Health economic impact of patients with phenylketonuria (PKU) in France - A nationwide study of health insurance claims data.

Background: Phenylketonuria (PKU) is an inherited metabolic disease. If left untreated, it can lead to severe irreversible intellectual disability and can cause seizures, behavior disturbance, and white matter disease. This study aimed at evaluating the health economic impact of patients with PKU in France. Methods: This retrospective observational study used health insurance claims data from the French SNDS (Système National des Données de Santé) database, which contains data from over 66 million French inhabitants. Patients with PKU were identified by ICD-10 diagnosis codes E70.0 (PKU) and E70.1 (Other hyperphenylalaninemia) documented as a chronic condition (affection de longue durée - ALD) or in the inpatient setting in the SNDS database between 2006 and 2018. Patients with PKU were matched to controls without PKU by age, sex, and region. Patients with early- and late-diagnosed PKU were defined as patients born after and before the implementation of nationwide newborn screening in France in 1972, respectively. Outcomes were analyzed for the year 2018. Results: Overall, 3549 patients with PKU were identified in the database on January 1st, 2018. Of those, 3158 patients versus 15,703 controls with at least one healthcare consumption in 2018 were available for outcome analyses. Patients with PKU had 7.7 times higher healthcare costs than non-PKU controls in 2018 (€11,144 versus 1456 mean costs; p < 0.0001). Pharmaceutical costs including dietary amino acid supplements were the cost driver and contributed 80.0% of the overall mean difference (MD) between patients with PKU and matched non-PKU controls. More than half (52.4%) of the mean pharmaceutical costs per patient with PKU was attributable to medical foods including dietary amino acid supplements.Of the 3158 patients with PKU, 2548 (80.7%) were classified as early-diagnosed and 610 (19.7%) as late-diagnosed. Increased healthcare costs, in comparison to non-PKU controls, were more evident in early-diagnosed patients (€11,263 versus €855 mean costs; 13.2-fold increase; p < 0.0001). For patients with late-diagnosed PKU, healthcare costs were 2.7-fold higher compared to matched non-PKU controls (€10,644 versus €3951 mean costs; p < 0.0001). Outpatient pharmaceutical costs accounted for 89.1% of the MD between early-diagnosed patients and controls. Among late-diagnosed patients, 55.5% of the MD were attributable to costs for inpatient care, followed by costs for outpatient care (23.9%) and outpatient pharmaceutical costs (20.6%). Conclusion: The results indicate that PKU is associated with substantially increased health care costs compared to non-PKU controls in France. The health economic impact was most evident in patients with early-diagnosed PKU due to increased outpatient pharmaceutical costs, especially for medical foods including dietary amino acid supplements. For late-diagnosed and by definition older patients with PKU, the excess costs compared with matched controls were mostly driven by costs for inpatient care.

Phenylketonuria - newborn screening as a health protection in society.

OBJECTIVE: Aim: Phenylketonuria is the most prevalent inherited metabolic disorder. Early detection and prompt treatment can prevent serious neurological consequences. This has become possible thanks to the implementation of newborn screening programmes. The objective of this review is to provide readers with a comprehensive understanding of the phenylketonuria and the role that neonatal screening plays in the protection of public health. PATIENTS AND METHODS: Materials and Methods: A review of the literature was conducted using the PubMed database, with the search period encompassing the most recently published scientific sources. Analysis of the literature. This article presents phenylketonuria as an example of an inherited metabolic disorder, outlines the treatment options, and discusses the potential implications of hyperphenylalaninemia. Furthermore, it also delineates the various aspects of health that are influenced by newborn screening. CONCLUSION: Conclusions: Phenylketonuria represents a significant health problem in the population. The development of screening tests has transformed healthcare, including improvements in quality of life, prognosis, and reductions in the number of comorbidities in patients. It is essential to disseminate knowledge among the society about the importance of newborn screening tests in order to enhance awareness and prevent refusal to participate.

Evaluating the Influence of Social Determinants of Health on Blood Phenylalanine Levels in Phenylketonuria Patients.

Phenylketonuria (PKU) is a genetic metabolic disorder that causes the accumulation of phenylalanine (Phe) in tissues, leading to intellectual disability, seizures, and socioemotional challenges. The role of social determinants of health (SDOH) in PKU management has not been formally studied, and this investigation evaluates the association between in-home and in-office factors on blood Phe levels in PKU patients. We conducted a retrospective chart review on over 200 patients attending the well-resourced PKU Clinic at Lurie Children's Hospital of Chicago. Data included patients' average Phe level, various demographic information, and CDC/ATSDR social vulnerability index (SVI) score. The analysis revealed no significant association between social vulnerability status and average Phe level. However, a significant correlation was found between sapropterin dihydrochloride use and average Phe level. Age interacted separately with sex assigned at birth, pegvaliase use, total Phe samples submitted, and the presence of genetic testing to significantly influence the average Phe level. This study highlights the multifactorial influences on PKU management and underscores the importance of social resources, such as clinic social workers and state-provided formula, in modulating the effects of SDOH on PKU control. Further research in different healthcare settings is needed to understand the social determinants affecting PKU patients comprehensively, which will strengthen advocacy efforts for this population.

Perspectives and Insights Into Phenylketonuria: Provider Narratives About the Early Years Following Newborn Screening.

The understanding of phenylketonuria (PKU), guidelines, and treatment landscape have evolved dramatically over the decades since newborn screen implementation. We capture this rich history from the stories and experiences of a multidisciplinary provider team from Boston Children's Hospital's PKU Clinic, who treated PKU from the early years of newborn screening and who worked together for over 40 years.

Determination of the Protein and Amino Acid Content of Fruit, Vegetables and Starchy Roots for Use in Inherited Metabolic Disorders.

Amino acid (AA)-related inherited metabolic disorders (IMDs) and urea cycle disorders (UCDs) require strict dietary management including foods low in protein such as fruits, vegetables and starchy roots. Despite this recommendation, there are limited data on the AA content of many of these foods. The aim of this study is to describe an analysis of the protein and AA content of a range of fruits, vegetables and starchy roots, specifically focusing on amino acids (AAs) relevant to AA-related IMDs such as phenylalanine (Phe), methionine (Met), leucine (Leu), lysine (Lys) and tyrosine (Tyr). AA analysis was performed using high-performance liquid chromatography (HPLC) on 165 food samples. Protein analysis was also carried out using the Dumas method. Foods were classified as either 'Fruits', 'Dried fruits', 'Cruciferous vegetables', 'Legumes', 'Other vegetables' or 'Starchy roots'. 'Dried fruits' and 'Legumes' had the highest median values of protein, while 'Fruits' and 'Cruciferous vegetables' contained the lowest median results. 'Legumes' contained the highest and 'Fruits' had the lowest median values for all five AAs. Variations were seen in AA content for individual foods. The results presented in this study provide useful data on the protein and AA content of fruits, vegetables and starchy roots which can be used in clinical practice. This further expansion of the current literature will help to improve diet quality and metabolic control among individuals with AA-related IMDs and UCDs.

Longitudinal Dietary Intake Data in Patients with Phenylketonuria from Europe: The Impact of Age and Phenylketonuria Severity.

In phenylketonuria (PKU), natural protein intake is thought to increase with age, particularly during childhood and adolescence. Longitudinal dietary intake data are scarce and lifelong phenylalanine tolerance remains unknown. Nine centres managing PKU in Europe and Turkey participated in a retrospective study. Data were collected from dietetic records between 2012 and 2018 on phenylalanine (Phe), natural protein, and protein substitute intake. A total of 1323 patients (age range: 1-57 y; 51% male) participated. Dietary intake data were available on 1163 (88%) patients. Patient numbers ranged from 59 to 320 in each centre. A total of 625 (47%) had classical PKU (cPKU), n = 357 (27%) had mild PKU (mPKU), n = 325 (25%) had hyperphenylalaninemia (HPA), and n = 16 (1%) were unknown. The mean percentage of blood Phe levels within target ranged from 65 ± 54% to 88 ± 49%. When intake was expressed as g/day, the mean Phe/natural protein and protein equivalent from protein substitute gradually increased during childhood, reaching a peak in adolescence, and then remained consistent during adulthood. When intake was expressed per kg body weight (g/kg/day), there was a decline in Phe/natural protein, protein equivalent from protein substitute, and total protein with increasing age. Overall, the mean daily intake (kg/day) was as follows: Phe, 904 mg ± 761 (22 ± 23 mg/kg/day), natural protein 19 g ± 16 (0.5 g/kg/day ± 0.5), protein equivalent from protein substitute 39 g ± 22 (1.1 g/kg/day ± 0.6), and total protein 59 g ± 21 (1.7 g/kg/day ± 0.6). Natural protein tolerance was similar between males and females. Patients with mPKU tolerated around 50% less Phe/natural protein than HPA, but 50% more than cPKU. Higher intakes of natural protein were observed in Southern Europe, with a higher prevalence of HPA and mPKU compared with patients from Northern European centres. Natural protein intake doubled with sapropterin usage. In sapropterin-responsive patients, 31% no longer used protein substitutes. Close monitoring and optimisation of protein intake prescriptions are needed, along with future guidelines specifically for different age groups and severities.

Meta-analysis of bone mineral density in adults with phenylketonuria.

BACKGROUND: Lifelong management of phenylketonuria (PKU) centers on medical nutrition therapy, including dietary phenylalanine (Phe) restriction in addition to Phe-free or low-Phe medical foods/protein substitutes. Studies have reported low bone mineral density (BMD) in mixed-age PKU populations, possibly related to long-term Phe restriction. Therefore, a meta-analysis investigating BMD specifically in adults with PKU was conducted. METHODS: Studies reporting BMD-related outcomes were identified from a systematic literature review evaluating somatic comorbidities experienced by adults with PKU on a Phe-restricted diet (searched February 1, 2022, updated November 1, 2023). Risk of study bias was assessed (Scottish Intercollegiate Guidelines Network checklists). The primary outcome of the meta-analysis was pooled mean BMD Z-scores of different bones. Secondary outcomes were the prevalence of low BMD Z-scores at pre-specified thresholds. Subgroup analyses of mean BMD Z-scores (decade of study publication, controlled versus uncontrolled blood Phe levels, gender) were conducted. RESULTS: BMD-related data from 4097 individuals across 10 studies rated as at least acceptable quality were included. Mean BMD Z-scores were statistically significantly lower compared with an age-matched control or reference (non-PKU) population, across bones, but still within the expected range for age (> -2.0): lumbar spine (seven studies, n = 304), -0.63 (95% confidence interval (CI): -0.74, -0.52); femoral neck (four studies, n = 170), -0.74 (95% CI: -1.25, -0.22); radius (three studies, n = 114), -0.77 (95% CI: -1.21, -0.32); total body (four studies, n = 157), -0.61 (95% CI: -0.77, -0.45). The small number of observations in the subgroup analyses resulted in a high degree of uncertainty, limiting interpretation. Estimated prevalence of BMD Z-scores ≤ -2.0 was 8% (95% CI: 5%, 13%; four studies, n = 221) and < -1.0 was 42% (95% CI: 35%, 51%; five studies, n = 144). CONCLUSIONS: Adults with PKU had lower BMD Z-scores than the reference (non-PKU) population but < 1 in 10 were below the expected range for age. The low number of studies prevents identification of which population characteristics are most impacting BMD. This meta-analysis was supported by BioMarin Pharmaceutical Inc., Novato, CA and is registered with the Research Registry (reviewregistry1476).

Perspectives and Insights Into Phenylketonuria: Patient Narratives About the Early Years Following Newborn Screening.

Newborn screening for Phenylketonuria (PKU) began in 1963, and since then knowledge and treatment recommendations have evolved. In the decades following newborn screening for PKU, individual and family experiences varied widely. We present narratives by people living with PKU during these years, including individuals actively following in PKU clinic and those who have been out of PKU clinic for many years. These stories describe different individual experiences, including diet discontinuation in childhood, changing treatment guidelines, and new treatments that have become available.

Long-term safety of sapropterin in paediatric and adult individuals with phenylalanine hydroxylase deficiency: Final results of the Kuvan® Adult Maternal Paediatric European Registry multinational observational study.

Phenylketonuria is a rare inherited disorder that disrupts the metabolism of phenylalanine (Phe) to tyrosine by phenylalanine hydroxylase (PAH). Sapropterin dihydrochloride (Kuvan®) is approved for use in Europe to reduce blood Phe levels and improve Phe tolerance in sapropterin-responsive individuals. KAMPER (NCT01016392) is an observational, multinational registry assessing long-term safety and efficacy of sapropterin. Five hundred and seventy-six participants with PAH deficiency were enrolled from nine European countries (69 sites; December 2009-May 2016). Participants were aged <4 years (n = 11), 4 to <12 years (n = 329), 12 to <18 years (n = 141), and ≥18 years (n = 95) at enrolment. Overall, 401 (69.6%) participants experienced a total of 1960 adverse events; 61 events in 42 participants were serious, and two were considered sapropterin-related by the investigator. Mean (standard deviation) actual dietary Phe intake increased from baseline across all age groups: 957 (799) mg/day to a maximum of 1959 (1121) mg/day over a total study period of 11 years. Most participants exhibited an increase in Phe tolerance while blood Phe levels remained in the target range for their age (120-360 µmol/L for <12 years; 120-600 µmol/L for ≥12 years). Most participants exhibited normal growth for height, weight, and body mass index. No additional safety concerns were identified. As an observational study, limitations include variability in routine care practices and inconsistent availability of data. Long-term sapropterin use demonstrates a favourable safety profile in real-world settings and increases Phe tolerance in participants with PAH deficiency while maintaining blood Phe levels in the target ranges.

The Experience of Phenylketonuria in Pregnancy and the Developing Maternal-Infant Relationship: A Qualitative Study.

Phenylketonuria (PKU) is a rare metabolic condition characterised by an inability to metabolise phenylalanine (Phe), found in many foods. When pregnant with PKU, women must adhere to a strict low-Phe diet. If they do not, foetal abnormalities or pregnancy loss can occur. Pregnancies are therefore closely clinically monitored and dominated by dietary management, leaving little "space" for women's emotional experience. This article explores the emotional impact of PKU during pregnancy and how this effects pre-natal bonding. Based on interviews with six women with PKU, conducted whilst they were pregnant, this article explores their unusual and previously undocumented experience. Image-making during interviews allowed women to uncover aspects of their experience that might otherwise have remained hidden. Interpretative phenomenological analysis of the transcripts and images generated five themes summarising the women's experiences. Some themes reiterated findings from previous studies, for example, the huge cognitive burden associated with PKU pregnancies and the importance of both expert and informal support to successful pregnancy management. However, new understanding also emerged, including rich description of the emotional load of these pregnancies and strategies that women use to manage this. Anxiety about baby safety was central to their experiences, and the effect of this on pre-natal bonding was explored. This article calls for increased formal and informal support for women with the emotional aspects of their PKU pregnancies, for example, the creation of "attachment-aware" services that support women with their anxiety, promoting strong pre-natal attachment and subsequently protecting maternal and infant mental health throughout pregnancy and beyond.

Systematic literature review of the somatic comorbidities experienced by adults with phenylketonuria.

BACKGROUND: Phenylketonuria (PKU) is an inborn error of phenylalanine (Phe) metabolism that, if untreated, causes Phe accumulation in the brain leading to neurophysiologic alterations and poor outcomes. Lifelong management centers on dietary Phe restriction, yet long-term complete metabolic control is unachievable for many adults. High blood Phe levels or chronic Phe and intact protein restriction in the diet may lead to somatic comorbidities. A systematic literature review was conducted to evaluate somatic comorbidities experienced by adults with PKU. METHODS: Clinical and observational studies reporting somatic comorbidities experienced by individuals with PKU aged ≥ 16 years (or classified as adults) evaluating a Phe-restricted diet with or without pharmacologic therapy versus no therapeutic intervention (including healthy controls), or pharmacologic therapy versus a Phe-restricted diet alone, were identified. PubMed® was searched (February 1, 2022 and updated November 1, 2023), using a pre-defined search strategy, followed by two-stage screening and data extraction. Included studies were grouped by PKU population comparison. RESULTS: 1185 records were screened; 51 studies across 12,602 individuals were extracted. Bone-related abnormalities were the most reported outcome (n = 21); several outcome measures were used. Original study groupings included: Phe-restricted diet versus healthy controls or reference values (n = 40); treatment-adherent versus those non-adherent (n = 12). Additional groups added as part of a protocol amendment included: different Phe-restricted diets (n = 4); severe versus less severe disease (n = 5). Vote counting indicated a higher burden of ≥ 1 comorbidity (or outcome measure) for the Phe-restricted diet group by 37 of 38 studies included in the analysis of Phe-restricted diet versus healthy controls; higher burden in healthy controls was reported in 12 studies. Vote counting was similar between those treatment adherent (n = 7) versus non-adherent (n = 10). CONCLUSIONS: Adults with PKU have a higher comorbidity burden than a non-PKU population. More robust studies are needed to better understand the relationship between effective metabolic control and comorbidity burden, using consistent outcome measures. This SLR was supported by BioMarin Pharmaceutical Inc., Novato, CA, and is registered with the Research Registry (reviewregistry1476).

High-Resolution Haplotyping of the PAH Gene Enables Early Gestation Noninvasive Prenatal Diagnosis of Phenylketonuria and Evolution Analysis of Recurrent Pathogenic Variations.

BACKGROUND: The clinical performance of RHDO-based NIPD for PKU during early gestation remains under-evaluated. Furthermore, studies focused on SNP loci obtained by next-generation sequencing to analyze the genetic evolution of pathogenic variations in PKU is limited. METHODS: Maternal peripheral blood, along with proband and paternal samples, was collected between 7 and 12 weeks of gestation. The PAH gene and surrounding high heterozygosity SNPs were targeted for enrichment and sequencing. Fetal genotypes were inferred using RHDO-based NIPD. High-resolution PAH haplotypes were used for the analysis of two common pathogenic variants in the Chinese population: c.728G>A and c.1238G>C. RESULTS: Sixty one PKU families participated with an average fetal fraction of 6.08%. The median gestational age was 8+6 weeks. RHDO-based NIPD successfully identified fetal genotypes in 59 cases (96.72%, 59/62). Two cases failed because of insufficient informative SNPs. In addition, a recombination event was assessed in one fetus of 59 cases. Six, and three haplotypes were identified for c.728G>A(p.Arg243Gln) and c.1238G>C(p.Arg413Pro), respectively. Hap_3 and hap_8 were identified as the ancestral haplotypes for these pathogenic variants, with other haplotypes arising from mutations or recombination based on these ancestral haplotypes. CONCLUSIONS: This study validates the feasibility of an RHDO-based assay for NIPD of PKU in early pregnancy and introduces its application in the demonstration of founder effects in recurrent pathogenic variations, offering new insights into the evolutionary analysis of PAH variations.

Navigating the Unique Challenges of Caregiving for Children with Rare Diseases: Are the Care Experiences of All Caregivers the Same? A Focus on Life-Limiting Rare Diseases.

Background: Caregiving experiences in rare diseases (RDs) vary based on factors such as specific clinical entity, disease severity, the child's age, and available support and resources, leading to challenges that significantly impact caregivers' lives. This study investigates whether caregivers of children with different RDs encounter varied aspects of care. Methods: This study was conducted as a self-administered, anonymous, computer-assisted online survey, focusing on the challenges of caregiving for children with RDs. Questions covered aspects such as information availability on RDs, diagnostic processes, modern treatment accessibility, family physicians and specialists, the impact of caregiving on personal life, family dynamics, and financial challenges. To achieve our study objectives, we categorized caregivers of children with RDs into two groups to compare various aspects of caregiving: caregivers of children with phenylketonuria (PKU) (n = 175) and those caring for children with life-limiting rare diseases (LLRD) (n = 226). Results: Caregivers of children with LLRD reported greater emotional challenges, personal sacrifices, and financial burdens compared to caregivers of children with PKU. Significant differences included heightened emotional distress, more frequent conflicts, and lower assessments of healthcare support among LLRD caregivers. Although family support ratings were similar between the groups, perceptions of financial concerns and interactions with the healthcare system varied significantly. Conclusions: This study, representing the inaugural systematic comparison of specific caregiver cohorts overseeing children with RDs across a substantial sample size, provides valuable insights. The findings lay a crucial foundation for precisely tailoring assistance and support initiatives to meet the unique needs of caregivers facing various RDs in diverse contexts.

Breastfeeding in PKU and Other Amino Acid Metabolism Disorders-A Single Centre Experience.

In addition to the numerous immunological and nutritional benefits that breast milk offers to infants, its proportion in the diet must be limited or even excluded in the case of inborn errors of amino acid metabolism (IEM). The objective of the study was to expand knowledge about breastfeeding and the degree of contribution of breast milk to the feeding of infants with IEM before and after the introduction of expanded newborn screening. A retrospective single-centre study was conducted on 127 infants born between 1997 and 2020: 66 with phenylketonuria (PKU), 45 with other IEM (non-PKU), all diagnosed through newborn screening (NBS), and 16 non-PKU diagnosed through selective screening (SS). The time of initiation of dietary treatment and the proportion of breast milk in the diet, both expressed and breastfed, with or without intake control, were analysed at 1, 3, and 6 months after birth. For 47% of the newborns in Groups 1 and 2, the dietary treatment was started before the 10th day of life; in Group 3, the dietary treatment was started after the 10th day of life for all children. During the first month of life, the proportion of infants receiving breast milk was higher in the NBS-PKU (74%) and the NBS non-PKU (80%) groups, compared with 38% in the SS non-PKU infants. In the subsequent months of life, the proportion of infants receiving human milk (either from the breast or a bottle) declined in all groups. This decline occurred more in bottle-fed rather than directly breast-fed infants. Our observations indicate that the model of feeding from a bottle with expressed milk may have had an adverse effect on maintaining lactation and may have contributed to a faster transition to formula milk. Maintaining lactation and extending the period of feeding the infant with human milk in the first 6 months of life is possible by breastfeeding on demand, under regular biochemical monitoring: preferably weekly in PKU infants, and at least every 2-4 weeks in infants with other IEM.

Patient and carer perceptions of video, telephone and in-person clinics for Phenylketonuria (PKU).

BACKGROUND: In phenylketonuria (PKU), attending multidisciplinary clinic reviews is an important aspect of life-long care. Since the COVID-19 pandemic, video and telephone clinics are used as alternative methods for people with PKU to have contact with their care team. There is limited research concerning patient preference, experience and perceptions of alternative types of clinic review. Individuals from the UK with PKU and their caregivers were invited to complete an online questionnaire, hosted on the National Society for PKU (NSPKU) website and social media platform. RESULTS: Data was available from 203 respondents. Forty one per cent of respondents (n = 49/119) preferred in-person clinics; 41% (n = 49) a hybrid of in-person, video and telephone clinics; 9% (n = 11) video clinics only, 6% (n = 7) telephone only and 3% (n = 3) were unsure. The main respondent obstacles to in-person clinics were costs, travel and time, but this was balanced by the benefits of a physical examination and better patient engagement/motivation. Twenty one per cent (n = 36/169) of respondents were uncomfortable with the number of healthcare professionals (HCPs) in a clinic room. Patients were less likely to consult with a doctor on video (64%, n = 91/143) or phone (50%, n = 59/119) reviews compared to in-person (80%, n = 146/183). Issues with video and telephone reviews included the shorter time length of review, distractions, technical issues and poor patient engagement. CONCLUSIONS: Online video and telephone clinic platforms were effective in overcoming the challenging circumstances in management, monitoring and treatment of patients with PKU during the COVID-19 pandemic. However, in-person clinics remain the preferred respondent option. It is important that HCPs are flexible, enabling people with PKU a choice of clinic options according to their individual clinical need and circumstances.

Effect of a four-week oral Phe administration on neural activation and cerebral blood flow in adults with early-treated phenylketonuria.

BACKGROUND: Phenylketonuria (PKU) is a rare inborn error of metabolism characterized by impaired catabolism of the amino acid phenylalanine (Phe) into tyrosine. Cross-sectional studies suggest slight alterations in cognitive performance and neural activation in adults with early-treated PKU. The influence of high Phe levels on brain function in adulthood, however, remains insufficiently studied. Therefore, we aimed to explore the effect of a four-week period of oral Phe administration - simulating a controlled discontinuation of Phe restriction and raising Phe to an off-diet scenario - on working memory-related neural activation and cerebral blood flow (CBF). METHODS: We conducted a randomized, placebo-controlled, double-blind, crossover, non-inferiority trial to assess the effect of a high Phe load on working memory-related neural activation and CBF in early-treated adults with classical PKU. Twenty-seven patients with early-treated classical PKU were included and underwent functional magnetic resonance imaging (fMRI) of the working memory network and arterial spin labeling (ASL) MRI to assess CBF before and after a four-week intervention with Phe and placebo. At each of the four study visits, fMRI working memory task performance (reaction time and accuracy) and plasma Phe, tyrosine, and tryptophan levels were obtained. Additionally, cerebral Phe was determined by 1H-MR spectroscopy. RESULTS: Plasma Phe and cerebral Phe were significantly increased after the Phe intervention. However, no significant effect of Phe compared to placebo was found on neural activation and CBF. Regarding fMRI task performance, a significant impact of the Phe intervention on 1-back reaction time was observed with slower reaction times following the Phe intervention, whereas 3-back reaction time and accuracy did not differ following the Phe intervention compared to the placebo intervention. CONCLUSION: Results from this present trial simulating a four-week discontinuation of the Phe-restricted diet showed that a high Phe load did not uniformly affect neural markers and cognition in a statistically significant manner. These results further contribute to the discussion on safe Phe levels during adulthood and suggest that a four-week discontinuation of Phe-restricted diet does not demonstrate significant changes in brain function.

Mutation Analysis of PAH Gene in Phenylketonuria Patients from the North of Iran: Identification of Three Novel Pathogenic Variants.

Background: There are more than 1100 different pathogenic variants in the phenylalanine hydroxylase (PAH) gene that are responsible for phenylketonuria (PKU) diseases, and the spectrum of these mutations varies in different ethnic groups. The aim of the present study was to identify the frequency of pathogenic variants in all 13 exons of the PAH gene among patients with PKU in Mazandaran and Golestan provinces in the north of Iran. Methods: Forty unrelated PKU patients from Mazandaran and Golestan provinces were enrolled in the study. Genomic DNA was extracted from leukocytes using a Qiagen DNA extraction kit and polymerase chain reaction - restriction fragment length polymorphism (PCR-RFLP), and Sanger sequencing methods were applied to detect the variants. In the case of new variants, the InterVar online tool (PMID: 28132688) was used to classify the variants. Results: Twenty-one different pathogenic variants were observed among the 40 investigated patients. The c.106611G>A variant had the highest frequency (27.5%) in the region, and the c.168+5G>C, c.473G>A, and c.782 G>A variants were the other most frequent mutations with allelic frequencies of 7.5, 5, and 5%, respectively. Three novel pathogenic variants including c.773T>G, c.878 T>C, and c. 1245del variants were observed among the investigated patients. Conclusions: The introduction of pathogenic variants in the PAH gene in each ethnic group provides valuable data regarding the understanding of the pathogenesis of the disease and can be helpful for prenatal diagnosis programs.

Pre-analytic decrease of phenylalanine in plasma of patients with phenylketonuria treated with pegvaliase.

Treatment of phenylketonuria (PKU) has evolved since the initial introduction of a phenylalanine (Phe) restricted diet. The most recent option for adults affected with PKU is treatment with an alternate enzyme, phenylalanine ammonia lyase (PAL), that metabolizes excess Phe. Proper management of all patients with PKU relies on accurate measurement of Phe levels in blood, to comply with guidance intended to minimize the neurological symptoms. Recently, our laboratory was notified of discrepant results for a patient with PKU who is treated with pegvaliase. Two specimens were collected at the same time but yielded unexpectedly different Phe concentrations. After exclusion of specimen mix-ups or analytical errors, we suspected that there was residual pegvaliase activity in the specimens continuing to degrade Phe after collection. To investigate this possibility, we performed spiking studies that showed the degradation of Phe over time at ambient temperatures. Sample preparation by protein crash appears to deactivate pegvaliase and prevents further Phe degradation. However, because pegvaliase deactivation would be required immediately following blood collection, appropriate mitigation measures must be implemented, including stringent pre-analytical requirements, alternate sample matrices such as dried blood spots, or point of care testing. Until then, health care professionals need to be cautious in their interpretation of Phe levels in their patients with PKU that are treated with pegvaliase.

Initial results from the PHEFREE longitudinal natural history study: Cross-sectional observations in a cohort of individuals with phenylalanine hydroxylase (PAH) deficiency.

Over fifty years have passed since the last large scale longitudinal study of individuals with PAH deficiency in the U.S. Since then, there have been significant changes in terms of treatment recommendations as well as treatment options. The Phenylalanine Families and Researchers Exploring Evidence (PHEFREE) Consortium was recently established to collect a more up-to-date and extensive longitudinal natural history in individuals with phenylketonuria across the lifespan. In the present paper, we describe the structure and methods of the PHEFREE longitudinal study protocol and report cross-sectional data from an initial sample of 73 individuals (5 months to 54 years of age) with PAH deficiency who have enrolled. Looking forward, the study holds the promise for advancing the field on several fronts including the validation of novel neurocognitive tools for assessment in individuals with PKU as well as evaluation of the long-term effects of changes in metabolic control (e.g., effects of Phe-lowering therapies) on outcome.