A placebo-controlled trial of folic acid and betaine in identical twins with Angelman syndrome.

BackgroundAngelman syndrome (AS) is a neurodevelopmental disorder that is caused by maternal genetic deficiency of a gene that encodes E6-AP ubiquitin-protein ligase (gene symbol UBE3A) mapping to chromosome 15q11-q13. AS leads to stiff and jerky gait, excess laughter, seizures, and severe intellectual disability. In some parts of the brain, the paternally inherited UBE3A gene is subject to genomic imprinting by the action of the UBE3A-antisense transcript (UBE3A-ATS) on the paternally inherited allele. Consequently, only the maternally inherited UBE3A gene is expressed in mature neurons. AS occurs due to deletions of the maternal 15q11 - 13 region, paternal uniparental disomy (UPD), imprinting center defects, mutations in the maternal UBE3A gene, or other unknown genetic malfunctions that result in a silenced maternal UBE3A gene in the specific imprinted regions of the brain.ResultsA potential treatment strategy for AS is to increase methylation of UBE3A-ATS to promote expression of the paternal UBE3A gene and thus ameliorate the clinical phenotypes of AS. We treated two sets of male identical twins with class I deletions with a 1 year treatment trial of either betaine and folic acid versus placebo. We found no statistically significant changes in the clinical parameters tested at the end of the 1 year trial, nor did we find any significant adverse events.ConclusionsThis study tested the hypothesis that by increasing the methylation of the UBE3A-antisense transcript in Angelman syndrome to promote expression of the silenced paternal UBE3A gene we may ameliorate the clinical phenotypes of AS. We treated two sets of identical twins with placebo versus betaine and folic acid. Although this study represented a novel approach to treating Angelman syndrome, the differences in the developmental testing results was not significant. This paper also discusses the value of monozygotic twin studies in minimizing confounding variables and its utility in conducting small treatment studies.Trial registrationNCT00348933 . Registered 6 July 2006

Treatment adherence during childhood in individuals with phenylketonuria: Early signs of treatment discontinuation

Introduction: Phenylketonuria (PKU) is an autosomal recessive disorder characterized by a deficiency in phenylalanine (Phe) hydroxylase activity. Early diagnosis and continuous treatment with a low Phe diet prevents severe neurological and cognitive impairment. Aims 1. Analyze how treatment adherence evolves through infancy, childhood, and early adolescence in individuals with PKU. 2. Identify early signs of treatment discontinuation. Methodology This longitudinal, retrospective study included 75 children diagnosed through newborn screening, ages 7 to 13 years. Data on blood Phe concentration, number of blood samples sent, proportion of samples with Phe concentrations over the recommended range, and number of visits to the metabolism clinic were recorded. Logistic regression analysis was used to identify the variables that predict treatment discontinuation before 13 years of age. Results: A progressive increase in mean blood Phe concentrations with age was identified. The greatest increase occurred between the first and second years of life. By age ten, mean Phe blood concentration of the group was above the recommended range. The proportion of samples with Phe concentrations over the recommended range also increased with age, from an average of 13% during the first year of life to 67% in early adolescence. Sixty-eight percent of the children attended the outpatient clinic and sent samples from birth to the time of the study. Individuals who discontinued follow-up showed significantly higher mean blood Phe concentrations (360 vs. 220.9 μmol/L; p = 0.004) and the proportion of samples over the recommended range (37% vs. 12% p = 0.002) was significantly higher during the second year of life. Mean age for children who discontinued treatment was 5.5 years of age. Blood Phe concentration values at 12 to 23 months of age and at 6 to 8 years of age significantly predicted treatment discontinuation before 13 years of age. Conclusion: Treatment adherence in PKU diminishes with age. Early signs of treatment discontinuation can be identified during the second year of life, allowing preventive interventions in high risk groups

Psychosocial developmental milestones in men with classic galactosemia

Patients with classic galactosemia suffer from several long term effects of their disease. Research in a group of mainly female patients has shown that these patients may also have a developmental delay with regard to their social aptitude. To study if male galactosemia patients achieve psychosocial developmental milestones more slowly than male peers from the general Dutch population, we assessed their development with the Course of Life Questionnaire (CoLQ). A total of 18 male galactosemia patients participated in this study (response rate 69%): 11 Dutch patients and seven American patients. We found severe delays in the social and psychosexual scales of this questionnaire, but not on the autonomy axis. These results are comparable to an earlier study with a limited number of male patients. The observed delays could be secondary to less developed social skills, cognitive dysfunction, or disrupted language development. We strongly recommend screening of galactosemia patients for developmental delays, to ensure early intervention through social skills training

Long-term effects of medical management on growth and weight in individuals with urea cycle disorders

Low protein diet and sodium or glycerol phenylbutyrate, two pillars of recommended long-term therapy of individuals with urea cycle disorders (UCDs), involve the risk of iatrogenic growth failure. Limited evidence-based studies hamper our knowledge on the long-term effects of the proposed medical management in individuals with UCDs. We studied the impact of medical management on growth and weight development in 307 individuals longitudinally followed by the Urea Cycle Disorders Consortium (UCDC) and the European registry and network for Intoxication type Metabolic Diseases (E-IMD). Intrauterine growth of all investigated UCDs and postnatal linear growth of asymptomatic individuals remained unaffected. Symptomatic individuals were at risk of progressive growth retardation independent from the underlying disease and the degree of natural protein restriction. Growth impairment was determined by disease severity and associated with reduced or borderline plasma branched-chain amino acid (BCAA) concentrations. Liver transplantation appeared to have a beneficial effect on growth. Weight development remained unaffected both in asymptomatic and symptomatic individuals. Progressive growth impairment depends on disease severity and plasma BCAA concentrations, but cannot be predicted by the amount of natural protein intake alone. Future clinical trials are necessary to evaluate whether supplementation with BCAAs might improve growth in UCDs

Impact of false-positive newborn metabolic screening results on early health care utilization

Purpose: To analyze the association between false-positive newborn screening results and health care utilization. Methods: We surveyed parents regarding their children's health care utilization. Parents of children who received false-positive newborn screening results were primarily enrolled by a screening laboratory in Pennsylvania. Parents of children with normal results were recruited through the Massachusetts birth registry. We used bivariate tests and multivariate regression to assess the association between newborn screening results and primary care utilization, emergency room use, and hospitalization by age six months. Results: Our sample included 200 children with false-positive results and 137 with normal results. Variation in recruitment strategies led to sample children with false-positive results being more likely to be non-white, have unmarried parents and be of lower socioeconomic status. After adjusting for significant covariates, such as age, race and socioeconomic status, there were no significant associations between newborn screening results and child health care utilization. Conclusions: Despite the reported negative psychosocial effects of false-positive results, our study found no impact on early health care utilization. These results may assist in economic analyses of newborn screening as they suggest that medical costs associated with false-positive results are limited to the cost of diagnostic testing and follow-up

Biochemical markers and neuropsychological functioning in distal urea cycle disorders

Urea cycle disorders often present as devastating metabolic conditions, resulting in high mortality and significant neuropsychological damage, despite treatment. The Urea Cycle Disorders Longitudinal Study is a natural history study that collects data from regular clinical follow-up and neuropsychological testing. This report examines links between biochemical markers (ammonia, glutamine, arginine, citrulline) and primary neuropsychological endpoints in three distal disorders, argininosuccinic acid synthetase deficiency (ASD or citrullinemia type I), argininosuccinic acid lyase deficiency (ASA or ALD), and arginase deficiency (ARGD). Laboratory results and test scores from neuropsychological evaluations were assessed in 145 study participants, ages 3 years and older, with ASD (n = 64), ASA (n = 65) and ARGD (n = 16). Mean full scale IQ was below the population mean of 100 ± 15 for all groups: (ASD = 79 ± 24; ASA = 71 ± 21; ARGD = 65 ± 19). The greatest deficits were noted in visual performance and motor skills for all groups. While ammonia levels remain prominent as prognostic biomarkers, other biomarkers may be equally valuable as correlates of neuropsychological functioning. Cumulative exposure to the biomarkers included in the study proved to be highly sensitive indicators of neuropsychological outcomes, even when below the cut-off levels generally considered toxic. Blood levels of biomarkers obtained on the day of neuropsychological evaluations were not correlated with measures of functioning for any disorder in any domain. The importance of cumulative exposure supports early identification and confirms the need for well-controlled management of all biochemical abnormalities (and not just ammonia) that occur in urea cycle disorders

Newborn Screening and Treatment of Phenylketonuria: Projected Health Outcomes and Cost-Effectiveness

The objective of this study was to evaluate the cost-effectiveness of newborn screening and treatment for phenylketonuria (PKU) in the context of new data on adherence to recommended diet treatment and a newly available drug treatment (sapropterin dihydrochloride). A computer simulation model was developed to project outcomes for a hypothetical cohort of newborns with PKU. Four strategies were compared: (1) clinical identification (CI) with diet treatment; (2) newborn screening (NBS) with diet treatment; (3) CI with diet and medication (sapropterin dihydrochloride); and (4) NBS with diet and medication. Data sources included published literature, primary data, and expert opinion. From a societal perspective, newborn screening with diet treatment had an incremental cost-effectiveness ratio of $6400/QALY compared to clinical identification with diet treatment. Adding medication to NBS with diet treatment resulted in an incremental cost-effectiveness ratio of more than$16,000,000/QALY. Uncertainty analyses did not substantially alter the cost-effectiveness results. Newborn screening for PKU with diet treatment yields a cost-effectiveness ratio lower than many other recommended childhood prevention programs even if adherence is lower than previously assumed. Adding medication yields cost-effectiveness results unlikely to be considered favorable. Future research should consider conditions under which sapropterin dihydrochloride would be more economically attractive

Cognitive functioning in mild hyperphenylalaninemia

Background: Hyperphenylalaninemia is a hereditary metabolic disorder that causes elevated blood phenylalanine (Phe). Hyperphenylalaninemias are classified as Phenylketonuria PKU (Phe > 6 mg/dL) or mild hyperphenylalaninemia (mHPA) (Phe 2–6 mg/dL). This study examines the cognitive functioning of early diagnosed children with mHPA compared with early diagnosed and treated children with PKU. Sample and methods: Psychomotor development (BSID-II) at 12 and 36 months of age, and cognitive performance at 4 and 7 years of age (WPPSI and WISC-R), were assessed in 118 PKU and 97 mHPA patients. Cognitive profile analysis of WISC-R subscales in school age children was performed and results were compared between the two groups. Results: Both groups preformed within the average range. Scores were significantly higher in the mHPA group. The mean Mental Development Index (MDI) at 12 months of age was 98.1 in the mHPA group and 92.3 in the PKU group (p < 0.0002). At 36 months the MDI was 94.6 in the mHPA group and 84.7 in the PKU group (p = 0.0001. At age four years the mean Full Scale IQ was 106.5 (mHPA group) and 95.9 (PKU group) (p < 0.0001). At age seven years the mean Full Scale IQ was 100.9 (mHPA group) and 89.9 (PKU group) (p < 0.005). The pattern of deficits was similar in both groups, with relative weaknesses in working memory and attention. Conclusions: Children with mHPA achieved cognitive performance well within the average range and attained significantly higher scores than children with PKU. However, they appeared to have relative weaknesses in working memory and attention, similar to children with PKU