Correlación clínico-patológica de enfermedades cutáneas de depósito lisosomal (I parte) / Clinico-pathological correlation of lysosomal storage skin diseases (part I)

Las enfermedades de depósito lisosomal corresponden a alteraciones congénitas del metabolismo, las cuales se heredan de forma autosómica recesiva y están caracterizadas por el déficit específico de una hidrolasa lisosomal y por el acúmulo de su sustrato en varios tejidos del organismo. Dependiendo de la naturaleza bioquímica del sustrato acumulado, éstas pueden dividirse en esfingolipidosis, oligosacaridosis, mucolipidosis, mucopolisacaridosis y otras.

Lysosomal storage diseases are autosomal recessive disorders of inborn errors of metabolism, characterized by a deficiency in a specific lysosomal hydrolase and by accumulation of its specific substrate in various body tissues. Depending on the basis of the biochemical nature of the accumulated substrate, they can be divided in sphingolipidoses, oligosaccharidoses, mucolipidoses, mucopolysaccharidoses, and others.

[Sphingolipids, vehicle for pathogenic agents and cause of genetic diseases]. / Les sphingolipides: vecteurs d'agents pathogènes et cause de maladies génétiques.

Sphingolipids are present in all eukaryotic cells and share a sphingoid base : sphingosine. They were first discovered in 1884 and for a long time they were thought to participate to membrane structure only. Recently it has been established that they are mainly located in particular areas of the membrane called rafts which are signalling platforms. It has also been demonstrated that sphingolipids are receptors and second messengers. They play a crucial role in cellular functioning and are necessary to maintenance and developing of living organisms. However due to their receptor properties, they are also gateway for penetration of pathogenic agents such as virus (Ebola, HIV) or toxins (botulinium, tetanus). These agents first bind to glycosphingolipids or proteins mainly located in rafts. The complex so formed is required for the crossing of the membrane by the pathogenic agent. Sphingolipids metabolism is regulated by numerous enzymes. A failure in the activity of one of them induces an accumulation of sphingolipids known as sphingolipidoses. These are genetic diseases having severe consequences for the survival of the organism. The precise mechanisms of the sphingolipidoses are still mainly unknown which explains why few therapeutic strategies are available. These particular properties of lipids rafts and sphingolipids explain why a growing number of studies in the medical and scientific fields are devoted to them.

Glycosphingolipidoses: beyond the enzymatic defect.

The glycosphingolipid lysosomal storage diseases are a group of monogenic human disorders caused by the impaired catalytic activity of enzymes responsible for glycosphingolipid catabolism. Clinical presentation of the diseases is heterogeneous, with little obvious correlation between the kind of accumulating glycosphingolipid and disease progression or pathogenesis. In this review, we discuss clinical symptoms of this group of diseases, and attempt to link disease progression and pathology with the biochemical and cellular pathways that may be potentially altered in the diseases.

[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.

Leukodystrophy incidence in Germany.

Through a survey of all departments of pediatrics, neurology and neuropathology in Germany, we calculated the incidence of all major forms of leukodystrophy. Only diagnoses based on specific biochemical tests in association with typical findings and/or neuroradiologically proven white matter involvement were accepted. In accordance with these strict criteria, 617 cases of leukodystrophy were found (incidence of all forms: app. 2.0/100,000). Minimal incidence was estimated at 0.8/100,000 for adrenoleukodystrophy/adrenomyeloneuropathy (ALD/AMN), 0.6/100,000 for metachromatic leukodystrophy (MLD), and 0.6/100,000 for Krabbe disease. Thus ALD/AMN is apparently underdiagnosed in Germany. A considerable proportion of leukodystrophies could not be classified in spite of adequate diagnostic procedures in experienced centers.

[Generalized GM1 gangliosidosis. Report of a case and review of the literature]. / Gangliosidosis GM1 generalizada. Aportación de un caso y revisión de la literatura.

Authors present the case of a child, daughter of non related parents with neurologic progressive affectation, retina and visceral implication with certain pseudogargolic clinical aspect without near familiar antecedents suggestive of this disease. Biochemistry and histologic studies revealed a B-galactosidase enzyme deficiency and lipidic intracellular increase in different viscera. Biochemistry, hystological and clinical aspects exposed are fundamentally differential of another causes of pseudo-Hurler syndrome.

Biochemical approaches to the nosology of nervous system defects, II.

The nature of the metabolic defects in all of the major lipid storage diseases has been established within the past four years. This infromation has come primarily from extensive enzymologic studies in human tissues using labeled complex lipids as substrates. A brief description is presented of the background and experiments which led to the identification of the biochemical lesion in Gaucher's disease, Niemann-Pick disease, Fabry's disease, and Tay-Sachs disease.