A clinical report of the massive CAG repeat expansion in spinocerebellar ataxia type 2: Severe onset in a Mexican child and review previous cases

Abstract The spinocerebellar ataxia type 2 is a neurodegenerative disease with autosomal dominant inheritance; clinically characterized by progressive cerebellar ataxia, slow ocular saccades, nystagmus, ophthalmoplegia, dysarthria, dysphagia, cognitive deterioration, mild dementia, peripheral neurop...

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Main Authors: José Sánchez-Corona, Sergio Alberto Ramirez-Garcia, Gema Castañeda-Cisneros, Susan Andrea Gutiérrez-Rubio, Víctor Volpini, Diana M. Sánchez-Garcia, José Elías García-Ortiz, Diana García-Cruz
Format: Article
Language:English
Published: Sociedade Brasileira de Genética 2020-08-01
Series:Genetics and Molecular Biology
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Online Access:http://www.scielo.br/scielo.php?script=sci_arttext&pid=S1415-47572020000500107&tlng=en
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Summary:Abstract The spinocerebellar ataxia type 2 is a neurodegenerative disease with autosomal dominant inheritance; clinically characterized by progressive cerebellar ataxia, slow ocular saccades, nystagmus, ophthalmoplegia, dysarthria, dysphagia, cognitive deterioration, mild dementia, peripheral neuropathy. Infantile onset is a rare presentation that only has been reported in four instances in the literature. In the present work a boy aged 5 years 7 months was studied due to horizontal gaze-evoked nystagmus, without saccades, ataxic gait, dysarthria, dysphagia, dysmetria, generalized spasticity mainly pelvic, bilateral Babinsky. The mother aged 27 years-old presented progressive cerebellar ataxia, dysarthria, dysmetria, dysdiadochokinesis, limb ataxia and olivopontocerebellar atrophy. The molecular analysis was made by identifying the expansion repeats in tandem by long PCR to analyze the repeats in the ATXN2 gene. We found an extreme CAG expansion repeats of ~884 repeats in the child. We describe a Mexican child affected by SCA2 with an infantile onset, associated with a high number of CAG repeats previously no reported and anticipation phenomenon.
ISSN:1678-4685