Neurocognitive functioning in adults with phenylketonuria: results of a long term study.

OBJECTIVES: A controlled long-term study was performed to assess the neurological and neuropsychological performance in adult patients with early-treated phenylketonuria (PKU). METHODS: We investigated 57 patients with early-treated classical PKU aged 19 to 41 years (mean age 31 years) and 46 matched healthy controls, matched for age and socioeconomic status. Patients and controls were assessed for their intelligence quotient (IQ), and attention and information-processing abilities. Magnetic resonance imaging (MRI) of the brain was performed in all patients. Neuropsychological assessments and MRI were repeated at a five-year-follow-up. RESULTS: In the five-year interval IQ, information processing and attention of patients and controls remained constant. At both assessment times the IQ scores were significantly lower in patients compared to controls. Older adult patients (>32 years) showed poorer information processing and attention at both assessment times compared to young adult patients (<32 years) and controls. IQ, information processing and attention showed no correlation to imaging results but were significantly correlated to blood phenylalanine (Phe) levels in patients' childhood and adolescence, and Phe levels had been higher in the adolescent years of older adult patients. CONCLUSIONS: Cognitive performance in adult patients with early-treated PKU does not seem to be subject to deterioration observable in a five-year interval. Neuropsychological assessment in adults with PKU revealed neurocognitive impairment particularly in older adult patients. This seems to refer to an early relaxation of diet that was recommended when the older patients were adolescents. Results indicate a benefit of dietary control during adolescence in PKU.

Dietary management of urea cycle disorders: European practice.

BACKGROUND: There is no published data comparing dietary management of urea cycle disorders (UCD) in different countries. METHODS: Cross-sectional data from 41 European Inherited Metabolic Disorder (IMD) centres (17 UK, 6 France, 5 Germany, 4 Belgium, 4 Portugal, 2 Netherlands, 1 Denmark, 1 Italy, 1 Sweden) was collected by questionnaire describing management of patients with UCD on prescribed protein restricted diets. RESULTS: Data for 464 patients: N-acetylglutamate synthase (NAGS) deficiency, n=10; carbamoyl phosphate synthetase (CPS1) deficiency, n=29; ornithine transcarbamoylase (OTC) deficiency, n=214; citrullinaemia, n=108; argininosuccinic aciduria (ASA), n=80; arginase deficiency, n=23 was reported. The majority of patients (70%; n=327) were aged 0-16y and 30% (n=137) >16y. Prescribed median protein intake/kg body weight decreased with age with little variation between disorders. The UK tended to give more total protein than other European countries particularly in infancy. Supplements of essential amino acids (EAA) were prescribed for 38% [n=174] of the patients overall, but were given more commonly in arginase deficiency (74%), CPS (48%) and citrullinaemia (46%). Patients in Germany (64%), Portugal (67%) and Sweden (100%) were the most frequent users of EAA. Only 18% [n=84] of patients were prescribed tube feeds, most commonly for CPS (41%); and 21% [n=97] were prescribed oral energy supplements. CONCLUSIONS: Dietary treatment for UCD varies significantly between different conditions, and between and within European IMD centres. Further studies examining the outcome of treatment compared with the type of dietary therapy and nutritional support received are required.

Propionic acidemia: neonatal versus selective metabolic screening.

BACKGROUND: Whereas propionic acidemia (PA) is a target disease of newborn screening (NBS) in many countries, it is not in others. Data on the benefit of NBS for PA are sparse. STUDY DESIGN: Twenty PA patients diagnosed through NBS were compared to 35 patients diagnosed by selective metabolic screening (SMS) prompted by clinical findings, family history, or routine laboratory test results. Clinical and biochemical data of patients from 16 metabolic centers in Germany, Austria, and Switzerland were evaluated retrospectively. Additionally, assessment of the intelligent quotient (IQ) was performed. In a second step, the number of PA patients who have died within the past 20 years was estimated based on information provided by the participating metabolic centers. RESULTS: Patients diagnosed through NBS had neither a milder clinical course regarding the number of metabolic crises nor a better neurological outcome. Among NBS patients, 63% were already symptomatic at the time of diagnosis, and <10% of all patients remained asymptomatic. Among all PA patients, 76% were found to be at least mildly mentally retarded, with an IQ <69. IQ was negatively correlated with the number of metabolic decompensations, but not simply with the patients' age. Physical development was also impaired in the majority of patients. Mortality rates tended to be lower in NBS patients compared with patients diagnosed by SMS. CONCLUSION: Early diagnosis of PA through NBS seems to be associated with a lower mortality rate. However, no significant benefit could be shown for surviving patients with regard to their clinical course, including the number of metabolic crises, physical and neurocognitive development, and long-term complications.

Mutation analysis in 54 propionic acidemia patients.

Deficiency of propionyl CoA carboxylase (PCC), a dodecamer of alpha and beta subunits, causes inherited propionic acidemia. We have studied, at the molecular level, PCC in 54 patients from 48 families comprised of 96 independent alleles. These patients of various ethnic backgrounds came from research centers and hospitals in Germany, Austria and Switzerland. The thorough clinical characterization of these patients was described in the accompanying paper (Grünert et al. 2012). In all 54 patients, many of whom originated from consanguineous families, the entire PCCB gene was examined by genomic DNA sequencing and in 39 individuals the PCCA gene was also studied. In three patients we found mutations in both PCC genes. In addition, in many patients RT-PCR analysis of lymphoblast RNA, lymphoblast enzyme assays, and expression of new mutations in E.coli were carried out. Eight new and eight previously detected mutations were identified in the PCCA gene while 15 new and 13 previously detected mutations were found in the PCCB gene. One missense mutation, p.V288I in the PCCB gene, when expressed in E.coli, yielded 134% of control activity and was consequently classified as a polymorphism in the coding region. Numerous new intronic polymorphisms in both PCC genes were identified. This study adds a considerable amount of new molecular data to the studies of this disease.

Glycogen storage disease type I and III and pyruvate carboxylase deficiency: results of long-term treatment with uncooked cornstarch.

Three patients with glycogen storage disease type I (GSD-I), three with glycogen storage disease type III (GSD-III) and one with pyruvate carboxylase deficiency (PCD) could be successfully switched over from continuous nocturnal gastric drip feeding (GDF) to nocturnal feeding with uncooked cornstarch in yoghurt or "quark" (CSF) at the age of 4-20 years. The new kind of therapy is much more convenient for the patients. When followed up to 30 months, patients on CSF showed the same clinical and laboratory findings as during the last two years with GDF. CSF was not introduced to three patients with GSD-I. Two of them refused the permanent starch-yoghurt meals. In the third patient the morning blood glucose concentrations were too variable.

[Treatment of phenylketonuria: wish and reality]. / Behandlung der Phenylketonurie: Wunsch und Wirklichkeit.

A diet strictly low in phenylalanine from soon after birth on can protect patients with phenylketonuria against intellectual and psychomotor retardation. Our study tries to answer the questions how the patients and their relations cope with the diet, and weather they reach the serum-phenylalanine-limits recommended by the German Association of Pediatric Metabolic Diseases in 1990.