RESUMO
Huntington's disease (HD) is a neurodegenerative disorder characterized by chorea, behavioral disturbances and dementia, caused by a pathological expansion of the CAG trinucleotide in the HTT gene. Several patients have been recognized with the typical HD phenotype without the expected mutation. The objective of this study was to assess the occurrence of diseases such as Huntington's disease-like 2 (HDL2), spinocerebellar ataxia (SCA) 1, SCA2, SCA3, SCA7, dentatorubral-pallidoluysian atrophy (DRPLA) and chorea-acanthocytosis (ChAc) among 29 Brazilian patients with a HD-like phenotype. In the group analyzed, we found 3 patients with HDL2 and 2 patients with ChAc. The diagnosis was not reached in 79.3 percent of the patients. HDL2 was the main cause of the HD-like phenotype in the group analyzed, and is attributable to the African ancestry of this population. However, the etiology of the disease remains undetermined in the majority of the HD negative patients with HD-like phenotype.
A doença de Huntington (DH) é uma doença neurodegenerativa caracterizada por coréia, alterações comportamentais e demência, causada por uma expansão patológica do trinucleotídeo CAG no gene HTT. Vários pacientes têm sido descritos com o fenótipo típico para a DH porém sem a mutação esperada. O objetivo deste estudo foi avaliar a ocorrência de doenças como doença de Huntington-símile 2 (DHS-2), ataxias espinocerebelares tipo 1, 2, 3 e 17, atrofia dentatorubral-palidoluisiana e coreo-acantocitose (CAc) entre 29 pacientes brasileiros com fenótipo doença de Huntington-símile. No grupo analisado, encontramos 3 pacientes com DHS-2 e 2 pacientes com CAc. O diagnóstico permaneceu obscuro em 79,3 por cento dos pacientes. DHS-2 foi a principal causa do fenótipo DH-símile no grupo analisado, provavelmente devido a ancestralidade africana na população brasileira. Entretanto, a etiologia permaneceu indeterminada na maioria dos pacientes avaliados.
Assuntos
Adulto , Feminino , Humanos , Masculino , Doença de Huntington/diagnóstico , Epilepsias Mioclônicas Progressivas/diagnóstico , Neuroacantocitose/diagnóstico , Ataxias Espinocerebelares/diagnóstico , Expansão das Repetições de Trinucleotídeos/genética , Estudos Transversais , Doença de Huntington/genética , Epilepsias Mioclônicas Progressivas/genética , Neuroacantocitose/genética , Fenótipo , Ataxias Espinocerebelares/genéticaRESUMO
The possible associations of myoclonic phenomenae, progressive or non-progressive encephalopathies and epileptic features are reviewed, with special emphasis on pediatric age. This leads to recognize the following five groups of conditions: (1) Myoclonus without encephalopathy and without epilepsy; (2) Encephalopathies with non-epileptic myoclonus; (3) Progressive encephalopathies presenting myoclonus seizures of epileptic syndromes (Progressive myoclonus epilepsies); (4) Epileptic encephalopathies with myoclonic seizures; (5) Myoclonic epilepsies. Within the first group, which also includes physiologic myoclonus, a more thorough description of "Benign sleep myoclonus of newborn" and "Benign myoclonus of early infancy" is given. Characteristics of group 2 are "Kinsbourne Syndrome" and certain types of "Hyperekplexia" which pose interesting differential diagnosis with stimulus-sensitive epilepsies. In group 3, the concept of progressive encephalopathies is stressed. The fourth group refers to severe epilepsies, mainly on infancy and childhood, which lead to mental retardation irrespective of their aetiology. Group 5 comprises the true myoclonic epilepsies, differentiating syndromes recognized as idiopathic--such as "Benign myoclonic epilepsy of infancy" and "Juvenile myoclonic epilepsy"--from those which are cryptogenic and carry a more cautious prognosis--as "Cryptogenic myoclonic and myoclonoastatic epilepsies" and "Severe myoclonic epilepsy of infancy". Other epileptic syndromes not usually considered as myoclonic epilepsies, but presenting sometimes as myoclonic seizures, are finally referred.