Evaluation of a New 'Mix-In' Style Glycomacropeptide-Based Protein Substitute for Food and Drinks in Patients with Phenylketonuria and Tyrosinemia.

(1) Background: Poor palatability, large volume, and lack of variety of some liquid and powdered protein substitutes (PSs) for patients with phenylketonuria (PKU) and tyrosinemia (TYR) can result in poor adherence. This study aimed to evaluate a new unflavoured, powdered GMP-based PS designed to be mixed into drinks, foods, or with other PSs, in patients with PKU and TYR. (2) Methods: Paediatric and adult community-based patients were recruited from eight metabolic centres and prescribed ≥1 sachet/day (10 g protein equivalent (PE)) of the Mix-In-style PS over 28 days. Adherence, palatability, GI tolerance, and metabolic control were recorded at baseline and follow-up. Patients who completed at least 7 days of intervention were included in the final analysis. (3) Results: Eighteen patients (3-45 years, nine males) with PKU (n = 12) and TYR (n = 6) used the Mix-In-style PS for ≥7 days (mean 26.4 days (SD 4.6), range 11-28 days) alongside their previous PS, with a mean intake of 16.7 g (SD 7.7) PE/day. Adherence was 86% (SD 25), and GI tolerance was stable, with n = 14 experiencing no/no new symptoms and n = 3 showing improved symptoms compared to baseline. Overall palatability was rated satisfactory by 78% of patients, who successfully used the Mix-In-style PS in various foods and drinks, including smoothies, squash, and milk alternatives, as a top-up to meet their protein needs. There was no concern regarding safety/metabolic control during the intervention. (4) Conclusions: The 'Mix-In'-style PS was well adhered to, accepted, and tolerated. Collectively, these data show that providing a flexible, convenient, and novel format of PS can help with adherence and meet patients' protein needs.

Casein Glycomacropeptide: An Alternative Protein Substitute in Tyrosinemia Type I.

Tyrosinemia type I (HTI) is treated with nitisinone, a tyrosine (Tyr) and phenylalanine (Phe)-restricted diet, and supplemented with a Tyr/Phe-free protein substitute (PS). Casein glycomacropeptide (CGMP), a bioactive peptide, is an alternative protein source to traditional amino acids (L-AA). CGMP contains residual Tyr and Phe and requires supplementation with tryptophan, histidine, methionine, leucine, cysteine and arginine. AIMS: a 2-part study assessed: (1) the tolerance and acceptability of a low Tyr/Phe CGMP-based PS over 28 days, and (2) its long-term impact on metabolic control and growth over 12 months. METHODS: 11 children with HTI were recruited and given a low Tyr/Phe CGMP to supply all or part of their PS intake. At enrolment, weeks 1 and 4, caregivers completed a questionnaire on gastrointestinal symptoms, acceptability and ease of PS use. In study part 1, blood Tyr and Phe were assessed weekly; in part 2, weekly to fortnightly. In parts 1 and 2, weight and height were assessed at the study start and end. RESULTS: Nine of eleven children (82%), median age 15 years (range 8.6-17.7), took low Tyr/Phe CGMP PS over 28 days; it was continued for 12 months in n = 5 children. It was well accepted by 67% (n = 6/9), tolerated by 100% (n = 9/9) and improved gastrointestinal symptoms in 2 children. The median daily dose of protein equivalent from protein substitute was 60 g/day (range 45-60 g) with a median of 20 g/day (range 15 to 30 g) from natural protein. In part 2 (n = 5), a trend for improved blood Tyr was observed: 12 months pre-study, median Tyr was 490 µmol/L (range 200-600) and Phe 50 µmol/L (range 30-100); in the 12 months taking low Tyr/Phe CGMP PS, median Tyr was 430 µmol/L (range 270-940) and Phe 40 µmol/L (range 20-70). Normal height, weight and BMI z scores were maintained over 12 months. CONCLUSIONS: In HTI children, CGMP was well tolerated, with no deterioration in metabolic control or growth when studied over 12 months. The efficacy of CGMP in HTI needs further investigation to evaluate the longer-term impact on blood Phe concentrations and its potential influence on gut microflora.

Natural Protein Tolerance and Metabolic Control in Patients with Hereditary Tyrosinaemia Type 1.

In a longitudinal retrospective study, we aimed to assess natural protein (NP) tolerance and metabolic control in a cohort of 20 Hereditary Tyrosinaemia type I (HTI) patients. Their median age was 12 years ([3.2-17.7 years], n = 11 female, n = 8 Caucasian, n = 8 Asian origin, n = 2 Arabic and n = 2 Indian). All were on nitisinone (NTBC) with a median dose of 0.7 g/kg/day (range 0.4-1.5 g/kg/day) and were prescribed a tyrosine (Tyr)/phenylalanine (Phe)-restricted diet supplemented with Tyr/Phe-free L-amino acids. Data were collected on clinical signs at presentation, medical history, annual dietary prescriptions, and blood Phe and Tyr levels from diagnosis until transition to the adult service (aged 16-18 years) or liver transplantation (if it preceded transition). The median age of diagnosis was 2 months (range: 0 to 24 months), with n = 1 diagnosed by newborn screening, n = 3 following phenylketonuria (PKU) screening and n = 7 by sibling screening. Five patients were transplanted (median age 6.3 years), and one died due to liver cancer. The median follow-up was 10 years (3-16 years), and daily prescribed NP intake increased from a median of 5 to 24 g/day. Lifetime median blood Tyr (370 µmol/L, range 280-420 µmol/L) and Phe (50 µmol/L, 45-70 µmol/L) were maintained within the target recommended ranges. This cohort of HTI patients were able to increase the daily NP intake with age while maintaining good metabolic control. Extra NP may improve lifelong adherence to the diet.

Dietary restriction of tyrosine and phenylalanine lowers tyrosinemia associated with nitisinone therapy of alkaptonuria.

Alkaptonuria (AKU) is caused by homogentisate 1,2-dioxygenase deficiency that leads to homogentisic acid (HGA) accumulation, ochronosis and severe osteoarthropathy. Recently, nitisinone treatment, which blocks HGA formation, has been effective in AKU patients. However, a consequence of nitisinone is elevated tyrosine that can cause keratopathy. The effect of tyrosine and phenylalanine dietary restriction was investigated in nitisinone-treated AKU mice, and in an observational study of dietary intervention in AKU patients. Nitisinone-treated AKU mice were fed tyrosine/phenylalanine-free and phenylalanine-free diets with phenylalanine supplementation in drinking water. Tyrosine metabolites were measured pre-nitisinone, post-nitisinone, and after dietary restriction. Subsequently an observational study was undertaken in 10 patients attending the National Alkaptonuria Centre (NAC), with tyrosine >700 µmol/L who had been advised to restrict dietary protein intake and where necessary, to use tyrosine/phenylalanine-free amino acid supplements. Elevated tyrosine (813 µmol/L) was significantly reduced in nitisinone-treated AKU mice fed a tyrosine/phenylalanine-free diet in a dose responsive manner. At 3 days of restriction, tyrosine was 389.3, 274.8, and 144.3 µmol/L with decreasing phenylalanine doses. In contrast, tyrosine was not effectively reduced in mice by a phenylalanine-free diet; at 3 days tyrosine was 757.3, 530.2, and 656.2 µmol/L, with no dose response to phenylalanine supplementation. In NAC patients, tyrosine was significantly reduced (P = .002) when restricting dietary protein alone, and when combined with tyrosine/phenylalanine-free amino acid supplementation; 4 out of 10 patients achieved tyrosine <700 µmol/L. Tyrosine/phenylalanine dietary restriction significantly reduced nitisinone-induced tyrosinemia in mice, with phenylalanine restriction alone proving ineffective. Similarly, protein restriction significantly reduced circulating tyrosine in AKU patients.

Long-Term Outcomes and Practical Considerations in the Pharmacological Management of Tyrosinemia Type 1.

Tyrosinemia type 1 (TT1) is a rare metabolic disease caused by a defect in tyrosine catabolism. TT1 is clinically characterized by acute liver failure, development of hepatocellular carcinoma, renal and neurological problems, and consequently an extremely poor outcome. This review showed that the introduction of 2-(2-nitro-4-trifluoromethylbenzoyl)-1,3-cyclohexanedione (NTBC) in 1992 has revolutionized the outcome of TT1 patients, especially when started pre-clinically. If started early, NTBC can prevent liver failure, renal problems, and neurological attacks and decrease the risk for hepatocellular carcinoma. NTBC has been shown to be safe and well tolerated, although the long-term effectiveness of treatment with NTBC needs to be awaited. The high tyrosine concentrations caused by treatment with NTBC could result in ophthalmological and skin problems and requires life-long dietary restriction of tyrosine and its precursor phenylalanine, which could be strenuous to adhere to. In addition, neurocognitive problems have been reported since the introduction of NTBC, with hypothesized but as yet unproven pathophysiological mechanisms. Further research should be done to investigate the possible relationship between important clinical outcomes and blood concentrations of biochemical parameters such as phenylalanine, tyrosine, succinylacetone, and NTBC, and to develop clear guidelines for treatment and follow-up with reliable measurements. This all in order to ultimately improve the combined NTBC and dietary treatment and limit possible complications such as hepatocellular carcinoma development, neurocognitive problems, and impaired quality of life.

Biomarkers of Micronutrients in Regular Follow-Up for Tyrosinemia Type 1 and Phenylketonuria Patients.

Phenylketonuria (PKU) is treated with dietary restrictions and sometimes tetrahydrobiopterin (BH4). PKU patients are at risk for developing micronutrient deficiencies, such as vitamin B12 and folic acid, likely due to their diet. Tyrosinemia type 1 (TT1) is similar to PKU in both pathogenesis and treatment. TT1 patients follow a similar diet, but nutritional deficiencies have not been investigated yet. In this retrospective study, biomarkers of micronutrients in TT1 and PKU patients were investigated and outcomes were correlated to dietary intake and anthropometric measurements from regular follow-up measurements from patients attending the outpatient clinic. Data was analyzed using Kruskal-Wallis, Fisher's exact and Spearman correlation tests. Furthermore, descriptive data were used. Overall, similar results for TT1 and PKU patients (with and without BH4) were observed. In all groups high vitamin B12 concentrations were seen rather than B12 deficiencies. Furthermore, all groups showed biochemical evidence of vitamin D deficiency. This study shows that micronutrients in TT1 and PKU patients are similar and often within the normal ranges and that vitamin D concentrations could be optimized.

Eficacia y seguridad de los suplementos nutricionales libres de tirosina y fenilalanina para el tratamiento de pacientes menores de 18 años con diagnóstico de tirosinemia tipo I / Efficacy and safety of tyrosine and phenylalanine free nutritional supplements for the treatment of patients under 18 years of age with diagnosis of tyrosinemia type I

INTRODUCCIÓN: La tirosinemia tipo 1 (HT-1) es una enfermedad genética infrecuente causada por la mutación del gen FAH. Esta mutación produce escasez de la enzima fumaril-aceto-acetato hidrolasa; responsable del último paso en la vía de degradación de la tirosina. El acúmulo de los metabolitos tóxicos de la tirosina interrumpe severamente el metabolismo intracelular del hígado y riñón; dañando estos órganos. La HT-1 se presenta en uno de cada 100.000 - 120.000 nacimientos alrededor del mundo. El tratamiento de los pacientes con HT-1 está dirigido a controlar los niveles plasmáticos de tirosina y evitar la formación de sus metabolitos tóxicos. El manejo nutricional reduce la ingesta de tirosina y fenilalanina mediante la dieta. El tratamiento farmacológico involucra el uso de nitisinona; la cual bloquea el segundo paso de la vía de degradación de la tirosina. De esta forma, se evita la formación de los metabolitos tóxicos de la tirosina; pero se incrementa el nivel plasmático de tirosina; lo cual produce, a su vez, molestias visuales debidas a la formación de cristales de tirosina. Para mantener el nivel de tirosina dentro del rango normal, la dieta debe estar reducida en tirosina y fenilalanina (precursor de la tirosina). Esto refuerza la importancia del manejo nutricional mediante la restricción de la ingesta de tirosina y fenilalanina en la dieta. Sin embargo, esta dieta podría no cubrir los demás requerimientos nutricionales, energéticos y proteicos de los pacientes con HT-1. Por lo tanto, los suplementos nutricionales serían necesarios para complementar la dieta. En EsSalud se dispone de suplementos nutricionales pediátricos. Sin embargo, estos no están libres de fenilalanina y tirosina. OBJETIVO: el presente dictamen preliminar expone la eficacia y seguridad de los suplementos nutricionales libres de fenilalanina y tirosina, junto con una dieta reducida en tirosina, comparado con una dieta reducida en tirosina para el tratamiento de los pacientes menores de 18 años, con diagnóstico de HT-1. METODOLOGÍA: Tras una búsqueda sistemática de literatura publicada hasta diciembre del 2018, no se encontró evidencia científica que evalúe el uso de suplementos nutricionales libres de fenilalanina y tirosina acompañados de una dieta reducida en tirosina, comparado con un manejo nutricional que involucre solo la dieta reducida en tirosina, en pacientes menores de 18 años con diagnóstico de HT-1. En su lugar, se hallaron tres artículos de recomendación tipo revisión que abordan el manejo nutricional de los pacientes con HT-1. Uno de ellos no menciona los suplementos libres de tirosina y fenilalanina. Los otros dos, mencionan que es necesario añadir estos suplementos a la dieta de todo paciente con HT-1. Sin embargo, esta afirmación no forma parte de las recomendaciones propiamente dichas, y no se mostraron las referencias de la evidencia utilizada para dar esta afirmación. RESULTADOS: Pese a la escasa evidencia científica disponible, la eficacia de los suplementos nutricionales libres de tirosina y fenilalanina tiene sustento biológico razonable. El requerimiento varía desde 3 g/kg/día, aproximadamente, en menores de 2 años hasta 1.5 g/Kg/día a los 10-14 años. Sin embargo, los requerimientos de tirosina y fenilalanina se alcanzan con pequeñas cantidades de proteína natural (0.5 a 1.0 g/Kg/día). Al restringir la ingesta de proteína natural (para evitar el exceso de tirosina y fenilalanina en pacientes con HT-1), se crea un déficit para cubrir el requerimiento proteico global. Si este déficit no se cubre, el paciente tendrá problemas en el crecimiento y desarrollo psicomotor. Por lo tanto, la inclusión de suplementos nutricionales libres de tirosina y fenilalanina en la dieta de los pacientes HT-1 ayuda a cubrir sus requerimientos proteicos, manteniendo las concentraciones plasmáticas de tirosina en el rango saludable. En línea con lo mencionado, el experto en pediatría de la institución, afirma que los suplementos nutricionales libres de tirosina y fenilalanina permiten el adecuado crecimiento y desarrollo neurológico mientras evita la aparición de problemas visuales. Por lo tanto, el experto en pediatría opina que estos suplementos nutricionales son un complemento terapéutico necesario para el tratamiento dietético. Esta posición coincide con la opinión de los expertos internacionales y las revisiones presentadas en el presente dictamen preliminar. CONCLUSIÓN: Con respecto a lo expuesto previamente, el equipo técnico del IETSI valoró los siguientes aspectos: i) La HT-1 es una enfermedad hereditaria, infrecuente, que afecta la calidad de vida del paciente desde edades muy tempranas y está asociada a una alta mortalidad si no es tratada adecuadamente ii) En el contexto de EsSalud existe un vacío terapéutico para la población objetivo, iii) Aunque la evidencia disponible actualmente es limitada, algunas guías mencionan el uso de suplementos nutricionales libres de tirosina y fenilalanina. Además, su uso cuenta con plausibilidad biológica, lo cual va en línea con lo recomendado por el experto clínico. Por todo lo mencionado, el Instituto de Evaluaciones de Tecnologías en Salud e Investigación ­ IETSI, aprueba el uso de suplementos libres de tirosina y fenilalanina para el manejo de pacientes menores de 18 años, con diagnóstico de HT-1, según lo establecido en el Anexo N° 1 La vigencia del presente dictamen preliminar es de dos años a partir de la fecha de publicación. Así, la continuación de dicha aprobación estará sujeta a la evaluación de los resultados obtenidos y de nueva evidencia que pueda surgir en el tiempo.

Dietary Considerations in Tyrosinemia Type I.

Since the introduction of 2-(2 nitro-4-3 trifluoro-methylbenzoyl)-1, 3-cyclohexanedione (NTBC), life expectancy of HT1 patients greatly improved. However, due to treatment with NTBC, tyrosine concentrations greatly increase. As a consequence to possible neurocognitive problems, the main objective of dietary therapy in HT1 is to provide adequate nutrition allowing normal growth and development while strictly controlling tyrosine levels in blood (and tissues). Although no well-defined target levels exist, tyrosine concentrations below 400 µmol/L are considered to be safe. To achieve this aim a diet restricted in natural protein and supplemented with a special tyrosine and phenylalanine-free amino acid mixture is necessary.Dietary management could be strenuous at diagnosis due to several different problems. If vomiting and diarrhea are a major issue at diagnosis, frequent feeding with additional energy from low protein food is needed for catch-up growth. Initiation of dietary treatment is usually easier if diagnosis is directly after birth. Based on newborn screening when infants are still reasonable healthy. If presenting clinically infants may experience serious difficulties in taking the amino acid mixtures probably due to feeding problems while when presenting after some 2-3 months taste development and the difference in the taste of amino acid mixtures compared to regular formula and breast milk increase difficulties with the treatment.Following a dietary treatment is even harder than taking some medicine. Older children and adolescents often relax the diet and at some age become reluctant to stick to a strict regimen. Therefore, adequate training and information should be given to the patients and the family at regular intervals. To achieve this, a multidisciplinary approach involving pediatricians/physicians, dieticians, psychologists and social workers is an asset for the care of patients with HT1.

Remaining Challenges in the Treatment of Tyrosinemia from the Clinician's Viewpoint.

This chapter provides a clinical perspective on the challenges that stand between current clinical practice and a cure for hepatorenal tyrosinemia (HT1). HT1 has been transformed in the last 50 years from an aggressive often undiagnosed childhood disease causing liver failure or liver cancer, with infant death in most patients, to a condition that is detectable at birth, and for which treatment with nitisinone (NTBC) and diet can prevent detectable liver or kidney abnormalities. What challenges remain? The properties of the affected metabolic pathway and the broad spectrum of severity seen in untreated patients are incompletely understood but potentially important for patients. Available treatments have potential complications, including liver transplantation (risks of surgery and of immunosuppression to prevent rejection), nitisinone and diet therapy (hypertyrosinemia, corneal opacities, nutritional imbalances and possibly developmental delay). The detection of liver cancer is imperfect and laborious. The effects of tyrosinemia during pregnancy are little-known. Although animal models of HT1 are becoming standard research tools in cell replacement and gene modification therapy, these techniques are not currently applicable to HT1 itself. Treatment adherence is variable, causing concern about long term outcome for some patients. Around the world, there are great disparities in the diagnosis and treatment of HT1. Most affected individuals are born in places where newborn screening for HT1 is not performed and where appropriate treatment is not available. We hope that this list will help to focus on some of these remaining obstacles to a cure for HT1.

Tyrosinemia type II: Mutation update, 11 novel mutations and description of 5 independent subjects with a novel founder mutation.

BACKGROUND: Tyrosinemia type II, also known as Richner-Hanhart Syndrome, is an extremely rare autosomal recessive disorder, caused by mutations in the gene encoding hepatic cytosolic tyrosine aminotransferase, leading to the accumulation of tyrosine and its metabolites which cause ocular and skin lesions, that may be accompanied by neurological manifestations, mostly intellectual disability. AIMS: To update disease-causing mutations and current clinical knowledge of the disease. MATERIALS AND METHODS: Genetic and clinical information were obtained from a collection of both unreported and previously reported cases. RESULTS: We report 106 families, represented by 143 individuals, carrying a total of 36 genetic variants, 11 of them not previously known to be associated with the disease. Variants include 3 large deletions, 21 non-synonymous and 5 nonsense amino-acid changes, 5 frameshifts and 2 splice variants. We also report 5 patients from Gran Canaria, representing the largest known group of unrelated families sharing the same P406L mutation. CONCLUSIONS: Data analysis did not reveal a genotype-phenotype correlation, but stressed the need of early diagnosis: All patients improved the oculocutaneous lesions after dietary treatment but neurological symptoms prevailed. The discovery of founder mutations in isolated populations, and the benefits of early intervention, should increase diagnostic awareness in newborns.

An unfortunate challenge: Ketogenic diet for the treatment of Lennox-Gastaut syndrome in tyrosinemia type 1.

The ketogenic diet is an evidence-based treatment for resistant epilepsy including Lennox-Gastaut syndrome. This diet is based on low carbohydrate-high fat intakes. Dietary treatment is also therapeutic for inborn errors of metabolism such as aminoacdiopathies. We report a child with both Lennox-Gastaut syndrome and tyrosinemia type 1. This epilepsy syndrome resulted form a porencephalic cyst secondary to brain abscesses that occurred during the management of malnutrition due to untreated tyrosinemia type 1. We used a ketogenic diet as treatment for Lennox-Gastaut syndrome taking into account dietary requirements for tyrosinemia type 1. The patient was transiently responder during a 6-month period. This report illustrates that ketogenic diet remains a therapeutic option even when additional dietary requirements are needed.

In vivo confocal microscopic features of corneal pseudodendritic lesions in tyrosinemia type II.

PURPOSE: To report the clinical and in vivo confocal microscopic (IVCM) findings of corneal deposits in a patient with tyrosinemia type II. METHODS: The pretreatment and 1-month posttreatment slit-lamp examination and IVCM findings of a patient with tyrosinemia type II are described. RESULTS: A 12-year-old girl diagnosed with tyrosinemia type II was evaluated for photophobia and bilateral ocular discomfort of 1-year duration. The patient had been placed on topical acyclovir treatment with the diagnosis of recurrent bilateral herpetic keratitis during the previous 12 months. Slit-lamp examination revealed bilateral dendritiform epithelial lesions in the central cornea, which stained poorly with fluorescein. IVCM highlighted multiple hyperreflective linear crystalline deposits at the level of superficial epithelium. One month after discontinuation of acyclovir treatment and initiation of a protein-restricted diet therapy, improvement in the patient's symptoms and regression of corneal epithelial lesions was noted. Reduction in the extent of corneal deposits was also confirmed with IVCM. CONCLUSIONS: Corneal involvement, secondary to hereditary tyrosinemia type II, is characterized by pseudodendritic epithelial lesions on slit-lamp examination and hyperreflective linear deposits in the superficial epithelium using IVCM. These lesions may regress expeditiously with a low-protein diet. IVCM may be a useful tool in the differential diagnosis of this disorder by highlighting the crystalline structures in the superficial epithelial layers and also in evaluating the response to the treatment in patients with tyrosinemia type II.

Tyrosinemia: a report of three cases from India.

Tyrosinemia has rarely been reported from India due to lack of diagnostic facilities. We present three children, two boys and one girl, who presented with rickets and hepatomegaly. They had increased plasma and urine tyrosine levels, renal tubular acidosis, large kidneys, elevated urine succinylacetone, and chronic liver disease. Two patients also had elevated alpha-fetoprotein but no evidence of hepatocellular carcinoma. All patients are on low tyrosine-phenylalanine diet and on regular follow up.

Recommendations for the management of tyrosinaemia type 1.

The management of tyrosinaemia type 1 (HT1, fumarylacetoacetase deficiency) has been revolutionised by the introduction of nitisinone but dietary treatment remains essential and the management is not easy. In this review detailed recommendations for the management are made based on expert opinion, published case reports and investigational studies as the evidence base is limited and there are no prospective controlled studies.The added value of this paper is that it summarises in detail current clinical knowledge about HT1 and makes recommendations for the management.

Corneal depositions in tyrosinaemia type I during treatment with Nitisinone.

We present a 17-year-old boy, diagnosed with tyrosinaemia type I at an age of 7 months, with new complaints of severe intermittent photophobia and burning eyes. His tyrosinaemia type I is treated with nitisinone and a protein-restricted diet. Dietary compliance is low since he entered puberty. His ocular complaints are attributable to subepithelial corneal deposits, resembling the common corneal phenotype of tyrosinaemia type II. Serum tyrosine levels were markedly elevated. Tyrosinaemia is a metabolic disease of tyrosine metabolism, subdivided into two types. Corneal deposits and photophobia are cardinal features of untreated tyrosinaemia type II, but not of type I. Novel treatment strategies (with nitisinone) for type I tyrosinaemia lead to a phenotype comparable with type II, including these corneal deposits. At follow-up visits his ocular complaints unfortunately remained unchanged, though he states his dietary compliance improved through the years.

Behavioral and intellectual functioning in patients with tyrosinemia type I.

INTRODUCTION: In tyrosinemia type I (TT1) increased level of tyrosine and phenylalanine (both precursors of neurotransmitters), may potentially influence patients' cognitive development. AIM OF THE STUDY: Was to evaluate if the children during the treatment with phenylalanine- and tyrosine-restricted diet and nitisinone present with cognitive, emotional or behavioral problems and to find out whether plasma tyrosine and phenylalanine levels may have impact on this. MATERIAL AND METHODS: Cognitive development and behavior, together with plasma tyrosine and phenylalanine levels, were analyzed in eight patients during their first five years of nitisinone treatment. Psychological examination has been done using standard diagnostic methods: the Wechsler Intelligence Scale for Children (WISC-R) and Child Behavior Checklist CBCL/4-18 (parents version). RESULTS: The results showed that in the patients with TT1, attention deficit is not rare, and may be connected with the variation of the plasma tyrosine level. Moreover the reverse correlation between attention deficit and results from verbal scale may suggest decreased ability to verbal reasoning, comprehension, verbal expression and school difficulties. CONCLUSIONS: What is significant for the presence of attention disorders and the related difficulties in using the intellectual potential is not the level of tyrosine (high vs. low), but its changes (stability vs. instability). Therapeutic trials to stabilize the tyrosine level could alleviate the difficulties in focusing attention. Following a diet is necessary for keeping the normal level of tyrosine.

Tyrosinemia Type III detected via neonatal screening: management and outcome.

Tyrosinemia Type III is caused by the deficiency of 4-hydroxyphenylpyruvate dioxygenase (4-HPPD), an enzyme involved in the catabolic pathway of tyrosine. To our knowledge, only a few patients presenting with this disease have been described in the literature, and the clinical phenotype remains variable and unclear. We report the case of a boy with tyrosinemia Type III detected using neonatal screening, who is homozygous for the splice donor mutation IVS11+1G>A in intron 11 of the HPD gene. At the age of 30 months, the boy's outcome under mild protein restriction was characterized by normal growth and psychomotor development.