Evolution of maple syrup urine disease in patients diagnosed by newborn screening versus late diagnosis.

Maple syrup urine disease (MSUD) is a rare metabolic disorder for which the newborn screening (NBS) is possible but it has not been yet implemented for most Spanish regions. In the present study, we assess the clinical features and outcome of 14 MSUD Spanish patients with similar treatment protocol diagnosed either by NBS or by clinical symptoms. Eight patients were detected by NBS, four classic and four moderate MSUD. The average age at detection was 4.6 days, the mean plasmatic concentration of leucine at diagnosis was 1807 µM; the average number of days with leucine >1000 µM was 0.7 (0-4) and the mean number of total hospitalizations was 1.6 (0-5). Mean follow-up time was 70 months. They had good evolution: all remain asymptomatic, but 2 patients have attention deficit and hyperactivity disorder. Six patients with late diagnosis of classic MSUD were followed during 41 months. All presented with acute encephalopathy during the first month of life, mean leucine levels of 2355 µM, mean number of days with leucine >1000 µM of 6.6 (1-13) and mean number of total hospitalizations of 5.3 (4-7). Only two patients have a psychomotor development index in the lower limit (80 and 83). For all patients a good genotype-phenotype correlation was found and four novel mutations were identified: p.A311H, p.T84S, p.T397L, pL398P. Our study support that NBS improves prognosis of MSUD patients. But early diagnosis and an aggressive treatment together with a close monitoring of leucine levels improve neurological evolution in MSUD patients, even for those not detected by NBS.

Molecular epidemiology and BH4-responsiveness in patients with phenylalanine hydroxylase deficiency from Galicia region of Spain.

Knowledge of hyperphenylalaninemia (HPA) mutational spectrum in a population allows in many cases an accurate prediction of the phenotype and tetrahydrobiopterin (BH4) responsiveness, thus selecting an adequate treatment. In this work, we have performed the molecular characterization of 105 HPA patients from Galicia, in the northwest region of Spain, evaluating their phenotype and BH4 response. The mutational spectrum analysis showed 47 distinct mutations in 89 families, 37 of them (78.7%) corresponding to missense mutations. Six mutations account for 47.2% of all the investigated alleles, each one with a frequency ≥ 5% (IVS10-11G>A, p.R261Q, p.V388M, p.R176L, p.E280K, p.A300S). The most prevalent HPA mutations in Galicia are the common Mediterranean mutation IVS10-11G>A and p.R261Q, with frequencies of 13.8% and 10.5%, respectively. One novel mutation (p.K361Q; c.1081A>C) was also reported. Although a good genotype-phenotype correlation is observed, there is no exact correlation for some genotypes involving mutations p.R261Q, p.I65T or IVS10-11G>A. Forty seven patients were monitored for post-challenge BH4, establishing genotype-based predictions of BH4-responsiveness in all of them. All phenylketonuric patients with 2 nonresponsive mutations were unresponsive to BH4 and patients with mutations previously associated with BH4 responsiveness in the two alleles had a clear positive response to the test, with the exception of 5 patients with mutations p.R261Q, p.I65T and p.R68S. Our study supports a similar degree of heterogeneity of the HPA mutation spectrum in Galicia compared to reported data from Southern Europe. Patients carrying null mutations in both alleles showed the highest degree of concordance with the most severe phenotypes. Genotype is a good predictor of BH4 response.

Long-term pharmacological management of phenylketonuria, including patients below the age of 4 years.

BH4 therapy is an advancement in the treatment of phenylketonuria, reducing blood phenylalanine (phe) levels and increasing tolerance to natural proteins of responding patients. We report the results of 16 patients undergoing long-term BH4 treatment. Responding patients to BH4 was usually based on 24-h loading tests; a ≥30% decrease in blood phe was considered a positive response. Weekly loading made it possible to identify an additional "slow responder." The 16 responders constitute 24.6% of patients who completed the trial (87.5% of responders in mild hyperphenylalaninemia, 38.1% in mild PKU, and 2.8% in classical PKU).Mean dose of BH4 used was 9.75 ± 0.9 mg/kg per day, during a mean of 62 months. Age at treatment start was below 4 years in seven patients; five of which begun treatment during their first month since birth. All but one patient showed good treatment compliance; six continue on BH4 monotherapy without dietary phe restriction; six showed an increase in phe tolerance of 24-55%; and in the five patients who received treatment since the neonatal period an increase in phe tolerance following the phase of maximum growth has persisted. None of the patients showed side effects except one whom vomiting at the beginning of the treatment.Testing at the time of diagnosis in the neonatal period is very appropriate, and if there is a positive response, the patient can be treated with BH4 from onset with the advantage of being able to continue breast-feeding.

Hypermethioninaemia due to methionine adenosyltransferase I/III (MAT I/III) deficiency: diagnosis in an expanded neonatal screening programme.

The Expanded Newborn Screening Program (MS/MS) in the region of Galicia (NW Spain) was initiated in 2000 and includes the measurement of methionine levels in dried blood spots. Between June 2000 and June 2007, 140 818 newborns were analysed, and six cases of persistent hypermethioninaemia were detected: one homocystinuria due to cystathionine ß-synthase (CßS) deficiency, and five methionine adenosyltransferase I/III (MAT I/III) deficiencies. The five cases of MAT I/III deficiency represent an incidence of 1/28 163 newborns. In these five patients, methionine levels in dried blood spots ranged from 50 to 147 µmol/L. At confirmation of the persistence of the hypermethioninaemia in a subsequent plasma sample, plasma methionine concentrations were moderately elevated in 4 of the 5 patients (mean 256 µmol/L), while total homocysteine (tHcy) was normal; the remaining patient showed plasma methionine of 573 µmol/L and tHcy of 22.8 µmol/L. All five patients were heterozygous for the same dominant mutation, R264H in the MAT1A gene. With a diet not exceeding recommended protein requirements for their age, all patients maintained methionine levels below 300 µmol/L. Currently, with a mean of 2.5 years since diagnosis, the patients are asymptomatic and show developmental quotients within the normal range. Our results show a rather high frequency of hypermethioninaemia due to MAT I/III deficiency in the Galician neonatal population, indicating a need for further studies to evaluate the impact of persistent isolated hypermethioninaemia in neonatal screening programmes.

The tetrahydrobiopterin loading test in 36 patients with hyperphenylalaninaemia: evaluation of response and subsequent treatment.

The response to tetrahydrobiopterin (BH4) in patients with phenylalanine hydroxylase (PAH, EC 1.14.16.1) deficiency (OMIM 261600) has been widely reported. Here we report results of the BH4 loading test (20 mg/kg per day) in a group of 36 patients with PAH deficiency and phenotype of mild hyperphenylalaninaemia (HPA), mild phenylketonuria (PKU) or classic PKU. The patients ranged from neonates aged 7-15 days, detected in the Newborn Screening Programme for PKU in the population of Galicia (NW Spain), to adults aged up to 32 years who had been receiving a low-phenylalanine (Phe) diet for a period of years. Ten of the 36 patients showed a reduction of more than 30% in plasma Phe levels within 24 h of BH4 loading (ranging from 33.7% to 90.2%, mean 59.2%, SD 19.8%). All the patients with mild HPA (100%) showed a positive response; 57% of patients with mild PKU (4 of 7) showed a positive response. Of particular interest were positive responses in two patients with classic PKU, and in one patient with mutations of the phenylalanine hydroxylase (PAH) gene that have not to date been reported to be BH4-responsive (p.S303A and p.G46S). BH4 treatment (5-8 mg/kg per day) was commenced in 9 of the 10 BH4-responsive patients. The observed responses to treatment argue for application of the BH4 loading test in all patients with HPA or PKU, independently of genotype, phenotype or age.

[Mutation P28T in gene GK1 as the cause of a familial galactokinase deficiency]. / La mutación P28T del gen GK1 como causa de una deficiencia familiar de galactoquinasa.

OBJECTIVE/METHOD: To alert about galactokinase deficiency (GK) as a possible cause of infantile cataracts, and even presenile cataracts in heterozygous carriers. Diagnosis by enzyme and galactitol determination would lead to the introduction of a galactose-free diet which completely prevents the damage. RESULT/CONCLUSIONS: We report on a highly consanguineous Spanish family of gypsy ethnia, with three females of different sibships affected by GK deficiency. The deficiency was due to their homozygosis for mutation P28T in gene GK1. P28T mutation in european Romani gypsies, is also present in Spanish gypsies. It is important to bear in mind that GK deficiency may be an important cause of blindness in that endogamous group.

La mutación P28T del gen GK1 como causa de una deficiencia familiar de galactoquinasa / Mutation P28T in gene GK1 as the cause of a familial galactokinase deficiency

Objetivo/Método: Alertar sobre la deficiencia de galactoquinasa (GK), como posible causa de cataratas infantiles, e incluso cataratas preseniles en los heterozigotes portadores. El diagnóstico mediante determinación del enzima y del galactitol, permitiría la introducción de una dieta exenta de galactosa que previene totalmente el daño. Resultado/Conclusiones: Presentamos una familia española de etnia gitana con alto grado de consanguinidad con tres hembras, de fratrias distintas, afectas de deficiencia de GK. La deficiencia es debida a su homozigosis para la mutación P28T del gen GK1. P28T, con efecto fundador en gitanos Romani europeos, está también presente en los gitanos españoles. Por ello hay que tener en cuenta que la deficiencia de GK puede ser causa importante de ceguera en dicha población (AU)

Objective/Method: To alert about galactokinase deficiency (GK) as a possible cause of infantile cataracts, and even presenile cataracts in heterozygous carriers. Diagnosis by enzyme and galactitol determination would lead to the introduction of a galactose-free diet which completely prevents the damage. Result/Conclusions: We report on a highly consanguineous Spanish family of gypsy ethnia, with three females of different sibships affected by GK deficiency. The deficiency was due to their homozygosis for mutation P28T in gene GK1. P28T mutation in european Romani gypsies, is also present in Spanish gypsies. It is important to bear in mind that GK deficiency may be an important cause of blindness in that endogamous group (AU)

Continuous thin-layer chromatography of sugars of clinical interest in samples of urine impregnated on paper.

A procedure for the analysis of sugars of clinical interest in samples of urine impregnated on Whatman 3MM paper is described. The sugars are eluted from the sample and spotted directly on to the application zone of concentration-zone silica gel plates. followed by continuous development. The optimal composition of the eluent and developing solvent and the optimal development distance were established, together with the development time and its influence of the RF values. The locating reaction is based on the reduction of vanadium (V) to vanadium (IV) in acidic medium.