Estudio epidemiológico de las enfermedades metabólicas con homocistinuria en España / Epidemiological study of the metabolic diseases with homocystinuria in Spain

Objetivos: Conocer la prevalencia en España de los diferentes errores congénitos del metabolismo que presentan homocistinuria y establecer las medidas oportunas para garantizar su prevención, diagnóstico y tratamiento, en aquellos casos posibles. Material y métodos: En abril 2009 se realizó una encuesta nacional de carácter transversal mediante cuestionario enviado a 35 centros, en los que se atiende a pacientes infantiles y adultos. La finalidad de la encuesta era establecer la prevalencia en ese momento recogiendo el histórico de pacientes que cada centro tuviera documentados. Resultados: A través de los cuestionarios respondidos por 25 médicos de 16 centros, se han identificado 75 pacientes: 41 defectos de transulfuración (uno fallecido), 27 de remetilación (6 fallecidos) y 7 sin diagnóstico etiológico definitivo. La edad de diagnóstico muestra una amplia variación, en 18 casos había más de un hermano afectado. Las manifestaciones clínicas más graves inciden en el grupo de los pacientes afectados de trastornos de la remetilación. Destaca el alto porcentaje de déficit cognitivo, seguido de la patología de cristalino; casi la mitad de los pacientes presentan trastornos neurológicos, es elevada la afectación vascular en los adultos con deficiencia de CBS; las opciones terapéuticas más utilizadas han sido el ácido fólico, la hidroxicobalamina y la betaína. Conclusiones: A la vista de estos resultados, y en especial del escaso número de deficiencias de CBS detectadas, se concluye la necesidad de implantar el cribado neonatal para la homocistinuria clásica y asegurar la puesta en marcha del proceso diagnóstico oportuno en todos los pacientes de riesgo(AU)

Objectives: To determine the prevalence of homocystinuria in Spain and to establish the measures and mechanisms to ensure its prevention, diagnosis and treatment. Material and methods: A national cross-sectional survey was conducted by means of a questionnaire sent to 35 hospitals in which children and adult patients are treated. Results: Using the questionnaires submitted by 25 physicians from 16 centres, 75 patients were identified: 41 transsulphuration defects (one deceased), 27 remethylation (six deaths) and 7 without a syndromic diagnosis. The age at diagnosis varied widely, and 18 cases had more than one sibling affected. The more severe clinical manifestations involved the patients with remethylation defects. There was a high percentage of cognitive impairment, followed by lens diseases. Almost half of the patients had neurological disorders. There was increased vascular involvement in CBS-deficient adults. The therapeutic options most used were, folic acid, hydroxycobalamin and betaine. Conclusions: In view of these results and especially the small number of CBS deficiencies detected, we conclude that there is a need to introduce newborn screening for classical homocystinuria and ensure implementation of an appropriate diagnostic workup in all patients at risk(AU)

[Epidemiological study of the metabolic diseases with homocystinuria in Spain]. / Estudio epidemiológico de las enfermedades metabólicas con homocistinuria en España.

OBJECTIVES: To determine the prevalence of homocystinuria in Spain and to establish the measures and mechanisms to ensure its prevention, diagnosis and treatment. MATERIAL AND METHODS: A national cross-sectional survey was conducted by means of a questionnaire sent to 35 hospitals in which children and adult patients are treated. RESULTS: Using the questionnaires submitted by 25 physicians from 16 centres, 75 patients were identified: 41 transsulphuration defects (one deceased), 27 remethylation (six deaths) and 7 without a syndromic diagnosis. The age at diagnosis varied widely, and 18 cases had more than one sibling affected. The more severe clinical manifestations involved the patients with remethylation defects. There was a high percentage of cognitive impairment, followed by lens diseases. Almost half of the patients had neurological disorders. There was increased vascular involvement in CBS-deficient adults. The therapeutic options most used were, folic acid, hydroxycobalamin and betaine. CONCLUSIONS: In view of these results and especially the small number of CBS deficiencies detected, we conclude that there is a need to introduce newborn screening for classical homocystinuria and ensure implementation of an appropriate diagnostic workup in all patients at risk.

Long-chain polyunsaturated fatty acid concentration in patients with inborn errors of metabolism.

INTRODUCTION: Long-chain polyunsaturated fatty acid (LCPUFA) can be provided by diet (fatty fish, eggs, viscera and human milk) or synthetised from essential fatty acids linoleic and α-linolenic acids through the microsomal pathway. However, endogenous LCPUFA synthesis is rather low, especially for docosahexaenoic (DHA), and seems insufficient to achieve normal DHA values in individuals devoid of preformed dietary supply. Inborn errors of metabolism (IEMs) are therefore diseases with a special risk for LCPUFA deficient status. AIM: Our aim was to evaluate LCPUFA status in 132 patients with different IEMs. METHODS: We performed a cross-sectional study of plasma and erythrocyte LCPUFA composition of 63 patients with IEMs treated with protein-restricted diets compared with data from 69 patients with IEMs on protein-unrestricted diets, and 43 own reference values. RESULTS: Erythrocyte and plasma DHA and arachidonic acid concentrations were significantly decreased in patients treated with protein-restriction compared with those on protein-unrestricted diets and with our reference values (p < 0.0001). In the protein-restricted group, 45% of patients showed decreased erythrocyte and plasma DHA values (only 7% and 10%, respectively in the protein-unrestricted group) (p < 0.0001). Erythrocyte and plasma DHA values correlated with the natural protein intake in patients on protein-restriction (r = 0.257; p = 0.045; r = 0.313; p = 0.014, respectively). CONCLUSION: Plasma and erythrocyte DHA concentrations are decreased in patients with IEMs treated with protein restriction. DHA concentration correlates with the patients' protein intake. Supplementation of patients with LCPUFA would have a beneficial influence on their nutritional status.

Assessment of plasma ammonia and glutamine concentrations in urea cycle disorders.

OBJECTIVES: To analyze the association between ammonia and glutamine used for metabolic control in inherited urea cycle disorders (UCD) in a large series of patients. DESIGN AND METHODS: Paired plasma amino acid-ammonia data from 26 UCD patients were analyzed (n=921). RESULTS: Increased plasma glutamine values were consistently observed in UCD patients, despite normal plasma ammonia concentrations, especially for mitochondrial UCD. CONCLUSIONS: Further therapeutic efforts are probably needed to control increased glutamine values, considering their potentially neurotoxic effect.

Long-chain polyunsaturated fatty acid concentration in patients with inborn errors of metabolism / Concentración de ácidos grasos poliinsaturados de cadena larga en pacientes con errores innatos del metabolismo

Introduction: Long-chain polyunsaturated fatty acid (LCPUFA) can be provided by diet (fatty fish, eggs, viscera and human milk) or synthetised from essential fatty acids linoleic and α-linolenic acids through the microsomal pathway. However, endogenous LCPUFA synthesis is rather low, especially for docosahexaenoic (DHA), and seems insufficient to achieve normal DHA values in individuals devoid of preformed dietary supply. Inborn errors of metabolism (IEMs) are therefore diseases with a special risk for LCPUFA deficient status. Aim: Our aim was to evaluate LCPUFA status in 132 patients with different IEMs. Methods: We performed a cross-sectional study of plasma and erythrocyte LCPUFA composition of 63 patients with IEMs treated with protein-restricted diets compared with data from 69 patients with IEMs on protein-unrestricted diets, and 43 own reference values. Results: Erythrocyte and plasma DHA and arachidonic acid concentrations were significantly decreased in patients treated with protein-restriction compared with those on protein-unrestricted diets and with our reference values (p < 0.0001). In the protein-restricted group, 45% of patients showed decreased erythrocyte and plasma DHA values (only 7% and 10%, respectively in the protein-unrestricted group) (p < 0.0001). Erythrocyte and plasma DHA values correlated with the natural protein intake in patients on protein-restriction (r = 0.257; p = 0.045; r = 0.313; p = 0.014, respectively). Conclusion: Plasma and erythrocyte DHA concentrations are decreased in patients with IEMs treated with protein restriction. DHA concentration correlates with the patients' protein intake. Supplementation of patients with LCPUFA would have a beneficial influence on their nutritional status (AU)

Introducción: Los ácidos grasos poliinsaturados de cadena larga (LCPUFA) pueden ser suministrados por la dieta o sintetizados a partir de los ácidos grasos esenciales, linoleico y α-linolénico. La síntesis endógena de LCPUFA es escasa, especialmente la de ácido docosahe-xaenoico (DHA), e insuficiente para alcanzar los valores normales de DHA en individuos que carecen de un suministro dietético de dichos ácidos preformados. Por ello, los errores innatos del metabolismo (IEM) son enfermedades con riesgo especial de deficiencia de LCPUFAs. Objetivos: Evaluar el estado de LCPUFA en 132 pacientes con diferentes IEMs. Métodos: Estudio transversal de LCPUFA en plasma y eritrocitos de 63 pacientes con IEMs tratados con dieta restringida en proteínas comparados con 69 pacientes con IEMs con una dieta libre y 43 valores de referencia. Resultados: Las concentraciones de DHA y ácido ara-quidónico en plasma y eritrocitos se hallaron disminuidas en pacientes con restricción proteica comparados con pacientes con dieta libre y valores de referencia (p < 0,0001). El 45% de pacientes con restricción proteica mostró un descenso de DHA en plasma y eritrocitos (solo un 7% y un 10%, respectivamente en aquellos con dieta libre) (p < 0,0001). Los valores de DHA en eritrocitos y plasma correlacionaron con la ingesta de proteínas naturales en pacientes con restricción proteica (r = 0,257; p = 0,045; r = 0,313; p = 0,014, respectivamente). Conclusión: Las concentraciones de DHA en plasma y eritrocitos se hallaron descendidas en pacientes con IEMs con restricción proteica, correlacionando con la ingesta proteica de los pacientes. La suplementación de dichos pacientes con LCPUFA podría ser beneficiosa para su estado nutricional (AU)

Quality of dietary control in phenylketonuric patients and its relationship with general intelligence.

OBJECTIVES: Assessment of the quality of dietary treatment of phenylketonuria (PKU) patients and investigation of its relationship with the general intelligence of the patients. METHODS: Cross-sectional and longitudinal study of 105 PKU treated patients. The index of dietary control (IDC) was calculated as the phenylalanine (Phe) data reduction in half-year medians and the mean of all medians throughout the patient's life. We calculated four different IDCs related to age: IDC-A (< 6 years), IDC-B (6-12 years), IDC-C (13-18 years) and IDC-D (> 18 years). To evaluate the fluctuation of Phe values we calculated the standard error of the estimate of the regression of Phe concentration over age. Development quotient was calculated with the Brunet-Lezine test (< 4 years). Intelligence quotient was evaluated with the Kaufman Bit Intelligence Test (K-Bit), Wechsler Intelligence Scale for Children-Revised (WISC-R) and Wechsler Adult Intelligence Scale Third Edition (WAIS III). RESULTS: Cross-sectional study: The IDC in age groups were significantly different and so were the number of patients with good, acceptable and poor IDC related to age (p < 0.001). Sampling frequency was good in 72, acceptable in 23 and poor in 10 patients. The general intelligence (101 +/- 10) correlated negatively with the IDC (p < 0.0001) and Phe fluctuations (p < 0.004). Longitudinal study: Significant differences were observed between the IDC through the patients' lifetime except in the adolescent/adult period. CONCLUSIONS: 85% of PKU patients showed good/acceptable quality of dietary control. General intelligence correlates with the IDC at all ages, which highlights the importance of good control to achieve good prognosis.

Cognitive functions in patients with phenylketonuria in long-term treatment with tetrahydrobiopterin.

Cognitive functions were assessed in 9 patients with mild to moderate phenylketonuria (PKU) ranging from 6 to 18 years of age, who were in long-term treatment (>5 years) with 5-9 mg/kg/day tetrahydrobiopterin (BH4) on compassionate use, provided by Schircks Inc. An extensive study of cognitive functions (intelligence quotient (IQ), visuospatial, visual memory, fine motor, executive and attentional functions) was conducted, and behavior was assessed using the ADHD Rating Scale and the Behavior Rating Inventory of Executive Function (BRIEF). All patients had normal IQ (M=107, SD=10). The most notable area of impairment was fine motor function, but no significant difference was found between the PKU patients in BH4 treatment who participated in the current study and PKU patients in dietary treatment who participated in a previous study. These results, however, should be interpreted with caution. It is necessary to conduct further studies with a larger number of patients, using more sensitive tests of motor function and using the formulation of BH4 that is currently available.

Quality of dietary control in phenylketonuric patients and its relationship with general intelligence / Calidad del control de la dieta en pacientes fenilcetonúricos y su relación con la inteligencia general

Objectives: Assessment of the quality of dietary treatment of phenylketonuria (PKU) patients and investigation of its relationship with the general intelligence of the patients. Methods: Cross-sectional and longitudinal study of 105 PKU treated patients. The index of dietary control (IDC) was calculated as the phenylalanine (Phe) data reduction in half-year medians and the mean of all medians throughout the patient's life. We calculated four different IDCs related to age: IDC-A (< 6 years), IDC-B (6-12 years), IDC-C (13-18 years) and IDC-D (> 18 years). To evaluate the fluctuation of Phe values we calculated the standard error of the estimate of the regression of Phe concentration over age. Development quotient was calculated with the Brunet-Lezine test (< 4 years). Intelligence quotient was evaluated with the Kaufman Bit Intelligence Test (K-Bit), Wechsler Intelligence Scale for Children-Revised (WISC-R) and Wechsler Adult Intelligence Scale Third Edition (WAIS III). Results: Cross-sectional study: The IDC in age groups were significantly different and so were the number of patients with good, acceptable and poor IDC related to age (p < 0.001). Sampling frequency was good in 72, acceptable in 23 and poor in 10 patients. The general intelligence (101 ± 10) correlated negatively with the IDC (p < 0.0001) and Phe fluctuations (p < 0.004). Longitudinal study: Significant differences were observed between the IDC through the patients' lifetime except in the adolescent/adult period. Conclusions: 85% of PKU patients showed good/acceptable quality of dietary control. General intelligence correlates with the IDC at all ages, which highlights the importance of good control to achieve good prognosis (AU)

Objetivos: Evaluación de la calidad del control dietético en pacientes con fenilcetonuria (PKU) e investigación de su relacióncon el nivel de inteligencia. Métodos: Estudio transversal y longitudinal de 105 pacientes PKU en tratamiento dietético. El índice de control de la dieta (IDC) se ha calculado como la reducción de los valores de fenilalanina (Phe) a las medianas de cada 6 meses y la media de todas las medianas a lo largo de la vida del paciente. Se han calculado cuatro diferentes IDC según la edad: IDC-A (< 6 años), IDC-B (6-12 años), IDC-C (13-18 años) and IDC-D (> 18 años). Para evaluar las fluctuaciones de los valores de Phe hemos calculado el error estándar de la regresión estimada de la concentración de Phe según la edad. El índice de inteligencia se ha evaluado mediante el test de Brunet-Lezine (< 4 años) y el coeficiente de inteligencia mediante Kaufman Bit Intelligence Test (K-Bit), Wechsler Intelligence Scale for Children-Revised (WISC-R) y Wechsler Adult Intelligence Scale Third Edition (WAIS III). Resultados: Estudio transversal: El IDC en los diferentes grupos de edad es significativamente diferente y también lo son el número de pacientes con un IDC bueno, aceptable y malo en relación con la edad (p < 0,001). La frecuencia de controles de Phe fue buena en 72 pacientes, aceptable en 23 y mala en 10. La inteligencia general (101 ± 10) se correlaciona negativamente con el IDC (p < 0,0001) y con las fluctuaciones de Phe (p < 0,004). Estudio longitudinal: Se han observado diferencias significativas entre ICD a lo largo de la vida de los pacientes a excepción del período adolescencia/edad adulta. Conclusiones: El 85% de pacientes PKU mostraron una calidad del control de la dieta buena/aceptable. Los niveles de inteligencia general se correlacionan con el IDC en todas las edades, lo que muestra la importancia del buen control de la dieta para lograr un buen pronóstico (AU)

Tirosinemia tipo I: dos formas atípicas de presentación clínica / Tyrosinemia type I: two atypical forms of clinical presentation

Se exponen dos casos de tirosinemia tipo I con presentación atípica. El primero se inicia con crisis convulsivas secundarias a hipoglucemias graves. En el estudio metabólico para el diagnóstico de las hipoglucemias se detecta un perfil típico de tirosinemia tipo I en sangre y orina. El segundo caso fue un hallazgo casual en el contexto de un ingreso por bronquitis. Ambos casos siguen tratamiento con 2-(2-nitro-4-trifluorometilbenzoil}-1-3-ciclohexanediona( NTBC) en combinación con dieta con bajo contenido en proteínas naturales suplementas con fórmula especial sin tirosina ni fenilalanina. En la actua.lidad no presentan alteraciones clínico-analíticas ni complicaciones

The authors describe two cases of tyrosinemia type 1 with atypical clinical presentation. The first patient presented with refractory seizure secondary to hypoglycemic episodes. The metabolic study for the differential diagnosis of hypoglycemi, revealed a pattern suggestive of tyrosinemia type I. In the second patient the presence of tyrosinemia was detected during a hospital stayowing to bronchitis. In both cases, treatment with 2-(2-nitro-4, trifluoromethylbenzoyl)-1,3-cyclohexane(NTBC) combine (with a low protein diet supplemented with a tyrosine-and phenylalanine-free formula was prescribed. There have beenn no complications during the follow-up period in either case and, at the present time, the clinical and analytical findings are normal

Platelet serotonin concentrations in PKU patients under dietary control and tetrahydrobiopterin treatment.

Tetrahydrobiopterin (BH4) supplementation has been applied in PKU treatment, resulting in successful control of blood phenylalanine (Phe) concentrations. We evaluated serotonin status in PKU patients under classical dietary treatment (n = 40) and in a group of 11 PKU patients under BH4 treatment, both during a 6-month period. Platelet serotonin values were significantly lower in PKU patients under dietary treatment when compared with controls. A negative correlation was observed between plasma Phe and platelet serotonin concentrations (r = -0.367, p = 0.017) in PKU patients. Platelet serotonin concentration increased significantly after both 1 and 6 months of BH4 therapy when compared with baseline conditions (Wilcoxon test: p = 0.013 and p = 0.021, respectively), while no differences were observed when comparing plasma Phe concentrations at the different points. Our results indicate that PKU patients under classical treatment have decreased platelet serotonin concentrations, probably owing to continued high Phe values, while BH4 supplementation restored platelet serotonin values.

Two successful pregnancies in pyridoxine-nonresponsive homocystinuria.

Two successful pregnancies are reported in a pyridoxine-nonresponsive woman who was also homozygous for the MTHFR 677C>T polymorphism. Two healthy children were delivered, although there had also been an early miscarriage of an apparently normal fetus in another pregnancy. Management of the patient's homocystine and methionine levels was maintained throughout pregnancy and, in view of the increased thromboembolic risk, anticoagulation therapy was also included in management.

Plasma thiols and their determinants in phenylketonuria.

OBJECTIVE: Treatment of phenylketonuria (PKU) patients consists of a phenylalanine-restricted diet supplemented with a tyrosine-, vitamin- and oligoelement-enriched amino-acid mixture. Vitamins and oligoelements may be deficient when compliance with the supplemented special formula is poor. Plasma thiol concentrations (especially homocysteine) depend mainly on B-vitamin intake. Our aim was to evaluate the plasma thiol concentrations (homocysteine, cysteine and glutathione) and their determinants (methionine, cobalamin and folate) in PKU patients under dietary treatment compared with age-matched controls. DESIGN AND SETTING: Cross-sectional study performed in a tertiary care Hospital. SUBJECTS: PKU (42) patients under dietary treatment compared with 42 age-matched controls. INTERVENTIONS: Plasma total homocysteine, cysteine and glutathione were analyzed by HPLC with fluorescence detection. Plasma phenylalanine and methionine were analyzed by ion exchange chromatography. Serum folate and cobalamin were analyzed by radioimmunoassay procedures. RESULTS: Total homocysteine concentrations were significantly lower in the PKU patients compared with the control group (Students t-test; P<0.0001). Serum folate and cobalamin were significantly higher in the PKU group (t-Student; P<0.0001) compared with controls. A significantly negative correlation was observed between total homocysteine and folate (r=-0.378; P=0.016), and between cobalamin and phenylalanine concentrations (r=-0.367; P=0.022) in the PKU group. CONCLUSIONS: Plasma total homocysteine values are lower in the PKU group than in the controls, probably because of high folate values. High phenylalanine values, an indicator of poor dietary compliance, are negatively associated with cobalamin, which might be deficient in some cases.

Do adult patients with phenylketonuria improve their quality of life after introduction/resumption of a phenylalanine-restricted diet?

AIM: To evaluate the possible influence of dietary treatment on the quality of life of adult patients with PKU (phenylketonuria) following late introduction or resumption of a Phe-restricted diet. METHODS: Fifteen adult patients with classical PKU (10F, 5M; mean age: 27.5 y, range: 16.4-37.5 y) were selected for the study. These patients had either resumed a restricted diet after a period of discontinuation, or were placed on a restricted diet after late diagnosis. All of them were interviewed about their quality of life using a 24-item questionnaire. RESULTS: The index of dietary control was poor (median Phe: 954 micromol/L) in 8/15 patients, regular (Phe: 514 micromol/L) in 4/15 and good (Phe: 354 micromol/L) in 3/15 patients. Fifty-three percent of patients reported that their state of health was very good, 47% described it as good, and 40% felt that their present health on-diet was better than it had been off-diet; 53% believed that they were calmer, quieter and less easily upset and 40% were more alert and were more able to maintain attention while on-diet. Thirty-three percent of the patients felt happier, and 27% felt more vital; 20% thought that they were less impulsive and aggressive, and that they were now less argumentative than before. Sixty percent of the patients felt that their quality of life had improved on-diet compared with the situation off-diet. CONCLUSION: More than half of our patients believed that their quality of life improved with a Phe-restricted diet; they reported feeling calmer, quieter, and less easily upset. Only 47% attained regular to good dietary control.

New approach to osteopenia in phenylketonuric patients.

AIM: To study bone mineralization in a group of phenylketonuric patients and to search for a possible relationship between bone mineral density, dietary control, serum minerals and nutrition intake. The response to treatment with low-dose 1.25-(OH)2 vitamin D in patients with osteopenia was evaluated. METHODS: Twenty-eight phenylketonuric patients (age range: 10-33 y) on dietary treatment were investigated. Bone density at the lumbar spine (Dual Energy X-ray Absorptiometry), bone formation markers (osteocalcin and bone alkaline phosphatase), serum minerals, index of dietary control and protein, vitamin D and mineral intakes were determined. RESULTS: Of the patients studied, 78.6% had good dietary compliance (462 +/- 89 micromol/L). Mean protein, vitamin D and mineral intakes met the recommended dietary allowances (RDAs). Nevertheless, 8 patients had calcium intakes lower than 1000 g/d, and a positive correlation between Z-score and calcium (r = 0.585; p = 0.002) or phosphorus intake (r = 0.546; p = 0.005) was observed. Osteopenia was detected in 14 patients (50%). Moreover, bone alkaline phosphatase in phenylketonuric patients older than 18 y of age was significantly lower than that in controls (p < 0.0001). No correlation was found between bone mineral density, age, serum minerals, bone formation markers or index of dietary control. Treatment with 0.25 microg/d calcitriol significantly increased bone density in 6 patients. CONCLUSION: A defect in bone mineralization was detected in 50% of patients in our series. The correct amount of formula intake seems to be necessary for bone mineralization in phenylketonuric patients. Calcitriol can be a useful treatment for these patients, although more studies are needed to confirm these results. Hypercalcaemia and hypercalciuria need to be carefully monitored.

Phenotype and genotype heterogeneity in Mediterranean citrullinemia.

We summarize the diagnosis, outcome, and molecular studies of five Mediterranean patients with citrullinemia: four neonatal classical forms and one subacute form, who also suffers from Down syndrome and presented with severe hepatic encephalopathy at age 7. Mutational analysis revealed three alleles with a common mutation and five new mutations: two Moroccan siblings are homozygous for G390R, the subacute form is compound heterozygous for G390R/G117D (new mutation), and the two other neonatal forms are compound heterozygous for four new mutations: V69A/E270Q and T119I(R108L)/?.

Plasma phenylalanine is associated with decreased serum ubiquinone-10 concentrations in phenylketonuria.

Decreased serum ubiquinone-10 concentrations is a common condition in patients with phenylketonuria (PKU) under dietary treatment. Our aim was to investigate the implication of the metabolic abnormalities of PKU (low concentrations of tyrosine and high concentrations of phenylalanine) and the effect of treatment with phenylalanine-restricted diets in decreased ubiquinone-10 concentrations in PKU patients. We studied 30 PKU patients (age range 5 months to 35 years; median age 7 years) under dietary treatment. Correlation between plasma tyrosine or phenylalanine and serum ubiquinone-10 concentrations was investigated. Daily cholesterol intake was calculated from the data obtained through a dietary questionnaire. The index of dietary control (IDC) was calculated as the average of the medians of plasma phenylalanine concentrations obtained every 6 months in the metabolic control of patients. Negative correlations were observed between serum ubiquinone and the IDC (r=-0.46; p<0.01) in PKU patients. No correlation was observed between tyrosine or daily cholesterol intake and serum ubiquinone concentrations. After adjustment for daily cholesterol intake by multiple linear regression analysis, for each 113 units of increase in IDC values serum ubiquinone decreased 0.1 micromol/L. According to our results, the main factor associated with the decreased serum ubiquinone concentrations was high plasma phenylalanine values. Although daily cholesterol intake seems to be associated with ubiquinone concentrations, it may not be relevant if we take into account the low intake of cholesterol in treated PKU patients.

Is there a relationship between plasma phenylalanine and cholesterol in phenylketonuric patients under dietary treatment?

OBJECTIVES: To study the lipid profile in a group of treated phenylketonuric patients (PKU; n = 61) compared with a group of inborn error of intermediary metabolism patients (IEM; n = 22), a group of hyperphenylalaninemic children (HPA; n = 37), and a control group without dietary restriction (n = 41). DESIGN AND METHODS: Phenylalanine was analyzed by ion exchange chromatography and triglycerides, cholesterol and HDL were determined by standard procedures with the Cobas Integra analyzer. RESULTS: Serum total cholesterol concentrations were significantly lower in PKU patients compared with IEM patients (whose cholesterol daily intake was similar to those of PKU patients), HPA children and the control group. A negative correlation was observed between cholesterol and phenylalanine concentrations in the PKU patients. CONCLUSIONS: Our findings support the hypothesis of a relationship between high plasma phenylalanine levels and an inhibition of cholesterogenesis, although the low cholesterol intake of the special diets may also decrease serum cholesterol values.

Large de novo deletion in chromosome 12 affecting the PAH, IGF1, ASCL1, and TRA1 genes.

Phenylketonuria is one of the most common genetic diseases in humans, affecting 1 in 10,000 whites. Deletions are generally uncommon in genes in which no long highly homologous segments are present, and in phenylalanine hydroxylase (PAH) deficiency they represent only 5% of cases. We present the case of a girl affected by classical phenylketonuria who has been screened for mutations in the PAH gene. During the molecular study a large de novo deletion has detected in 12qter, including PAH, and the genes for insulin-like growth factor 1 (IGF1), human achaete-scute homolog 1 (ASCL1), and tumor rejection antigen (TRA1). The patient showed phenylketonuria, short stature, and pathological electro-oculography results in both eyes, with high affectation of the relative electrogenesis of the photoreceptor-pigment epithelium complex. She had previously been misdiagnosed as homozygous for the IVS8nt-7A-G mutation, instead of heterozygous for a mutation and a de novo deletion. As a result incorrect genetic counseling had been given. The deletion of the PAH, IGF1, and ASCL1 genes could explain the patient's phenotype corresponding to a contiguous gene syndrome. We stress the relevance of polymorphic marker haplotype analysis and the importance of family study in genetic recessive diseases, such as phenylketonuria, to avoid incorrect diagnosis and genetic counseling.