Doença de Tay-Sachs: relato de caso / Tay-Sachs disease: a case report

RESUMO A doença de Tay-Sachs é um distúrbio neurodegenerativo autossômico recessivo, o qual envolve o metabolismo dos lipídios, levando ao acúmulo de gangliosídeos nos tecidos, devido à deficiência da enzima hexosaminidase A. Esse depósito progressivo resulta em perda da função neurológica e, quando acomete as células ganglionares da mácula, causa o achado típico da doença, a "mácula em cereja". A patologia é diagnosticada por meio dos níveis de hexosaminidase A e hexosaminidase total no soro, além análise do DNA do gene HEXA. Este caso relata uma criança com doença de Tay-Sachs cujo diagnóstico foi suspeitado por conta dos achados oftalmológicos.

ABSTRACT Tay-Sachs Disease is an autosomal recessive neurodegenerative disorder, which involves the metabolism of lipids, leading to the accumulation of gangliosides in the tissues, due to the deficiency of the enzyme Hexosaminidase A. This progressive deposit results in loss of neurological function and, when it affects macula ganglion cells, it causes the typical disease finding, the "cherry red spot". The pathology is diagnosed through the levels of Hex A and total Hexosaminidase in the serum, in addition to the analysis of the DNA of the HEXA gene. This case reports a child with Tay-Sachs disease with a suspected diagnosis was through ophthalmologic findings.

In silico analysis of the effects of disease-associated mutations of b-hexosaminidase A in Tay–Sachs disease

Tay–Sachs disease (TSD), a deficiency of b-hexosaminidase A (Hex A), is a rare but debilitating hereditary metabolic disorder. Symptoms include extensive neurodegeneration and often result in death in infancy. We report an in silico study of 42 Hex A variants associated with the disease. Variants were separated into three groups according to the age of onset: infantile (n=28), juvenile (n=9) and adult (n=5). Protein stability, aggregation potential and the degree of conservation of residues were predicted using a range of in silico tools. We explored the relationship between these properties and the age of onset of TSD. There was no significant relationship between protein stability and disease severity or between protein aggregation and disease severity. Infantile TSD had a significantly higher mean conservation score than nondisease associated variants. This was not seen in either juvenile or adult TSD. This study has established that the degree of residue conservation may be predictive of infantile TSD. It is possible that these more highly conserved residues are involved in trafficking of the protein to the lysosome. In addition, we developed and validated software tools to automate the process of in silico analysis of proteins involved in inherited metabolic diseases. Further work is required to identify the function of well-conserved residues to establish an in silico predictive model of TSD severity

Tay-Sachs disease / Enfermedad de Tay-Sachs

Abstract Introduction: Lysosomal storage disease is caused by the deficiency of a single hydrolase (lysosomal enzymes). GM2 gangliosidoses are autosomal recessive disorders caused by deficiency of β-hexosaminidase and Tay-Sachs disease (TSD) is one of its three forms. Objective: To perform a review of the state of the art on TSD and describe its definition, epidemiology, etiology, physiopathology, clinical manifestations, as well as advances regarding its diagnosis and treatment. Materials and methods: A literature search was carried out in PubMed using the MeSH terms "Tay-Sachs Disease". Results: after the initial search was conducted, 1 233 results were retrieved, of which 53 articles were finally selected. TSD is caused by the deficiency of the lysosomal enzyme β-hexosaminidase A (HexA), and is characterized by neurodevelopmental regression, hypotonia, hyperacusis and cherry-red spots in the macula. Research on molecular pathogenesis and the development of possible treatments has been limited, consequently there is no treatment established to date. Conclusion: TSD is an autosomal recessive neurodegenerative disorder. Death usually occurs before the age of five. More research and studies on this type of gangliosidosis are needed in order to find an adequate treatment.

Resumen Introducción. La deficiencia de una sola hidrolasa (enzimas lisosomales) da como resultado una enfermedad de almacenamiento lisosomal. Las gangliosidosis GM2 son trastornos autosómicos recesivos causados por la deficiencia de β-hexosaminidasa. La enfermedad de Tay-Sachs (TSD, por sus siglas en inglés) es una de las tres presentaciones de este tipo de gangliosidosis. Objetivo. Realizar una revisión del estado del arte de la TSD describiendo su definición, epidemiología, etiología, fisiopatología, manifestaciones clínicas y actualidades en su diagnóstico y tratamiento. Materiales y métodos. Se realizó una búsqueda bibliográfica en PubMed utilizando como único término MeSH "Tay-Sachs Disease". Resultados. Se encontraron 1 233 publicaciones y se seleccionaron 53 artículos. La TSD es originada por la deficiencia de la enzima lisosomal β-hexosaminidasa A (HexA) y se caracteriza por regresión del neurodesarrollo, hipotonía, hiperacusia y manchas maculares rojo cereza. La investigación de la patogenia molecular y el desarrollo de posibles tratamientos han sido limitados y en la actualidad no se cuenta con uno plenamente establecido. Conclusiones. La TSD es un trastorno neurodegenerativo autosómico recesivo y por lo general la muerte se produce antes de los 5 años de edad. Son necesarias más investigaciones y estudios sobre este tipo de gangliosidosis con el fin de encontrar un tratamiento adecuado.

A Case Refort of Sandhoff Disease

Sandhoff disease is a rare autosomal recessive metabolic disease presenting bilateral optic atrophy and a cherry red spot in the macula. This case report presents the characteristics of a patient with Sandhoff disease as assessed by ophthalmic, neuroimaging, and laboratory procedures. Ophthalmologic examination revealed that the patient could not fixate her eyes on objects nor follow moving targets. A pale optic disc and a cherry red spot in the macula were seen in both eyes. Low signal intensity at the thalamus and high signal intensity at the cerebral white matter were noted in a T2-weighted brain MR image. A lysosomal enzyme assay using fibroblasts showed the marked reduction of both total beta-hexosaminidases, A and B. Based on the above clinical manifestations and laboratory findings, we diagnosed the patient as having Sandhoff disease.