Molecular analysis of Sanfilippo syndrome type C in Spain: seven novel HGSNAT mutations and characterization of the mutant alleles

The Sanfilippo syndrome type C [mucopolysaccharidosis IIIC (MPS IIIC)] is caused by mutations in the HGSNAT gene, encoding an enzyme involved in heparan sulphate degradation. We report the first molecular study on several Spanish Sanfilippo syndrome type C patients. Seven Spanish patients, one Argentinean and three Moroccan patients were analysed. All mutant alleles were identified and comprised nine distinct mutant alleles, seven of which were novel, including four missense mutations (p.A54V, p.L113P, p.G424V and p.L445P) and three splicing mutations due to two point mutations (c.633+1G>A and c.1378-1G>A) and an intronic deletion (c.821-31_821-13del). Furthermore, we found a new single nucleotide polymorphism (SNP) (c.564-98T>C). The two most frequent changes were the previously described c.372-2A>G and c.234+1G>A mutations. All five splicing mutations were experimentally confirmed by studies at the RNA level, and a minigene experiment was carried out in one case for which no fibroblasts were available. Expression assays allowed us to show the pathogenic effect of the four novel missense mutations and to confirm that the already known c.710C>A (p.P237Q) is a non-pathogenic SNP. Haplotype analyses suggested that the two mutations (c.234+1G>A and c.372-2A>G) that were present in more than one patient have a common origin, including one (c.234+1G>A) that was found in Spanish and Moroccan patients.

Clinical experience with miglustat therapy in pediatric patients with Niemann-Pick disease type C: a case series

Niemann-Pick disease type C (NP-C) is an inherited neurovisceral lysosomal lipid storage disease characterized by progressive neurological deterioration. Different clinical forms have been defined based on patient age at onset: perinatal, early-infantile (EI), late-infantile (Li), juvenile and adult. We evaluated the efficacy and tolerability of miglustat in 16 symptomatic NP-C patients, with comparative reference to one neurologically asymptomatic, untreated patient. All patients were categorized according to age at neurological disease onset, and were assessed using a standardized clinical assessment protocol: disability and cognitive function scales, positron emission tomography (PET), and biochemical markers. PET and disability scale evaluations indicated that cerebral hypometabolism and neurological symptoms were stabilized during treatment in juvenile-onset NP-C patients. EI and Li NP-C patients, who had higher disease severity at baseline (treatment start), showed increased disability scores and progressive cerebral hypometabolism during follow up. Similarly, while cognitive scale scores remained relatively stable in patients with juvenile NP-C, cognition deteriorated in EI and Li patients. Plasma chitotriosidase (ChT) activity was lower in the juvenile NP-C subgroup than in EI and Li patients, and generally increased in patients who discontinued treatment. Plasma CCL18/PARC and ChT activities indicated greater macrophagic activity in EI and Li patients versus juveniles. Miglustat was generally well tolerated; frequent adverse events included diarrhea and flatulence, which were managed effectively by dietary modification and loperamide. Overall, miglustat appeared to stabilize neurological status in juvenile-onset NP-C patients, but therapeutic benefits appeared smaller among younger patients who were at a more advanced stage of disease at baseline.

Response to creatine analogs in fibroblasts and patients with creatine transporter deficiency

Creatine transporter (CRTR) deficiency is one of the most frequent causes of X-linked mental retardation. The lack of an effective treatment for this disease, in contrast to creatine (Cr) biosynthesis disorders that respond to Cr monohydrate (CM), led us to analyze the efficacy of a lipophilic molecule derived from Cr, creatine ethyl ester (CEE), in fibroblasts and patients with CRTR deficiency. CM and CEE uptake studies were performed in six controls and four fibroblast cell lines from patients. We found a significant increase in Cr uptake after 72 h of incubation with CEE (500 micromol/L) in patients and control fibroblasts compared to incubation with CM. Subsequently, we assayed the clinical effect of CEE administration in four patients with CRTR deficiency. After 1 year of treatment, a lack of significant improvement in neuropsychological assessment or changes in Cr level in brain (1)H MRS was observed, and CEE was discontinued. In conclusion, this 12-month trial with CEE did not increase the brain concentration of Cr. Our in vitro data lend support to the idea of a certain passive transport of CEE in both pathological and control cells, although more lipophilic molecules or other cell systems that mimic the BBB should be used for a better approach to the in vivo system.

Changes induced by the Pepper mild mottle tobamovirus on the chloroplast proteome of Nicotiana benthamiana

We have analyzed the chloroplast proteome of Nicotiana benthamiana using two-dimensional gel electrophoresis and mass spectrometry followed by a database search. In order to improve the resolution of the two-dimensional electrophoresis gels, we have made separate maps for the low and the high pH range. At least 200 spots were detected. We identified 72 polypeptides, some being isoforms of different multiprotein families. In addition, changes in this chloroplast proteome induced by the infection with the Spanish strain of the Pepper mild mottle virus were investigated. Viral infection induced the down-regulation of several chloroplastidic proteins involved in both the photosynthetic electron-transport chain and the Benson-Calvin cycle.

Cross-sectional survey on the knowledge, attitude and practice of male Filipino seafarers on sexual health

The Philippines is currently the world's leading supplier of seafarers aboard foreign vessels, accounting for nearly a quarter of the world's maritime industry. Seafarers, being mobile, have a significant contribution impact on the worldwide spread of infectious diseases such as sexually transmitted infections (STIs). This study aims to determine the level of knowledge, as well as the attitudes and practices (KAP) of male Filipino seafarers regarding sexual health. A cross-sectional survey was administered through convenience sampling of male Filipino seafarers. The respondents showed the least knowledge about prevention, followed by transmission of STIs. The respondents showed adequate knowledge about risk factors such as multiple sex partners, and about transmission such as vertical spread. In addition, the respondents indicated their attitude and level of responsibility in informing their sexual partners in case they contract STIs and avoidance of high-risk partners. They also showed attitudes that predispose them to high-risk behaviour such as decreased sexual sensation caused by use of condoms and added pleasure in having intercourse with strangers. The majority of respondents were sexually active. Most have STI/HIV screening as part of their pre-employment medical exam. Positive practices include use of condoms, voluntary medical evaluation for STI's, and avoidance of high-risk partners. Negative practices include going to bars closely linked with prostitution, and most of the respondents had had sexual intercourse with sex workers overseas. Male seafarers appear to have double standards regarding women as sexual partners - about half had intercourse outside their stable relationships. They perceive protection as their sole discretion.

Updating the profile of C-terminal MECP2 deletions in Rett syndrome

OBJECTIVES

This study aimed to compare the phenotype of Rett syndrome cases with C-terminal deletions to that of cases with different MECP2 mutations and to examine the phenotypic variation within C-terminal deletions.

METHODS

Cases were selected from InterRett, an international database and from the population-based Australian Rett Syndrome Database. Cases (n=832) were included if they had a pathogenic MECP2 mutation in which the nature of the amino acid change was known. Three severity scale systems were used, and individual aspects of the phenotype were also compared.

RESULTS

Lower severity was associated with C-terminal deletions (n=79) compared to all other MECP2 mutations (e.g. Pineda scale C-terminals mean 15.0 (95% CI 14.0-16.0) vs 16.2 (15.9-16.5). Cases with C-terminal deletions were more likely to have a normal head circumference (odds ratio 3.22, 95% CI 1.53 - 6.79) and weight (odds ratio 2.97, 95% CI 1.25-5.76). Onset of stereotypies tended to be later (median age 2.5 years vs 2 years, p<0.001 from survival analysis), and age of learning to walk tended to be earlier (median age 1.6 years vs 2 years, p=0.002 from survival analysis). Those with C-terminal deletions occurring later in the region had lower average severity scores than those occurring earlier in the region.

CONCLUSION

In terms of overall severity C-terminal deletion cases would appear to be in the middle of the range. In terms of individual aspects of phenotype growth and ability to ambulate appear to be particular strengths. By pooling data internationally this study has achieved the case numbers to provide a phenotypic profile of C-terminal deletions in Rett syndrome.

Miglustat in patients with Niemann-Pick disease Type C (NP-C): a multicenter observational retrospective cohort study

Miglustat has been shown to stabilize disease progression in children, juveniles and adults with Niemann-Pick disease type C (NP-C), a rare genetic disorder characterized by progressive neurological deterioration. We report findings from a retrospective observational cohort study assessing the effects of miglustat on neurological disease progression in patients treated in the clinical practice setting. Data from all NP-C patients prescribed miglustat at 25 expert centers were evaluated using a disease disability scale. The scale analyzed four key parameters of neurological disease progression in NP-C (ambulation, manipulation, language, swallowing). Mean individual parameter scores and a composite score were calculated at baseline (time of diagnosis) and up to 4 follow-up visits. Overall, 66 patients were included (mean [SD] age at diagnosis, 9.7 [7.6] years, and at treatment start, 12.8 [9.5] years). The median (range) miglustat exposure was 1.46 (0.05-4.51) years. Mean annual progression was +0.11 score units/year from diagnosis to treatment start, indicating disease progression prior to therapy, and decreasing to -0.01 score units/year from treatment start to last clinic visit, indicating stabilization. Stabilization of neurological disease on miglustat was observed in all age groups, but the magnitude of the effect was greater in patients diagnosed in late childhood and in juveniles and adults. Stabilization of neurological disease was also observed in a subset of 19 patients with extended pre-treatment information. Overall, these data support previous clinical trial findings indicating clinically relevant beneficial effects of miglustat on neurological disease progression in patients with NP-C.

Do retinal haemorrhages occur in infants with convulsions?

AIM

To determine the prevalence of retinal haemorrhages in infants presenting with convulsions and admitted to hospital, and to consider whether this finding indicates shaken baby syndrome.

METHODS

Prospective study of children aged 15 days to 2 years admitted with a diagnosis of first convulsion over a 2-year period (May 2004-May 2006). All infants were examined by an experienced ophthalmologist using indirect ophthalmoscopy within 72 h of admission.

RESULTS

182 of 389 children seen in the accident and emergency department were admitted and two were found to have retinal haemorrhages. Both children were eventually diagnosed as being abused.

CONCLUSIONS

Convulsions alone are unlikely to cause retinal haemorrhages in children under 2 years of age.

Mental retardation and inborn errors of metabolism

In countries where clinical phenylketonuria is detected by newborn screening inborn errors of metabolism are rare causes of isolated mental retardation. There is no international agreement about what type of metabolic tests must be applied in patients with unspecific mental retardation. However, and although infrequent, there are a number of inborn errors of metabolism that can present in this way. Because of the high recurrence risk and the possibility of specific therapies, guidelines need to be developed and adapted to different populations. The application of a universal protocol may result in a low diagnostic performance in individual ethnic populations. Consideration of associated signs (extraneurological manifestations, psychiatric signs, autistic traits, cerebellar dysfunction, epilepsy or dysmorphic traits) greatly improves the diagnostic fulfilment.

Inborn errors of metabolism and motor disturbances in children

Motor disturbances are very common in paediatric neurology. Often families can be reassured that these are just variants of normal development. However, abnormal movements can also be the hallmark of severe brain dysfunction of different and complex origins. This review concentrates on motor disturbances as frequent and important symptoms of inborn errors of metabolism. A structured diagnostic approach is developed taking into account age-dependent physiological developments and pathophysiological responses of gross and fine motor functions. A series of investigations are presented with the primary aim of early diagnosis of treatable conditions. The correct recognition and differentiation of movement disorders (ataxia, rigid akinetic syndrome (Fparkinsonism_), dystonia, athetosis, tremor,and others), spasticity, and neuromuscular disorders, requires profound neurological expertise. A high level of suspicion and close interaction between paediatric neurologists and specialists in inborn errors of metabolism are indispensable to effectively and timely identify patients in whom motor disturbances are the presenting and/or main symptom of an inborn error.

Long-term evolution of eight Spanish patients with CDG type Ia: typical and atypical manifestations

Congenital disorder of glycosylation Ia (CDG-Ia) is a metabolic disease with a broad spectrum of clinical signs, including recently described mild phenotypes. Our aim was to describe the clinical presentation and follow-up of eight CDG-Ia patients highlighting atypical features and aspects of evolution of the disease. CDG diagnosis was confirmed by enzymatic analysis of phosphomannomutase (PMM2) and molecular studies of the PMM2 gene. Four neonates presented with cerebral haemorrhage (1), failure to thrive (2) and non-immune hydrops (1) and a fatal course to death (2); pathological examination of the brain in one case revealed olivopontocerebellar atrophy of prenatal origin. During infancy failure to thrive, coagulopathy and hepatopathy were the most significant causes of morbidity, but these disappeared after the first years of life in most patients. Three patients are currently in their 20s; they present mental retardation and severe motor impairment but no acute decompensations were noticed after the first decade of life. They do not present spinal or thoracic deformities otherwise observed in patients from northern countries. A 10-year-old patient who manifested gastrointestinal dysfunction in early childhood showed normal neurodevelopment. Mutation analysis of the PMM2 gene showed great variability, with all patients being compound heterozygous for two different mutations. Long-term evolution in our patients indicates that CDG-Ia is a stable systemic and neurological condition after the first decade of life. The diverse phenotypes and atypical manifestations in our series may be due to their genetic heterogeneity.

Novel FOXG1 mutations associated with the congenital variant of Rett syndrome

BACKGROUND

Rett syndrome is a severe neurodevelopmental disorder representing one of the most common genetic causes of mental retardation in girls. The classic form is caused by MECP2 mutations. In two patients affected by the congenital variant of Rett we have recently identified mutations in the FOXG1 gene encoding a brain specific transcriptional repressor, essential for early development of the telencephalon.

METHODS

60 MECP2/CDKL5 mutation negative European Rett patients (classic and variants), 43 patients with encephalopathy with early onset seizures, and four atypical Rett patients were analysed for mutations in FOXG1.

RESULTS AND CONCLUSIONS

Mutations have been identified in four patients, independently classified as congenital Rett variants from France, Spain and Latvia. Clinical data have been compared with the two previously reported patients with mutations in FOXG1. In all cases hypotonia, irresponsiveness and irritability were present in the neonatal period. At birth, head circumference was normal while a deceleration of growth was recognised soon afterwards, leading to severe microcephaly. Motor development was severely impaired and voluntary hand use was absent. In contrast with classic Rett, patients showed poor eye contact. Typical stereotypic hand movements with hand washing and hand mouthing activities were present continuously. Some patients showed abnormal movements of the tongue and jerky movements of the limbs. Brain magnetic resonance imaging showed corpus callosum hypoplasia in most cases, while epilepsy was a variable sign. Scoliosis was present and severe in the older patients. Neurovegetative symptoms typical of Rett were frequently present.

InterRett, a model for international data collection in a rare genetic disorder

Rett syndrome (RTT) is a rare genetic disorder within the autistic spectrum. This study compared socio-demographic, clinical and genetic characteristics of the international database, InterRett, and the population based Australian Rett syndrome database (ARSD). It also explored the strengths and limitations of InterRett in comparison with other studies. A literature review compared InterRett with RTT population-based and case-based studies of thirty or more cases that investigated genotype and/or phenotype relationships. Questionnaire data were used to determine case status and to investigate the comparability of InterRett and ARSD. Twenty four case series, five population based studies and a MECP2 mutation database were identified of which twenty one (70%) collected phenotype and genotype data. Only three studies were representative of their underlying case population and many had low numbers. Of one thousand one hundred and fourteen InterRett subjects, nine hundred and thirty five born after 1976 could be verified as Rett cases and compared with the two hundred and ninety five ARSD subjects. Although more InterRett families had higher education and occupation levels and their children were marginally less severe, the distribution of MECP2 mutation types was similar. The InterRett can be used with confidence to investigate genotype phenotype associations and clinical variation in RTT and provides an exemplary international model for other rare disorders.

Seizures versus dystonia in encephalopathic crisis of glutaric aciduria type I

In more than two thirds of cases, glutaric aciduria type I begins in the first 3 years of life with an acute encephalopathic crisis with hypotonia or generalized rigidity, neurologic depression, irritability, seizures, and dystonia. The clinical histories were reviewed for 13 glutaric aciduria type I patients (9 male, 4 female; mean age, 8.7 months; range, 3-15 months) with encephalopathic crisis seen at Sant Joan de Déu Hospital, to describe the clinical features and the initial electroencephalographic (EEG) findings. Twelve of the patients (92%) had paroxysmal episodes at onset. Other clinical features included irritability (12/13), neurologic depression (11/13), and hypotonia (7/13). All patients evolved to dystonic tetraparesis. Thirty-five EEGs were recorded in the acute stage and during the first year of follow-up. Spike discharges on EEG were observed in only 2 of the 13 patients, and 8 had slow background activity. No patient developed seizures during follow-up. Seizures may be part of the symptomatology at the onset of glutaric aciduria type I, but most paroxysmal movements appear to be dystonic episodes. This hypothesis is supported by four facts: seizures do not occur after dystonic tetraparesis is noticed, EEG paroxysms are infrequent in the acute stage, antiepileptic drugs are not needed in the long term, and epilepsy is rare in the follow-up.

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 (beta-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.

Arginine supplementation in four patients with X-linked creatine transporter defect

BACKGROUND

Treatment with oral creatine monohydrate has not shown efficacy in patients with creatine transporter deficiency (CRTR-D). Another therapeutic option proposed is L-arginine, the substrate for the enzyme L-arginine:glycine amidinotransferase (AGAT). We evaluate clinical characteristics and cerebral creatine replenishment after L-arginine therapy in four patients with CRTR-D.

PATIENTS AND METHODS

Four boys with genetically confirmed diagnosis of CRTR-D (ages 9-16 years) were supplemented with L-arginine (0.4 g/kg per day) for a period of 9 months. Treatment efficacy was evaluated by clinical and neuropsychological assessment and determination of creatine signals by brain proton magnetic resonance spectroscopy ((1)H-MRS).

RESULTS

Epileptic seizures remained well controlled with antiepileptic drugs in three cases, both before and after L-arginine supplementation. Vineland Adaptive Behaviour Scale did not show any change in communication, daily living skills, socialization or motor skills, and a lack of improvement in brain (1)H-MRS follow-up was observed. L-Arginine was discontinued at the end of the observation period.

CONCLUSIONS

Nine months of L-arginine supplementation did not show effectiveness in the four patients affected with CRTR-D in this protocol.