Overweight/obesity in adolescents with phenylketonuria: protective and predisposing factors

Hormonal Crossroads in Inborn Errors of the Metabolism Impact of Puberty and Dietary Interventions on Metabolic Health

Background/Objectives: Inborn errors of metabolism (IEMs) represent a diverse group of genetic disorders characterized by enzymatic defects that disrupt metabolic pathways, leading to toxic metabolite accumulation, deficits, or impaired macromolecule synthesis. While strict dietary interventions are critical for managing many of these conditions, hormonal and metabolic changes during puberty introduce new challenges. Advancements in early diagnosis and treatment have significantly extended the lifespan of individuals with IEMs. However, this increased longevity is associated with heightened risks of new medical problems, including obesity, insulin resistance, and type 2 diabetes mellitus (T2DM), as these complications share mechanistic features with those seen in obesity and T2DM. Methods: This mini-review examines current knowledge of the intricate interplay between pubertal hormones and metabolic pathways in IEM patients. Results: We address critical questions, such as if puberty intensifies the risk of metabolic derangements in these individuals and if there is a metabolic intersection where these disorders converge, leading to shared complications. We highlight the impact of puberty-induced hormonal fluctuations, such as growth hormone (GH) surges and sex steroid activity, on disorders like phenylketonuria, urea cycle defects, and fatty acid oxidation disorders. Moreover, we explore the role of dietary interventions in mitigating or exacerbating these effects, emphasizing the importance of balancing nutritional needs during growth spurts. Conclusions: A multidisciplinary approach integrating endocrinology, nutrition, and emerging therapies is advocated to optimize metabolic health during puberty. Addressing these challenges is critical for improving long-term outcomes for individuals with IEMs, particularly during this pivotal developmental phase.

Executive Functions and Long-Term Metabolic Control in Adults with Phenylketonuria (PKU)

Background/Objectives: Phenylketonuria (PKU) is a rare inherited metabolic disorder caused by phenylalanine hydroxylase deficiency, resulting in highly elevated blood phenylalanine (Phe) concentrations, leading to neurotoxic effects. Despite advancements in treatment, adult patients with PKU may experience impairments in executive functions (EFs). This study investigates the influence of metabolic control across different life stages on EFs and sociodemographic outcomes in adult PKU. Methods: We conducted a monocentric study with 36 early-diagnosed and treated PKU patients (mean age: 34.8 years). EFs were assessed using the Test Battery for Attentional Performance (TAP) and the Tower of London (TL-D). Metabolic data were extracted from medical records, focusing on childhood and adulthood metabolic control, including Phe fluctuations. Sociodemographic data were collected via questionnaires. Statistical analyses explored relationships between EFs, metabolic control, and sociodemographic data. Results: EFs in the cohort were within the lower average range. Significant negative correlations could be observed between EF performance and dried blood Phe concentrations during childhood (ages 0-10 years) as well as current Phe concentrations and Phe variation. Elevated childhood Phe concentrations were associated with lower educational attainment. Sociodemographic characteristics, such as employment status and living arrangements, aligned with those of the general population. Conclusions: Optimal cognitive development in PKU requires good metabolic control, particularly in early childhood. In adulthood, while dietary restrictions may be relaxed, maintaining low and stable Phe concentrations is crucial for EFs. Consistent monitoring and tailored therapeutic approaches throughout life seem essential for optimizing metabolic and neurocognitive outcome in PKU.

Evaluating Therapy and Growth in Children with Phenylketonuria: A Retrospective Longitudinal Study from Two Romanian Centers

Background and Objectives: Phenylketonuria (PKU) is a rare genetic disorder characterized by the inability to convert the essential amino acid phenylalanine into tyrosine. Early dietary treatment can successfully prevent complications, but controversies still exist regarding the attainment of normal growth in these patients. Materials and Methods: Eighteen patients with PKU from two Romanian reference centers were compared to eighteen non-PKU controls, matched for age and gender. The comparisons used weight-for-height, weight-for-age, height/length-for-age, and body mass index-for-age z-scores from birth to three years of age. Results: The PKU study group consisted of nine boys and nine girls, with a median follow-up period of thirty-six months (interquartile range = 9.75). While median values of all four growth metrics remained within the normal range across the entire study period, weight-for-age z-scores were significantly lower in PKU patients throughout most of the study (p < 0.001). Conclusions: The persistent lower weight-for-age z-scores of the PKU patients compared to controls indicate that ongoing monitoring and potential adjustments in dietary therapy may be necessary to further optimize growth outcomes.

Dietary intake in individuals with phenylketonuria: an integrative review

Introduction

Introduction: the dietary intake of individuals with phenylketonuria (PKU) may vary widely according to different cultural eating habits, lifestyle, access to multidisciplinary team, and metabolic formulas available. Thus, knowing the dietary intake of this population makes it possible to tailor nutritional treatment strategies to impact their health. Objective: to analyze the evidence on the dietary intake of individuals with PKU. Methods: an integrative literature review was conducted on the dietary intake of individuals with PKU in the databases PUBMED, BIREME and Science Direct. Original articles that addressed the energy and macronutrient food intake of children, adolescents and/or adults with PKU were included in the study, without time restriction, in any language. A total of 384 articles were found and 27 articles were selected and analyzed. Results: evidence about the nutritional composition of their diet showed that individuals with PKU consume between 1160-2721 kcal of energy -7.2-17.4 % (32.4-76.9 g) of energy as protein, 45.9-69.2 % of energy as carbohydrates, 16.6-39 % of energy as lipids- and between 7.6 and 20 g of fiber. Conclusion: most individuals with PKU have low energy, protein and fiber intake, adequate lipid intake, and high carbohydrate intake. Metabolic control of the disease is still a challenge in all countries. Nutritional strategies to improve dietary nutritional composition and phenylalanine blood levels in individuals with PKU remain an urgent issue.

Body Composition Evaluation and Clinical Markers of Cardiometabolic Risk in Patients with Phenylketonuria

Cardiovascular diseases are the main cause of mortality worldwide. Patients with phenylketonuria (PKU) may be at increased cardiovascular risk. This review provides an overview of clinical and metabolic cardiovascular risk factors, explores the connections between body composition (including fat mass and ectopic fat) and cardiovascular risk, and examines various methods for evaluating body composition. It particularly focuses on nutritional ultrasound, given its emerging availability and practical utility in clinical settings. Possible causes of increased cardiometabolic risk in PKU are also explored, including an increased intake of carbohydrates, chronic exposure to amino acids, and characteristics of microbiota. It is important to evaluate cardiovascular risk factors and body composition in patients with PKU. We suggest systematic monitoring of body composition to develop nutritional management and hydration strategies to optimize performance within the limits of nutritional therapy.

Low bone mineralization in phenylketonuria may be due to undiagnosed metabolic acidosis

Background

Dietary intervention is to date the mainstay treatment to prevent toxic phenylalanine (Phe) accumulation in PKU patients. Despite success preventing central nervous system damage, there is increasing evidence of possible other unfavorable outcomes affecting other systems, e.g. kidney and bone; underlying mechanisms are yet to be fully elucidated.

Methods

This observational, cross-sectional and descriptive study investigated 20 adult with PKU evaluating biochemical parameters, BMD measurements and extrapolating data from 3-days food records and protein substitutes (PS) and special low protein foods (SLPF) composition.

Results

Blood gas venous analysis (VBG) indices were indicative of metabolic acidosis in 60% of PKU patients and VBG pH significantly correlated with BMD's Z-score (p-value = 0.022) even if its overall mean was in range (-1.29). Low bone mineral density for chronological age (Z-score < - 2.0) was found in 4 patients (20%). Indices of kidney function were not impaired. All used PS had a moderate excess of acidity, while SLPF were alkalizing and type/variety of consumed vegetables did not determine significant changes in acid-base equilibrium. Total intakes of potassium and magnesium were lower than expected.

Discussion

PKU patients seem to be at risk of metabolic acidosis, directly linked to possible low bone mineralization. This may be related to the acidic composition of PS, potentially capable of acidifying the entire diet. Reported low intakes of potassium and magnesium may be relevant to these observations. Further studies are needed to better address these topics.

The correlation of lipid profile and waist circumference with phenylalanine levels in adult patients with classical phenylketonuria

INTRODUCTION AND OBJECTIVES

Some studies have pointed to a relationship between Phenyketonuria (PKU) and an increased cardiovascular risk (CVR). This study aimed to evaluate the influence of metabolic control on classical CVR factors in adult patients with PKU.

MATERIAL AND METHODS

It was a cross-sectional study conducted in patients older than 18 years with a diagnosis of classical PKU and under strict dietary control. Demographic, epidemiological and laboratory variables related to CVR were collected. The variables of metabolic control were some parameters related to phenylalanine (Phe) plasma levels.

RESULTS

A total of 47 patients were included with a mean age of 36±10 years of which 30 (64%) were women. Multivariate analysis revealed that range Phe (B=-2.211, P=0.044, 95%CI: -4.354-(-0.068)) levels were within the model for triglyceride concentrations, while minimum (B=-2.803, P=0.051, 95%CI: -5.612-0.007) and range (B=-1.515, P=0.039, 95%CI: -2.945-(-0.084)) Phe levels were within the model for high-density lipoprotein cholesterol concentrations. Median Phe levels showed a stronger correlation with waist circumference (WC) (B=1.216, P=0.002, 95%CI: 0.462-1.969) than with body mass index (B=0.355, P=0.052, 95%CI: -0.004-0.714).

CONCLUSIONS

High Phe levels and wide Phe fluctuations were related to weight gain, increased WC and lipid profile abnormalities. Systematic CVR assessments and comprehensive monitoring of Phe levels may be desirable to prevent or delay cardiovascular disease in PKU patients.

Metabolomic Profiles Associated with Obesity and Periodontitis during Pregnancy: Cross-Sectional Study with Proton Nuclear Magnetic Resonance (1H-NMR)-Based Analysis

This study aimed to elucidate the metabolomic signature associated with obesity and periodontitis during pregnancy in plasma and saliva biofluids. Ninety-eight pregnant women were divided into: with obesity and periodontitis (OP = 20), with obesity but without periodontitis (OWP = 27), with normal BMI but with periodontitis (NP = 21), with normal BMI and without periodontitis (NWP = 30). Saliva and plasma were analyzed by 1H-NMR for metabolites identification. Partial Least Squares-Discriminant Analysis (PLS-DA), Sparse PLS-DA (sPLS-DA), and Variable Importance of Projection (VIP) were performed. ANOVA and Pearson’s correlation were applied (p < 0.05). Plasmatic analysis indicated the levels of glucose (p = 0.041) and phenylalanine (p = 0.015) were positively correlated with periodontal parameters and BMI, respectively. In saliva, periodontitis was mainly associated with high levels of acetic acid (p = 0.024), isovaleric acid, butyric acid, leucine, valine, isoleucine, and propionic acid (p < 0.001). High salivary concentrations of glycine (p = 0.015), succinic acid (p = 0.015), and lactate (p = 0.026) were associated with obesity. Saliva demonstrated a more elucidative difference than plasma, indicating the glucose-alanine cycle, alanine metabolism, valine, leucine and isoleucine degradation, glutamate metabolism, and Warburg effect as the main metabolic pathways.

Anti-Obesity Effect of Theabrownin from Dark Tea in C57BL/6J Mice Fed a High-Fat Diet by Metabolic Profiles through Gut Microbiota Using Untargeted Metabolomics

The epidemic of obesity is a serious public health problem. In this study, the effect of theabrownin from dark tea on obesity was evaluated by biochemical tests and nuclear magnetic resonance in C57BL/6J mice fed a high-fat diet. A mixture of antibiotics was used to deplete gut microbiota and then fecal microbiota transplant was used to restore gut microbiota. Untargeted metabolomics was used to reveal the effects of theabrownin on metabolic profiles through gut microbiota. The results showed that theabrownin significantly reduced body weight gain (83.0%) and body fat accumulation (30.29%) without affecting appetite. Also, theabrownin promoted lipid clearance with a hepatoprotective effect. The extra antibiotics disrupted the regulation of theabrownin on weight control while fecal microbiota transplant restored the beneficial regulation. That is, gut microbiota was important for theabrownin to reduce body weight gain. The untargeted metabolomics indicated that 18 metabolites were related to the anti-obesity effect of theabrownin mediated by gut microbiota. Furthermore, phenylalanine metabolism, histidine metabolism, as well as protein digestion and absorption pathway played a role in the anti-obesity of theabrownin. Our findings suggested that theabrownin significantly alleviated obesity via gut microbiota-related metabolic pathways, and theabrownin could be used for the prevention and treatment of obesity.

Burden of phenylketonuria in Latin American patients: a systematic review and meta-analysis of observational studies

Background

Phenylketonuria (PKU) is an inborn error of metabolism caused by a deficiency of the enzyme phenylalanine hydroxylase. If untreated, the complications of PKU lead to significant neucognitive and neuropsychiatric impairments, placing a burden on both the individual’s quality of life and on the healthcare system. We conducted a systematic literature review to characterize the impact of PKU on affected individuals and on healthcare resources in Latin American (LATAM) countries.

Methods

Searches of the global medical literature as well as regional and local medical literature up to September 2021. Observational studies on patients with PKU from any LATAM country. Pairs of reviewers independently screened eligible articles, extracted data from included studies, and assessed their risk of bias.

Results

79 unique studies (47 cross-sectional studies, 18 case series, 12 case reports, and two cohort studies) with a total of 4090 patients were eligible. Of these studies, 20 had data available evaluating early-diagnosed PKU patients for meta-analysis of burden outcomes. Intellectual disability in the pooled studies was 18% [95% Confidence Interval (CI) 0.04–0.38; I² = 83.7%, p = 0.0133; two studies; n = 114]. Motor delay was 15% [95% CI 0.04–0.30; I² = 74.5%, p = 0.0083; four studies; n = 132]. Speech deficit was 35% [95% CI 0.08–0.68; I² = 93.9%, p < 0.0001; five studies; n = 162].

Conclusions

There is currently evidence of high clinical burden in PKU patients in LATAM countries. Recognition that there are many unmet neuropsychological needs and socioeconomic challenges faced in the LATAM countries is the first step in planning cost-effective interventions.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13023-022-02450-2.

The Impact of the Quality of Nutrition and Lifestyle in the Reproductive Years of Women with PKU on the Long-Term Health of Their Children

A woman’s nutritional status before and during pregnancy can affect the health of her progeny. Phenylketonuria (PKU), a rare disorder causing high blood and brain phenylalanine (Phe) concentrations, is associated with neurocognitive disability. Lifelong treatment is mainly dietetic with a Phe-restricted diet, supplemented with a low-Phe protein substitute. Treatment adherence commonly decreases in adolescence, with some adults ceasing dietary treatment. In maternal PKU, elevated blood Phe is harmful to the fetus so a strict Phe-restricted diet must be re-established preconception, and this is particularly difficult to achieve. A woman’s reproductive years introduces an opportunity to adopt healthier behaviours to prepare for successful pregnancies and positive health outcomes for both themselves and their children. Several factors can influence the health status of women with PKU. Political, socioeconomic, and individual food and lifestyle choices affect diet quality, metabolic control, and epigenetics, which then pre-condition the overall maternal health and long-term health of the child. Here, we reflect on a comprehensive approach to treatment and introduce practical recommendations to optimize the wellbeing of women with PKU and the resultant health of their children.