Sphingolipidoses in Morocco: Chemical profiling for an affordable and rapid diagnosis strategy.

Sphingolipidoses are a group of metabolic diseases in which lysosomal hydrolases dysfunction disrupt normal sphingolipids' metabolism, leading to excess accumulation in cellular compartments and excretion in urine. These pathologies represent a significant burden among Moroccan population, for which an easy access to enzymatic assays and genetic tests is not guaranteed. Parallel analytical methods thus have to be developed for preliminary screening. In this study, 107 patients were addressed to the metabolic platform of the Marrakesh Faculty of Medicine for diagnosis confirmation. Thin-Layer Chromatography was used as a first step to perform chemical profiling of the patients' urinary lipids, allowing 36% of the patients to be efficiently oriented towards the adequate enzymatic assay. UPLC-MS/MS analyses of urinary sulfatides excreted in urines patient had been used to control the reliability of TLC analysis and to obtain more accurate information related to the sulfatides isoforms. This analytical process combining TLC with UPLC-MS/MS has enabled rapid and appropriate patient management in a reduced time and with reduced resources.

Rare Diseases in Glycosphingolipid Metabolism.

Sphingolipidoses is a cluster of genetic rare disorders regarding glycosphingolipid metabolism, classified as lysosomal storage disorders (LSD). Here, we focus on eight inheritable diseases, including GM1 gangliosidosis, GM2 gangliosidosis, Fabry disease, Gaucher's disease, metachromatic leukodystrophy, Krabbe disease, Niemann-Pick disease A and B, and Farber disease. Mostly, pathogenic mutations in the key enzyme are loss-function, resulting in accumulation of substrates and deficiency of products. Thus, cellular overload of substrates causes lipotoxicity, which is deleterious to cellular and organ function. In the terms of clinical manifestations in sphingolipidoses, multiple systems and organs, especially central nervous system (CNS) are usually affected. As for diagnosis strategy, enzymatic activity assay and genetic sequencing are helpful. Up till now, limited treatment approaches have approved for treating sphingolipidoses, with some potential strategies for further evaluation. In general, enzyme replacement therapy (ERT), substrate reduction therapy (SRT), and molecular chaperones are feasible choices for enzyme deficiency disorders, but these therapies are limited to relieve CNS lesions and symptoms due to prevention from blood-brain barrier. Other possible treatments such as gene therapy, bone marrow transplantation (BMT), and hematopoietic stem cell transplantation (HSCT) need further evaluation.

Plasma and dried blood spot lysosphingolipids for the diagnosis of different sphingolipidoses: a comparative study.

Background Lysosphingolipids, the N-deacylated forms of sphingolipids, have been identified as potential biomarkers of several sphingolipidoses, such as Gaucher, Fabry, Krabbe and Niemann-Pick diseases and in GM1 and GM2 gangliosidoses. To date, different methods have been developed to measure various lysosphingolipids (LysoSLs) in plasma. Here, we present a novel liquid chromatography tandem mass spectrometry (LC-MS/MS) assay for a simultaneous quantification of LysoSLs (HexSph, LysoGb3, LysoGM1, LysoGM2, LysoSM and LysoSM509) in dried blood spot (DBS). This LC-MS/MS method was used to compare the levels of LysoSLs in DBS and plasma in both affected patients and healthy controls. Methods Lysosphingolipids were extracted from a 3.2 mm diameter DBS with a mixture of methanol:acetonitrile:water (80:15:5, v/v) containing internal stable isotope standards. Chromatographic separation was performed using a C18 column with a gradient of water and acetonitrile both with 0.1% formic acid in a total run time of 4 min. The compounds were detected in the positive ion mode electrospray ionization (ESI)-MS/MS by multiple reaction monitoring (MRM). Results The method was validated on DBS to demonstrate specificity, linearity, lowest limit of quantification, accuracy and precision. The reference ranges were determined in pediatric and adult populations. The elevated levels of LysoSLs were identified in Gaucher disease (HexSph), Fabry disease (LysoGb3), prosaposin deficiency (HexSph and LysoGb3) and Niemann-Pick disease types A/B and C (LysoSM and LysoSM509). The correlation in the levels between DBS and plasma was excellent for LysoGb3 and HexSph but poor for LysoSM and LysoSM509. Conclusions Despite the fact that plasma LysoSLs determination remains the gold standard, our LC-MS/MS method allows a rapid and reliable quantification of lysosphingolipids in DBS. The method is a useful tool for the diagnosis of different sphingolipidoses except for Niemann-Pick type C.

Diagnosis of sphingolipidoses: a new simultaneous measurement of lysosphingolipids by LC-MS/MS.

BACKGROUND: Lysosphingolipids (LysoSLs) are derivatives of sphingolipids which have lost the amide-linked acyl chain. More recently, LysoSLs have been identified as storage compounds in several sphingolipidoses, including Gaucher, Fabry and Niemann-Pick diseases. To date, different methods have been developed to measure each individual lysosphingolipid in plasma. This report describes a rapid liquid chromatography coupled with tandem mass spectrometry (LC-MS/MS) assay for simultaneous quantification of several LysoSLs in plasma. METHODS: We analyzed the following compounds: hexosylsphingosine (HexSph), globotriaosylsphingosine (LysoGb3), lysosphingomyelin (LysoSM) and lysosphingomyelin-509 (LysoSM-509). The sample preparation requires only 100 µL of plasma and consists of an extraction with a mixture of MeOH/acetone/H2O (45:45:10, v/v). RESULTS: The method validation showed high sensitivity, an excellent accuracy and precision. Reference ranges were determined in healthy adult and pediatric population. The results demonstrate that the LC-MS/MS method can quantify different LysoSLs and can be used to identify patients with Fabry (LysoGb3), Gaucher and Krabbe (HexSph) diseases, prosaposine deficiency (LysoGb3 and HexSph), and Niemann-Pick disease types A/B and C (LysoSM and LysoSM-509). CONCLUSIONS: This LC-MS/MS method allows a rapid and simultaneous quantification of LysoSLs and is useful as a biochemical diagnostic tool for sphingolipidoses.

Tandem Mass Spectrometry of Sphingolipids: Applications for Diagnosis of Sphingolipidoses.

In recent years, mass spectrometry (MS) has become the dominant technology in lipidomic analysis. It is widely used in diagnosis and research of lipid metabolism disorders including those characterized by impairment of lysosomal functions and storage of nondegraded-degraded substrates. These rare diseases, which include sphingolipidoses, have severe and often fatal clinical consequences. Modern MS methods have contributed significantly to achieve a definitive diagnosis, which is essential in clinical practice to begin properly targeted patient care. Here we summarize MS and tandem MS methods used for qualitative and quantitative analysis of sphingolipids (SL) relative to the diagnostic process for sphingolipidoses and studies focusing on alterations in cell functions due to these disorders. This review covers the following topics: Tandem MS is sensitive and robust in determining the composition of sphingolipid classes in various biological materials. Its ability to establish SL metabolomic profiles using MS bench-top analyzers, significantly benefits the first stages of a diagnosis as well as metabolic studies of these disorders. It can thus contribute to a better understanding of the biological significance of SL.

Enfermedad por depósito lisosomal con peculiaridades diferenciales: gangliosidosis GM1 tipo II / Disease due to lysosomal deposits with differential peculiarities: type II GM1 gangliosidosis

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Beyond the cherry-red spot: Ocular manifestations of sphingolipid-mediated neurodegenerative and inflammatory disorders.

Sphingolipids are a ubiquitous membrane lipid present in every cell and found most abundantly in neural tissues. Disorders such as Tay-Sachs or Niemann-Pick disease are the most familiar examples of dysfunction in sphingolipid metabolism and are typically associated with neurodegeneration and ocular findings such as blindness. More recently, the role of bioactive sphingolipids has been established in a multitude of cellular events, including cell survival, growth, senescence and apoptosis, inflammation, and neovascularization. We discuss our current knowledge and understanding of sphingolipid metabolism and signaling in the pathogenesis of ocular diseases.

[Lysosomal storage diseases]. / Lysosomale Speicherkrankheiten.

Lysosomal storage diseases are a heterogeneous group of disorders caused by lysosomal enzyme dysfunction. Individually they are very rare, but this group as a whole has a prevalence of more than 1:8,000 live births. While severe phenotypes are easily diagnosed this can be a real challenge with attenuated forms. Because musculoskeletal complaints are frequently the first reason for the patient to seek medical advice, the rheumatologist plays a key role for the early recognition of these diseases. Since several of these can be treated very effectively by enzyme replacement, a timely diagnosis and start of therapy are essential to avoid irreversible organ damage and poor quality of life. Therefore, each clinical rheumatologist should be aware of the cardinal symptoms of lysosomal storage diseases.

Musculoskeletal manifestations of lysosomal storage disorders.

Lysosomal storage disorders (LSDs), a heterogeneous group of inborn metabolic disorders, are far more common than most doctors presume. Although patients with a severe LSD subtype are often readily diagnosed, the more attenuated subtypes are frequently missed or diagnosis is significantly delayed. The presenting manifestations often involve the bones and/or joints and therefore these patients are frequently under specialist care by (paediatric) rheumatologists, receiving inadequate treatment. Since effective disease-specific treatments, including enzyme replacement therapy and stem cell transplantation, have become available for certain LSDs and timely initiation of these treatments is necessary to prevent the development of severe, disabling and irreversible manifestations, early diagnosis has become essential. The challenge is to raise awareness for better recognition of the presenting signs and symptoms of LSDs by all doctors who may encounter these patients, including rheumatologists.

Prenatal diagnosis of perplexing cases of lipidoses.

OBJECTIVE: To present and discuss the technical, ethical and counseling difficulties that were encountered in the prenatal diagnosis of some perplexing cases of lipidoses. PATIENTS: Four pregnant women were referred to us for prenatal diagnosis with the diagnosis of lipidosis in an affected sibling. DISCUSSION: (1) It is recommended to do the enzyme assays as the first choice in all cases suspected clinically to have lipidoses in order to establish the diagnosis instead of doing invasive procedures as liver and bone marrow biopsies. (2) Activity of more than one enzyme should be assayed to confirm specific deficiency against reference values. (3) Suspected prenatal diagnosis and indefinite diagnosis should only be considered after detailed and non-directive counseling (Tab. 1, Fig. 4, Ref. 5).

Difficulty in recognizing multiple sulfatase deficiency in an infant.

We describe the difficulty in recognizing multiple sulfatase deficiency (MSD; Online Mendelian Inheritance in Man [OMIM] database No. 272200) in an infant. MSD is a rare autosomal recessive disorder that affects the posttranslational activation of various sulfatase enzymes. It is both biochemically and clinically variable. Currently, there are 12 known sulfatases in humans, and the clinical presentation of MSD is a unique composite of those individual enzyme defects. Here we report a black girl who presented with bilateral broad thumbs and great toes, both with angulation deformities at birth. Rubinstein-Taybi syndrome (OMIM No. 180849) was considered initially. The detection of inclusion bodies in her white blood cells at 37 months of age led to the appropriate diagnostic workups for lysosomal storage diseases. Elevation of urine mucopolysaccharides provided additional clues, and the fibroblast enzyme assays finally established the diagnosis. Broad thumbs and great toes are rare features of MSD, and to the best of our knowledge such a bilateral congenital anomaly with angulation deformities has never been reported before to be associated with MSD.

Sphingolipidoses in Turkey.

During the last 5 years 2057 children under the age of 5 with various neurologic symptoms with the suspected diagnosis of lysosomal storage diseases were referred to our hospital from different universities and state hospitals. We were able to separate sphingolipidoses by lysosomal enzyme screening. A total of 300 patients (15%) with sphingolipidoses were diagnosed; there were deficiencies of arylsulfatase A [metachromatic leukodystrophy (MLD)] in 93 (31%), hexosaminidase [Sandhoff disease (SHD)] in 62 (20.7%), hexosaminidase A [Tay-Sachs disease (TSD)] in 15 (5%), beta-galactosidase (GM1 gangliosidosis) in 35 (11.7%), alpha-galactosidase (Fabry disease) in one (0.3%) cerebroside beta-galactosidase (Krabbe disease) in 65 (21.7%) and glucosylceramidase (Gaucher disease) in 29 (9.6%). SHD (20.7%), MLD (31%) and Krabbe disease (21.7%) were common. Prenatal enzymatic diagnosis was made in 70 at risk pregnancies, 64 for TSD and SHD, three for MLD and three for GM1 gangliosidosis by using chorionic villus biopsy in 54, cord blood samples in 12 and cultured amniotic fluid cells in four. Seventeen fetuses were found to be affected. We have calculated the relative frequency and minimum incidence of sphingolipidoses in Turkey. The combined incidence of sphingolipidoses is 4.615 per 100,000 live births. The calculated incidences are 1.43, 0.95, 1, 0.23, 0.54, 0.45, 0.015 per 100,000 live births for MLD, SHD, Krabbe, Gaucher, TSD, GM1 gangliosidosis and Fabry diseases, respectively. The real incidence, which covers all subtypes of this group of diseases, should be greater than this number. The results suggested that, as a group, sphingolipidoses are relatively common and represent an important health problem in Turkey and some rare autosomal recessive diseases of Turkey are due to 'founder effect' created by consanguineous marriages.

The latest on leukodystrophies.

PURPOSE OF REVIEW: Important advances in our understanding of genetic disorders of the white matter have been made and are discussed here. RECENT FINDINGS: It has recently been discovered that mutations in the genes encoding the five subunits of eukaryocytic initiation factor 2B (eIF2B) are the cause of vanishing white-matter disease/childhood ataxia with central hypomyelination syndrome. The extension of the clinical features of the eIF2B-related disorders to encompass both infant- and adult-onset disorders is discussed. New clinico-imaging syndromes such as hypomyelination with atrophy of the basal ganglia and cerebellum and leukoencephalopathy with brain-stem and spinal cord involvement and elevated white-matter lactate are described. Recent findings include evidence that mitochondrial fat-oxidation abnormalities may be important in the pathogenesis of adrenoleukodystrophy, and that a mutant myelin protein can cause maldistribution of other myelin proteins, causing dysmyelination, axonal damage, or both. SUMMARY: This review focuses on advances in the understanding of the role of eIF2B as a cause of a common leukodystrophy syndrome. eIF2B-related disorders have a clinical spectrum ranging from a severe, rapidly progressive congenital or early infantile encephalopathy to a slowly progressive cognitive and motor deterioration often associated with premature ovarian failure. Two newly recognized leukodystrophy syndromes are described: hypomyelination with atrophy of the basal ganglia and cerebellum, and leukoencephalopathy with brain-stem and spinal cord involvement and elevated white-matter lactate. An update is also given for adrenoleukodystrophy and myelin-protein-related disorders. This update demonstrates that an increasing number of genetic defects are being identified that may cause primary white-matter disorders.

Mass spectrometry in the study of lysosomal storage disorders.

Lysosomal storage disorders represent a group of over 45 distinct genetic diseases, each one resulting from a deficiency of a particular lysosomal protein or, in a few cases, from non-lysosomal proteins that are involved in lysosomal biogenesis. A common biochemical feature of this group of disorders is the accumulation within lysosomes of undegraded or partially degraded substrates that are normally degraded within, and transported out of the lysosome. The particular substrates stored and the site(s) of storage vary with disease type and enzyme/protein deficiency. The nature of the substrate can be used to group the disorders into broad categories including the mucopolysaccharidoses, lipidoses, glycogenoses and oligosaccharidoses. These categories show many clinical similarities within groups as well as significant similarities between groups. For most lysosomal storage disorders the relationship between the stored substrates (type, amount and location) and the disease pathology is not well understood. The use of mass spectrometry and in particular tandem mass spectrometry provides a powerful tool for the investigation of stored substrates in this group of disorders. In this review we will describe the use of mass spectrometry for the analysis of stored substrates. We will discuss progress in the field, limitations of current methods, and summarise issues relating to the diagnosis and treatment of some of the more prevalent lysosomal storage disorders.

[Degenerative neurological diseases of the central nervous system related to genetic neurolipidoses]. / Etat actuel des maladies dégénératives du système nerveux central liées à des neurolipidoses d'origine génétique.

Genetic neurometabolic diseases in childhood are multisystemic. Surprisingly, these genetic diseases can manifest for the first time during adolescence and adulthood. In this case, the clinical presentation and evolutivity are very different. In childhood, many neurological systems are touched and their evolution is rapidly lethal. In the adult, their presentation may be that of a degenerative disease of the central nervous system and, according to the disease, the syndrome is very particular and very systematized. From our clinical and biological experience, we would like to suggest a decision tree.

Mild ichthyosis in a 4-year-old boy with multiple sulphatase deficiency.

We report a 4-year-old boy with multiple sulphatase deficiency (MSD). His early health was good. By the end of his first year there were concerns about developmental delay but by 26 months he showed clear evidence of regression in that he was barely able to sit unsupported and had lost all fine motor and communication skills. At that time he also had widespread mild ichthyosis that cleared completely with the use of emollients. The neurological deterioration suggested a diagnosis of metachromatic leucodystrophy, and a reduction in the leucocyte arylsulphatase A activity was detected. The ichthyosis suggested steroid sulphatase deficiency, and a reduction in the leucocyte steroid sulphatase activity was detected. The enzyme deficiency was much less marked for steroid sulphatase than for arylsulphatase A in this boy. This diversity in enzyme activities is typical of MSD and correlates with the mild ichthyosis in this child. This case shows that even mild ichthyosis should prompt measurement of steroid sulphatase activity in a child of either sex with unexplained neurological deterioration.

[Non specific leukodystrophy. A new case of vacuolizing leukoencephalopathy with megalencephaly]. / Leucodistrofias indeterminadas. Un nuevo caso de leucoencefalopatía vacuolizante con megalencefalia.

INTRODUCTION: Amongst the conditions affecting the white matter, the disorders of myelinization, including the leukodystrophies, are important in the field of paediatric neurology. Although classically they have been classified according to whether the metabolic defect was known or not, at the present time great advances in neuroimaging have clarified many genetic disorders involving the white matter and new classifications have been devised. The group of unknown aetiology includes the so called non specific leukodystrophies, characterized by their onset in infancy with a usually more moderate clinical course, and neuro imaging (computerized tomography CT magnetic resonance MR ) with alteration of the signal from the white matter which is symmetrical, bilateral and diffuse. Study and investigation of the patterns of MR has permitted isolation of two new clinical conditions of the non specific leukodystrophies group: leukodystrophy with megalencephaly and temporal cysts (Van der Knaap, 1995) for which currently the term vacuolizing leukoencephalopathy with megalencephaly is preferred and the CASH syndrome (childhood ataxia with central hypomyelinization or vanishing white matter disease) (Van der Knaap, 1997). DEVELOPMENT: We present a review of nine cases of non specific leukodystrophies with an average course of 13 years. They were studied using the protocol of the European working party on demyelinating diseases. One of these fulfilled clinical and radiological criteria for the diagnosis of vacuolizing leukoencephalopathy with megalencephayl: onset in early childhood, macrocephaly, normal metabolic studies, moderate progression and alteration of the white matter signal which was bilateral, symmetrical and diffuse with the presence of oedema and temporal subcortical cysts. We discuss the most relevant articles currently published on this condition.

Manifestações esqueléticas da doença de gaucher / Skeletal manifestations in Gaucher's disease

A doença de Gaucher é manifestação genética causada pela deficiência da enzima glicocerebrosidase, resultando no acúmulo secundário de glicocerebrosídeos nos órgãos do sistema reticuloendotelial. Apresenta-se sob três formas clínicas distintas, podendo ser rapidamente fatal ou crônica com poucos sintomas. O presente trabalho tem o objetivo de analisar os achados da radiografia simples do esqueleto em 32 pacientes comprovadamente portadores da doença, de ambos os sexos e em diferentes faixas etárias. Foram observadas as seguintes alterações: osteopenia difusa em todos os casos, deformidade em "frasco de Erlenmeyer" em 93,7 por cento, alterações articulares em 40,6 por cento, necrose da cabeça do fêmur e lesões líticas em 28,1 por cento, respectivamente, fratura patológica em 9,3 por cento e necrose da cabeça do úmero em 6,2 por cento dos casos. Estes resultados encontram-se de acordo com as descrições da literatura, demonstrando a importância da radiologia convencional como método complementar no diagnóstico desta enfermidade

Gaucher's disease has a genetic background and is characterized by the deficiency of enzyme glucocerebrosidase, resulting in secondary accumulation of glucocerebrosides in the reticuloendothelial organs. The objective of the present study is to evaluate the x-ray findings in the skeleton of a group of 32 male and female patients of different ages, with biochemical diagnosis of Gaucher's disease. The following bone lesions were observed: diffuse osteopenia (100% of the patients), "Erlenmeyer flask" deformities (93.7% of the patients), abnormalities of the joints (40.6% of the patients), necrosis of the femoral head (28.1% of the patients), lytic lesions (28.1% of the patients), pathological fractures (9.3% of the patients) and necrosis of the humeral head (6.2% of the patients). These results are concordant with the literature, and demonstrate the importance of conventional x-ray as a complementary method in the diagnosis of Gaucher's disease.

Pitfalls in the diagnosis of multiple sulfatase deficiency.

Multiple sulfatase deficiency (MSD, OMIM 272200) is an autosomal recessive leukodystrophy associated with the deficiency of several, in total seven, sulfatases. The disorder is clinically and biochemically variable. The clinical picture combines features of mucopolysaccharidosis and metachromatic leukodystrophy (MLD, OMIM 250100) in a variable spectrum. Here we report a 3-year old Iranian girl with an MLD-like presentation of MSD. Arylsulfatase A deficiency and sulfatide excretion were found. Differently from what was previously reported in the literature, this girl never showed abnormal mucopolysaccharide excretion in the urine. There were no additional visceral or skeletal signs. She was originally diagnosed as having MLD. Only when she developed ichthyosis were seven additional sulfatases measured. In leukocytes, arylsulfatase A, steroid sulfatase and N-acetylglucosamine-6 sulfatase were profoundly deficient, while iduronate-2 sulfatase and arylsulfatase B were moderately reduced. In fibroblasts, N-acetylglucosamine-6 sulfatase was deficient, while arylsulfatase A was moderately reduced. This case illustrates the possible pitfalls in the clinical and laboratory diagnosis of MSD.