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Electron microscopy of skin and peripheral blood lymphocytes in infantile (Santavuori) neuronal ceroid lipofuscinosis.

Skin punch biopsies and peripheral blood lymphocyte preparations from two siblings with early infantile (Santavuori) neuronal ceroid lipofuscinosis have been examined by electron microscopy. In both cases characteristic osmiophilic inclusion bodies were found in various cells in the skin and in lymphocytes. In one case, lymphocyte inclusions were detected before the onset of any symptoms as a result of a family study. This indicates the possibility of screening lymphocytes of siblings of affected patients as a result of a family study. This indicates the possibility of screening lymphocytes of siblings of affected patients with a view to early detection of the disorder.

Ceroid↗

Juvenile type of generalized ceroid-lipofuscinosis (Spielmeyer-Sjögren syndrome) I. Clinical findings.

Thirteen patients with the clinical course of the juvenile type of generalized ceroid-lipofuscinosis were examined clinically, ophthalmologically, neurologically and psychiatrically. This included registration of EEG, x-ray, brain scintigraphy, motor nerve conduction velocity, ERG, fundus photography and bioptical investigations including electron microscopy. The children suffered from progressing decrease of visual acuity, decline of mental capacities, and later on speech and gait disturbances. The most characteristic findings are presented in case reports, two tables and fourteen pictures.

Adolescent↗

Juvenile type of generalized ceroid-lipofuscinosis (Spielmeyer-Sjögren syndrome1 II. Biopsy findings.

Rectal biopsies were obtained from 11 children, clinically presumed to suffer from the juvenile type of generalized ceroid-lipofuscinosis. In addition, sural nerve biopsies were performed in 4 cases. Of the various staining procedures applied for light microscopy, Sundan Black B was found to be the most useful, revealing in each of the rectal biopsies at least some nerve cells with coarse black droplets as well as numerous mucosal macrophages with a more greyish, dustlike material. In sural nerve biopsies a slight reduction of the thick myelinated nerve fibers was seen in two cases, accompanied by regeneration phenomena. The latter were also detectable in one other case, the remaining sural nerve biopsy being histologically unremarkable. By electron microscopy neuronal perikarya revealed lipopigment bodies with a fingerprint-like pattern in each of the rectal biopsies. In one case only was this pattern combined with distinct curvilinear profiles. In 4 cases, however, the fingerprint-like deposits were intermingled with different lamellated bodies, some of them reminiscent of MCB's or zebra bodies. In two of the 4 cases, these were even seen exclusively in some neurons. In each of the rectal as well as the sural nerve biopsies, most of the non-neuronal cell types presented lipopigment bodies, likewise, displaying both curvilinear and fingerpring-like profiles, with some characteristics related to the various cell types. With regard to generalized ceroid-lipofuscinosis the diagnostic value of rectal biopsies, though being disputed in the literature, appears reestablished by the findings presented.

Biopsy↗

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.

Brain↗

An electrophoretic variant of beta-galactosidase with altered catalytic properties in a patient with GM1 gangliosidosis.

In nine patients with GM1 gangliosidosis, liver ganglioside GM1 beta-galactosidase (EC 3.2.1.23) activity ranged from less than 0.01% to 0.05% of normal. In a tenth patient's liver, much higher activity was found (0.5% of normal). In this patient the residual enzyme had the same molecular weight as beta-galactosidase A, the major form of beta-galactosidase of normal human liver. No activity was found that corresponded to beta-galactosidase B, the minor form of human liver beta-galactosidase. On starch gel electrophoresis, the patient's enzyme migrated less anodally than normal beta-galactosidase A, both before and after treatment with neuraminidase. Beta-Galactosidase from the patient had a Km that was higher then normal; 5-fold higher with ganglioside GM1 and 2-fold higher with 4-methylumbelliferyl beta-galactoside. The patient's enzyme crossreacted immunologically with normal beta-galactosidase A and had about 100-fold more antigenic activity per unit catalytic activity than the normal enzyme. The results indicate that in this patient a beta-galactosidase A protein with altered charge and altered catalytic properties was present in relatively normal amounts, the first electrophoretic variant reported for a patient with a lysosomal hydrolase deficiency.

Brain↗

Role of prosaposin in the male reproductive system: effect of prosaposin inactivation on the testis, epididymis, prostate, and seminal vesicles.

SGP-1/prosaposin can be secreted or targeted to the lysosomes where it is processed into smaller saposins (A, B, C, and D) required for the hydrolysis of glycosphingolipids. The deficiency of saposins B and C results in variant forms of metachromatic leukodystrophy and Gaucher's disease, respectively, which are characterized by lysosomal storage of undegraded glycosphingolipids. In the nervous system, prosaposin presents trophic activity. A mouse model was recently developed by creating a null allele in embryonic stem cells through gene targeting to investigate the phenotypic diversity of prosaposin mutations and the involvement of this protein in lysosomal storage diseases, and for the development of therapeutic approaches. Mice homozygous mutants die at the age of 35-40 days and neurological disorders contribute to the early demise of the mutant mice. The male reproductive organs in homozygous mutants show several abnormalities, such as a decrease in testis size with reduced spermiogenesis and an involution of the prostate, seminal vesicles, and epididymis. In these animals, the blood levels of testosterone remain normal. In the prostate of homozygous mutants, only the basal epithelial cells appear to be present, while the secretory cells are absent. These findings suggest that prosaposin may be involved in the development and maintenance of the male reproductive organs, as well as, in cellular differentiation.

Animals↗

Imino sugar inhibitors for treating the lysosomal glycosphingolipidoses.

The inherited metabolic disorders of glycosphingolipid (GSL) metabolism are a relatively rare group of diseases that have diverse and often neurodegenerative phenotypes. Typically, a deficiency in catabolic enzyme activity leads to lysosomal storage of GSL substrates and in many diseases, several other glycoconjugates. A novel generic approach to treating these diseases has been termed substrate reduction therapy (SRT), and the discovery and development of N-alkylated imino sugars as effective and approved drugs is discussed. An understanding of the molecular mechanism for the inhibition of the key enzyme in GSL biosynthesis, ceramide glucosyltransferase (CGT) by N-alkylated imino sugars, has also lead to compound design for improvements to inhibitory potency, bioavailability, enzyme selectivity, and biological safety. Following a successful clinical evaluation of one compound, N-butyl-deoxynojirimycin [(NB-DNJ), miglustat, Zavesca], for treating type I Gaucher disease, issues regarding the significance of side effects and CNS access have been addressed as exposure of drug to patients has increased. An alternative experimental approach to treat specific glycosphingolipid (GSL) lysosomal storage diseases is to use imino sugars as molecular chaperons that assist protein folding and stability of mutant enzymes. The principles of chaperon-mediated therapy (CMT) are described, and the potential efficacy and preclinical status of imino sugars is compared with substrate reduction therapy (SRT). The increasing use of imino sugars for clinical evaluation of a group of storage diseases that are complex and often intractable disorders to treat has considerable benefit. This is particularly so given the ability of small molecules to be orally available, penetrate the central nervous system (CNS), and have well-characterized biological and pharmacological properties.

Animals↗

A novel mutation in the coding region of the prosaposin gene leads to a complete deficiency of prosaposin and saposins, and is associated with a complex sphingolipidosis dominated by lactosylceramide accumulation.

A fatal infantile storage disorder with hepatosplenomegaly and severe neurological disease is described. Sphingolipids, including monohexosylceramides (mainly glucosylceramide), dihexosylceramides (mainly lactosylceramide), globotriaosyl ceramide, sulphatides, ceramides and globotetraosyl ceramide, were stored in the tissues. In general, cholesterol and sphingomyelin levels were unaltered. The storage process was generalized and affected a number of cell types, with histiocytes, which infiltrated a number of visceral organs and the brain, especially involved. The ultrastructure of the storage lysosomes was membranous with oligolamellar, mainly vesicular, profiles. Infrequently, there were Gaucher-like lysosomes in histiocytes. The neuropathology was severe and featured neuronal storage and loss with a massive depopulation of cortical neurons and pronounced fibrillary astrocytosis. There was a paucity of myelin and stainable axons in the white matter with signs of active demyelination. Immunohistochemical investigations indicated that saposins A, B, C and D were all deficient. The patient was homozygous for a 1 bp deletion (c.803delG) within the SAP-B domain of the prosaposin gene which leads to a frameshift and premature stop codon. In the heterozygous parents, mutant cDNA was detected by amplification refractory mutation analysis in the nuclear, but not the cytoplasmic, fraction of fibroblast RNA, indicating that the mutant mRNA was rapidly degraded. The storage process in the proband resembled that of a published case from an unrelated family. Saposins were also deficient in this case, leading to its reclassification as prosaposin deficiency, and her mother was found to be a carrier for the same c.803delG mutation. Both of the investigated families came from the same district of eastern Slovakia.

Antigens, CD↗

Cerebellar involvement in murine sphingomyelinosis: a new model of Niemann-Pick disease.

Mice with sphingomyelinosis (spm) with a C57BL/KsJ inbred background showed hepatosplenomegaly as early as four weeks (wk) of age and cerebellar signs around seven wk. Almost all animals died by 14 wk. Sudanophilic lipid accumulated in the liver, spleen, and lymph nodes as well as in the brain. The striking neuropathological change was a marked atrophy of the cerebellum, where Purkinje cells were predominantly involved. Loss of Purkinje cells started at the age of six wk before the cerebellar signs had become evident clinically. The cell loss appeared to be more marked in the vermis than in the hemispheres. Cytoplasmic inclusions in most cells consisted of myelin figures composed of concentric membranous lamellae. These inclusions were found mainly in the Purkinje cells at an early stage; thereafter, they were widely distributed in the granule cells, Golgi cells, some glial cells, macrophages and endothelial cells. The neuronal inclusions were frequently located in the vicinity of the Golgi apparatus; there were no unusual mitochondrial configurations. The clinicopathological characteristics of the mutant mice are similar to those of the human Niemann-Pick disease type C.

Animals↗

Saul R. Korey Lecture. Molecular genetics of Tay-Sachs and related disorders: a personal account.

The history of human genetic lysosomal disorders began in 1881 with the description of what is now known as Tay-Sachs disease. In the early 1960s, when I entered the field while I was a neurology resident, the first phase of studies of lysosomal disorders was being replaced with the second analytical biochemistry phase. Saul Korey, the first Chairman of the Department of Neurology, Albert Einstein College of Medicine, initiated the first integrated approach with a team consisting of clinical neurologists, neuropathologists, electron microscopists, cell biologists, organic chemists, and enzymologists. Despite his tragic death in 1963 in his mid-forties, the field flourished along the line of his vision through the third enzymology phase to the fourth and current molecular biology phase. The concept of Tay-Sachs disease as the only ganglioside storage disease has expanded to two forms of gangliosidoses, GM1- and GM2-gangliosidoses, and the latter into three distinct genetic disorders. Tay-Sachs disease, Sandhoff disease and the GM2 activator protein deficiency. More recently, all three genes coding for the three proteins each responsible for distinct genetic forms of GM2-gangliosidosis--beta-hexosaminidase alpha and beta subunits and the GM2 activator protein--have been cloned and many disease-causing mutations have been identified. We have reached the halfway point in our quest for eventual understanding of the pathogenesis and effective treatment of these disorders, starting from the clinical phenotype through biochemistry to the gene. With this new knowledge on the gene level, we should be tracing the route back to enzymology, biology and pathogenetic mechanism of these disorders in the years to come.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

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.

Adrenoleukodystrophy↗