Mercè Pineda

Recommendations on the diagnosis and management of Niemann-Pick disease type C

Niemann-Pick disease type C (NP-C) is a lysosomal storage disease in which impaired intracellular lipid trafficking leads to excess storage of cholesterol and glycosphingolipids in the brain and other tissues. It is characterized clinically by a variety of progressive, disabling neurological symptoms including clumsiness, limb and gait ataxia, dysarthria, dysphagia and cognitive deterioration (dementia). Until recently, there has been no disease-modifying therapy available for NP-C, with treatment limited to supportive measures. In most countries, NP-C is managed through specialist centers, with non-specialist support provided locally. However, effective patient support is hampered by the absence of national or international clinical management guidelines. In this paper, we seek to address this important gap in the current literature. An expert panel was convened in Paris, France in January 2009 to discuss best care practices for NP-C. This commentary reviews current literature on key aspects of the clinical management of NP-C in children, juveniles and adults, and provides recommendations based on consensus between the experts at the meeting.

Coenzyme Q deficiency triggers mitochondria degradation by mitophagy

Coenzyme Q10 (CoQ) is a small lipophilic molecule critical for the transport of electrons from complexes I and II to complex III in the mitochondrial respiratory chain. CoQ deficiency is a rare human genetic condition that has been associated with a variety of clinical phenotypes. With the aim of elucidating how CoQ deficiency affects an organism, we have investigated the pathophysiologic processes present within fibroblasts derived from 4 patients with CoQ deficiency. Assays of cultured fibroblasts revealed decreased activities of complex II+III, complex III, and complex IV, reduced expression of mitochondrial proteins involved in oxidative phosphorylation, decreased mitochondrial membrane potential, increased production of reactive oxygen species (ROS), activation of mitochondrial permeability transition (MPT), and reduced growth rates. These abnormalities were partially restored by CoQ supplementation. Moreover, we demonstrate that CoQ deficient fibroblasts exhibited increased levels of lysosomal markers (β-galactosidase, cathepsin, LC3, and Lyso Tracker), and enhanced expression of autophagic genes at both transcriptional and translational levels, indicating the presence of autophagy. Electron microscopy studies confirmed a massive degradation of the altered mitochondria by mitophagy. Autophagy in CoQ deficient fibroblasts was abolished by antioxidants or cyclosporin treatments suggesting that both ROS and MPT participate in this process. Furthermore, prevention of autophagy in CoQ deficient fibroblasts by 3-methyl adenine or wortmannin, as well as the induction of CoQ deficiency in cells lacking autophagy (by means of genetic knockout of the Atg5 gene in mouse embryonic fibroblasts) resulted in apoptotic cell death, suggesting a protective role of autophagy in CoQ deficiency.

Niemann-Pick C disease in Spain: clinical spectrum and development of a disability scale.

OBJECTIVES To describe the clinical evolution of Niemann-Pick C disease to identify possible factors involved in the diagnosis and severity of the disease. METHODS A clinical database and a severity scale was created to evaluate 45 patients diagnosed with Niemann-Pick type C in the last 28 years in Spain. RESULTS Complete clinical data were obtained from 30 patients, all were confirmed to have mutations in the NPC1 gene. Regarding clinical form, 3 were perinatal, 7 severe infantile, 6 late infantile, 11 juvenile and 3 adult. Biochemical phenotype was classic in 26. Splenomegaly was present in 28 patients (93%) with a wide range of age at detection. The first symptom of neurological disease was clumsiness, followed in 2-4 years by cerebellar signs. Ophthalmoplegia appeared 2-4 years later and became complete 1-2 years after onset. Dysarthria appeared by the time of complete ophthalmoplegia. Diagnosis was made before the onset of neurological signs in patients with the severe infantile form, at the time of onset of cerebellar signs in the late infantile form and complete ophthalmoplegia in late onset forms. CONCLUSIONS In our series, splenomegaly is present in 96% of patients, even in late onset forms during the first years of life. Clumsiness in children with otherwise normal motor development precedes the onset of ataxia by 2-4 years in Niemann Pick type C. A disability scale could be useful for monitoring evolution, establishing possible phenotypic correlations and evaluating future therapies.

Glutaryl-CoA Dehydrogenase Deficiency in Spain: Evidence of Two Groups of Patients, Genetically, and Biochemically Distinct

Glutaryl-CoA dehydrogenase (GCDH) deficiency causes glutaric aciduria type I (GA I), an inborn error of metabolism that is characterized clinically by dystonia and dyskinesia and pathologically by neural degeneration of the caudate and putamen. Studies of metabolite excretion allowed us to categorize 43 GA I Spanish patients into two groups: group 1 (26 patients), those presenting with high excretion of both glutarate and 3-hydroxyglutarate, and group 2 (17 patients) , those who might not be detected by routine urine organic acid analysis because glutarate might be normal and 3-hydroxyglutarate only slightly higher than controls. Single-strand conformation polymorphism (SSCP) screening and sequence analysis of the 11 exons and the corresponding intron boundaries of the GCDH gene allowed us to identify 13 novel and 10 previously described mutations. The most frequent mutations in group 1 were A293T and R402W with an allele frequency of 30% and 28%, respectively. These two mutations were also found in group 2, but always in heterozygosity, in particular in combination with mutations V400M or R227P. Interestingly, mutations V400M and R227P were only found in group 2, and at least one of these mutations was found in 11 of 15 unrelated alleles, accounting together for 53% of the mutant alleles in group 2. Therefore, it seems clear that two genetically and biochemically distinct groups of patients exist. The severity of the clinical phenotype seems to be closely linked to the development of encephalopathic crises rather than to residual enzyme activity or genotype. Comparison of GCDH protein with other acyl-CoA dehydrogenases (whose x-ray crystal structure has been determined) reveals that most of the mutations identified in GCDH protein seem to affect folding and tetramerization, as has been described for a number of mutations affecting mitochondrial β-oxidation acyl-CoA dehydrogenases.

Idebenone treatment in paediatric and adult patients with Friedreich ataxia: Long-term follow-up

BACKGROUND Antioxidant therapy is a new therapeutical approach for patients with Friedreich ataxia. AIMS To assess the effectiveness of long-term idebenone treatment in Friedreich ataxia patients. METHODS An open-labelled prospective study. Ten paediatric patients (age range 8-18 years) and 14 adults (age range 18-46 years) with genetic diagnosis of Friedreich ataxia were treated with idebenone (5-20mg/kg/day) for 3-5 years. Neurological evolution was evaluated using the International Cooperative Ataxia Rating Scale (ICARS), and cardiological outcomes using echocardiography. RESULTS In paediatric patients, no significant differences were observed in ICARS scores and echocardiographic measurements when comparing baseline status and after 5 years of follow-up. Concerning adult cases, ICARS scores showed a significant increase in neurological dysfunctions during 3 years of therapy (Wilcoxon test, p=0.005), while echocardiographic measurements remained unchanged. CONCLUSIONS Our results indicate that longer-term idebenone treatment prevented progression of cardiomyopathy in both paediatric and adult patients, whereas its stabilizing effect on neurological dysfunction was present only in the paediatric population, mainly before puberty. This suggests that the age at which idebenone treatment is initiated may be an important factor in the effectiveness of the therapy.

Disease and patient characteristics in NP-C patients: findings from an international disease registry

BackgroundNiemann-Pick disease type C (NP-C) is a rare neurovisceral disease characterized by progressive neurodegeneration and premature death. We report data recorded at enrolment in an ongoing international NP-C registry initiated in September 2009 to describe disease natural history, clinical course and treatment experience of NP-C patients in clinical practice settings.MethodsThe NPC Registry is a prospective observational cohort study. Participating sites are encouraged to evaluate all consecutive patients with a confirmed diagnosis of NP-C, regardless of their treatment status. All patients undergo clinical assessments and medical care as determined by their physicians. Data are collected through a secure internet-based data collection system.ResultsAs of 19th March, 2012, 163 patients have been enrolled in centres across 14 European countries, Australia, Brazil and Canada. The mean (SD) age at enrolment was 19.6 (13.0) years. In general there was a long lag time between the mean (SD) age at neurological onset (10.9 (9.8) years) and age at diagnosis (15.0 (12.2) years). Among all enrolled patients, 107 were diagnosed based on combined genetic testing and filipin staining. Sixteen (11%) out of 145 patients with available age-at-neurological-onset data had early-infantile neurological onset, 45 (31%) had late-infantile onset; 45 (31%) had juvenile onset and 39 (27%) had adolescent/adult onset. The frequencies of neonatal jaundice, hepatomegaly and/or splenomegaly during infancy were greatest among early-infantile patients, and decreased with increasing age at neurological onset. The most frequent neurological manifestations were: ataxia (70%), vertical supranuclear gaze palsy (VSGP; 70%), dysarthria (66%), cognitive impairment (62%), dysphagia (52%). There were no notable differences in composite NP-C disability scores between age-at-neurological-onset groups. Miglustat therapy at enrolment was recorded in 117/163 (72%) patients.ConclusionsApproximately two-thirds of this NP-C cohort had infantile or juvenile onset of neurological manifestations, while the remaining third presented in adolescence or adulthood. While systemic symptoms were most common among patients with early-childhood onset disease, they were also common among patients with adolescent/adult onset. The profiles of neurological manifestations in this Registry were in line with previous publications.

Cerebellar ataxia with coenzyme Q10 deficiency: diagnosis and follow-up after coenzyme Q10 supplementation.

UNLABELLED Our aim was to report a new case with cerebellar ataxia associated with coenzyme Q10 (CoQ) deficiency, the biochemical findings caused by this deficiency and the response to CoQ supplementation. PATIENT A 12-year-old girl presenting ataxia and cerebellar atrophy. BIOCHEMICAL STUDIES: Coenzyme Q10 in muscle was analysed by HPLC with electrochemical detection and mitochondrial respiratory chain (MRC) enzyme activities by spectrophotometric methods. CoQ biosynthesis in fibroblasts was assayed by studying the incorporation of radiolabeled 4-hydroxy[U 14C] benzoic acid by HPLC with radiometric detection. RESULTS Mitochondrial respiratory chain enzyme analysis showed a decrease in complex I + III and complex II + III activities. CoQ concentration in muscle was decreased (56 nmol/g of protein: reference values: 157-488 nmol/g protein). A reduced incorporation of radiolabeled 4-hydroxy[U- 14C] benzoic acid was observed in the patient (19% of incorporation respect to the median control values). After 16 months of CoQ supplementation, the patient is now able to walk unaided and cerebellar signs have disappeared. CONCLUSIONS Cerebellar ataxia associated with CoQ deficiency in our case might be allocated in the transprenylation pathway or in the metabolic steps after condensation of 4-hydroxybenzoate and the prenyl side chain of CoQ. Clinical improvement after CoQ supplementation was remarkable, supporting the importance of an early diagnosis of this kind of disorders.

Cerebral folate deficiency and leukoencephalopathy caused by a mitochondrial DNA deletion.

Our aim was to describe a child with an incomplete form of Kearns–Sayre syndrome who presented profound cerebrospinal fluid (CSF) folate deficiency and his response to folinic acid supplementation

Molecular Characterization of 3-Phosphoglycerate Dehydrogenase Deficiency—a Neurometabolic Disorder Associated with Reduced L-Serine Biosynthesis

3-phosphoglycerate dehydrogenase (PHGDH) deficiency is a disorder of L-serine biosynthesis that is characterized by congenital microcephaly, psychomotor retardation, and seizures. To investigate the molecular basis for this disorder, the PHGDH mRNA sequence was characterized, and six patients from four families were analyzed for sequence variations. Five patients from three different families were homozygous for a single nucleotide substitution predicted to change valine at position 490 to methionine. The sixth patient was homozygous for a valine to methionine substitution at position 425; both mutations are located in the carboxyterminal part of PHGDH. In vitro expression of these mutant proteins resulted in significant reduction of PHGDH enzyme activities. RNA-blot analysis indicated abundant expression of PHGDH in adult and fetal brain tissue. Taken together with the severe neurological impairment in our patients, the data presented in this paper suggest an important role for PHGDH activity and L-serine biosynthesis in the metabolism, development, and function of the central nervous system.

Rett syndrome in Spain: mutation analysis and clinical correlations

Rett syndrome (RTT) is an X-linked neurodevelopmental disease that affects girls almost exclusively. In a high proportion of patients the disease is caused by de novo mutations at the MECP2 gene, encoding methyl-CpG-binding protein 2. With the aim to characterize the spectrum of mutations in a series of sporadic RTT patients, including an affected male, and to relate the genetic results to the clinical features of the disease, a clinical checklist and a score system were elaborated to evaluate the clinical severity of the disease. Mutation analysis of the MECP2 coding region was done by direct sequencing. De novo mutations were found in 60% of the patients, including both classic and atypical forms. The change R133H was identified in a 13-year-old boy showing a classic RTT phenotype and normal karyotype. Significant differences were observed among missense and truncating mutations regarding disease severity, age of onset of stereotypies, and the ability of the patients to sit alone and to walk.