Morquio B disease: From pathophysiology towards diagnosis.

Morquio B disease is an attenuated phenotype within the spectrum of beta galactosidase (GLB1) deficiencies. It is characterised by dysostosis multiplex, ligament laxity, mildly coarse facies and heart valve defects due to keratan sulphate accumulation, predominantly in the cartilage. Morquio B patients have normal neurological development, setting them apart from those with the more severe GM1 gangliosidosis. Morquio B disease, with an incidence of 1:250.000 to 1:1.000.000 live births, is very rare. Here we report the clinical-biochemical data of nine patients. High amounts of keratan sulfate were detected using LC-MS/MS in the patients' urinary samples, while electrophoresis, the standard procedure of qualitative glycosaminoglycans analysis, failed to identify this metabolite in any of the patients' samples. We performed molecular analyses at gene, gene expression and protein expression levels, for both isoforms of the GLB1 gene, lysosomal GLB1, and the cell-surface expressed Elastin Binding Protein. We characterised three novel GLB1 mutations [c.75 + 2 T > G, c.575A > G (p.Tyr192Cys) and c.2030 T > G (p.Val677Gly)] identified in three heterozygous patients. We also set up a copy number variation assay by quantitative PCR to evaluate the presence of deletions/ insertions in the GLB1 gene. We propose a diagnostic plan, setting out the specific clinical- biochemical and molecular features of Morquio B, in order to avoid misdiagnoses and improve patients' management.

Molecular diagnosis of patients affected by mucopolysaccharidosis: a multicenter study.

Mucopolysaccharidoses (MPS) are a subgroup of 11 monogenic lysosomal storage disorders due to the deficit of activity of the lysosomal hydrolases deputed to the degradation of mucopolysaccharides. Although individually rare, all together they account for at least 1:25,000 live births. In this study, we present the genetic analysis of a population of 71 MPS patients enrolled in a multicenter Italian study. We re-annotated all variants, according to the latest recommendations, and re-classified them as suggested by the American College of Medical Genetics and Genomics. Variant distribution per type was mainly represented by missense mutations. Overall, 10 patients had received no molecular diagnosis, although 6 of them had undergone either HSCT or ERT, based on clinical and enzymatic evaluations. Moreover, nine novel variants are reported.Conclusions: Our analysis underlines the need to complete the molecular diagnosis in patients previously diagnosed only on a biochemical basis, suggests a periodical re-annotation of the variants and solicits their deposition in public databases freely available to clinicians and researchers. We strongly recommend a molecular diagnosis based on the analysis of the "trio" instead of the sole proband. These recommendations will help to obtain a complete and correct diagnosis of mucopolysaccharidosis, rendering also possible genetic counseling. What is known • MPS are a group of 11 metabolic genetic disorders due to deficits of enzymes involved in the mucopolysaccharides degradation. • Molecular analysis is commonly performed to confirm enzymatic assays. What is new • Eighty-six percent of the 71 patients we collected received a molecular diagnosis; among them, 9 novel variants were reported. • We stress the importance of molecular diagnosis in biochemically diagnosed patients, encourage a periodical re-annotation of variants according to the recent nomenclature and their publication in open databases.

The treatment of juvenile/adult GM1-gangliosidosis with Miglustat may reverse disease progression.

Juvenile and adult GM1-gangliosidosis are invariably characterized by progressive neurological deterioration. To date only symptomatic therapies are available. We report for the first time the positive results of Miglustat (OGT 918, N-butyl-deoxynojirimycin) treatment on three Italian GM1-gangliosidosis patients. The first two patients had a juvenile form (enzyme activity ≤5%, GLB1 genotype p.R201H/c.1068 + 1G > T; p.R201H/p.I51N), while the third patient had an adult form (enzyme activity about 7%, p.T329A/p.R442Q). Treatment with Miglustat at the dose of 600 mg/day was started at the age of 10, 17 and 28 years; age at last evaluation was 21, 20 and 38 respectively. Response to treatment was evaluated using neurological examinations in all three patients every 4-6 months, the assessment of Movement Disorder-Childhood Rating Scale (MD-CRS) in the second patient, and the 6-Minute Walking Test (6-MWT) in the third patient. The baseline neurological status was severely impaired, with loss of autonomous ambulation and speech in the first two patients, and gait and language difficulties in the third patient. All three patients showed gradual improvement while being treated; both juvenile patients regained the ability to walk without assistance for few meters, and increased alertness and vocalization. The MD-CRS class score in the second patient decreased from 4 to 2. The third patient improved in movement and speech control, the distance covered during the 6-MWT increased from 338 to 475 m. These results suggest that Miglustat may help slow down or reverse the disease progression in juvenile/adult GM1-gangliosidosis.

Cardiac involvement in MPS patients: incidence and response to therapy in an Italian multicentre study.

BACKGROUND: Mucopolysaccharidoses (MPSs) are a group of lysosomal storage disorders caused by the deficit of lysosomal hydrolases involved in the degradation of glycosaminoglycans (GAGs). The course is chronic and progressive, with multisystemic involvement that often leads to cardiovascular disease. We describe the overall incidence and type of cardiac damage in a cohort of Italian MPS patients, and their progression over time, also with reference to treatment efficacy in patients under Enzyme Replacement Therapy (ERT). Moreover, we report a possible association between genetic variants and cardiac phenotype in homozygous and hemizygous patients to understand whether a more aggressive clinical phenotype would predict a greater cardiac damage. RESULTS: Our findings confirm that cardiac involvement is very common, already at diagnosis, in MPS VI (85.7% of our cohort), and in MPS II (68% of our cohort) followed by MPS I subjects (55% of our cohort). The most frequent heart defect observed in each MPS and at any time-point of evaluation was mitral insufficiency; 37% of our patients had mitral insufficiency already at diagnosis, and 60% at post-ERT follow-up. After at least six years of treatment, we observed in some cases (including 6 MPS II, 2 MPS IV and 2 MPS VI) a total regression or improvement of some signs of the cardiac pathology, including some valve defects, though excluding aortic insufficiency, the only valvulopathy for which no regression was found despite ERT. The general clinical phenotype proved not to be strictly correlated with the cardiac one, in fact in some cases patients with an attenuated phenotype developed more severe heart damage than patients with severe phenotype. CONCLUSIONS: In conclusion, our analysis confirms the wide presence of cardiopathies, at different extent, in the MPS population. Since cardiac pathology is the main cause of death in many MPS subtypes, it is necessary to raise awareness among cardiologists about early cardiac morpho-structural abnormalities. The encouraging data regarding the long-term effects of ERT, also on heart damage, underlines the importance of an early diagnosis and timely start of ERT.

Brain and spine MRI features of Hunter disease: frequency, natural evolution and response to therapy.

BACKGROUND: Hunter disease is a rare X-linked mucopolysaccharidosis. Despite frequent neurological involvement, characterizing the severe phenotype, neuroimaging studies are scarce. OBJECTIVES: To determine frequency and severity of neuroradiological mucopolysaccharidosis-related features; to correlate them with clinical phenotype; to evaluate their natural evolution and the impact of intravenous enzymatic replacement therapy (ERT). METHODS: Sixty nine brain MRI examinations of 36 Italian patients (mean-age 10.4 years; age-range 2.2-30.8; severe phenotype in 22 patients) were evaluated. Twenty patients had multiple MRIs (median follow-up 3.1 years, range 1-16.9): among them 15 had MRIs before and after ERT, six had repeated MRIs without being on ERT and five while on ERT. Perivascular, subarachnoid and ventricle space enlargement, white matter abnormality (WMA) burden, pituitary sella/skull/posterior fossa abnormalities, periodontoid thickening, spinal stenosis, dens hypoplasia, myelopathy, vertebral and intervertebral disc abnormalities were graded by means of dedicated scales. RESULTS: Perivascular spaces enlargement (89%), WMAs (97%), subarachnoid space enlargement (83%), IIIrd-ventricle dilatation (100%), pituitary sella abnormalities (80%), cranial hyperostosis (19%), craniosynostosis (19%), enlarged cisterna magna (39%), dens hypoplasia (66%), periodontoid thickening (94%), spinal stenosis (46%), platyspondylia (84%) and disc abnormalities (79%) were frequently detected. WMAs, IIIrd-ventricle dilatation and hyperostosis correlated with the severe phenotype (p < 0.05). Subarachnoid spaces and ventricle enlargement, WMAs and spinal stenosis progressed despite ERT, while other MR features showed minimal or no changes. CONCLUSIONS: The spectrum of brain and spine MRI abnormalities in Hunter disease is extremely wide and requires a thorough evaluation. WMAs, atrophy/communicating hydrocephalus and spinal stenosis progress over time and might represent possible disease severity markers for new treatment efficacy assessment.

Hunter syndrome in an 11-year old girl on enzyme replacement therapy with idursulfase: brain magnetic resonance imaging features and evolution.

Mucopolysaccharidosis type II (MPS-II, Hunter disease) is a X-linked recessive disorder. Affected females are extremely rare, mostly due to skewed X chromosome inactivation. A few papers outline MPS-II brain magnetic resonance imaging (MRI) "gestalt" in males, but neuroradiological reports on females are still lacking. We present an 11-year-old girl affected by the severe form of MPS-II who was followed up over a time span of 8 years, focusing on clinical and brain MRI evolution. In the last 2.5 years, the patient has been treated with enzyme replacement therapy (ERT) with idursulfase (Elaprase™, Shire Human Genetic Therapies AB, Sweden). On brain and cervical MRI examination, abnormalities in our patient did not differ from those detected in male patients: J-shaped pituitary sella, enlargement of perivascular spaces, brain atrophy, mild T2-hyperintensity in the paratrigonal white matter, diffuse platyspondylia, and mild odontoid dysplasia with odontoid cup. Brain atrophy progressed despite ERT introduction, whereas perivascular space enlargement did not change significantly before and after ERT. Cognitive impairment worsened independently from the course of white matter abnormality. Despite a profound knowledge of genetic and biochemical aspects in MPS-II, neuroradiology is still poorly characterized, especially in female patients. Spinal and brain involvement and its natural course and evolution after ERT introduction still need to be clarified.

Setup and Validation of a Targeted Next-Generation Sequencing Approach for the Diagnosis of Lysosomal Storage Disorders.

Lysosomal storage disorders (LSDs) are monogenic diseases, due to accumulation of specific undegraded substrates into lysosomes. LSD diagnosis could take several years because of both poor knowledge of these diseases and shared clinical features. The diagnostic approach includes clinical evaluations, biochemical tests, and genetic analysis of the suspected gene. In this study, we evaluated an LSD targeted sequencing panel as a tool capable to potentially reverse this classic diagnostic route. The panel includes 50 LSD genes and 230 intronic sequences conserved among 33 placental mammals. For the validation phase, 56 positive controls, 13 biochemically diagnosed patients, and nine undiagnosed patients were analyzed. Disease-causing variants were identified in 66% of the positive control alleles and in 62% of the biochemically diagnosed patients. Three undiagnosed patients were diagnosed. Eight patients undiagnosed by the panel were analyzed by whole exome sequencing: for two of them, the disease-causing variants were identified. Five patients, undiagnosed by both panel and exome analyses, were investigated through array comparative genomic hybridization: one of them was diagnosed. Conserved intronic fragment analysis, performed in cases unresolved by the first-level analysis, evidenced no candidate intronic variants. Targeted sequencing has low sequencing costs and short sequencing time. However, a coverage >60× to 80× must be ensured and/or Sanger validation should be performed. Moreover, it must be supported by a thorough clinical phenotyping.

Mucopolysaccharidosis VI: the Italian experience.

The current paper describes the natural history and management of mucopolysaccharidosis VI (MPS VI) in all patients currently diagnosed with the disease in Italy. Nine patients (5.5-14.4 years) were included in the data review in March 2008. Gestational and perinatal data were normal for all patients. Median age at diagnosis was 1.9 years. During the course of the disease, all patients developed coarsened facial features, short stature, heart valve disease, eye problems, musculoskeletal problems, hepatosplenomegaly and neurological abnormalities. All patients received rhASB enzyme replacement therapy (ERT) and showed improvement or stabilisation in clinical manifestations after onset of therapy. The most frequently reported improvements were increased joint mobility and reduced hepatosplenomegaly. No relevant safety issues of ERT were reported. In conclusion, patients in Italy with MPS VI are diagnosed early in life. All patients have access to ERT and appear to benefit from this therapy.

The Complexity of Pain Management in Children Affected by Mucopolysaccharidoses.

Mucopolysaccharidoses (MPSs) are a group of rare, genetic lysosomal storage disorders. They are caused by deficiencies of the lysosomal enzymes involved in the degradation of glycosaminoglycans (GAGs). Pain is a common feature in mucopolysaccharidoses. However, the pathophysiology of pain in this group of diseases is still unclear and genesis of pain is multifactorial. Currently, poor data about pain management in these patients are available. Here, we present our clinical experience in complex pain management in three children with MPS.

Chiari 1 malformation and holocord syringomyelia in hunter syndrome.

Compressive cervical myelopathy is a well-known life-threatening complication in mucopolysaccharidosis (MPS) patients. Glycosaminoglycan accumulation in the growing cartilage results in dens dysplasia, atlanto-axial instability, and subsequent periodontoid fibrocartilaginous tissue deposition with upper cervical stenosis.Chiari malformation type 1 (CM1) is a congenital downward cerebellar tonsil ectopia determined by clivus and posterior cranial fossa underdevelopment, possibly leading to progressive spinal cord cavitation (syringomyelia) and severe neurological impairment.We present a boy affected with Hunter syndrome (MPS II) and cerebellar tonsil ectopia who developed a holocord syringomyelia at the age of 6 years. The child underwent atlanto-occipital decompressive surgery with rapid clinical and neuroimaging improvement.Sharing a primary mesenchymal involvement of the cervical-occipital region, the coexistence of CM1 in MPS might be not unexpected and complicate further the disease course. In these patients, strict monitoring and prompt treatment might be of foremost importance for preventing major neurological complications.

Nocturnal frontal lobe epilepsy in mucopolysaccharidosis.

Nocturnal frontal lobe epilepsy (NFLE) is an epileptic syndrome that is primarily characterized by seizures with motor signs occurring almost exclusively during sleep. We describe 2 children with mucopolysaccharidosis (MPS) who were referred for significant sleep disturbance. Long term video-EEG monitoring (LT-VEEGM) demonstrated sleep-related hypermotor seizures consistent with NFLE. No case of sleep-related hypermotor seizures has ever been reported to date in MPS. However, differential diagnosis with parasomnias has been previously discussed. The high frequency of frontal lobe seizures causes sleep fragmentation, which may result in sleep disturbances observed in at least a small percentage of MPS patients. We suggest monitoring individuals with MPS using periodic LT-VEEGM, particularly when sleep disorder is present. Moreover, our cases confirm that NFLE in lysosomal storage diseases may occur, and this finding extends the etiologic spectrum of NFLE.

A Hunter Patient with a Severe Phenotype Reveals Two Large Deletions and Two Duplications Extending 1.2 Mb Distally to IDS Locus.

Mucopolysaccharidosis type II (Hunter syndrome, MPS II) is an X-linked lysosomal storage disorder caused by the deficit of iduronate 2-sulfatase (IDS), an enzyme involved in the glycosaminoglycans (GAGs) degradation. We here report the case of a 9-year-old boy who was diagnosed with an extremely severe form of MPS II at 10 months of age. Sequencing of the IDS gene revealed the deletion of exons 1-7, extending distally and removing the entire pseudogene IDSP1. The difficulty to define the boundaries of the deletion and the particular severity of the patient phenotype suggested to verify the presence of pathological copy number variations (CNVs) in the genome, by the array CGH (aCGH) technology. The examination revealed the presence of two deletions alternate with two duplications, overall affecting a region of about 1.2 Mb distally to IDS gene. This is the first complex rearrangement involving IDS and extending to a large region located distally to it described in a severe Hunter patient, as evidenced by the CNVs databases interrogated. The analysis of the genes involved in the rearrangement and of the disorders correlated with them did not help to clarify the phenotype observed in our patient, except for the deletion of the IDS gene, which explains per se the Hunter phenotype. However, this cannot exclude a potential "contiguous gene syndrome" as well as the future rising of additional pathological symptoms associated with the other extra genes involved in the identified rearrangement.

Clinical efficacy of enzyme replacement therapy in paediatric Hunter patients, an independent study of 3.5 years.

BACKGROUND: Hunter Syndrome is an X-linked lysosomal storage disorder due to the deficit of iduronate 2-sulfatase, an enzyme catalysing the degradation of the glycosaminoglycans (GAG) dermatan- and heparan-sulfate. Treatment of the disease is mainly performed by Enzyme Replacement Therapy (ERT) with idursulfase, in use since 2006. Clinical efficacy of ERT has been monitored mainly by the Hunter Outcome Survey (HOS) while very few independent studies have been so far conducted. The present study is a 3.5-years independent follow-up of 27 Hunter patients, starting ERT between 1.6 and 27 years of age, with the primary aim to evaluate efficacy of the therapy started at an early age (<12 years). METHODS: In this study, we evaluated: urinary GAG content, hepato/splenomegaly, heart valvulopathies, otorinolaryngological symptoms, joint range of motion, growth, distance covered in the 6-minute walk test, neurological involvement. For data analysis, the 27 patients were divided into three groups according to the age at start of ERT: ≤5 years, >5 and ≤ 12 years and > 12 years. Patients were analysed both as 3 separate groups and also as one group; in addition, the 20 patients who started ERT up to 12 years of age were analysed as one group. Finally, patients presenting a "severe" phenotype were compared with "attenuated" ones. RESULTS: Data analysis revealed a statistically significant reduction of the urinary GAG in patients ≤5 years and ≤ 12 years and of the hepatomegaly in the group aged >5 and ≤ 12 years. Although other clinical signs improved in some of the patients monitored, statistical analysis of their variation did not reveal any significant changes following enzyme administration. The evaluation of ERT efficacy in relation to the severity of the disease evidenced slightly higher improvements as for hepatomegaly, splenomegaly, otological disorders and adenotonsillar hypertrophy in severe vs attenuated patients. CONCLUSIONS: Although the present protocol of idursulfase administration may result efficacious in delaying the MPS II somatic disease progression at some extent, in this study we observed that several signs and symptoms did not improve during the therapy. Therefore, a strict monitoring of the efficacy obtained in the patients under ERT is becoming mandatory for clinical, ethical and economic reasons.

The role of visual electrophysiology in mucopolysaccharidoses.

Visual electrophysiological techniques represent excellent means for assessing retinal, optic pathways and visual cortex function. Electroretinograms, visual evoked potentials, and clinical records of 17 patients with mucopolysaccharidosis registered in the neurophysiological database of our institution were reviewed retrospectively. Ten patients were on enzyme replacement therapy, 2 underwent bone marrow transplantation, one also keratoplasty. Changes in the electroretinogram pointed to the diagnosis of retinal dystrophy type rod-cone in 8 patients. In patients in whom severe corneal clouding precluded fundus oculi inspection and at an early stage before typical fundus appearance diagnosis was possible only using the electroretinogram. Visual evoked potentials were useful to confirm the loss of visual function in patients difficult to test clinically. The authors suggest the use of electroretinogram and visual evoked potentials primarily as research tools to describe the natural history and ophthalmologic outcome in mucopolysaccharidoses, although they may have clinical utility in very selected cases.

Difficulties in diagnosing slowly progressive mucopolysaccharidosis VI: A case series.

An Erratum for this article can be found here: http://iospress.metapress.com/content/e16437020701m0u5/?p=df8dd6709cf44367a0c0e5d917aaeddf&pi=11We describe the cases of two adult sisters recently diagnosed with the attenuated form of mucopolysaccharidosis VI (MPS VI, Maroteaux-Lamy syndrome). MPS VI is a rare, clinically heterogeneous lysosomal storage disorder that is characterized by a deficiency in the glycosaminoglycan-degrading enzyme arylsulfatase B. Both cases had been misdiagnosed for over 30 years despite the presence of several characteristics of the disease, including short stature (mild), coarse facial features, skeletal dysmorphisms, carpal tunnel syndrome, heart valve disease, and spinal cord compression, which together are suggestive of a lysosomal storage disease. Awareness about the clinical features of MPS VI should be communicated amongst treating neurologists, rheumatologists and other specialists who are involved in the healthcare decisions of these patients with presenting symptoms, so they can refer them to specialized centers for proper diagnosis and treatment.