Caracterización integral de la ataxia espinocerebelosa 2 en Cuba y su aplicación en proyectos de intervención / Comprehensive characterization of spinocerebellar ataxia type 2 in Cuba and its application in intervention projects

Introducción Cuba es el país con mayores tasas de prevalencia e incidencia para las ataxias hereditarias, lo que constituye un problema de salud que motivó la creación del Centro para la Investigación y Rehabilitación de Ataxias Hereditarias en Holguín. Objetivos Describir los principales resultados, aportes científicos, estrategias de intervención e impactos que durante más de 10 años se han obtenido por el citado centro, como modelo para el abordaje integral de las ataxias hereditarias en Cuba. Fuente de datos Se realizó una revisión en las bases de datos Pubmed-Medline y Scopus, analizando todos los artículos relevantes, comprendidos en el periodo 1978-2011. Se utilizó el descriptor «ataxia espinocerebelar¼, de elevada especificidad y sensibilidad para el tema en análisis. Síntesis de los datos La prevalencia de la enfermedad se ha mantenido constante durante 40 años, extendiéndose a toda la isla. La mutación ataxia espinocerebelosa tipo 2 es responsable del 60 % de la variabilidad fenotípica mientras que el 40 % restante se debe a factores modificadores genéticos y/o ambientales. Se ha descrito la existencia de un daño oxidativo severo, disminución de neuroprotectores y oligoelementos. Los estudios neurofisiológicos permitieron definir etapas evolutivas desde estadios preclínicos de la enfermedad así como biomarcadores de progresión y daño genético. Estos resultados proiciaron el diseño y ejecución de varios ensayos clínicos controlados en busca de un protocolo de tratamiento contra la enfermedad. Adicionalmente se brinda un servicio de diagnostico prenatal y presintomático con un impacto positivo sobre las familias afectadas. Conclusiones Las investigaciones sobre la ataxia espinocerebelosa tipo 2 cubana, como problema de salud, han tenido un enfoque integral. Los nuevos descubrimientos sobre la patogenia, la identificación de biomarcadores, los ensayos clínicos, el diagnóstico prenatal y presintomático permitieron conformar un nuevo modelo cubano para el abordaje de las ataxias hereditarias y el estudio de otras enfermedades neurodegenerativas.

Introduction Cuba is one of the countries with high rates of prevalence and incidence of hereditary ataxias, which is a health problem that encouraged the foundation of the Center for Research and Rehabilitation of Hereditary Ataxias in Holguín province. Objectives To describe the main results, scientific achievements, intervention strategies and impacts of this institution for more than 10 years, as a sort of pattern to be followed to approach hereditary ataxias in Cuba in a more comprehensive way. Data source Pubmed-Medline and Scopus database were reviewed in which all the relevant articles published from 1978 to 2011 were analyzed. Spinocerebelar ataxia, highly specific and sensitive subject headings, were used for the topic under analysis. Data synthesis The prevalence of this disease has remained unchanged for 40 years, being extended to the whole island. Spinocerebelar ataxia type 2 mutation accounts for 60% of the phenotypical variability whereas the remaining 40% is caused by genetic and/or environmental modifying factors. Severe oxidative damage, reduction of neuroprotectors and of oligoelements have been described. The neurophysiological studies allowed defining evolutionary phases from the preclinical stagings as well as progression and genetic damage biomarkers. These results allowed designing several controlled clinical assays in search of one treatment protocol for the disease. Additionally, prenatal and pre-symptomatic diagnosis service is rendered, with positive impact on affected families. Conclusions The research studies on spinocerebelar ataxia type 2 in Cuba as a health problem have had comprehensive approach. The new breakthroughs on pathogeny, identification of biomarkers, clinical assays, prenatal and presymptomatic diagnosis allowed making a new Cuban model to approach hereditary ataxias and the study of other neurodegenerative diseases.

Molecular epidemiology of spinocerebellar ataxias in Cuba: Insights into SCA2founder effect in Holguin

The objective of this study was to determine the prevalence of hereditaryataxias in Cuba, with a specialfocus on the clinical and molecular features of SCA2. Clinical assessmentswere performed by neurologicalexaminations and application of the SARA scale. Molecular analyses ofgenes SCA1–3, SCA6, SCA17and DRPLA identified 753 patients with SCA and 7173 asymptomaticrelatives, belonging to 200 unrelatedfamilies. 86.79 percent of all SCA patients were affected with SCA2. In the Holguin province, the averagepopulation prevalence of SCA2 is 40.18×105 inhabitants, with theremarkable figure of 141.66×105 inthe Baguanos municipality. The high prevalence of the SCA2 mutation inHolguin reflects most likelya founder effect. The stabilization of the prevalence along time suggeststhe existence of premutatedchromosomes with pure CAG, acting as reservoir for further expansions. CAGrepeat length correlatedinversely with age at onset, accounting for 80 percent of the variability. Genetic anticipation was observed in the 80 percent of transmissions. Repeat instability was greater in paternaltransmissions whereas CAG expansionswithout anticipation was observed in 10.97 percent suggesting the effect of CAA interruptions in the CAGsegment, which decrease the toxicity of the abnormal ataxin-2, and/orother protective factors...(AU)

Molecular epidemiology of spinocerebellar ataxias in Cuba: insights into SCA2 founder effect in Holguin.

The objective of this study was to determine the prevalence of hereditary ataxias in Cuba, with a special focus on the clinical and molecular features of SCA2. Clinical assessments were performed by neurological examinations and application of the SARA scale. Molecular analyses of genes SCA1-3, SCA6, SCA17 and DRPLA identified 753 patients with SCA and 7173 asymptomatic relatives, belonging to 200 unrelated families. 86.79% of all SCA patients were affected with SCA2. In the Holguin province, the average population prevalence of SCA2 is 40.18x10(5) inhabitants, with the remarkable figure of 141.66x10(5) in the Baguanos municipality. The high prevalence of the SCA2 mutation in Holguin reflects most likely a founder effect. The stabilization of the prevalence along time suggests the existence of premutated chromosomes with pure CAG, acting as reservoir for further expansions. CAG repeat length correlated inversely with age at onset, accounting for 80% of the variability. Genetic anticipation was observed in the 80% of transmissions. Repeat instability was greater in paternal transmissions whereas CAG expansions without anticipation was observed in 10.97% suggesting the effect of CAA interruptions in the CAG segment, which decrease the toxicity of the abnormal ataxin-2, and/or other protective factors.

Genes modificadrres en enfermedades poliglutamínicas / Modifying genes in poliglutaminic diseases

Las enfermedades poliglutamínicas constituyen un grupo creciente de enfermedades neurodegenerativas humanas, causadas por la expansión de secuencias repetitivas de CAG que son traducidas para dar lugar a proteínas con dominios poliglutamínicos expandidos. La edad de inicio es un marcador fenotípico para estas enfermedades, y muestra una gran variación en las familias afectadas. El número de repeticiones de CAG contenido en los genes causales, explica entre el 47 y 80% de la variabilidad observada en la edad de inicio. Para explicar la varianza restante ha sido propuesta la hipótesis de la existencia de genes modificadores. Aquí realizamos una revisión actualizada acerca de esta temática, abordando las estrategias más usadas para su identificación, los principales hallazgos obtenidos y sus implicaciones. La identificación de estos genes contribuye al esclarecimiento de los mecanismo patológicos involucrados en estas enfermedades, y puede conducir a la proposición y diseño de estrategias terapéuticas potenciales.

Poliglutaminic diseases are an increasing group of human neurodegenerative diseases caused by the expansion of repetitive sequences of CAG which give way to expanded poliglutaminic domains proteins. Ages of onset are a phenotypic marker for these diseases and show a great variation in the affected families. The number of CAG content repetitions in the causal genes, explains a 47 to 80 % of the variability of the age of onset. To explain the remaining variability, the hypothesis of modifying genes has been proposed. We have performed an updated revision of the the subject approaching the more utilized techniques to its identification, the principal findings and its implications. The identification of these genes contribute to clarify the involved pathological mechanisms in these diseases and might conduct to the proposition of potential therapeutic strategies.

Genes modificadores en enfermedades poliglutamínicas / Modifying genes in poliglutaminic diseases

Las enfermedades poliglutamínicas constituyen un grupo creciente de enfermedades neurodegenerativas humanas, causadas por la expansión de secuencias repetitivas de CAG que son traducidas para dar lugar a proteínas con dominios poliglutamínicos expandidos. La edad de inicio es un marcador fenotípico para estas enfermedades, y muestra una gran variación en las familias afectadas. El número de repeticiones de CAG contenido en los genes causales, explica entre el 47 y 80 por ciento de la variabilidad observada en la edad de inicio. Para explicar la varianza restante ha sido propuesta la hipótesis de la existencia de genes modificadores. Aquí realizamos una revisión actualizada acerca de esta temática, abordando las estrategias más usadas para su identificación, los principales hallazgos obtenidos y sus implicaciones. La identificación de estos genes contribuye al esclarecimiento de los mecanismo patológicos involucrados en estas enfermedades, y puede conducir a la proposición y diseño de estrategias terapéuticas potenciales(AU)

Poliglutaminic diseases are an increasing group of human neurodegenerative diseases caused by the expansion of repetitive sequences of CAG which give way to expanded poliglutaminic domains proteins. Ages of onset are a phenotypic marker for these diseases and show a great variation in the affected families. The number of CAG content repetitions in the causal genes, explains a 47 to 80 percent of the variability of the age of onset. To explain the remaining variability, the hypothesis of modifying genes has been proposed. We have performed an updated revision of the the subject approaching the more utilized techniques to its identification, the principal findings and its implications. The identification of these genes contribute to clarify the involved pathological mechanisms in these diseases and might conduct to the proposition of potential therapeutic strategies(AU)

Antigliadin antibodies in Spinocerebellar AtaxiaType 2 Cuban patients

The relevance of gluten sensitivity in hereditary ataxia pathogenesis is unclear. To evaluate the significance of antigliadin antibodies levels forspinocerebellar ataxia type 2. We determined antigliadin antibodies in 64 spinocerebellar ataxia type 2 patients and in 65 healthy matched controls. The clinical assessment was carried out using the International Cooperative Ataxia Rating Scale and CAG repeat number was assessed by PCR. Results: Antibodies were positive in 23,4 percent of the ataxia patients and 9,09 percent of the controls. Statistical comparison using (chi)2 test with Yatess correction reveal significant differences between these two groups ( 2 3,94; p 0,047). The same was obtained for strongly positive antigliadin antibodies ( 2 4,62; p 0,032). There were not significant differences between AGA positive and AGA negative patients in age at onset, disease duration, ataxia score, or CAG repeat number;neither in the prevalence of gastrointestinal symptoms, prevalence of wheat intolerance,or body weight. These results demonstrates an association between antigliadin antibodies serum levels and SCA2. However, more work has to be done to clarify the clinical consequences of such an association...(AU)