Elevated Phenylalanine Levels Research Articles

Longitudinal associations of plasma amino acid levels with recovery from malarial coma

BackgroundDisordered amino acid metabolism is observed in cerebral malaria (CM). This study sought to determine whether abnormal amino acid concentrations were associated with level of consciousness in children recovering from coma. Twenty-one amino acids and coma scores were quantified longitudinally and the data were analysed for associations.MethodsIn a prospective observational study, 42 children with CM were enrolled. Amino acid levels were measured at entry and at frequent intervals thereafter and consciousness was assessed by Blantyre Coma Scores (BCS). Thirty-six healthy children served as controls for in-country normal amino acid ranges. Logistic regression was employed using a generalized linear mixed-effects model to assess associations between out-of-range amino acid levels and BCS.ResultsAt entry 16/21 amino acid levels were out-of-range. Longitudinal analysis revealed 10/21 out-of-range amino acids were significantly associated with BCS. Elevated phenylalanine levels showed the highest association with low BCS. This finding held when out-of-normal-range data were analysed at each sampling time.ConclusionLongitudinal data is provided for associations between abnormal amino acid levels and recovery from CM. Of 10 amino acids significantly associated with BCS, elevated phenylalanine may be a surrogate for impaired clearance of ether lipid mediators of inflammation and may contribute to CM pathogenesis.

Metabolome and transcriptome unveil the mechanism of light on regulating beauvericin synthesis in Cordyceps chanhua

Cordyceps chanhua, an important cordycipitoid medical mushroom with wide use in Asia, has gained attention for its bioactive component beauvericin (BEA), which is of medicinal value as a drug lead, but also of food safety risk. Recent observations by our group revealed a significant decrease of BEA content in C. chanhua when exposed to light, but the underlying regulatory mechanisms remain elusive. In this study, a comprehensive approach combining metabolomics and transcriptomics was employed to investigate the effects of white light on the secondary metabolism of C. chanhua for elucidation of the influence of light on BEA biosynthesis in this fungus. The result showed that the genes and metabolites involved in the synthesis of D-hydroxyisovaleric acid, a precursor of BEA synthesis, were down-regulated under light exposure, while those associated with the synthesis of phenylalanine, another precursor of BEA synthesis, were up-regulated leading to elevated phenylalanine levels. It suggested that the suppressive effect of light on BEA synthesis in C. chanhua occurred primarily through the inhibition of D-hydroxyisovaleric acid synthesis, while the enhanced phenylalanine biosynthesis likely directed towards other metabolic pathway such as pigment synthesis. These results contributed to a better understanding on how light modulates the secondary metabolism of C. chanhua and provided valuable guidance for optimizing BEA production in cultivation practices.

Prognostic Significance of Phenylalanine in Heart Failure: Clinical Insights and Inter-Organ Crosstalk Snapshot.

Background: Heart failure (HF) remains a leading cause of morbidity and mortality globally, necessitating the identification of reliable prognostic biomarkers to guide therapeutic interventions. Recent clinical observations have underscored phenylalanine (PHE) as a prognostic marker in HF, although the mechanisms involving inter-organ crosstalk remain understood. Methods: This study adopted a dull approach, with a retrospective analysis of 550 HF patients to establish the prognostic value of pre-discharge PHE levels and a study on the inter-organ crosstalk of PHE among 24 patients. We analyzed the correlations between PHE concentrations and clinical outcomes, alongside a comprehensive examination of PHE metabolism across the skeletal muscle, liver, heart, kidney, and lung. Results: In the clinical prognostic analysis of 550 patients hospitalized for acute decompensated HF, elevated PHE levels (≥65.6 μM) were significantly and independently associated with increased all-cause mortality during a median follow-up of 4.5 years (log rank = 36.7, p < 0.001), underscoring its value as a prognostic marker in HF. The inter-organic crosstalk study elucidated the mechanism associated with PHE elevation in patients with HF, characterized by an increase in PHE output in skeletal muscle and a decrease in hepatic and cardiac PHE uptakes. Notably, PHE concentration gradients across these organs were correlated with HF severity, such as the NYHA functional class, B-type natriuretic peptide levels, and the presence of acute HF. Conclusions: Our findings confirm the prognostic significance of PHE in patients with HF and unveil the complex metabolic interplay among key organs that contribute to PHE dysregulation. These insights not only reinforce the importance of metabolic monitoring in HF management but also open avenues for therapeutic targets.

Eight-day fasting modulates serum kynurenines in healthy men at rest and after exercise.

Tryptophan's (Trp) metabolites are undervalued markers of human health. Their serum concentrations are modified by physical exercise and other factors, among which fasting has a well-documented role. Although this mechanism is hardly explored, thus, the study aimed to determine the effect of the 8-day fasting period and the impact of such a procedure on a single bout of an endurance exercise on the concentration of kynurenine pathway (KP) metabolites. 10 participants fasted for 8 days, and 10 as a control group participated in the study. The exercise was performed at baseline after an overnight fast and repeated post 8 days. The 8 days of fasting increased the resting 3-hydroxy-L-kynurenine (3HK), picolinic acid (PA), kynurenic acid (KYNA), and xanthurenic acid (XA) serum concentration. Also elevated phenylalanine (Phe) and tyrosine (Tyr) levels were recorded, suggesting expanded proteolysis of muscle proteins. In turn, physical activity caused a decrease in the concentration of 3-hydroxyanthranilic acid (3HAA) and PA after fasting. The obtained results were not recorded in controls. The results of this study show that the health-promoting effects of fasting are associated with changes in the KYN pathway. The increase in the concentration of PA and XA metabolites following fasting is capable of penetrating the blood-brain barrier, and KYNA, which initiates several beneficial changes, supports this assumption.

Longitudinal associations of plasma amino acid levels with recovery from malarial coma.

Disordered amino acid metabolism is observed in cerebral malaria (CM). We sought to determine whether abnormal amino acid concentrations were associated with level of consciousness in children recovering from coma. We quantified 21 amino acids and coma scores longitudinally and analyzed data for associations. In a prospective observational study, we enrolled 42 children with CM. We measured amino acid levels at entry and at frequent intervals thereafter and assessed consciousness by Blantyre Coma Scores (BCS). Thirty-six healthy children served as controls for in-country normal amino acid ranges. We employed logistic regression using a generalized linear mixed-effects model to assess associations between out-of-range amino acid levels and BCS. At entry 16/21 amino acid levels were out-of-range. Longitudinal analysis revealed 10/21 out-of-range amino acids were significantly associated with BCS. Elevated phenylalanine levels showed the highest association with low BCS. This finding held when out-of-normal-range data were analyzed at each sampling time. We provide longitudinal data for associations between abnormal amino acid levels and recovery from CM. Of 10 amino acids significantly associated with BCS, we propose that elevated phenylalanine may be a surrogate for impaired clearance of ether lipid mediators of inflammation contributing to CM pathogenesis.

Efficacy and safety of sapropterin before and during pregnancy: Final analysis of the Kuvan® Adult Maternal Paediatric European Registry (KAMPER) maternal and Phenylketonuria Developmental Outcomes and Safety (PKUDOS) PKU-MOMs sub-registries.

Infants born to mothers with phenylketonuria (PKU) may develop congenital abnormalities because of elevated phenylalanine (Phe) levels in the mother during pregnancy. Maintenance of blood Phe levels between 120 and 360 μmol/L reduces risks of birth defects. Sapropterin dihydrochloride helps maintain blood Phe control, but there is limited evidence on its risk-benefit ratio when used during pregnancy. Data from the maternal sub-registries-KAMPER (NCT01016392) and PKUDOS (NCT00778206; PKU-MOMs sub-registry)-were collected to assess the long-term safety and efficacy of sapropterin in pregnant women in a real-life setting. Pregnancy and infant outcomes, and the safety of sapropterin were assessed. Final data from 79 pregnancies in 57 women with PKU are reported. Sapropterin dose was fairly constant before and during pregnancy, with blood Phe levels maintained in the recommended target range during the majority (82%) of pregnancies. Most pregnancies were carried to term, and the majority of liveborn infants were reported as 'normal' at birth. Few adverse and serious adverse events were considered related to sapropterin, with these occurring in participants with high blood Phe levels. This report represents the largest population of pregnant women with PKU exposed to sapropterin. Results demonstrate that exposure to sapropterin during pregnancy was well-tolerated and facilitated maintenance of blood Phe levels within the target range, resulting in normal delivery. This critical real-world data may facilitate physicians and patients to make informed treatment decisions about using sapropterin in pregnant women with PKU and in women of childbearing age with PKU who are responsive to sapropterin.

Gender-Dependent Cholinergic System Alterations in a Phenylketonuria Model

Introduction: Phenylketonuria (PKU) is a rare inherited metabolic disorder characterized by a deficiency of the enzyme phenylalanine hydroxylase. The absence of this enzyme leads to elevated levels of phenylalanine in the blood, causing accumulation in the brain and resulting in permanent brain damage. To investigate the neurological effects of PKU, an experimental PKU model was developed, and cholinergic parameters were analyzed in brain tissue and serum from both female and male rats. Serum AChE, BChE, and total ChE activities were examined, while AChE activity was specifically analyzed in hippocampal tissue. Material and Methods: Brain tissue and serum samples were collected from female and male rats from an induced phenylketonuria model for analysis. AChE, BChE, and total ChE activities were measured in serum samples, while AChE activity was examined in hippocampal tissue. Enzyme activities were measured according to Ellman assay. The data analysis and graphical presentations were done by GraphPad prism. Results: Hippocampal AChE activity was significantly increased in both PKU groups compared to the control groups (Male ***p=0.0001; female *p=0.046). Serum analysis revealed decreased total serum cholinergic activity in both the female and male PKU groups compared with the control groups (**p≤0.002 and ***p≤0.0003, respectively). These results were consistent with findings from total serum cholinergic activity analysis. Additionally, the AChE activity in both the female and male PKU groups was decreased compared to their respective control groups (***p≤0.002 and ***p≤0.0006, respectively). It was also found that BChE activity in the serum of male rats in the PKU group was decreased compared to male rats in the control group (*p=0.038). Conclusion: These findings indicate that the cholinergic system in the phenylketonuria model may vary according to gender. The observed changes in both brain tissue and serum provide new insights into the gender-dependent neurological effects of PKU. Keywords: Phenylketonuria, cholinergic system, enzyme activity, hippocampal tissue, gender differences

Phenylketonuria at HMIMV Rabat: About 15 Cases

Phenylketonuria is a disorder of amino acid metabolism causing an intellectually handicapping disease with cognitive and behavioral disorders, caused by elevated serum levels of phenylalanine. The primary cause is phenylalanine hydroxylase deficiency. Diagnosis is based on the detection of elevated phenylalanine and normal or low tyrosine levels. Treatment is lifelong dietary restriction of phenylalanine. The prognosis is excellent under treatment.

Breast feeding in infants diagnosed with phenylketonuria (PKU): a scoping review

BackgroundPhenylketonuria (PKU) is the most common inherited disease of amino acid metabolism, characterised by elevated levels of phenylalanine (Phe). There is a lack of infant feeding guidance for those with...

Modulation of Neurotransmitter Pathways and Associated Metabolites by Systemic Silencing of Gut Genes in C. elegans.

The gut is now recognized as the "second brain" of the human body due to its integral role in neuronal health and functioning. Although we know that the gut communicates with the brain via immunological factors, microbial metabolites, and neurotransmitters, the interplay of these systems remains poorly understood. To investigate this interplay, we silenced 48 genes that are exclusively or primarily expressed in the C. elegans intestine. We studied the associated effects on various aspects of neurodegeneration, including proteotoxicity induced by α-Syn expression. We also assayed behaviours, such as mobility and cognition, that are governed by various neurotransmitters. We identified nine gut genes that significantly modulated these events. We further performed HR-MAS NMR-based metabolomics to recognize the metabolic variability induced by the respective RNAi conditions of R07E3.1, C14A6.1, K09D9.2, ZK593.2, F41H10.8, M02D8.4, M88.1, C03G6.15 and T01D3.6. We found that key metabolites such as phenylalanine, tyrosine, inosine, and glutamine showed significant variation among the groups. Gut genes that demonstrated neuroprotective effects (R07E3.1, C14A6.1, K09D9.2, and ZK593.2) showed elevated levels of inosine, phenylalanine, and tyrosine; whereas, genes that aggravated neurotransmitter levels demonstrated decreased levels of the same metabolites. Our results shed light on the intricate roles of gut genes in the context of neurodegeneration and suggest a new perspective on the reciprocal interrelation of gut genes, neurotransmitters, and associated metabolites. Further studies are needed to decipher the intricate roles of these genes in context of neurodegeneration in greater detail.

Phenylketonuria and the brain

Classic phenylketonuria (PKU) is caused by defective activity of phenylalanine hydroxylase (PAH), the enzyme that coverts phenylalanine (Phe) to tyrosine. Toxic accumulation of phenylalanine and its metabolites, left untreated, affects brain development and function depending on the timing of exposure to elevated levels. The specific mechanisms of Phe-induced brain damage are not completely understood, but they correlate to phenylalanine levels and on the stage of brain growth. During fetal life, high levels of phenylalanine such as those seen in maternal PKU can result in microcephaly, neuronal loss and corpus callosum hypoplasia. Elevated phenylalanine levels during the first few years of life can cause acquired microcephaly, severe cognitive impairment and epilepsy, likely due to the impairment of synaptogenesis. During late childhood, elevated phenylalanine can cause alterations in neurological functioning, leading to ADHD, speech delay and mild IQ reduction. In adolescents and adults, executive function and mood are affected, with some of the abnormalities reversed by better control of phenylalanine levels. Altered brain myelination can be present at this stage. In this article, we review the current knowledge about the consequences of high phenylalanine levels in PKU patients and animal models through different stages of brain development and its effect on cognitive, behavioural and neuropsychological function.

Fetal effects of mild maternal COVID-19 infection: metabolomic profiling of cord blood

The impact of maternal coronavirus disease 2019 (COVID-19) infection on fetal health remains to be precisely characterized. Using metabolomic profiling of newborn umbilical cord blood, we aimed to investigate the potential fetal biological consequences of maternal COVID-19 infection. Cord blood plasma samples from 23 mild COVID-19 cases (mother infected/newborn negative) and 23 gestational age-matched controls were analyzed using nuclear magnetic spectroscopy and liquid chromatography coupled with mass spectrometry. Metabolite set enrichment analysis (MSEA) was used to evaluate altered biochemical pathways due to COVID-19 intrauterine exposure. Logistic regression models were developed using metabolites to predict intrauterine exposure. Significant concentration differences between groups (p-value < 0.05) were observed in 19 metabolites. Elevated levels of glucocorticoids, pyruvate, lactate, purine metabolites, phenylalanine, and branched-chain amino acids of valine and isoleucine were discovered in cases while ceramide subclasses were decreased. The top metabolite model including cortisol and ceramide (d18:1/23:0) achieved an Area under the Receiver Operating Characteristics curve (95% CI) = 0.841 (0.725-0.957) for detecting fetal exposure to maternal COVID-19 infection. MSEA highlighted steroidogenesis, pyruvate metabolism, gluconeogenesis, and the Warburg effect as the major perturbed metabolic pathways (p-value < 0.05). These changes indicate fetal increased oxidative metabolism, hyperinsulinemia, and inflammatory response. We present fetal biochemical changes related to intrauterine inflammation and altered energy metabolism in cases of mild maternal COVID-19 infection despite the absence of viral infection. Elucidation of the long-term consequences of these findings is imperative considering the large number of exposures in the population.

The impact of phenylalanine levels during pregnancy on birth weight and later development in children born to women with phenylketonuria.

Strict metabolic control with dietary treatment during pregnancy is essential for women with phenylketonuria (PKU), as elevated levels of phenylalanine (Phe) are toxic to the developing fetus. Maternal delay in achievement of the recommended Phe level during pregnancy is associated with delayed development of the child. However, the extent to which risk is changed by later or less stringently performed dietary treatment is unclear. The aim of this study was to investigate the impact of Phe levels and time of initiation of a Phe-restricted diet in pregnant women with PKU on birth weight, head circumference and later development of their children. Birth data were obtained from the medical records of women with PKU giving birth in the period 1980-2020. Later development was investigated by interviewing the mothers about their children's development and health. We included 79 children of 41 women with PKU. The women showed good adherence with the diet and had mean blood Phe levels within target range (248 ± 62 μmol/L). The children's development was not affected by fluctuations in the women's Phe levels, that occurred especially in first trimester. Despite maternal Phe levels being within target range, 19 children (26.8%) had low birth weight below 10th percentile. This study indicates that with dietary treatment, the children are born with the same prospect for normal development and health as children born to non-PKU mothers. This is despite maternal fluctuations in the Phe levels during first trimester.

Modulating phenylalanine metabolism by L. acidophilus alleviates alcohol-related liver disease through enhancing intestinal barrier function

BackgroundImpaired metabolic functions of gut microbiota have been demonstrated in alcohol-related liver disease (ALD), but little is known about changes in phenylalanine metabolism.MethodsBacterial genomics and fecal metabolomics analysis were used to recognize the changes of phenylalanine metabolism and its relationship with intestinal flora. Intestinal barrier function was detected by intestinal alkaline phosphatase (IAP) activity, levels of tight junction protein expression, colonic inflammation and levels of serum LPS. Lactobacillus acidophilus was chosen to correct phenylalanine metabolism of ALD mice by redundancy analysis and Pearson correlation analysis.ResultsUsing 16S rRNA sequencing and ultra-performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) methods, we identified elevated levels of phenylalanine and its’ metabolites in the gut of alcohol-fed mice compared to control mice and were negatively correlated with the abundance of Lactobacillus, which mainly metabolized phenylalanine. The intestinal phenylalanine level was positively correlated with the colon inflammatory factors TNF-α and IL-6, and negatively correlated with ZO-1 and Occludin. While intestinal alkaline phosphatase (IAP) activity was negatively correlated with the colon inflammatory factors TNF-α, IL-6 and MCP-1, and positively correlated with ZO-1 and Occludin. Increased phenylalanine inhibited IAP activity, blocked LPS dephosphorylation, increased colonic inflammation and bacterial translocation. Phenylalanine supplementation aggravated alcohol-induced liver injury and intestinal barrier dysfunction. Among the 37 Lactobacillus species, the abundance of Lactobacillus acidophilus was most significantly decreased in ALD mice. Supplementation with L. acidophilus recovered phenylalanine metabolism and protected mice from alcohol-induced steatohepatitis.ConclusionsRecovery of phenylalanine metabolism through the oral supplementation of L. acidophilus boosted intestinal barrier integrity and ameliorated experimental ALD.

Результаты клинической апробации специализированного продукта диетического лечебного питания «Бифинилан» для детей старше семи лет, больных фенилкетонурией

Objective. To evaluate the efficacy, safety, and tolerability of a specialized food product for dietary therapeutic nutrition “Bifinilan” in children over 7 years of age with phenylketonuria. Patients and methods. An open-label prospective study was conducted in outpatient clinical settings. It included 17 children with phenylketonuria aged between 8 and 15 years (12 girls and 5 boys), who received a specialized product “Bifinilan” for 30 ± 2 days. Clinical and anamnestic characteristics, blood phenylalanine levels determined by the fluorescent method were assessed at the beginning and at the end of the study. Results. During the study, blood phenylalanine levels decreased significantly and were within the reference range (median before the study was 9.11 mg/dL, at the end of the study – 6.17 mg/dL, p &lt; 0.05). At the same time, in children with initially elevated phenylalanine level, it decreased to an acceptable range, and in children with a normal phenylalanine level, it remained within the same range. Patients, their parents, and physicians were completely satisfied with the use of the product, which was well tolerated and the transition to which was not followed by an adaptation period. Conclusion. The efficacy, safety, and good tolerability of a specialized food product for dietary therapeutic nutrition “Bifinilan” in children over 7 years of age with phenylketonuria was demonstrated. Key words: children, specialized food product for dietary therapeutic nutrition, phenylalanine, phenylketonuria

Growth and Nutritional Status of Phenylketonuric Children and Adolescents

BackgroundThe goal of this study was to assess the anthropometric and biochemical parameters of children and adolescents with phenylketonuria (PKU).MethodsThe participants in this cross-sectional study ranged in age from four to 18 years old. Biochemical markers such as vitamin B12, folic acid, iron, ferritin, calcium, 25-hydroxy vitamin D3, zinc, plasma phenylalanine (Phe) and tyrosine (Tyr) levels in blood were evaluated, as well as demographics and anthropometric measurements. A three-day dietary recall questionnaire was completed by all individuals.Results80% (64) of the 80 patients (42 females, 52.5%) had typical PKU. Consanguineous marriages were found in 57.5% (46) of the patients’ parents. According to the height for age index, 17.5% of the study group (n = 14) were short or very short. According to age-related weight and body mass index (BMI), 37.5% (n = 30) and 43.8% (n = 35) of people are obese or overweight, respectively. Biochemical tests revealed increased vitamin B12 levels and 25-hydroxy vitamin D3 deficiency in 35% (n = 28) of the patients, insufficient folic acid in 12.5% (n = 10), and elevated phenylalanine levels in 70.3% (n = 45) of children under 12 years old, and adolescents 62.5% (n = 10). A high Phe intake (OR = 4.44, CI %95 = 1.27–15.57) is a risk factor for obesity and overweight.ConclusionPatients with PKU had a high rate of overweight and obesity. PKU patients who are overweight or obese do not differ from normal-weight patients in terms of dietary intake or laboratory findings (except for serum iron levels). One-third of patients with phenylketonuria were vitamin D deficient and had a BMI/A index of overweight/obese. It is recommended to use special medical food to help solve energy and nutrient deficiencies.

Case study on phenylketonuria: a memic autism

Phenylketonuria (PKU) is a phenylalanine catabolism metabolic condition characterized by a decrease in the activity of the phenylalanine hydroxylase or Dihydro pteridine reductase enzyme. This inherited condition causes a build-up of phenylalanine in the bloodstream. Elevated phenylalanine levels in the blood can cause muscle rigidity, choreoathetosis, tremors, hyperreflexia, dermatitis, pale skin, and pseudo-scleroderma. The central nervous system deficiencies in PKU are caused by phenylalanine and phenyl pyruvic acid competing for dopamine, adrenaline, norepinephrine, and serotonin in the brain. Structural changes are caused by neurotransmitter inhibition and phenylalanine and phenyl pyruvic accumulations in the white matter of the posterior periventricular, frontal, and subcortical areas of the brain1. Greater myelin turnover decreased synaptogenesis, and reduced neuronal digenesis ensues from myelin deficit, resulting in cognitive development and mental retardation1. The patient in this case study is an 8-year-old boy who has been diagnosed with phenylketonuria. The patient’s parents had a history of consanguinity marriage. The patient has had seizures since he was nine months old. Speech and language delays, hearing loss, and tooth discoloration are all common symptoms. He had an MRI and a brain scan, as well as a blood amino acids test, which revealed that he has mild developmental delays. Mild to Moderate Autistic Features is Delayed.

Dysregulated Phenylalanine Catabolism Plays a Key Role in the Trajectory of Cardiac Aging.

Aging myocardium undergoes progressive cardiac hypertrophy and interstitial fibrosis with diastolic and systolic dysfunction. Recent metabolomics studies shed light on amino acids in aging. The present study aimed to dissect how aging leads to elevated plasma levels of the essential amino acid phenylalanine and how it may promote age-related cardiac dysfunction. We studied cardiac structure and function, together with phenylalanine catabolism in wild-type (WT) and p21-/- mice (male; 2-24 months), with the latter known to be protected from cellular senescence. To explore phenylalanine's effects on cellular senescence and ectopic phenylalanine catabolism, we treated cardiomyocytes (primary adult rat or human AC-16) with phenylalanine. To establish a role for phenylalanine in driving cardiac aging, WT male mice were treated twice a day with phenylalanine (200 mg/kg) for a month. We also treated aged WT mice with tetrahydrobiopterin (10 mg/kg), the essential cofactor for the phenylalanine-degrading enzyme PAH (phenylalanine hydroxylase), or restricted dietary phenylalanine intake. The impact of senescence on hepatic phenylalanine catabolism was explored in vitro in AML12 hepatocytes treated with Nutlin3a (a p53 activator), with or without p21-targeting small interfering RNA or tetrahydrobiopterin, with quantification of PAH and tyrosine levels. Natural aging is associated with a progressive increase in plasma phenylalanine levels concomitant with cardiac dysfunction, whereas p21 deletion delayed these changes. Phenylalanine treatment induced premature cardiac deterioration in young WT mice, strikingly akin to that occurring with aging, while triggering cellular senescence, redox, and epigenetic changes. Pharmacological restoration of phenylalanine catabolism with tetrahydrobiopterin administration or dietary phenylalanine restriction abrogated the rise in plasma phenylalanine and reversed cardiac senescent alterations in aged WT mice. Observations from aged mice and human samples implicated age-related decline in hepatic phenylalanine catabolism as a key driver of elevated plasma phenylalanine levels and showed increased myocardial PAH-mediated phenylalanine catabolism, a novel signature of cardiac aging. Our findings establish a pathogenic role for increased phenylalanine levels in cardiac aging, linking plasma phenylalanine levels to cardiac senescence via dysregulated phenylalanine catabolism along a hepatic-cardiac axis. They highlight phenylalanine/PAH modulation as a potential therapeutic strategy for age-associated cardiac impairment.

Insights from Animal Models on the Pathophysiology of Hyperphenylalaninemia: Role of Mitochondrial Dysfunction, Oxidative Stress and Inflammation.

Phenylketonuria (PKU) is an inborn error of metabolism caused by phenylalanine hydroxylase (PAH) deficiency and characterized by elevated plasma levels of phenylalanine (hyperphenylalaninemia-HPA). In severe cases, PKU patients present with neurological dysfunction and hepatic damage, but the underlying mechanisms are not fully elucidated. Other forms of HPA also characterized by neurological symptoms occur in rare instances due to defects in the metabolism of the PAH cofactor tetrahydrobiopterin. This review aims to gather the knowledge acquired on the phenylalanine-induced toxicity focusing on findings obtained from pre-clinical studies. Mounting evidence obtained from PKU genetic mice, rats submitted to different HPA models, and cell cultures exposed to phenylalanine has shown that high levels of this amino acid impair mitochondrial bioenergetics, provoke changes in oxidative and inflammatory status, and induce apoptosis. Noteworthy, some data demonstrated that phenylalanine-induced oxidative stress occurs specifically in mitochondria. Further studies have shown that the metabolites derived from phenylalanine, namely phenylpyruvate, phenyllactate, and phenylacetate, also disturb oxidative status. Therefore, it may be presumed that mitochondrial damage is one of the most important mechanisms responsible for phenylalanine toxicity. It is expected that the findings reviewed here may contribute to the understanding of PKU and HPA pathophysiology and to the development of novel therapeutic strategies for these disorders.

Retrospective analysis of 19 patients with 6-Pyruvoyl Tetrahydropterin Synthase Deficiency: Prolactin levels inversely correlate with growth

BackgroundPyruvoyl Tetrahydropterin Synthase (PTPS) Deficiency is the most common form of BH4 deficiency resulting in hyperphenylalaninemia. It can have variable clinical severity and there is limited information on the clinical presentation, natural history and effectiveness of newborn screening for this condition. MethodsRetrospective data (growth and clinical parameters, biochemical and genetic testing results, treatment) were collected from 19 patients with PTPS deficiency in different centers, to evaluate biochemical and clinical outcomes. Descriptive statistics was used for qualitative variables, while linear regression analysis was used to correlate quantitative variables. ResultsPatients with PTPS deficiency had an increased incidence of prematurity (4/18) with an average gestational age only mildly reduced (37.8 ± 2.4 weeks) and low birth weight (−1.14 ± 0.97 SD below that predicted for gestational age). With time, weight and height approached normal. Values. All patients were identified by newborn screening for an elevated phenylalanine level. However, phenylalanine levels were normal in two whose testing was performed at or before 24 h of age. Sapropterin dihydrochloride treatment normalized phenylalanine levels. Molecular testing identified novel variants in the PTS gene, some of which present in more than one affected family. The neurotransmitter derivatives 5-hydroxyindoleacetic acid (5HIAA) and homovanillic acid (HVA) in the CSF were decreased in most cases except in 2 families with the peripheral form of PTPS deficiency. With time, HVA and 5HIAA became abnormally low in two of these patients requiring therapy. Prolactin (whose secretion is inhibited by dopamine) levels were elevated in several patients with PTPS deficiency and inversely correlated with the z-scores for height (p < 0.01) and weight (p < 0.05). Most patients with PTPS deficiency had delayed development early in life, improving around school age with IQs mostly in the normal range, with a small decline in older individuals. From a neurological standpoint, most patients had normal brain MRI and minor EEG anomalies, although some had persistent neurological symptoms. DiscussionPatients with PTPS deficiency have not only an increased incidence of prematurity, but also decreased birth weight when corrected for gestational age. Hyperphenylalaninemia can be absent in the first day of life. Therapy with sapropterin dihydrochloride normalizes phenylalanine levels and neurotransmitter precursors can improve CSF neurotransmitter metabolites levels. Insufficient dopaminergic stimulation (as seen from elevated prolactin) might result in decreased height in patients with PTPS deficiency. Despite early delays in development, many patients can achieve independence in adult life, with usually normal neuroimaging and EEG.