Combined malonic and methylmalonic aciduria due to ACSF3 mutations: Benign clinical course in an unselected cohort.

BACKGROUND: The clinical significance of combined malonic and methylmalonic aciduria due to ACSF3 deficiency (CMAMMA) is controversial. In most publications, affected patients were identified during the investigation of various complaints. METHODS: Using a cross-sectional multicenter retrospective natural history study, we describe the course of all known CMAMMA individuals in the province of Quebec. RESULTS: We identified 25 CMAMMA patients (6 months to 30 years old) with a favorable outcome regardless of treatment. All but one came to clinical attention through the Provincial Neonatal Urine Screening Program (screening on day 21 of life). Median methylmalonic acid (MMA) levels ranged from 107 to 857 mmol/mol creatinine in urine (<10) and from 8 to 42 µmol/L in plasma (<0.4); median urine malonic acid (MA) levels ranged from 9 to 280 mmol/mol creatinine (<5). MMA was consistently higher than MA. These findings are comparable to those previously reported in CMAMMA. Causal ACSF3 mutations were identified in all patients for whom genotyping was performed (76% of cases). The most common ACSF3 mutations in our cohort were c.1075G > A (p.E359K) and c.1672C > T (p.R558W), representing 38.2 and 20.6% of alleles in genotyped families, respectively; we also report several novel mutations. CONCLUSION: Because our province still performs urine newborn screening, our patient cohort is the only one free of selection bias. Therefore, the favorable clinical course observed suggests that CMAMMA is probably a benign condition, although we cannot exclude the possibility that a small minority of patients may present symptoms attributable to CMAMMA, perhaps as a result of interactions with other genetic or environmental factors.

Application of a policy framework for the public funding of drugs for rare diseases.

BACKGROUND: In many countries, decisions about the public funding of drugs are preferentially based on the results of randomized trials. For truly rare diseases, such trials are not typically available, and approaches by public payers are highly variable. In view of this, a policy framework intended to fairly evaluate these drugs was developed by the Drugs for Rare Diseases Working Group (DRDWG) at the request of the Ontario Public Drug Programs. OBJECTIVE: To report the initial experience of applying a novel evaluation framework to funding applications for drugs for rare diseases. METHODS: Retrospective observational cohort study. MEASURES: Clinical effectiveness, costs, funding recommendations, funding approval. KEY RESULTS: Between March 2008 and February 2013, eight drugs were evaluated using the DRDWG framework. The estimated average annual drug cost per patient ranged from 28,000 to 1,200,000 Canadian dollars (CAD). For five drugs, full evaluations were completed, specific funding recommendations were made by the DRDWG, and funding was approved after risk-sharing agreements with the manufacturers were negotiated. For two drugs, the disease indications were determined to be ineligible for consideration. For one drug, there was insufficient natural history data for the disease to provide a basis for recommendation. For the five drugs fully evaluated, 32 patients met the predefined eligibility criteria for funding, and five were denied based on predefined exclusion criteria. CONCLUSIONS: The framework improved transparency and consistency for evaluation and public funding of drugs for rare diseases in Ontario. The evaluation process will continue to be iteratively refined as feedback on actual versus expected clinical and economic outcomes is incorporated.

Toward a functional definition of a "rare disease" for regulatory authorities and funding agencies.

BACKGROUND: The designation of a disease as "rare" is associated with some substantial benefits for companies involved in new drug development, including expedited review by regulatory authorities and relaxed criteria for reimbursement. How "rare disease" is defined therefore has major financial implications, both for pharmaceutical companies and for insurers or public drug reimbursement programs. All existing definitions are based, somewhat arbitrarily, on disease incidence or prevalence. OBJECTIVES: What is proposed here is a functional definition of rare based on an assessment of the feasibility of measuring the efficacy of a new treatment in conventional randomized controlled trials, to inform regulatory authorities and funding agencies charged with assessing new therapies being considered for public funding. METHODS: It involves a five-step process, involving significant negotiations between patient advocacy groups, pharmaceutical companies, physicians, and public drug reimbursement programs, designed to establish the feasibility of carrying out a randomized controlled trial with sufficient statistical power to show a clinically significant treatment effect. RESULTS AND CONCLUSIONS: The steps are as follows: 1) identification of a specific disease, including appropriate genetic definition; 2) identification of clinically relevant outcomes to evaluate efficacy; 3) establishment of the inherent variability of measurements of clinically relevant outcomes; 4) calculation of the sample size required to assess the efficacy of a new treatment with acceptable statistical power; and 5) estimation of the difficulty of recruiting an adequate sample size given the estimated prevalence or incidence of the disorder in the population and the inclusion criteria to be used.

Changes in plasma and urine globotriaosylceramide levels do not predict Fabry disease progression over 1 year of agalsidase alfa.

PURPOSE: Globotriaosylceramide concentrations were assessed as potential predictors of change from baseline after 12 months by estimated glomerular filtration rate and left-ventricular mass index using pooled data from three randomized, placebo-controlled agalsidase alfa trials and open-label extensions of patients with Fabry disease. METHODS: Males (aged 18 years or older) with Fabry disease received agalsidase alfa (0.2 mg/kg every other week for 12 months). A backward-elimination approach evaluated potential predictors (baseline estimated glomerular filtration rate and left-ventricular mass index; age at first dose; baseline and change from baseline at 12 months of globotriaosylceramide (urine, plasma); urine protein excretion; and systolic and diastolic blood pressure). Subgroups included patients randomized to placebo or agalsidase alfa (double-blind phase), then to agalsidase alfa (open-label extensions; placebo→agalsidase alfa or agalsidase alfa→agalsidase alfa, respectively) and stage 2/3 chronic kidney disease patients. RESULTS: Baseline estimated glomerular filtration rate, age at first dose, baseline urine globotriaosylceramide excretion, and baseline and change from baseline urine protein excretion significantly predicted change from baseline estimated glomerular filtration rate in the analysis population (N = 73; all P<0.05), although not in all subgroups. Change from baseline urine and plasma globotriaosylceramide (baseline and change from baseline) concentrations did not predict change from baseline estimated glomerular filtration rate. No predictors of left-ventricular mass index were significant. CONCLUSION: Changes in globotriaosylceramide concentrations do not appear to be useful biomarkers for prediction of Fabry disease-related changes in estimated glomerular filtration rate or left-ventricular mass index.

Urinary globotriaosylsphingosine-related biomarkers for Fabry disease targeted by metabolomics.

Fabry disease is a lysosomal storage disorder caused by deficiency of α-galactosidase A, resulting in glycosphingolipid accumulation in organs and tissues, including plasma and urine. Two disease-specific Fabry biomarkers have been identified and quantified in plasma and urine: globotriaosylceramide (Gb(3)) and globotriaosylsphingosine (lyso-Gb(3)). The search continues for biomarkers that might be reliable indicators of disease severity and response to treatment. The main objective of this study was to target other urinary biomarkers using a time-of-flight mass spectrometry metabolomic approach. Urinary metabolites of 63 untreated Fabry patients and 59 controls were analyzed. A multivariate statistical analysis performed on a subset of male samples revealed seven novel Fabry biomarkers in urine, all lyso-Gb(3) analogues having modified sphingosine moieties. The empirical formulas of the sphingosine modifications were determined by exact mass measurements (- C(2)H(4), - C(2)H(4) + O, - H(2), - H(2) + O, + O, + H(2)O(2), + H(2)O(3)). We evaluated the relative concentration of lyso-Gb(3) and its seven analogues by measuring area counts for each analogue in all Fabry patients. All samples were normalized to creatinine. We found higher concentrations for males with Fabry disease compared to females. None of these biomarkers were detected in controls. To our knowledge, this is the first time that lyso-Gb(3)-related Fabry disease biomarkers are detected in urine.

An evaluation framework for funding drugs for rare diseases.

OBJECTIVES: For rare diseases it may be difficult to generate data from randomized trials to support funding of a drug. Enzyme replacement therapies for diseases of inherited metabolic enzyme deficiency provide an example of this dilemma. The Ontario Public Drug Programs convened the Drugs for Rare Diseases Working Group to develop a policy for assessing these drugs. METHODS: The Drugs for Rare Diseases Working Group developed terms of reference expecting that the ideal policy product would be transparent and consistent and address unique aspects of the treatment of a specific rare condition while being adaptable to other dissimilar conditions. The perspective was that of a public payer addressing requests for funding generated for a specific drug, and included respect for the principles of "accountability for reasonableness" of Daniels and Sabin. RESULTS: A seven-step framework was developed and tested by using the case study of idursulfase for mucopolysaccharidosis II (Hunter disease). Estimation of clinical effectiveness was done by using decision modeling. The model developed informed funding recommendations and ultimately led to an agreement with the manufacturer allowing funding of idursulfase in Ontario. CONCLUSIONS: This policy framework attempts to address the policy challenges of funding drugs for rare diseases. The framework will be used to assess other drugs in future and will inevitably require modification with experience. It is hoped that it may be of value to other policymakers.

Source document verification in the Mucopolysaccharidosis Type I Registry.

PURPOSE: The Mucopolysaccharidosis Type I (MPS I) Registry is an international observational database that tracks the natural history and the outcomes of patients with MPS I. The Registry was a regulatory requirement following the approval of laronidase enzyme replacement therapy for MPS I in 2003. All data are collected voluntarily after informed consent from the patient or family. Data are checked through queries, monthly reviews, and electronic audits to identify missing, inconsistent, or invalid data. This analysis sought to determine overall data accuracy in the Registry through source document verification (SDV). METHODS: Two phases of SDV were performed. In each phase, Registry data were compared against source documents at sites in Europe, Latin America, and North America. Three patients were randomly selected for SDV at each of the selected sites among all patients enrolled ≥18 months and ever receiving laronidase. Key parameters central to MPS I and its treatment were examined from the baseline and the last available assessments. RESULTS: Results indicate an overall source-to-database error rate in the MPS I Registry of 2.7% (47 discrepancies out of 1715 items; 95% confidence interval [2.2%, 3.5%]) in Phase 1 and 3.7% (64 discrepancies out of 1732 items; 95% confidence interval [2.9%, 4.7%]) in Phase 2. No systematic errors were found. CONCLUSIONS: The overall error rates in both phases of SDV demonstrate acceptable data accuracy in the MPS I Registry within the data fields that were assessed. Copyright © 2011 John Wiley & Sons, Ltd.

Systolic myocardial mechanics in patients with Anderson-Fabry disease with and without left ventricular hypertrophy and in comparison to nonobstructive hypertrophic cardiomyopathy.

OBJECTIVES: Anderson-Fabry disease (AFD) is a lysosomal storage disease, which can involve the heart, mimicking hypertrophic cardiomyopathy (HCM). The underlying mechanism of disease in AFD is an infiltrative, diffuse process, whereas HCM is a primary heart muscle condition with patchy distribution, which may prompt differences in myocardial mechanics. The aim of this study was to assess myocardial mechanics in AFD according to the presence of left ventricular hypertrophy (LVH) compared to nonobstructive HCM (NHCM) and healthy controls. METHODS AND RESULTS: We carried out a single-center, retrospective study in a small, genetically confirmed AFD cohort, which was divided into a subgroup with LVH (LVH+, n = 19), and without LVH (LVH-, n = 21). Comparison groups were healthy controls (n = 40) and NHCM patients (n = 19). Vector Velocity Imaging was applied to two-dimensional echocardiography studies for assessment of longitudinal strain (LS), circumferential strain (CS), and base-to-apex CS gradients. AFD LVH+ patients had lower global LS than AFD LVH- patients (-14 ± 4% vs -17 ± 3%, P < 0.05), but similarly lowered global CS (-24 ± 5% vs -22 ± 5%, P = ns). AFD LVH+ and NHCM had similarly lowered global LS compared to normals, but significantly lower global CS was observed in AFD LVH+ (-24 ± 5% vs -28 ± 4%, P < 0.05), whereas it was significantly increased in NHCM (-31 ± 2% vs -28 ± 4%, P < 0.05). Unlike NHCM, in both AFD subgroups, patients lost their normal base-to-apex CS gradient. CONCLUSIONS: AFD patients without LVH already show abnormal systolic myocardial mechanics. Relevant differences in myocardial mechanics between AFD patients with LVH compared to NHCM reflect the different underlying mechanisms of disease.

An open-label Phase I/II clinical trial of pyrimethamine for the treatment of patients affected with chronic GM2 gangliosidosis (Tay-Sachs or Sandhoff variants).

Late-onset GM2 gangliosidosis is an autosomal recessive, neurodegenerative, lysosomal storage disease, caused by deficiency of ß-hexosaminidase A (Hex A), resulting from mutations in the HEXA (Tay-Sachs variant) or the HEXB (Sandhoff variant) genes. The enzyme deficiency in many patients with juvenile or adult onset forms of the disease results from the production of an unstable protein, which becomes targeted for premature degradation by the quality control system of the smooth endoplasmic reticulum and is not transported to lysosomes. In vitro studies have shown that many mutations in either the α or ß subunit of Hex A can be partially rescued, i.e. enhanced levels of both enzyme protein and activity in lysosomes, following the growth of patient cells in the presence of the drug, pyrimethamine. The objectives of the present clinical trial were to establish the tolerability and efficacy of the treatment of late-onset GM2 gangliosidosis patients with escalating doses of pyrimethamine, to a maximum of 100 mg per day, administered orally in a single daily dose, over a 16-week period . The primary objective, tolerability, was assessed by regular clinical examinations, along with a panel of hematologic and biochemical studies. Although clinical efficacy could not be assessed in this short trial, treatment efficacy was evaluated by repeated measurements of leukocyte Hex A activity, expressed relative to the activity of lysosomal ß-glucuronidase. A total of 11 patients were enrolled, 8 males and 3 females, aged 23 to 50 years. One subject failed the initial screen, another was omitted from analysis because of the large number of protocol violations, and a third was withdrawn very early as a result of adverse events which were not drug-related. For the remaining 8 subjects, up to a 4-fold enhancement of Hex A activity at doses of 50 mg per day or less was observed. Additionally marked individual variations in the pharmacokinetics of the drug among the patients were noted. However, the study also found that significant side effects were experienced by most patients at or above 75 mg pyrimethamine per day. We concluded that pyrimethamine treatment enhances leukocyte Hex A activity in patients with late-onset GM2 gangliosidosis at doses lower than those associated with unacceptable side effects. Further plans are underway to extend these trials and to develop methods to assess clinical efficacy.

Efficient analysis of urinary glycosaminoglycans by LC-MS/MS in mucopolysaccharidoses type I, II and VI.

Mucopolysaccharidoses (MPSs) are complex storage disorders caused by specific lysosomal enzyme deficiencies, resulting in the accumulation of glycosaminoglycans (GAGs) in urine, plasma, as well as in various tissues. We devised and validated a straightforward, but accurate and precise tandem mass spectrometry methodology coupled to high performance liquid chromatography (LC-MS/MS) for the quantification of GAGs in urine. The method is applicable to the investigation of patients with MPS I, II, and VI, by quantifying dermatan sulfate (DS) and heparan sulfate (HS) in urine. We analyzed urine samples from 28 MPS patients, aged 1 to 42 years, and 55 control subjects (41 days to 18 years old). Levels of DS and HS in urine from healthy controls of all ages were below the limit of quantification. The levels of DS and HS in urine from 6 treated patients with MPS I were lower than in 6 untreated patients in DS (0.7-45 vs 9.3-177 mg/mmol creat) and HS (0-123 mg/mmol creatinine vs 38-418 mg/mmol creatinine); similar results were obtained for 9 patients with MPS II and 7 patients with MPS VI. Analyses were performed on as little as 250 µL of urine. Methanolysis took 75 min per sample; the total analysis run time for each LC-MS/MS injection was 8 min. Results indicate that the method is applicable to a wide variety of situations in which high accuracy and precision are required, including the evaluation of the effectiveness of existing and emerging treatments.

X-linked adrenoleukodystrophy: ABCD1 de novo mutations and mosaicism.

X-linked adrenoleukodystrophy (X-ALD) is a progressive peroxisomal disorder affecting adrenal glands, testes and myelin stability that is caused by mutations in the ABCD1 (NM_000033) gene. Males with X-ALD may be diagnosed by the demonstration of elevated very long chain fatty acid (VLCFA) levels in plasma. In contrast, only 80% of female carriers have elevated plasma VLCFA; therefore targeted mutation analysis is the most effective means for carrier detection. Amongst 489 X-ALD families tested at Kennedy Krieger Institute, we identified 20 cases in which the ABCD1 mutation was de novo in the index case, indicating that the mutation arose in the maternal germ line and supporting a new mutation rate of at least 4.1% for this group. In addition, we identified 10 cases in which a de novo mutation arose in the mother or the grandmother of the index case. In two of these cases studies indicated that the mothers were low level gonosomal mosaics. In a third case biochemical, molecular and pedigree analysis indicated the mother was a gonadal mosaic. To the best of our knowledge mosaicism has not been previously reported in X-ALD. In addition, we identified one pedigree in which the maternal grandfather was mosaic for the familial ABCD1 mutation. Less than 1% of our patient population had evidence of gonadal or gonosomal mosaicism, suggesting it is a rare occurrence for this gene and its associated disorders. However, the residual maternal risk for having additional ovum carrying the mutant allele identified in an index case that appears to have a de novo mutation is at least 13%.

Impact of measures to enhance the value of observational surveys in rare diseases: the Fabry Outcome Survey (FOS).

BACKGROUND: Disease registries are an important source of information on the natural history of rare diseases and the response to new therapies in a real-world setting. The value of the information, however, is directly related to the completeness of the data entered for each patient over the course of time. The Fabry Outcome Survey (FOS) is a Shire Human Genetic Therapies-sponsored, physician-directed registry of patients with Fabry disease, a rare, multisystem, lysosomal storage disorder, established in 2001. OBJECTIVE AND METHODS: In 2005, measures were introduced to improve the completeness of data capture, including a focus on centers with 20 or more patients enrolled in the FOS, concentration on a limited number of core variables (i.e., serum creatinine, urinary protein, left ventricular mass [echocardiography], blood pressure [systolic and diastolic], pain, quality of life, and other Fabry disease-related signs and symptoms, as well as height and weight) and the introduction of Clinical Project Associates (CPAs) to facilitate data management by participating treatment centers. RESULTS: An analysis of random samples of approximately 25% of patients in the registry in 2008 showed significant increases in data capture for most of the core variables examined. CONCLUSIONS: We conclude that the measures introduced in 2005 significantly improved the value of the information in the registry, which has contributed greatly to our understanding of patients' real-world experience with enzyme replacement therapy for Fabry disease.

An overview of L-2-hydroxyglutarate dehydrogenase gene (L2HGDH) variants: a genotype-phenotype study.

L-2-Hydroxyglutaric aciduria (L2HGA) is a rare, neurometabolic disorder with an autosomal recessive mode of inheritance. Affected individuals only have neurological manifestations, including psychomotor retardation, cerebellar ataxia, and more variably macrocephaly, or epilepsy. The diagnosis of L2HGA can be made based on magnetic resonance imaging (MRI), biochemical analysis, and mutational analysis of L2HGDH. About 200 patients with elevated concentrations of 2-hydroxyglutarate (2HG) in the urine were referred for chiral determination of 2HG and L2HGDH mutational analysis. All patients with increased L2HG (n=106; 83 families) were included. Clinical information on 61 patients was obtained via questionnaires. In 82 families the mutations were detected by direct sequence analysis and/or multiplex ligation dependent probe amplification (MLPA), including one case where MLPA was essential to detect the second allele. In another case RT-PCR followed by deep intronic sequencing was needed to detect the mutation. Thirty-five novel mutations as well as 35 reported mutations and 14 nondisease-related variants are reviewed and included in a novel Leiden Open source Variation Database (LOVD) for L2HGDH variants (http://www.LOVD.nl/L2HGDH). Every user can access the database and submit variants/patients. Furthermore, we report on the phenotype, including neurological manifestations and urinary levels of L2HG, and we evaluate the phenotype-genotype relationship.

A validated disease severity scoring system for Fabry disease.

Fabry disease is a lysosomal storage disorder with onset of adverse signs and symptoms usually during childhood and progressive life-threatening decline in organ functions. A validated and feasible Fabry disease severity scoring system (DS3) is needed to reliably quantify the disease burden, monitor disease progression and treatment response, and compare disease status among patient cohorts in clinical studies. We developed a new Fabry DS3 and tested its reliability and validity using a combination of expert consensus formation and statistical techniques. Relevant Fabry disease domains and items were identified, inclusion of items was refined and scaling of scores for individual assessments was optimized to maximize the correlation between the instrument's total score and the assigned clinical global impression of severity (CGI-S scores). Furthermore, the minimum clinically important difference in each of the instrument's domains was estimated and the DS3's quantitative content validity was judged. The current Fabry DS3 working model has 5 domains; 4 clinical domains (Peripheral Nervous System, Renal, and Cardiac, each with 3 items, Central Nervous System with 2 items) and a patient-reported domain (Patient-Reported domain with one item). The domain score is obtained by averaging the scores for all domain items. The Content Validity Index and Feasibility Index were shown to be good; 0.96 and 0.97, respectively. There was no significant inter-rater difference and the level of concordance was high. Correlation with the CGI-S was R(2)=0.89 indicating excellent criterion and construct (convergent) validity. In summary, initial estimations of validity, reliability and feasibility for the new Fabry DS3 instrument suggest that it is a feasible and reliable means of assessing disease severity and progression over time and comparing inter-patient severity of Fabry disease. Our results demonstrate that the Fabry DS3 correlates highly with the clinical assessment by Fabry disease experts.

Four-year prospective clinical trial of agalsidase alfa in children with Fabry disease.

OBJECTIVES: To investigate a 4-year prospective clinical trial of agalsidase alfa in children with Fabry disease, an X-linked metabolic disorder caused by a deficiency of the lysosomal enzyme alpha-galactosidase A. STUDY DESIGN: Seventeen (16 boys, 1 girl; age range, 7.3 to 18.4 years) of the 24 children who completed a 6-month, open-label agalsidase alfa study enrolled in a 3.5-year extension study that investigated the safety and potential efficacy of long-term treatment. All 17 patients completed the initial 6-month study, and 10 patients (9 boys) completed the extension study. RESULTS: Agalsidase alfa was well tolerated. In treated boys, there were sustained, statistically-significant improvements in the clinical features of Fabry disease, including reduced plasma globotriaosylceramide levels, reduced pain severity assessed by the Brief Pain Index, and improved heart rate variability. Mean urine globotriaosylceramide levels were reduced to normal range (P < .05 compared with baseline during 1.5 to 4 years). Kidney function and left ventricular mass indexed to height remained stable throughout. CONCLUSIONS: This clinical trial demonstrates that treatment with agalsidase alfa was well tolerated and associated with improvement of Fabry disease-related features.

Childhood onset of Scheie syndrome, the attenuated form of mucopolysaccharidosis I.

Scheie syndrome is the most attenuated and rarest form of mucopolysaccharidosis type I (MPS I), an inherited lysosomal storage disorder. Only small patient series have previously been reported. Using natural history data from the uniquely large population of 78 Scheie patients enrolled in the MPS I Registry, we characterized the onset and prevalence of clinical manifestations and explored reasons for delayed diagnosis of the disease. Median patient age was 17.5 years; 46% of the patients were male, and 88% were Caucasian. Of 25 MPS I-related clinical features, cardiac valve abnormalities, joint contractures, and corneal clouding were each reported by >80% and all three by 53% of patients. Carpal tunnel syndrome, hernia, coarse facial features, and hepatomegaly were each reported by >50% of patients. Age at onset of the clinical features varied widely between individuals, but the median age at onset was 3 years for hernia and between 5 and 12 years for most features, including coarse facial features, hepatomegaly, joint contractures, bone deformities, cardiac valve abnormalities, cognitive impairment, and corneal clouding. Carpal tunnel syndrome, cardiomyopathy, and myelopathy arose more commonly during adolescence or adulthood. Delays up to 47 years intervened between symptom onset and disease diagnosis, and the longest delays were associated with later age at symptom onset and symptom onset before 1980. In summary, Scheie syndrome usually emerges during childhood, and recognition of attenuated MPS I requires awareness of the multisystemic disease manifestations and their diverse presentation. Given the availability of etiologic treatment, prompt diagnosis is important.

Agalsidase alfa and kidney dysfunction in Fabry disease.

In male patients with Fabry disease, an X-linked disorder of glycosphingolipid metabolism caused by deficient activity of the lysosomal enzyme alpha-galactosidase A, kidney dysfunction becomes apparent by the third decade of life and invariably progresses to ESRD without treatment. Here, we summarize the effects of agalsidase alfa on kidney function from three prospective, randomized, placebo-controlled trials and their open-label extension studies involving 108 adult male patients. The mean baseline GFR among 54 nonhyperfiltrating patients (measured GFR <135 ml/min per 1.73 m(2)) treated with placebo was 85.4 +/- 29.6 ml/min per 1.73 m(2); during 6 mo of placebo, the mean annualized rate of change in GFR was -7.0 +/- 32.9 ml/min per 1.73 m(2). Among 85 nonhyperfiltrating patients treated with agalsidase alfa, the annualized rate of change was -2.9 +/- 8.7 ml/min per 1.73 m(2). Treatment with agalsidase alfa did not affect proteinuria. Multivariate analysis revealed that GFR and proteinuria category (< 1 or > or = 1 g/d) at baseline significantly predicted the rate of decline of GFR during treatment. This summary represents the largest group of male patients who had Fabry disease and for whom the effects of enzyme replacement therapy on kidney function have been studied. These data suggest that agalsidase alfa may stabilize kidney function in these patients.

Hunter disease eClinic: interactive, computer-assisted, problem-based approach to independent learning about a rare genetic disease.

BACKGROUND: Computer-based teaching (CBT) is a well-known educational device, but it has never been applied systematically to the teaching of a complex, rare, genetic disease, such as Hunter disease (MPS II). AIM: To develop interactive teaching software functioning as a virtual clinic for the management of MPS II. IMPLEMENTATION AND RESULTS: The Hunter disease eClinic, a self-training, user-friendly educational software program, available at the Lysosomal Storage Research Group (http://www.lysosomalstorageresearch.ca), was developed using the Adobe Flash multimedia platform. It was designed to function both to provide a realistic, interactive virtual clinic and instantaneous access to supporting literature on Hunter disease. The Hunter disease eClinic consists of an eBook and an eClinic. The eClinic is the interactive virtual clinic component of the software. Within an environment resembling a real clinic, the trainee is instructed to perform a medical history, to examine the patient, and to order appropriate investigation. The program provides clinical data derived from the management of actual patients with Hunter disease. The eBook provides instantaneous, electronic access to a vast collection of reference information to provide detailed background clinical and basic science, including relevant biochemistry, physiology, and genetics. In the eClinic, the trainee is presented with quizzes designed to provide immediate feedback on both trainee effectiveness and efficiency. User feedback on the merits of the program was collected at several seminars and formal clinical rounds at several medical centres, primarily in Canada. In addition, online usage statistics were documented for a 2-year period. Feedback was consistently positive and confirmed the practical benefit of the program. The online English-language version is accessed daily by users from all over the world; a Japanese translation of the program is also available. CONCLUSIONS: The Hunter disease eClinic employs a CBT model providing the trainee with realistic clinical problems, coupled with comprehensive basic and clinical reference information by instantaneous access to an electronic textbook, the eBook. The program was rated highly by attendees at national and international presentations. It provides a potential model for use as an educational approach to other rare genetic diseases.

Fabry disease urinary globotriaosylceramide/creatinine biomarker evaluation by liquid chromatography-tandem mass spectrometry in healthy infants from birth to 6 months.

Fabry disease is an X-linked lysosomal storage disorder caused by deficiency of alpha-galactosidase A, resulting in accumulation of the principal substrate, globotriaosylceramide (Gb(3)), in various physiological fluids and tissues in affected patients. The recognition that accumulation of Gb(3) begins in utero, combined with the fact that the diagnosis of the disease is often delayed until after the development of irreversible tissue damage, has generated pressure to develop techniques for the early, pre-symptomatic diagnosis of the disease. Measurements of urinary Gb(3) have been shown to be useful for the diagnosis of Fabry disease in adults. The objective of this work was to measure the Gb(3)/creatinine biomarker in urine of healthy infants from birth to 6 months, including the establishment of reference ranges for urinary Gb(3) excretion at various postnatal ages, in male and female infants. We employed liquid chromatography-tandem mass spectrometry (LC-MS/MS) to determine Gb(3)/creatinine ratios in urine specimens dried on filter paper and mailed to the laboratory by participating parents. A total of 728 urine specimens were obtained at intervals from birth to 6 months of age from 68 healthy infants (35 male and 33 female). Parental participation was good, with 90% of the expected specimens received by the laboratory. The results of the analyses were grouped by the age of the infants into four periods. We have determined that both postnatal age and sex have an effect on urinary Gb(3) excretion levels which vary considerably in newborns. We conclude that screening for Fabry disease by measurement of urinary Gb(3) excretion is unlikely to be reliable before 30 days of age.

A dose-optimization trial of laronidase (Aldurazyme) in patients with mucopolysaccharidosis I.

Recombinant human alpha-l-iduronidase (Aldurazyme), laronidase) is approved as an enzyme replacement therapy to treat the lysosomal storage disorder, mucopolysaccharidosis type I (MPS I) at a dose of 0.58 mg/kg by once-weekly intravenous infusion. To assess whether alternate dosing regimens might provide a better reduction in lysosomal storage, a 26-week, randomized, open-label, multinational dose-optimization trial was conducted. The pharmacodynamic effect and safety of the approved laronidase dose was compared to three alternative regimens (1.2mg/kg every 2 weeks; 1.2mg/kg every week; 1.8 mg/kg every 2 weeks) among 33 MPS I patients. The four treatment regimens showed no significant differences in the reduction of urinary glycosaminoglycan excretion or liver volume. Laronidase had an acceptable safety profile in all dose regimen groups. Infusion-associated reactions were the most common drug-related adverse events across dose regimens (by patient incidence), and included pyrexia (21%), vomiting (15%), rash (15%), and urticaria (12%). Patients in the approved dose group had the lowest incidence of drug-related adverse events (38% vs. 63-75%) and infusion-associated reactions (25% vs. 25-63%). There was one death: a patient with acute bronchitis died of respiratory failure 6h after completing the first laronidase infusion. The approved 0.58 mg/kg/week laronidase dose regimen provided near-maximal reductions in glycosaminoglycan storage and the best benefit-to-risk ratio. The 1.2mg/kg every 2 weeks regimen may be an acceptable alternative for patients with difficulty receiving weekly infusions, but the long-term effects of this regimen are unknown.