[Show abstract][Hide abstract] ABSTRACT: Autosomal Dominant Hypercholesterolemia (ADH) is a human disorder characterized phenotypically by isolated high cholesterol levels. Mutations in the LDLR, APOB and PCSK9 genes are well known to be associated with the disease. To characterize the genetic background associated with ADH in France, the three ADH-associated genes were sequenced in a cohort of 120 children and 109 adult patients. Fifty-one percent of the cohort had a possible deleterious variant in LDLR, 3.1% in APOB and 1.7% in PCSK9. We identified 18 new variants in LDLR and 2 in PCSK9. Three LDLR variants, including two newly identified, were studied by minigene reporter assay confirming the predicted effects on splicing. Additionally, as recently an in-frame deletion in the APOE gene was found to be linked to ADH, the sequencing of this latter gene was performed in patients without a deleterious variant in the three former genes. An APOE variant was identified in three patients with isolated severe hypercholesterolemia giving a frequency of 1.3% in the cohort. Therefore, even though LDLR mutations are the major cause of ADH with a large mutation spectrum, APOE variants were found to be significantly associated with the disease. Furthermore, using structural analysis and modelling, the identified APOE sequence changes were predicted to impact protein function.
Full-text · Article · Jan 2016 · The Journal of Lipid Research
[Show abstract][Hide abstract] ABSTRACT: The current standard of care for diagnosis of severe intellectual disability (ID) and epileptic encephalopathy (EE) results in a diagnostic yield of ~50%. Affected individuals nonetheless undergo multiple clinical evaluations and low-yield laboratory tests often referred to as a "diagnostic odyssey". This study was aimed at assessing the utility of clinical whole-exome sequencing (WES) in individuals with undiagnosed and severe forms of ID and EE, and the feasibility of its implementation in routine practice by a small regional genetic center. We performed WES in a cohort of 43 unrelated individuals with undiagnosed ID and/or EE. All individuals had undergone multiple clinical evaluations and diagnostic tests over the years, with no definitive diagnosis. Sequencing data analysis and interpretation were carried out at the local molecular genetics laboratory. The diagnostic rate of WES reached 32.5% (14 out of 43 individuals). Genetic diagnosis had a direct impact on clinical management in four families, including a prenatal diagnostic test in one family. Our data emphasize the clinical utility and feasibility of WES in individuals with undiagnosed forms of ID and EE, and highlight the necessity of close collaborations between ordering physicians, molecular geneticists, bioinformaticians and researchers for accurate data interpretation.
No preview · Article · Jan 2016 · Clinical Genetics
[Show abstract][Hide abstract] ABSTRACT: Background:
Mutations in Phenylalanine Hydroxylase (PAH) gene cause phenylketonuria. Sapropterin (BH4), the enzyme cofactor, is an important therapeutical strategy in phenylketonuria. However, PAH is a highly polymorphic gene and it is difficult to identify BH4-responsive genotypes. We seek here to improve prediction of BH4-responsiveness through comparison of genotypes, BH4-loading test, predictions of responsiveness according to the literature and types and locations of mutations.
A total of 364 French patients among which, 9 % had mild hyperphenylalaninemia, 17.7 % mild phenylketonuria and 73.1 % classical phenylketonuria, benefited from a 24-hour BH4-loading test and had the PAH gene sequenced and analyzed by Multiplex Ligation Probe Amplification.
Overall, 31.6 % of patients were BH4-responsive. The number of different mutations found was 127, including 26 new mutations. The mutations c.434A > T, c.500A > T, c.529G > C, c.1045 T > G and c.1196 T > C were newly classified as being BH4-responsive. We identified 261 genotypes, among which 46 were newly recognized as being BH4-responsive. Even though patients carry 2 responsive alleles, BH4-responsiveness cannot be predicted with certainty unless they present mild hyperphenylalaninemia. BH4-responsiveness cannot be predicted in patients carrying one responsive mutation only. In general, the milder the phenotype is, the stronger the BH4-response is. Almost exclusively missense mutations, particularly in exons 12, 11 and 8, are associated with BH4-responsiveness and any other type of mutation predicts a negative response.
This study is the first of its kind, in a French population, to identify the phenotype associated with several combinations of PAH mutations. As others, it highlights the necessity of performing simultaneously BH4 loading test and molecular analysis in monitoring phenylketonuria patients.
Preview · Article · Dec 2015 · Orphanet Journal of Rare Diseases
[Show abstract][Hide abstract] ABSTRACT: Introduction:
The few published case reports of co-existent disease with phenylketonuria (PKU) are mainly genetic and familial conditions from consanguineous marriages. The clinical and demographic features of 30 subjects with PKU and co-existent conditions were described in this multi-centre, retrospective cohort study.
Diagnostic age of PKU and co-existent condition, treatment regimen, and impact of co-existent condition on blood phenylalanine (Phe) control and PKU management were reported.
30 patients (11 males and 19 females), with PKU and a co-existent condition, current median age of 14years (range 0.4 to 40years) from 13 treatment centres from Europe and Turkey were described. There were 21 co-existent conditions with PKU; 9 were autoimmune; 6 gastrointestinal, 3 chromosomal abnormalities, and 3 inherited conditions. There were only 5 cases of parental consanguinity. Some patients required conflicting diet therapy (n=5), nutritional support (n=7) and 5 children had feeding problems. There was delayed diagnosis of co-existent conditions (n=3); delayed treatment of PKU (n=1) and amenorrhea associated with Grave's disease that masked a PKU pregnancy for 12weeks. Co-existent conditions adversely affected blood Phe control in 47% (n=14) of patients. Some co-existent conditions increased the complexity of disease management and increased management burden for patients and caregivers.
Occurrence of co-existent disease is not uncommon in patients with PKU and so investigation for co-existent disorders when the clinical history is not completely consistent with PKU is essential. Integrating care of a second condition with PKU management is challenging.
Full-text · Article · Oct 2015 · Molecular Genetics and Metabolism
[Show abstract][Hide abstract] ABSTRACT: Background Lysosomal acid lipase is an essential lipid-metabolizing enzyme that breaks down endocytosed lipid particles and regulates lipid metabolism. We conducted a phase 3 trial of enzyme-replacement therapy in children and adults with lysosomal acid lipase deficiency, an underappreciated cause of cirrhosis and severe dyslipidemia. Methods In this multicenter, randomized, double-blind, placebo-controlled study involving 66 patients, we evaluated the safety and effectiveness of enzyme-replacement therapy with sebelipase alfa (administered intravenously at a dose of 1 mg per kilogram of body weight every other week); the placebo-controlled phase of the study was 20 weeks long and was followed by open-label treatment for all patients. The primary end point was normalization of the alanine aminotransferase level. Secondary end points included additional disease-related efficacy assessments, safety, and side-effect profile. Results Substantial disease burden at baseline included a very high level of low-density lipoprotein cholesterol (≥190 mg per deciliter) in 38 of 66 patients (58%) and cirrhosis in 10 of 32 patients (31%) who underwent biopsy. A total of 65 of the 66 patients who underwent randomization completed the double-blind portion of the trial and continued with open-label treatment. At 20 weeks, the alanine aminotransferase level was normal in 11 of 36 patients (31%) in the sebelipase alfa group and in 2 of 30 (7%) in the placebo group (P=0.03), with mean changes from baseline of -58 U per liter versus -7 U per liter (P<0.001). With respect to prespecified key secondary efficacy end points, we observed improvements in lipid levels and reduction in hepatic fat content (P<0.001 for all comparisons, except P=0.04 for triglycerides). The number of patients with adverse events was similar in the two groups; most events were mild and were considered by the investigator to be unrelated to treatment. Conclusions Sebelipase alfa therapy resulted in a reduction in multiple disease-related hepatic and lipid abnormalities in children and adults with lysosomal acid lipase deficiency. (Funded by Synageva BioPharma and others; ARISE ClinicalTrials.gov number, NCT01757184 .).
Full-text · Article · Sep 2015 · New England Journal of Medicine
[Show abstract][Hide abstract] ABSTRACT: Conclusion:
Targeted efforts by health care professionals and governments are needed to optimise diagnostic and management approaches for PKU in Southern and Eastern Europe. "What is Known" • PKU must be detected early and optimally managed throughout life to avoid poor outcomes, yet newborn screening is not universal and diagnostic and management practices for PKU are known to vary widely between different centres and countries. • Targeted efforts by health care professionals and governments are needed to optimise diagnostic and management approaches. "What is New" • PKU management practices are documented in 19 South and Eastern European countries indicating a heterogeneous situation across the region. • Key areas for improvement identified in surveyed centres include a need for comprehensive screening in all countries, increased number of metabolic dietitians and specialised adult PKU clinics, delayed time to treatment initiation, appropriate Phe thresholds, Phe targets and monitoring frequencies, and universal access to currently available treatment options.
Full-text · Article · Sep 2015 · European Journal of Pediatrics
[Show abstract][Hide abstract] ABSTRACT: Mucopolysaccharidosis II (MPS II) is associated with a broad spectrum of chronic and progressive, life-limiting symptoms. Idursulfase is approved for MPS II enzyme replacement therapy (ERT) in over 50 countries. This retrospective study evaluated the MPS II burden, organization of clinical care, and effects of idursulfase treatment on the disease in France.
MPS II patients who had received idursulfase ERT in the French healthcare system were enrolled. In addition to clinician and patient questionnaires, the Clinical Global Impression-Improvement (CGI-I); Patient Global Impression-Improvement (PGI-I); KIDSCREEN-27, and EuroQoL-5D for adult patients scales were used to assess quality of life (QoL) and efficacy.
Fifty-two patients were enrolled from 5 sites in France. The majority of patients (69.2%) presented a severe MPS II phenotype with progressive neurocognitive impairment. Major impacts on QoL were apparent, with at least 1 member of the family having to reorganize working hours (45.5%) or to stop working (22.7%). KIDSCREEN-27 and EuroQoL-5D scale scores were well below those for referent (control) populations. Most families (70.0%) experienced a diagnostic delay of at least 3 years after the initial observation of symptoms. The MPS II diagnosis was often delivered without adequate sensitivity, psychological support, or comprehensive information about the disease. The study population had received a mean of 3.8 ± 1.3 years ERT. Forty-four percent of patients with the attenuated phenotype (without progressive neurocognitive impairment) showed symptom improvement during both the first year (Period 1) and from the end of the first year of treatment to "the present" (Period 2), as measured by CGI-I/PGI-I. 30.3% and 9.1% of severe patients experienced symptom improvement during Periods 1 and 2, respectively, while 63.6% and 51.5% displayed no change. The most common adverse reactions reported were skin rash and other infusion-associated reactions.
MPS II adversely affects multiple domains of QoL for patients and families, requiring multiple healthcare services and social aid programs. The majority of patients with either phenotype experienced either improvement or stability in their symptoms during the first year of ERT, but this was clearly less so for patients with the severe phenotype after the first year of treatment.
[Show abstract][Hide abstract] ABSTRACT: Sapropterin dihydrochloride (Kuvan(®)), a synthetic 6R-diastereoisomer of tetrahydrobiopterin (BH4), is approved in Europe for the treatment of patients aged ≥4 years with hyperphenylalaninaemia (HPA) due to BH4-responsive phenylalanine hydroxylase (PAH) deficiency, in conjunction with a phenylalanine-restricted diet, and also for the treatment of patients with BH4 deficiency.
KAMPER is an ongoing, observational, multicentre registry with the primary objective of providing information over 15 years on long-term safety of sapropterin dihydrochloride treatment in patients with HPA. Here we report initial data on characteristics from patients recruited by the time of the third interim analysis and results at 1 year.
Overall, 325 patients from 55 sites in seven European countries were included in the analysis: 296 (91.1%) patients with PAH deficiency (median [Q1, Q3] age, 10.3 [7.2, 15.0] years) and 29 (8.9%) with BH4 deficiency (12.8 [6.6, 18.9] years). Fifty-nine patients (18.2%) were aged ≥18 years; 4 patients were pregnant. No elderly patients (aged ≥65 years) or patients with renal or hepatic insufficiency were enroled in the study. Twelve-month data were available for 164 patients with PAH deficiency and 16 with BH4 deficiency. No new safety concerns were identified as of May 2013.
Initial data from KAMPER show that sapropterin dihydrochloride has a favourable safety profile. Registry data collected over time will provide insight into the management and outcomes of patients with PAH deficiency and BH4 deficiency, including long-term safety, impact on growth and neurocognitive outcomes and the effect of sapropterin dihydrochloride treatment on populations of special interest.
[Show abstract][Hide abstract] ABSTRACT: Neonatal loading studies with tetrahydrobiopterin (BH4) are used to detect hyperphenylalaninemia due to BH4 deficiency by evaluating decreases in blood phenylalanine (Phe) concentrations post BH4 load. BH4 responsiveness in phenylalanine hydroxylase (PAH)-deficient patients introduced a new diagnostic aspect for this test. In older children, a broad spectrum of different levels of responsiveness has been described. The primary objective of this study was to develop a pharmacodynamic model to improve the description of individual sensitivity to BH4 in the neonatal period. Secondary objectives were to evaluate BH4 responsiveness in a large number of PAH-deficient patients from a neonatal screening program and in patients with various confirmed BH4 deficiencies from the BIODEF database.
No preview · Article · Feb 2015 · Molecular Genetics and Metabolism
[Show abstract][Hide abstract] ABSTRACT: Fructose-1,6-bisphosphatase (FBPase) deficiency is a very rare autosomal recessive disorder caused by a mutation of the fructose-1,6-bisphosphatase gene(FBP1). Disease is mainly revealed by hypoglycemia and lactic acidosis, both symptoms being characteristic for an enzymatic block in the last steps of the gluconeogenesis. Twelve patients with FBPase deficiency were diagnosed in France in the 2001-2013 period, using a diagnostic system based on a single blood sample which allows simultaneous enzyme activity measurement on mononuclear white blood cells and molecular analysis. Sequencing of exons and intron-exon junctions of FBP1 gene was completed in unsolved cases by a gene dosage assay developed for each exon. For most patients, first metabolic decompensation occurred before two years of age with a similar sequence: the triggering factors were fever, fasting, or decrease of food intake. However, diagnosis was made late at a mean age of 3 years, as mitochondrial defects or glycogen storage diseases were firstly suspected. Enzyme activity in leukocytes was dramatically decreased (<10 %). Twelve different mutations were identified in 22 alleles among them seven were novels: one missense mutation c.472C > T, one point deletion c.48del, one point duplication c.865dupA, one deletion-insertion, and two splice mutations (c.427-1del and c.825 + 1G > A). We described the first intragenic deletion in FBP1 (g.97,364,754_97,382,011del) in homozygous state. Our report also confirms that this very rare disease is misdiagnosed, as other energetic defects are firstly suspected.
No preview · Article · Jan 2015 · Journal of Inherited Metabolic Disease
[Show abstract][Hide abstract] ABSTRACT: In phenylketonuria, genetic heterogeneity, frequent compound heterozygosity, and the lack of functional data for phenylalanine hydroxylase genotypes hamper reliable phenotype prediction and individualised treatment.
A literature search revealed 690 different phenylalanine hydroxylase genotypes in 3066 phenylketonuria patients from Europe and the Middle East. We determined phenylalanine hydroxylase function of 30 frequent homozygous and compound heterozygous genotypes covering 55% of the study population, generated activity landscapes, and assessed the phenylalanine hydroxylase working range in the metabolic (phenylalanine) and therapeutic (tetrahydrobiopterin) space.
Shared patterns in genotype-specific functional landscapes were linked to biochemical and pharmacological phenotypes, where (1) residual activity below 3.5% was associated with classical phenylketonuria unresponsive to pharmacological treatment; (2) lack of defined peak activity induced loss of response to tetrahydrobiopterin; (3) a higher cofactor need was linked to inconsistent clinical phenotypes and low rates of tetrahydrobiopterin response; and (4) residual activity above 5%, a defined peak of activity, and a normal cofactor need were associated with pharmacologically treatable mild phenotypes. In addition, we provide a web application for retrieving country-specific information on genotypes and genotype-specific phenylalanine hydroxylase function that warrants continuous extension, updates, and research on demand.
The combination of genotype-specific functional analyses with biochemical, clinical, and therapeutic data of individual patients may serve as a powerful tool to enable phenotype prediction and to establish personalised medicine strategies for dietary regimens and pharmacological treatment in phenylketonuria.
Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://group.bmj.com/group/rights-licensing/permissions.
Full-text · Article · Jan 2015 · Journal of Medical Genetics
[Show abstract][Hide abstract] ABSTRACT: Phenylketonuria (PKU) is no longer considered merely a pediatric concern; current guidelines recommend life-long treatment. However, information on the adult PKU patient population is scarce. A survey was initiated on behalf of the European PKU Group (EPG) that focused specifically on early-treated adult patients diagnosed by neonatal screening. The online survey was sent via email to 204 healthcare professionals (HCPs) in 33 countries. Eighty-one HCPs from 24 countries responded. The main findings were that the majority of adult patients with PKU in active follow-up are under 30 years of age and are managed in centers that also treat children. Seventy-eight percent of adult PKU patients in follow-up receive treatment, mainly by diet (71 %), with BH4 treatment rarely used in adulthood. Only 26 % of responding HCPs perform routine neurocognitive testing in all their adult patients. There was little consensus regarding target blood phenylalanine (Phe) concentrations, although the majority of respondents reported that their patients achieved blood Phe concentrations below 1200 μmol/l.
Conclusion: This survey highlights the need for blood Phe concentration target recommendations and consensus guidelines, more research into adult PKU patient management, and the need to identify those patients lost to follow-up to ensure PKU is managed for life.
Full-text · Article · Dec 2014 · European Journal of Pediatrics
[Show abstract][Hide abstract] ABSTRACT: Epileptic encephalopathy (EE) refers to a clinically and genetically heterogeneous group of severe disorders characterized by seizures, abnormal interictal electro-encephalogram, psychomotor delay, and/or cognitive deterioration. We ascertained two multiplex families (including one consanguineous family) consistent with an autosomal-recessive inheritance pattern of EE. All seven affected individuals developed subclinical seizures as early as the first day of life, severe epileptic disease, and profound developmental delay with no facial dysmorphism. Given the similarity in clinical presentation in the two families, we hypothesized that the observed phenotype was due to mutations in the same gene, and we performed exome sequencing in three affected individuals. Analysis of rare variants in genes consistent with an autosomal-recessive mode of inheritance led to identification of mutations in SLC13A5, which encodes the cytoplasmic sodium-dependent citrate carrier, notably expressed in neurons. Disease association was confirmed by cosegregation analysis in additional family members. Screening of 68 additional unrelated individuals with early-onset epileptic encephalopathy for SLC13A5 mutations led to identification of one additional subject with compound heterozygous mutations of SLC13A5 and a similar clinical presentation as the index subjects. Mutations affected key residues for sodium binding, which is critical for citrate transport. These findings underline the value of careful clinical characterization for genetic investigations in highly heterogeneous conditions such as EE and further highlight the role of citrate metabolism in epilepsy.
Full-text · Article · Jul 2014 · The American Journal of Human Genetics