Analysis of<scp>CAG</scp>repeats in five<scp>SCA</scp>loci in Mexican population: epidemiological evidence of a<scp>SCA7</scp>founder effect

Magaña, Jonathan J.; Tapia-Guerrero, Y. S.; Velázquez‐Pérez, Luis; Cerecedo-Zapata, César M.; Maldonado-Rodríguez, M.; Jano-Ito, Joan; Leyva-García, Norberto; González-Piña, Rigoberto; Martínez-Cruz, Emilio; Hernández-Hernández, Óscar; Cisneros, Bulmaro

doi:10.1111/cge.12114

Cited by 25 publications

(22 citation statements)

References 30 publications

(50 reference statements)

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“…In terms of clinical profile, although most of the SCAs were found to be rather typical, it is important to highlight the fact that SCA10 was originally described in Mexico with a phenotype of pure cerebellar ataxia and seizures, occasionally added by mild pyramidal and neuropsychiatric signs . A case‐finding study restricted to the genetic analysis of SCA1, 2, 3, 6, and 7 in 5 communities of Veracruz State identified 64 SCA cases from 10 families, most of them (8 families, 55 individuals) with SCA7 in addition to 2 families with SCA2, but none with the other forms tested …”

Section: Resultsmentioning

confidence: 99%

“…Several assumptions can be made in view of the data presented in this review. The high frequency of SCA7 in the Mexican State of Veracruz and in Venezuela, both close to Caribbean, is quite intriguing because the disease is more commonly found in patients from countries such as Finland, Sweden, the Netherlands, and South Africa . The Mexican cluster could be explained by the fact that the Mexican communities analyzed, founded by Spanish landowners and populated by Native Americans, were settled in a region in which the geography may have undermined communication with other populations and limited human migration.…”

Section: Discussionmentioning

confidence: 99%

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The Geographic Diversity of Spinocerebellar Ataxias (SCAs) in the Americas: A Systematic Review

Teive

Meira

Camargo

et al. 2019

Movement Disord Clin Pract

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Background The frequency and presentation of each of the most common forms of spinocerebellar ataxias (SCAs) varies widely. In the case of the Americas, this diversity is particularly dynamic given additional social, demographic, and cultural characteristics. Objective To describe the regional prevalence and clinical phenotypes of SCAs throughout the continent. Methods A literature search was performed in both MEDLINE and LILACS databases. The research was broadened to include the screening of reference lists of systematic review articles for additional studies. Investigations dating from the earliest available through 2019. Only studies in English, Portuguese, and Spanish were included. We analyzed publications with genetically confirmed cases only, ranging from robust samples with epidemiological data to case reports and case series from each country or regions. Results Overall, SCA3 is the most common form in the continent. Region‐specific prevalence and ranking of the common forms vary. On the other hand, region‐specific phenotypic variations were not consistently found based on the available literature analyzed, with the exception of the absence of epilepsy in SCA10 consistently described in a particular cluster of cases in South Brazil. Conclusion Systematic, multinational studies analyzing in detail the true frequencies of SCAs across the Americas as well as distinct clinical signs and clues of each form would be ideal to look for these potential variations.

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Section: Resultsmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

The Geographic Diversity of Spinocerebellar Ataxias (SCAs) in the Americas: A Systematic Review

Teive

Meira

Camargo

et al. 2019

Movement Disord Clin Pract

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show abstract

“…Nevertheless, a high prevalence of SCA7 is found in a particular region of Mexico (the Veracruz State) [11,12], which allowed us to perform a detailed characterization of the neurophysiological pattern of Mexican patients, a necessary step to the subsequent development of medical treatments.…”

Section: Discussionmentioning

confidence: 99%

“…Genotyping of patients was performed using a fluorescent multiplex polymerase chain reaction assay, as previously reported [11]. …”

Section: Methodsmentioning

confidence: 99%

“…However, the study of these disorders in Latin American populations has revealed that SCA3 is the most prevalent form in Brazil [3,4,5], while SCA2 has the highest incidence in Cuba and Mexico [6,7,8]. In addition, SCA7, one of the rarest forms of SCA [9,10], is prevalent (∼800/100,000 inhabitants) in certain regions of Mexico [11], due to a founder mutation effect [12]. SCA7 is characterized by cerebellar, brainstem and retinal degeneration that leads to motor abnormalities, blindness, and mortality [13].…”

Section: Introductionmentioning

confidence: 99%

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Spinocerebellar Ataxia Type 7: A Neurodegenerative Disorder with Peripheral Neuropathy

Salas-Vargas¹,

Mancera-Gervacio²,

Velázquez‐Pérez³

et al. 2015

Eur Neurol

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Background: Autosomal dominant spinocerebellar ataxias (SCA) are a group of inherited neurodegenerative disorders that typically show peripheral neuropathy. SCA7 is one of the rarest forms of SCA (<1/100,000 individuals). However, the disease shows a prevalence of ∼800/100,000 inhabitants in certain regions of Mexico. This low global prevalence may explain, at least in part, the isolated anecdotal and limited clinical data regarding peripheral neuropathy in SCA7 patients. Aim: To assess sensory and motor peripheral nerve action potentials in an SCA7 patients group and in healthy volunteers, and subsequently correlate the electrophysiological findings with clinical and genetic features. Materials and Methods: We enrolled in our study, 13 symptomatic SCA7 patients with a confirmed molecular and clinical diagnosis, and 19 healthy volunteers as the control group. Nerve conduction studies were carried out using standard electromyography recording methods. The sensory and motor latency, amplitude and conduction velocity were recorded in both experimental groups and analyzed using the Student's t-test. Results: SCA7 patients showed a significant prolongation of sensory nerve conduction latencies, as well as a decrease in sensory amplitudes. Decreases in motor amplitudes and peroneal conduction velocity were also observed. Finally, we found an association between CAG repeats and the severity of cerebellar and non-cerebellar symptoms with electrophysiological signs of demyelinization. Discussion: Our results reveal the existence of a critical sensorimotor peripheral neuropathy in SCA7 patients. Moreover, we show that using sensitive electrophysiological tools to evaluate nerve conduction can improve the diagnosis and design of therapeutic options based on pharmacological and rehabilitative strategies. Conclusion: These findings demonstrate that SCA7 is a disease that globally affects the peripheral nervous system.

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Spinocerebellar Ataxia Type 7: From Mechanistic Pathways to Therapeutic Opportunities

Świtoński

Spada

2023

Contemporary Clinical Neuroscience

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Analysis ofCAGrepeats in fiveSCAloci in Mexican population: epidemiological evidence of aSCA7founder effect

Cited by 25 publications

References 30 publications

The Geographic Diversity of Spinocerebellar Ataxias (SCAs) in the Americas: A Systematic Review

The Geographic Diversity of Spinocerebellar Ataxias (SCAs) in the Americas: A Systematic Review

Spinocerebellar Ataxia Type 7: A Neurodegenerative Disorder with Peripheral Neuropathy

Spinocerebellar Ataxia Type 7: From Mechanistic Pathways to Therapeutic Opportunities

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