Long-Term Follow-Up of Cognition and Mental Health in Adult Phenylketonuria: A PKU-COBESO Study

Emphasis on the importance of comprehensive clinical and genetic analysis - spinal muscular atrophy combined with phenylketonuria: A case report

RATIONALE

Both spinal muscular atrophy (SMA) and Phenylketonuria (PKU) are caused by biallelic pathogenic mutations. However, there has been no report on case who suffering from both diseases simultaneously. SMA mainly affects the motor function while PKU may have an impact on both the intelligence and motor function. But if only 1 disease is treated while neglecting the other, the treatment effect will be compromised. Here, for the first time, we report a case from China diagnosed with both these diseases and treated properly.

PATIENT CONCERNS

A boy was admitted to the Children's Hospital Affiliated to Shandong University (Jinan, China) due to "limb weakness for 19 months" when he was 22 months old. Considering that the child's motor function development is delayed, we made a comprehensive examinations including inherited metabolic diseases and found a significantly increase of phenylalanine concentration in the blood which indicating PKU. Combined with his typical clinical manifestations of SMA, target capture sequencing followed by Sanger sequencing and multiplex ligation-dependent probe amplification (MLPA) technologies were used for genetic confirmation.

DIAGNOSES

SMA and PKU was confirmed.

INTERVENTIONS

The child was treated with risdiplam and low phenylalanine formula immediately when he was diagnosed with both SMA and PKU.

OUTCOMES

The child showed remarkable improvement in motor function and significant decrease of blood phenylalanine concentration after treatment.

LESSONS

To our knowledge, this is the first reported case of SMA combined with PKU. This case expands our understanding of diagnosis for synchronous SMA and PKU and highlights the importance of comprehensive examinations and the utilizing of various genetic testing methods to make an accurate diagnosis of genetic diseases, which may help avoiding the progressive damage caused by certain genetic disease with insidious clinical symptoms.

The clinical relevance of novel biomarkers as outcome parameter in adults with phenylketonuria

Recent studies in PKU patients identified alternative biomarkers in blood using untargeted metabolomics. To test the added clinical value of these novel biomarkers, targeted metabolomics of 11 PKU biomarkers (phenylalanine, glutamyl-phenylalanine, glutamyl-glutamyl-phenylalanine, N-lactoyl-phenylalanine, N-acetyl-phenylalanine, the dipeptides phenylalanyl-phenylalanine and phenylalanyl-leucine, phenylalanine-hexose conjugate, phenyllactate, phenylpyruvate, and phenylacetate) was performed in stored serum samples of the well-defined PKU patient-COBESO cohort and a healthy control group. Serum samples of 35 PKU adults and 20 healthy age- and sex-matched controls were analyzed using ultra-high performance liquid chromatography quadrupole time-of-flight mass spectrometry. Group differences were tested using the Mann-Whitney U test. Multiple linear regression analyses were performed with these biomarkers as predictors of (neuro-)cognitive functions working memory, sustained attention, inhibitory control, and mental health. Compared to healthy controls, phenylalanine, glutamyl-phenylalanine, N-lactoyl-phenylalanine, N-acetyl-phenylalanine, phenylalanine-hexose conjugate, phenyllactate, phenylpyruvate, and phenylacetate were significant elevated in PKU adults (p < 0.001). The remaining three were below limit of detection in PKU and controls. Both phenylalanine and N-lactoyl-phenylalanine were associated with DSM-VI Attention deficit/hyperactivity (R2 = 0.195, p = 0.039 and R2 = 0.335, p = 0.002, respectively) of the ASR questionnaire. In addition, N-lactoyl-phenylalanine showed significant associations with ASR DSM-VI avoidant personality (R2 = 0.265, p = 0.010), internalizing (R2 = 0.192, p = 0.046) and externalizing problems (R2 = 0.217, p = 0.029) of the ASR questionnaire and multiple aspects of the MS2D and FI tests, reflecting working memory with R2 between 0.178 (p = 0.048) and 0.204 (p = 0.033). Even though the strength of the models was not considered strong, N-lactoyl-phenylalanine outperformed phenylalanine in its association with working memory and mental health outcomes.

No Impairment in Bone Turnover or Executive Functions in Well-Treated Preschoolers with Phenylketonuria-A Pilot Study

Patients with phenylketonuria (PKU) present signs of impaired executive functioning and bone health in adolescence and adulthood, depending in part on the success of therapy in childhood. Therefore, nine children with well-treated PKU (4-7 years old, 22.2% ♀, seven with a full set of data, two included into partial analysis) and 18 age-, gender- and season-matched controls were analyzed for differences in executive functioning and bone parameters in plasma. Plasma was analyzed with commercially available kits. Cognitive performance in tonic alertness, visuo-spatial working memory, inhibitory control and task switching was assessed by a task battery presented on a touch screen. Regarding cognition, only the performance in incongruent conditions in inhibitory control was significantly better in children with PKU than in controls. No further differences in cognitive tests were detected. Furthermore, no significant difference in the bone turnover markers osteocalcin, undercarboxylated osteocalcin and CTX were detected between children with PKU and controls, while children with PKU had a significantly higher vitamin D concentration (69.44 ± 12.83 nmol/L vs. 41.87 ± 15.99 nmol/L, p < 0.001) and trended towards lower parathyroid hormone concentrations than controls (48.27 ± 15.16 pg/mL vs. 70.61 ± 30.53 pg/mL, p = 0.066). In this small group of well-treated preschoolers with PKU, no impairments in cognitive performance and bone turnover were observed, while vitamin D supplementation of amino acid supplements seems to be sufficient to achieve good vitamin D status.

Current Advances and Material Innovations in the Search for Novel Treatments of Phenylketonuria

Phenylketonuria (PKU) is a genetically inherited disease caused by a mutation of the gene encoding phenylalanine hydroxylase (PAH) and is the most common inborn error of amino acid metabolism. A deficiency of PAH leads to increased blood and brain levels of phenylalanine (Phe), which may cause permanent neurocognitive symptoms and developmental delays if untreated. Current management strategies for PKU consist of early detection through neonatal screening and implementation of a restrictive diet with minimal amounts of natural protein in combination with Phe-free supplements and low-protein foods to meet nutritional requirements. For milder forms of PKU, oral treatment with synthetic sapropterin (BH4), the cofactor of PAH, may improve metabolic control of Phe and allow for more natural protein to be included in the patient's diet. For more severe forms, daily injections of pegvaliase, a PEGylated variant of phenylalanine ammonia-lyase (PAL), may allow for normalization of blood Phe levels. However, the latter treatment has considerable drawbacks, notably a strong immunogenicity of the exogenous enzyme and the attached polymeric chains. Research for novel therapies of PKU makes use of innovative materials for drug delivery and state-of-the-art protein engineering techniques to develop treatments which are safer, more effective, and potentially permanent.

Phenylketonuria from the perspectives of patients in Türkiye

BACKGROUND

The present study aimed to determine the problems, unmet needs and expectations of phenylketonuria (PKU) patients in Türkiye regarding follow-up and treatment in order to provide data for future planning and implementations on PKU.

METHODS

The study included patients diagnosed with PKU and/or their parents. They were informed about the study via phone calls and their verbal consents were obtained. Questions in the data collection forms, which were established separately for pediatric, adolescent, and adult age groups, were applied during the interviews and the answers were recorded.

RESULTS

Among 182 classical PKU patients, 66 (36.3%) were in the pediatric group (0-12 years old), 44 (24.2%) were in the adolescent group (13-19 years old), and 72 (39.5%) were in the adult group (≥ 20 years old). In all patient groups, phenylalanine-restricted diet and medical nutrition products were the main options for treatment. The median of the last measured blood phenylalanine concentration (patient-reported) was 290 µmol/L, 425 µmol/L, and 750 µmol/L in the pediatric, adolescent, and adult groups, respectively. The frequency of blood testing for serum phenylalanine level according to the age groups was appropriate in nearly half of the patients. While the majority of the patients have been visiting the metabolism center they have been diagnosed with PKU for control, considerable proportion of the patients would like to change the center or the doctor they visit for control if they could. It was determined that nearly half of the patients had trouble in accessing the metabolism center. Treatment options' being limited and expensive were the major problems. The main requests of the patients and patient relatives included easier access to the metabolism centers and more options for treatment and diet.

CONCLUSIONS

Access to the services should be easier to improve the patients' follow-up and treatment. There is need for low-cost, easily applicable, and accessible nutrition products and effective novel pharmacological agents. Focusing on these issues in health policies by providing pedagogic/psychological support, establishing support programs also comprising the families, and increasing the awareness activities were the key outcomes.

Metabolic control and clinical outcome in adolescents with phenylketonuria

The main neurological, cognitive, and behavioural consequences of phenylketonuria have been eradicated thanks to new-born screening and Phe-restricted diet therapy. However, the effects of high phenylalanine levels during adolescence and adulthood on neurocognitive functions remain a concern. This systematic review aimed at collecting clinical data suggesting the safest metabolic target for early treated PKU during the second decade of life. Twenty studies met the inclusion criteria for full-text review. Relevant studies included papers that (a) examined the relationship between metabolic control and neurocognitive functions during adolescence or (b) investigated the impact of metabolic control in adolescence on adult outcomes. Most studies showed a positive correlation between metabolic control during adolescence and neurocognitive outcomes across ages. This was true both for IQ and executive functions, although data on executive functions were less clear, and it remains to be established whether they are more vulnerable to Phe than IQ. Taken together present evidence confirm brain vulnerability to Phe during adolescence and suggests that low average Phe levels and low Phe fluctuations should be maintained throughout life. While results are fully compatible with current European recommendations, clinical and methodological limitations coupled with remarkable interindividual variability prevented a clear identification of a safe threshold for Phe blood levels during adolescence.

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.

Adult PKU Clinics in the UK-Users' Experiences and Perspectives

Adults with PKU require life-long management, and ideally, their care should be in a specialised adult metabolic clinic. Their outcomes and co-morbidities have received much attention, but data are lacking on their experience, satisfaction and expectations about the care they receive. This survey reports the experiences and care adults with PKU receive from specialist metabolic clinics in the UK. The online survey developed by the UK NSPKU (National Society for Phenylketonuria), was placed on the NSPKU website from February 2021 to December 2022, and was completed by adults with PKU (≥18 years) or their carers/family members. Sixty-five adult PKU patients and 9 caregivers of adult patients completed the questionnaire (63% female in total). Only 32% of respondents were following a Phe-restricted diet with protein substitute intake as prescribed; the rest were partially adherent or not on dietary restrictions. Nineteen per cent (n = 14/74) had not been reviewed in clinic for two years. Half of the respondents (50%) described their experience in adult clinics as "good". Half of the patients were unable to contact their dietitians with questions or concerns, and only 24% considered that they received adequate support. Clinic reviews usually included anthropometric (82%) and dietary assessments (64%), discussion on management of PKU in daily life (78%) and a blood test (71%). Eighty-eight per cent reported they had at least one neurocognitive, mental health or behavioural co-morbidity but less than half of the patients reported an assessment on their neurocognitive functioning or mental health issues. Adult male patients appeared to have less detailed clinic review than females. Less than half (44%) of the respondents reported that they performed a blood spot for blood Phe at least monthly, but only 32% considered they had been informed about the risk of high Phe levels in adulthood. Although time, cost and stress related to travelling were barriers to a face-to-face review, more than 40% of patients had concerns about remote appointments. The frequency and extent of monitoring of adults with PKU, attending specialist adult services, were less than those specified by the PKU European guidelines. The care of women of reproductive age is prioritised over men. Adult metabolic health services require further attention, development and resources to provide a high standard and equitable service to patients with PKU.

Health-related quality of life in a european sample of adults with early-treated classical PKU

BACKGROUND

Phenylketonuria (PKU) is a rare inborn error of metabolism affecting the catabolism of phenylalanine (Phe). To date, findings regarding health-related quality of life (HRQoL) in adults with early-treated classical PKU are discrepant. Moreover, little is known about metabolic, demographic, and cognitive factors associated with HRQoL. Hence, we aimed to investigate HRQoL and its association with demographic, metabolic, and cognitive characteristics in a large European sample of adults with early-treated classical PKU.

RESULTS

This cross-sectional study included 124 adults with early-treated classical PKU from Hungary, Italy, Spain, Switzerland, and Turkey. All participants prospectively completed the PKU quality of life questionnaire (PKU-QoL), a questionnaire specifically designed to evaluate the impact of PKU and its treatment on HRQoL in individuals with PKU. In addition, information about Phe levels (concurrent and past year), demographic (age and sex), and cognitive variables (intelligence quotient, IQ) were collected. Most domains revealed little or no impact of PKU on HRQoL and more than three-quarters of the patients rated their health status as good, very good, or excellent. Nevertheless, some areas of concern for patients were identified. Patients were worried about the guilt that they experience if they do not adhere to the dietary protein restriction and they were most concerned about high Phe levels during pregnancy. Further, tiredness was the most affected symptom, and the supplements' taste was considered a main issue for individuals with PKU. The overall impact of PKU on HRQoL was higher in women (U = 1315.5, p = .012) and in adults with a lower IQ (rs = - 0.448, p = .005). The overall impact of dietary protein restriction was higher in adults with higher concurrent Phe levels (rs = 0.272, p = .007) and higher Phe levels during the past year (rs = 0.280, p = .009).

CONCLUSION

The impact of PKU on most domains assessed in the PKU-QoL was considered to be low. These results likely reflect the successful implementation of the newborn screening resulting in the prevention of severe adverse long-term outcomes. However, a particular clinical focus should be given to patients with lower IQ, higher Phe levels, and women, as these variables were associated with a lower HRQoL.

Expert Consensus on the Long-Term Effectiveness of Medical Nutrition Therapy and Its Impact on the Outcomes of Adults with Phenylketonuria

Many adults with phenylketonuria (PKU) rely on medical nutrition therapy (MNT; low phenylalanine (Phe) diet with protein substitutes/medical foods) to maintain blood Phe concentrations within recommended ranges and prevent PKU-associated comorbidities. Despite disease detection through newborn screening and introduction of MNT as early as birth, adherence to MNT often deteriorates from childhood onwards, complicating the assessment of its effectiveness in the long term. Via a modified Delphi process, consensus (≥70% agreement) was sought on 19 statements among an international, multidisciplinary 13-member expert panel. After three iterative voting rounds, the panel achieved consensus on 17 statements related to the limitations of the long-term effectiveness of MNT (7), the burden of long-term reliance on MNT (4), and its potential long-term detrimental health effects (6). According to the expert panel, the effectiveness of MNT is limited in the long term, is associated with a high treatment burden, and demonstrates that adults with PKU are often unable to achieve metabolic control through dietary management alone, creating an unmet need in the adult PKU population.

Neuropsychiatric Function Improvement in Pediatric Patients with Phenylketonuria

OBJECTIVE

To evaluate effects of sapropterin dihydrochloride on blood phenylalanine (Phe) and symptoms of neuropsychiatric impairment in children and adolescents with phenylketonuria (PKU).

STUDY DESIGN

PKU subjects 8-17 years of age (n = 86) were randomized to double-blind treatment with sapropterin (n = 43) or placebo (n = 43) for 13 weeks, then all received open-label sapropterin therapy for an additional 13 weeks. Blood Phe and symptoms of inattention, hyperactivity/impulsivity (Attention-Deficit/Hyperactivity Disorder Rating Scale IV [ADHD RS-IV]), executive functioning (Behavior Rating Inventory of Executive Function), depression (Hamilton Rating Scale for Depression), and anxiety (Hamilton Rating Scale for Anxiety) were assessed.

RESULTS

Following the 13-week randomization phase, the sapropterin and placebo groups had mean changes in blood Phe of -20.9% and +2.9%, respectively. Corresponding least square mean differences in ADHD RS-IV scores were significantly greater for the sapropterin vs the placebo group: Total (-3.2 points, P = .02), Inattention subscale (-1.8 points, P = .04), and Hyperactivity/Impulsivity subscale (-1.6 points, P = .02). Forest plots favored sapropterin treatment over placebo for all ADHD RS-IV and Behavior Rating Inventory of Executive Function indices. There were no significant differences in reported problems with attention or executive function between the 2 groups at baseline or at week 26 following the 13-week open-label treatment period. Anxiety and depression scores did not differ significantly between cohorts at any time. Sapropterin was well tolerated, with a favorable safety profile.

CONCLUSIONS

Sapropterin reduced blood Phe and was associated with significant improvement in parent-reported symptoms of inattention, hyperactivity/impulsivity, and executive functioning in children and adolescents with PKU.

TRIAL REGISTRATION

ClinicalTrials.gov, NCT01114737. Registered 27 April 2010, https://clinicaltrials.gov/ct2/show/NCT01114737.

Drosophila as a diet discovery tool for treating amino acid disorders

Amino acid disorders (AADs) are a large group of rare inherited conditions that collectively impact one in 6500 live births, often resulting in rapid neurological decline and death during infancy. For several AADs, including phenylketonuria, dietary modification prevents physiological deterioration and ameliorates symptoms. Despite this remarkable potential for treatment success, dietary therapy for most AADs remains largely unexplored. Although animal models have provided novel insights into AAD mechanisms, few have been used for therapeutic diet discovery. Here, we find that of all the animal models, Drosophila is particularly well suited for nutrigenomic disease modelling, having amino acid pathways conserved with humans, exceptional genetic tractability, and the unique availability of a synthetic customisable diet.

The impact of metabolic control on cognition, neurophysiology, and well-being in PKU: A systematic review and meta-analysis of the within-participant literature

Phenylketonuria (PKU) is a metabolic disease where Phenylalanine (Phe) rises much above normal levels. Cross-sectional and correlational studies provide valuable information on the importance of maintaining low blood-Phe to achieve good outcomes, but they may be confounded, at least partially, by differences in participant demographics. Moreover, the effect of Phe at older ages is difficult to ascertain because of strong associations between Phe levels across ages. Within-participant studies avoid confounding issues. We have reviewed these studies. We followed PRISMA guidelines to search the literature for studies reporting the impact of Phe changes within participants. Phe was either increased or decreased through diet relaxation/resumption or through pharmacological interventions. Forty-six separate articles reported, singly or in combination, results on cognition (N = 37), well-being (N = 22) and neurophysiological health (N = 14). For all studies, we established, in a binary way, whether a benefit of lower Phe was or was not demonstrated and compared numbers showing benefit versus a null or negative outcome. We then analyzed whether critical parameters (e.g., length of the study/condition for the change, size of Phe change achieved) influenced presence or absence of benefit. For a subset of studies that reported quantitative cognitive outcomes, we carried out a meta-analysis to estimate the size of change in cognitive performance associated with a change in Phe and its significance. There were significantly more studies with benefits than no benefits, both for cognitive and well-being outcomes, and a trend in this direction for neurophysiological outcomes. The meta-analysis showed a highly significant effect size both overall (0.55) and when studies with adults/adolescents were considered separately (0.57). There was some indication that benefits were easier to demonstrate when differences in Phe were larger and achieved across a longer period, but these effects were not always consistent. These results reinforce results from the literature by demonstrating the importance of lower Phe in children as well as in adolescents and adults, even when confounding factors in group composition are eliminated. The field would benefit from further studies where Phe levels are contrasted within-participants to ascertain how much Phe needs to be changed and for how long to see a difference and which measures demonstrate a difference (e.g., which cognitive tasks).

Neurocognitive outcome and mental health in children with tyrosinemia type 1 and phenylketonuria: A comparison between two genetic disorders affecting the same metabolic pathway

Tyrosinemia type 1 (TT1) and phenylketonuria (PKU) are both inborn errors of phenylalanine-tyrosine metabolism. Neurocognitive and behavioral outcomes have always featured in PKU research but received less attention in TT1 research. This study aimed to investigate and compare neurocognitive, behavioral, and social outcomes of treated TT1 and PKU patients. We included 33 TT1 patients (mean age 11.24 years; 16 male), 31 PKU patients (mean age 10.84; 14 male), and 58 age- and gender-matched healthy controls (mean age 10.82 years; 29 male). IQ (Wechsler-subtests), executive functioning (the Behavioral Rating Inventory of Executive Functioning), mental health (the Achenbach-scales), and social functioning (the Social Skills Rating System) were assessed. Results of TT1 patients, PKU patients, and healthy controls were compared using Kruskal-Wallis tests with post-hoc Mann-Whitney U tests. TT1 patients showed a lower IQ and poorer executive functioning, mental health, and social functioning compared to healthy controls and PKU patients. PKU patients did not differ from healthy controls regarding these outcome measures. Relatively poor outcomes for TT1 patients were particularly evident for verbal IQ, BRIEF dimensions "working memory", "plan and organize" and "monitor", ASEBA dimensions "social problems" and "attention problems", and for the SSRS "assertiveness" scale (all p values <0.001). To conclude, TT1 patients showed cognitive impairments on all domains studied, and appeared to be significantly more affected than PKU patients. More attention should be paid to investigating and monitoring neurocognitive outcome in TT1 and research should focus on explaining the underlying pathophysiological mechanism.

Metabolic control during the neonatal period in phenylketonuria: associations with childhood IQ

BACKGROUND

In phenylketonuria, treatment and subsequent lowering of phenylalanine levels usually occur within the first month of life. This study investigated whether different indicators of metabolic control during the neonatal period were associated with IQ during late childhood/early adolescence.

METHODS

Overall phenylalanine concentration during the first month of life (total "area under the curve"), proportion of phenylalanine concentrations above upper target level (360 μmol/L) and proportion below lower target level (120 μmol/L) during this period, diagnostic phenylalanine levels, number of days until phenylalanine levels were <360 μmol/L, and lifetime and concurrent phenylalanine levels were correlated with IQ scores of 64 PKU patients (mean age 10.8 years, SD 2.9).

RESULTS

Overall phenylalanine concentration and proportion of phenylalanine concentrations >360 μmol/L during the first month of life negatively correlated with IQ in late childhood/early adolescence. Separately, phenylalanine concentrations during different periods within the first month of life (0-10 days, 11-20 days, 21-30 days) were negatively correlated with later IQ as well, but correlation strengths did not differ significantly. No further significant associations were found.

CONCLUSIONS

In phenylketonuria, achievement of target-range phenylalanine levels during the neonatal period is important for cognition later in life, also when compared to other indicators of metabolic control.

IMPACT

In phenylketonuria, it remains unclear during which age periods or developmental stages metabolic control is most important for later cognitive outcomes. Phenylalanine levels during the neonatal period were clearly and negatively related to later IQ, whereas no significant associations were observed for other indices of metabolic control. This emphasizes the relative importance of this period for cognitive development in phenylketonuria. No further distinctions were observed in strength of associations with later IQ between different indicators of metabolic control during the neonatal period. Thus, achievement of good metabolic control within 1 month after birth appears "safe" with respect to later cognitive outcomes.

A non-interventional observational study to identify and validate clinical outcome assessments for adults with phenylketonuria for use in clinical trials

Introduction

Current clinical outcome assessments (COAs) are not effectively capturing the complex array of symptoms of adults with phenylketonuria (PKU). This study aimed to identify concepts of interest relevant to adults with PKU. Based on these concepts, COAs for patient-reported outcomes (PROs), observer-reported outcomes (ObsROs), and clinician-reported outcomes (ClinROs) were selected or developed and content validity was assessed.

Materials and methods

Concept-elicitation interviews were conducted with an international cohort of adults with PKU (n = 30), family member observers (n = 14), and clinical experts (n = 8). Observers and clinical experts were included to overcome the risk of lack of self-awareness among adults with PKU. The concepts of interests endorsed by ≥30% of patients, observers, and/or clinical experts were selected, mapped to items in existing COAs, and used to develop global impression items for patients, observers, and clinicians. Next, the content validity of the COAs and global impression items was evaluated by cognitive interviews with patients (n = 22), observers (n = 11), and clinical experts (n = 8). All patients were categorized according to blood phenylalanine (Phe) levels (i.e., <600 μmol/L, 600–1200 μmol/L, and >1200 μmol/L).

Results

Concepts of interests were identified across four domains: emotional, cognitive, physical, and behavioral. After mapping, eight existing COAs were selected based on the concept coverage (six PROs, one ObsRO, and one ClinRO). The six PRO measures were considered as potentially fit-for-purpose. The ObsRO measure was not deemed relevant for use in observers of adults with PKU and only a subscale of the ClinRO measure was considered valid for assessing adults with PKU by clinicians. Due to the lack of existing COAs covering all concepts of interests, global impression items for symptom severity and change in symptoms were developed, which were limited to one question covering in total 14 concepts. Upon validation, some of the patient and observer global impression items were excluded as they were subject to lack of insight or could not be reported by observers. Due to the limited interaction time between clinician and patient, use of the clinician global impression items was not supported.

Conclusion

Existing COAs relevant to adults with PKU were selected and PKU-specific global impression items were developed by mapping the most frequently identified concepts of interests from internationally-conducted in-depth interviews. Future studies should address the appropriateness of the selected COAs and global impression items to assess if these can be used as efficacy endpoints in PKU clinical trials.

Natural history of children and adults with phenylketonuria in the NBS-PKU Connect registry

PURPOSE

Phenylalanine hydroxylase deficiency, or phenylketonuria (PKU), is a rare autosomal recessive metabolic disorder. Early diagnosis via newborn screening (NBS) and initiation of treatment prevent the development of cognitive impairment and other co-morbidities. The purpose of this study is to describe the natural history of PKU in the United States, including prevalence of co-morbidities and predictors of outcomes.

METHODS

We analyzed data from a self-report survey in the NBS-PKU Connect online registry. We describe the participants' nutrition management strategies, barriers to management, outcomes of bone disorders, skin, and psychological co-morbidities, and the use of special education or other special services. Predictors of outcomes were identified and assessed, including the impact of sex, age, age at diagnosis, blood phenylalanine concentration, use of sapropterin, use of medical food, adherence to prescribed diet, use of low protein modified foods, whether they had ever been off-diet, and use of tyrosine supplementation.

RESULTS

The 219 respondents included individuals with PKU or hyperphenylalanemia (n = 78), or their caregivers (n = 141). Most (84.3%) started treatment before the age of two weeks. About one-third indicated that they had been off-diet at some point in their lives, and 81.4% reported that they currently adhered to their prescribed diet, with adherence to prescribed diet decreasing with age. Blood phenylalanine concentration was under the recommended threshold of 360 μmol/L for 68.5% of participants. One-quarter of respondents reported psychological co-morbidities, with anxiety and ADD/ADHD being the most common. The incidence of psychological co-morbidities increased with age and with ever having been off diet. Special education or other special services were more likely to be reported by individuals who were diagnosed after one week of age. Skin disorders such as acne and eczema were more common in females than males, and a minority of participants reported bone disorders.

CONCLUSIONS

Despite recommendations to maintain blood phenylalanine concentrations in the therapeutic range throughout life, it is not uncommon for adults with PKU to discontinue dietary management of their disorder. Early diagnosis was associated with reduced need for special education or other special services, and continuous treatment was associated with decreased psychological co-morbidities.

Effects of Internet Language Related to COVID-19 on Mental Health in College Students: The Mediating Effect of Cognitive Flexibility

During the COVID-19 pandemic, Internet language (INL) has influenced daily life extensively. However, the process by which INL influences people's psychology and behavior is unclear. This study explored the effects of INL on mental health (anxiety and depression). A pilot study was conducted to develop a qualified scale for INL related to COVID-19 (CINL) in college students using an online questionnaire. The CINL scale was found to have two dimensions: frequency and comprehension, as well as good reliability and validity. A formal study explored the mediating effect of cognitive flexibility on the relationship between CINL and mental health. The results showed that CINL positively predicted mental health when it was mediated by cognitive flexibility. These results not only provide a new perspective on understanding the effects of cyber behavior on human mental health from a positive perspective, but also provide practitioners with new insights for interventions on college students' mental health.

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.

Patient's thoughts and expectations about centres of expertise for PKU

BACKGROUND

In the Netherlands (NL) the government assigned 2 hospitals as centres of expertise (CE) for Phenylketonuria (PKU), while in the United Kingdom (UK) and Germany no centres are assigned specifically as PKU CE's.

METHODS

To identify expectations of patients/caregivers with PKU of CEs, a web-based survey was distributed through the national Phenylketonuria societies of Germany, NL and UK.

RESULTS

In total, 105 responded (43 patients, 56 parents, 4 grandparents, 2 other) of whom 59 were from NL, 33 from UK and 13 from Germany. All participants (n = 105) agreed that patients and/or practitioners would benefit from CEs. The frequency patients would want to visit a CE, when not treated in a CE (n = 83) varied: every hospital visit (24%, n = 20), annual or bi-annual (45%, n = 37), at defined patient ages (6%, n = 5), one visit only (22%, n = 18), or never (4%, n = 3). Distance was reported as a major barrier (42%, n = 35). 78% (n = 65) expected CE physicians and dieticians to have a higher level of knowledge than in non-CE centres. For participants already treated in a CE (n = 68), 66% requested a more extensive annual or bi-annual review. In general, psychology review and neuropsychologist assessment were identified as necessary by approximately half of the 105 participants. In addition, 66% (n = 68) expected a strong collaboration with patient associations.

CONCLUSION

In this small study, most participants expected that assigning CEs will change the structure of and delivery of Phenylketonuria care.

The PKU & ME study: A qualitative exploration, through co-creative sessions, of attitudes and experience of the disease among adults with phenylketonuria in Italy

Background

Phenylketonuria (PKU) is a hereditary metabolic disease that can be diagnosed and successfully treated from birth with a lifelong phenylalanine-restricted dietary regimen. However, optimal adherence to diet remains an issue and often progressively decreases after adolescence. The study aimed to explore the experience of adults living with PKU in order to gain insights related to their adherence to diet and engagement in managing their condition.

Methods

The study adopted a qualitative methodology in sessions that combined specifically designed co-creation exercises with focus group discussion. Adults with early-treated classic PKU were enrolled for 2 different sessions - one for adherent and one for non-adherent patients. The verbatim notes of both sessions and focus group were analyzed using content analysis.

Results

Twelve adherent and nine non-adherent adults with PKU participated. Besides the behavioral dictates of following a strict diet, adherent adults reported a positive mental approach and organizational rigor; they seemed aware of the consequences of high-phenylalanine levels, reporting that it can affect mood and consequently social interactions which they value highly. In the non-adherent group, the individuals seemed to not fully accept their disease: they were aware of the consequences of non-adherence in children but not in adults, they felt the management of PKU was an individual burden and they experienced a feeling of 'diversity' in the social context (related to eating) that caused emotional distress. PKU seemed a very influential element of the identity both for adherent and non-adherent adults, but with different consequences for the two groups. Finally, all participants reported the desire to be assisted in a healthcare setting dedicated to adults.

Conclusions

The findings expand the understanding of the psychological experience of adult patients with PKU in relation to their disease and its dietary requirements, highlighting specific factors that might drive tailored educational or psychological intervention to improve adherence and engagement in the care process.

Impact of phenylalanine on cognitive, cerebral, and neurometabolic parameters in adult patients with phenylketonuria (the PICO study): a randomized, placebo-controlled, crossover, noninferiority trial

Background

The population of adult patients with early-treated phenylketonuria (PKU) following newborn screening is growing substantially. The ideal target range of blood phenylalanine (Phe) levels in adults outside pregnancy is a matter of debate. Therefore, prospective intervention studies are needed to evaluate the effects of an elevated Phe concentration on cognition and structural, functional, and neurometabolic parameters of the brain.

Methods

The PICO (Phenylalanine and Its Impact on Cognition) Study evaluates the effect of a 4-week Phe load on cognition and cerebral parameters in adults with early-treated PKU in a double-blind, randomized, placebo-controlled, crossover, noninferiority trial.

Participants

Thirty adult patients with early-treated PKU and 30 healthy controls comparable to patients with regard to age, sex, and educational level will be recruited from the University Hospitals Bern and Zurich, Switzerland. Patients are eligible for the study if they are 18 years of age or older and had PKU diagnosed after a positive newborn screening and were treated with a Phe-restricted diet starting within the first 30 days of life.

Intervention: The cross-over intervention consists of 4-week oral Phe or placebo administration in patients with PKU. The study design mimics a Phe-restricted and a Phe-unrestricted diet using a double-blinded, placebo-controlled approach.

Objectives

The primary objective of the PICO Study is to prospectively assess whether a temporarily elevated Phe level influences cognitive performance (working memory assessed with a n-back task) in adults with early-treated PKU. As a secondary objective, the PICO Study will elucidate the cerebral (fMRI, neural activation during a n-back task; rsfMRI, functional connectivity at rest; DTI, white matter integrity; and ASL, cerebral blood flow) and neurometabolic mechanisms (cerebral Phe level) that accompany changes in Phe concentration. Cognition, and structural and functional parameters of the brain of adult patients with early-treated PKU will be cross-sectionally compared to healthy controls. All assessments will take place at the University Hospital Bern, Switzerland.

Randomization

Central randomization will be used to assign participants to the different treatment arms with age, sex, and center serving as the stratification factors. Randomization lists will be generated by an independent statistician.

Blinding: All trial personnel other than the statistician generating the randomization list and the personnel at the facility preparing the interventional product are blinded to the assigned treatment.

Discussion

Using a combination of neuropsychological and neuroimaging data, the PICO Study will considerably contribute to improve the currently insufficient level of evidence on how adult patients with early-treated PKU should be managed.

Trial registration

The study is registered at clinicaltrials.gov (NCT03788343) on the 27th of December 2018, at kofam.ch (SNCTP000003117) on the 17th of December 2018, and on the International Clinical Trials Registry Platform of the WHO.

Neurological manifestations in adults with phenylketonuria: new cases and review of the literature

OBJECTIVE

Phenylketonuria (PKU) is a rare autosomal recessive disease characterised by high plasma phenylalanine levels inducing, if untreated, serious neurological manifestations in children but also, rarely, in adults who stopped their diet. The objective of the study was to describe the neurological manifestations observed in adults with PKU.

METHODS

We analysed cases reported in French reference centres for inborn errors of metabolism and cases already reported in the literature.

RESULTS

We report 8 new cases of neurological manifestations and 22 cases in the literature, which occurred in adult PKU patients, associated with chronic or rapid increase of phenylalanine levels, mostly when strict low-phenylalanine diet was stopped early in life. Neurological symptoms consisted in cerebellar ataxia, tremor, brisk reflexes, visual loss, sensory manifestations, and/or headaches. Visual loss was more frequent in the new cases (4/8) of the present series than in the literature (4/22). These neurological complications were associated with leucopathy on brain magnetic resonance imaging (27/29). The start of a low-phenylalanine diet improved or fully reversed neurological manifestations, even in patients with late diagnosis during adulthood.

CONCLUSION

Neurological manifestations can complicate PKU in adult patients with elevated phenylalanine levels, after long or short period of diet discontinuation. Neurologists should be aware of this diagnosis, and measure phenylalaninemia in case of neurological symptoms associated with non-specific leucopathy on brain MRI. PKU patients should be systematically encouraged to continue their diet and their medical follow-up to avoid neurological complications.

Prescribing issues experienced by people living with phenylketonuria in the UK

Background

Foods for Special Medical purposes (Phe-free protein substitutes [PS] and low protein foods [LPFs]) are central to successful dietary management of patients with phenylketonuria (PKU). In the UK, PS and LPFs are prescribed by primary care general practitioners (GPs) and dispensed by high street pharmacists or via home delivery companies. As patients and carers commonly reported access issues with PS and LPFs through the National Society for PKU (NSPKU) helpline, the NSPKU collected more information about the extent of prescriptions issues via a questionnaire.

Methods

A cross sectional online survey was carried out consisting of 7 multiple choice and 3 open questions. The questionnaire was available via the NSPKU website over a 9-month period (15th May 2018–31st January 2019). Carers or patients with PKU were invited to participate if they had any problems accessing PS and LPF.

Results

There were 252 responses. 65% for children and 35% for adults, aged ≥18y with PKU. 59% (n = 146/246) of responses described difficulties accessing basic LPF (bread, pasta) and 33% (n = 81/248) PS. 36% (n = 88/248) said problems had re-occurred >1y, and 40% (n = 99/248) for <3 months. 59% (n = 146/246) had supply issues with LPF and 33% (n = 81/246) with PS. 18% (n = 42/234) reported that the local NHS authority had refused, restricted or had a policy to block treatment access; 27% (n = 63/234) cited GPs declining requests or restricting prescription amounts. 21% (n = 49/234) could not access all their products via a pharmacy, 40% (n = 93/234) said their home delivery system failed, and 15% (n = 34/234) of the dispensed prescribed products were out of date, incorrect, damaged or poor quality. For patients and carers these issues caused: stress (87%, n = 210/241); they considered PKU was not taken seriously by professionals (66%, n = 160/241); they reduced patient access to LPF and PS (53%, n = 128/241); and affected the patients' health (53%, n = 128/241).

Discussion

Access to PKU dietary treatment is frequently disrupted for reasons relating to GP prescriptions and unreliable dispensing and delivery practices. These issues require immediate attention by UK health professionals in order to create a fairer and more efficient system for everyone.

Predictability and inconsistencies of cognitive outcome in patients with phenylketonuria and personalised therapy: the challenge for the future guidelines

Phenylketonuria (PKU) is a prototypical model of a neurodevelopmental metabolic disease that follows a cascade of pathological events affecting brain maturation and functioning. Neonatal screening and early treatment have eradicated the classical PKU phenotype in patients with early and continuously treated phenylketonuria (ECTPKU). However, effort is required to optimise the treatment of the disease to minimise the risk of lifelong neurological, cognitive and behavioural impairment, and to solve issues on the variability in clinical outcome that are rather not understood and has yet hampered a more personalised approach to its treatment. The aim of the present review is to focus on the inconsistencies in the clinical outcome of adult patients with ECTPKU unexplained by the biochemical markers adopted for the monitoring of the disease to date. The interindividual variability of clinical outcome in late as well as in early treated patients under similar biochemical control suggests the existence of disease-independent determinants influencing the individual vulnerability to the neurotoxic effect of phenylalanine. This is further supported by the low predictive power of blood phenylalanine on the clinical outcome from the second decade of life onwards. In conclusion, individual vulnerability to the metabolic alterations of PKU contributes to the prognosis of PKU, also in patients with ECTPKU. The biological factors constitutive of this vulnerability are unknown (but have not been the object of many studies so far) and should be the target of further research as prerequisite for a personalised treatment aimed at avoiding burden and costs of overtreatment and clinical consequences and risks of undertreatment in patients with PKU.

White and gray matter brain development in children and young adults with phenylketonuria

Phenylketonuria (PKU) is a recessive disorder characterized by disruption in the metabolism of the amino acid phenylalanine (Phe). Prior research indicates that individuals with PKU have substantial white matter (WM) compromise. Much less is known about gray matter (GM) in PKU, but a small body of research suggests volumetric differences compared to controls. To date, developmental trajectories of GM structure in individuals with PKU have not been examined, nor have trajectories of WM and GM been examined within a single study. To address this gap in the literature, we compared longitudinal brain development over a three-year period in individuals with PKU (n = 35; 18 male) and typically-developing controls (n = 71; 35 male) aged 7–21 years. Using diffusion tensor imaging (DTI) and structural magnetic resonance imaging (MRI), we observed whole-brain and regional WM differences between individuals with PKU and controls, which were often exacerbated with increasing age. In marked contrast with trajectories of WM development, trajectories of GM development did not differ between individuals with PKU and controls, indicating that neuropathology in PKU is more prominent in WM than GM. Within individuals with PKU, mediation analyses revealed that whole-brain mean diffusivity (MD) and regional MD in the corpus callosum and centrum semiovale mediated the relationship between dietary treatment compliance (i.e., Phe control) and executive abilities, suggesting a plausible neurobiological mechanism by which Phe control may influence cognitive outcomes. Our findings clarify the specificity, timing, and cognitive consequences of whole-brain and regional WM pathology, with implications for treatment and research in PKU.

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Individuals with PKU exhibited widespread, age-related white matter compromise.

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Developmental trajectories of gray matter were comparable for PKU and controls.

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Within PKU, white matter compromise influenced cognitive outcomes.

The neurological and psychological phenotype of adult patients with early-treated phenylketonuria: A systematic review

Newborn screening for phenylketonuria (PKU) and early introduction of dietary therapy has been remarkably successful in preventing the severe neurological features of PKU, including mental retardation and epilepsy. However, concerns remain that long-term outcome is still suboptimal, particularly in adult patients who are no longer on strict phenylalanine-restricted diets. With our systematic literature review we aimed to describe the neurological phenotype of adults with early-treated phenylketonuria (ETPKU). The literature search covered the period from 1 January 1990 up to 16 April 2018, using the NLM MEDLINE controlled vocabulary. Of the 643 records initially identified, 83 were included in the analysis. The most commonly reported neurological signs were tremor and hyperreflexia. The overall quality of life (QoL) of ETPKU adults was good or comparable to control populations, and there was no evidence for a significant incidence of psychiatric disease or social difficulties. Neuroimaging revealed that brain abnormalities are present in ETPKU adults, but their clinical significance remains unclear. Generally, intelligence quotient (IQ) appears normal but specific deficits in neuropsychological and social functioning were reported in early-treated adults compared with healthy individuals. However, accurately defining the prevalence of these deficits is complicated by the lack of standardized neuropsychological tests. Future research should employ standardized neurological, neuropsychological, and neuroimaging protocols, and consider other techniques such as advanced imaging analyses and the recently validated PKU-specific QoL questionnaire, to precisely define the nature of the impairments within the adult ETPKU population and how these relate to metabolic control throughout life.

The influence of blood phenylalanine levels on neurocognitive function in adult PKU patients

It is well known that hyperphenylalaninemia caused by phenylketonuria (PKU) negatively influences cognitive performance. Several tests have been used to study these functions. Until now, no universal, optimal tool has been developed for detecting PKU-caused brain dysfunctions. Using computerized neuropsychological tests during daily routine would be helpful for screening subclinical brain deficits in adult PKU patients. In a monocentric, cross-sectional study, adult patients with PKU (n = 46; median age = 29.5 years; female/male ratio = 21/25) were tested with the computerized Cambridge Cognition (CANTAB) test measuring neurocognitive functions. Patients were divided into two groups: The "on diet" group included patients whose blood Phe-level was under 600 μmol/l (n = 20), and the "loose diet" group included patients whose blood Phe-level was above 600 μmol/l (n = 26) at the examination time. The results of the PKU-affected individuals were compared with a healthy control group (n = 31; median age = 25 years; female/male ratio = 11/20). Compared with the control group, PKU patients had significantly worse test results in memory, problem-solving skills, and strategy. However, there were no significant differences in response speed or initial thinking time. There was no correlation between the blood Phe-level, tyrosine (Tyr)-level or Phe/Tyr ratio and the different cognitive test results. There were no significant differences in test results between the two PKU subgroups. Several cognitive functions measured by CANTAB are negatively influenced by hyperphenylalaninemia in adult PKU patients. However, response speed and initial thinking time were not impaired as seriously as other functions. Patients with lower Phe-levels failed to achieve better test results than patients whose Phe-levels were notably elevated.

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.

A systematic review of cognitive functioning in early treated adults with phenylketonuria

BACKGROUND

Even though early dietary management of phenylketonuria (PKU) successfully prevents severe neurological impairments, deficits in cognitive functioning are still observed. These deficits are believed to be the result of elevated levels of phenylalanine throughout life. Research on cognitive functioning in adults with PKU (AwPKU) often focuses on domains shown to be compromised in children with PKU, such as attention and executive functions, whereas other cognitive domains have received less attention. This systematic review aimed to provide an overview of cognitive functioning across domains examined in early treated (ET) AwPKU.

METHODS

A systematic search was performed in Ovid MEDLINE(R), PsycINFO, Web of Science, Cochrane, Scopus, Embase, ScienceDirect, and PubMed for observational studies on cognitive performance in ET AwPKU.

RESULTS

Twenty-two peer-reviewed publications, reporting on outcomes from 16 studies were reviewed. Collectively, the results most consistently showed deficits in vigilance, working memory and motor skills. Deficits in other cognitive domains were less consistently observed or were understudied. Furthermore, despite reports of several associations between cognitive performance and phenylalanine (Phe) levels throughout life the relationship remains unclear. Inconsistencies in findings across studies could be explained by the highly heterogeneous nature of study samples, resulting in large inter- and intra-variability in Phe levels, as well as the use of a variety of tests across cognitive domains, which differ in sensitivity. The long-term cognitive outcomes of early and continuous management of PKU remain unclear.

CONCLUSIONS

To better understand the development of cognitive deficits in ET AwPKU, future research would benefit from 1) (inter)national multicentre-studies; 2) more homogeneous study samples; 3) the inclusion of other nutritional measures that might influence cognitive functioning (e.g. Phe fluctuations, Phe:Tyrosine ratio and micronutrients such as vitamin B12); and 4) careful selection of appropriate cognitive tests.

Clinical and neuropsychological outcomes for children with phenylketonuria in Upper Egypt; a single-center study over 5 years

BACKGROUND

Phenylketonuria (PKU) is considered to be a rare inborn error of metabolism but one of the commonest causes of mental retardation if untreated.

OBJECTIVES

The present study was done to characterize the clinical patterns of PKU and analyze various neuropsychiatric outcomes in PKU children in Sohag Province, Egypt.

PATIENTS AND METHODS

A prospective cohort study was conducted on 113 PKU patients, diagnosed during the period from 2012 to 2017, at the Pediatric Neurology Clinic of Sohag University Hospital, Upper Egypt. One hundred and ten cases were diagnosed based on clinical suspicion combined with laboratory confirmation by measuring their plasma phenylalanine levels using amino acid analyzer, while 3 cases were detected during neonatal screening. With the exception of the 3 cases detected during neonatal screening, all patients were clinically diagnosed and treated late. Psychometric evaluations of PKU patients were done using intelligence quotient (IQ, Stanford- Binet V), Childhood Autism Rating Scale, and Children's Attention and Adjustment Survey. Dietetic management was applied. The results of neuroimaging (computed tomography or magnetic resonance imaging of the brain) and electroencephalography were included when available.

RESULTS

The overall results showed that 15.9% had hyperphenylalaninemia, 35.4% had mild to moderate PKU, and classic PKU was diagnosed in 48.7%. Global developmental delay (54.9%) and delayed language (29.2%) were the most frequent presentations. Moderately impaired or delayed overall IQ was present in 77%. While, 83.2% had moderately impaired or delayed verbal IQ, autism was diagnosed in 50.4%. Super average and average probability of attention-deficit hyperactivity disorder was diagnosed in 88.5%. Abnormal neuroimaging (white matter abnormalities and brain atrophy) was the most important significant predictor for poor language and motor developmental outcome (P<0.05).

CONCLUSION

PKU children had variable neuropsychological outcomes, mainly attention-deficit hyperactivity disorder and impaired verbal IQ, both of which were not related to the initial phenylalanine levels or to duration of dietary therapy, but were significantly related to early dietary intervention.