. The European PKU 2017 Guidelines recommends treatment with BH4 for cases of proven long-term BH4 responsiveness, with a recommended dosage of Sapropterin 10-20 mg/kg/day.We report four young Irish patients with mild PKU, known to be BH4 responsive, who were treated with lower doses of Sapropterin for over 7 years.Case 1: Female, currently age 20. Genotype p. 165T/p/F39L, c.[194T>C]; [117C>G]. Newborn Phe: 851 μmol/L. Pre-Sapropterin Phe tolerance: 600 mg Phe/day to maintain Phe levels <400 μmol/L. Commenced on Sapropterin 400 mg (6.5 mg/kg/day) with increase in Phe tolerance to 800 mg/day.Case 2: Female, currently age 23. Genotype p. 165T/pF39L; c.[194T>C]; [117C>G]. Newborn Phe: 714 μmol/L. Pre-Sapropterin Phe tolerance: 700 mg Phe/day. Commenced on Sapropterin 400 mg (8 mg/kg/day) with increase in Phe tolerance to 800 mg/day.Case 3: Male, currently age 22. Genotype p. 165T/p.S349P; c.[194T>C][1045T>C]. Newborn Phe: 1,036 μmol/L. Pre-Sapropterin Phe tolerance: 600 mg Phe/day. Commenced on Sapropterin 400 mg (5.4 mg/kg/day). Increased to 1,600 mg Phe/day.Case 4: Female, currently age 29. Genotype p.R408W/p/p.Y414C; c.[1222C>T], [1241A>G]. Newborn Phe: 1,600 μmol/L. Pre-Sapropterin tolerance: 450 mg/day. Commenced on Sapropterin 400 mg (5.0 mg/kg/day). Increased to 900 mg Phe/day.Almost 7 years of surveillance for these four patients has shown that this dose of Sapropterin (range 5-8 mg/kg day) was well tolerated and effective with a significant response to treatment and a marked improvement in quality of life at these lower Sapropterin doses.