Factors associated with ATXN2 CAG/CAA repeat intergenerational instability in Spinocerebellar ataxia type 2.

Spinocerebellar ataxia type 2 (SCA2) is a neurodegenerative disorder caused by the unstable expansion of a cytosine-adenine-guanine (CAG)/cytosine-adenine-adenine (CAA) repeat in the ATXN2 gene, which normally encodes 22 glutamines (Q22). A large study was conducted to characterize the CAG/CAA repeat intergenerational instability in SCA2 families. Large normal alleles (Q24-31) were significantly more unstable upon maternal transmissions. In contrast, expanded alleles (Q32-750) were significantly more unstable during paternal transmissions, in correlation with repeat length. Significant correlations were found between the instability and the age at conception in paternal transmissions. In conclusion, intergenerational instability at ATXN2 locus is influenced by the sex, repeat length and age at conception of the transmitting parent. These results have profound implications for genetic counseling services.

Role of glutathione S-transferases in the spinocerebellar ataxia type 2 clinical phenotype.

Spinocerebellar ataxia type 2 (SCA2) is a neurodegenerative and incurable hereditary disorder caused by a CAG repeat expansion mutation on ATXN2 gene. The identification of reliable biochemical markers of disease severity is of paramount significance for the development and assessment of clinical trials. In order to evaluate the potential use of glutathione-S-transferase (GST) activity as a biomarker for SCA2, a case-control study in 38 affected, presymptomatic individuals or healthy controls was conducted. An enlarged sample of 121 affected individuals was set to assess the impact of GST activity on SCA2 clinical expression. There was a significant increase in GST activity in affected individuals relative to controls, although sensibility and specificity were not high. GST activity was not significantly influenced by sex, age, disease duration or CAG repeat size and did not significantly influence disease severity markers. These findings show a disruption of in vivo GST activity in SCA2, suggesting a role for oxidative stress in the neurodegenerative process.

The Cuban program for predictive testing of SCA2: 11 years and 768 individuals to learn from.

Having reported the world's highest prevalence of spinocerebellar ataxia type 2 (SCA2), health professionals in Cuba developed a program for the predictive testing of this condition. Between February 2001 and December 2011, a total of 1050 individuals requested their inclusion in the presymptomatic testing (PST) program. Their medical records were retrospectively analyzed in the present descriptive study. A total of 768 participants completed the protocol, 204 withdrew and 78 were excluded. The PST uptake was 24.91%. Females predominated and 70.96% had negative test results. Their main motivations were risk assessment in their descendants, physical and psychological preparation to cope with the disease and planning for the future. The profile of Cuban participants in the predictive testing program is similar to the one reported for other programs all over the world, nevertheless the genetic counseling practice at the community level is a distinctive aspect, which is valuable in providing at-risk individuals with wide and proper knowledge before their testing inclusion request. The SCA2 predictive testing program has high uptake rates and is renowned in our population. Future research is needed to assess the long-term psychological impact in the participants, their partners and relatives.

Estimation of the age at onset in spinocerebellar ataxia type 2 Cuban patients by survival analysis.

Previous studies have investigated the close association that exists between CAG repeat number and the age at onset in SCA2 = spinocerebellar ataxia type 2. These studies have focused on affected individuals. To further characterize this association and estimate the risk of a carrier developing SCA2 at a particular age as a function of a specific CAG repeat size, we have analyzed a large group of 924 individuals, including 394 presymptomatic and 530 affected individuals with a CAG repeat length of 32-79 units. Using a Kaplan-Meier survival analysis, we obtained cumulative probability curves for disease manifestation at a particular age for each CAG repeat length in the 34-45 range. These curves were significantly different (p < 0.001) and showed small overlap. All these information may be very valuable in predictive-testing programs, in the planning of studies for the identification of other genetic and environmental factors as modifiers of age at onset, and in the design of clinical trials for people at enlarged risk for SCA2.

Saccade velocity is reduced in presymptomatic spinocerebellar ataxia type 2.

OBJECTIVE: A characteristic feature of spinocerebellar ataxia type 2 (SCA2) is saccadic slowing at early disease stages. We sought to determine whether this sign is detectable before clinical manifestation and quantifies the disease progression throughout life in linear fashion. METHODS: In a specialized ataxia clinic, 54 presymptomatic carriers of SCA2 polyglutamine expansions and 56 relatives without mutation were documented with regard to their maximal saccade velocity (MSV). RESULTS: Among the control individuals, a significant effect of aging on MSV was observed. After elimination of this age influence through a matched-pair approach, a presymptomatic decrease of MSV could be shown. The MSV reduction was stronger in carriers of large expansions. In the years before calculated disease manifestation, the MSV impairment advanced insidiously. CONCLUSION: Saccade velocity is a sensitive SCA2 endophenotype that reflects early pontine degeneration and may be a useful diagnostic parameter before the onset of ataxia. SIGNIFICANCE: Future neuroprotective therapies of polyglutamine neurodegeneration may be assessed by MSV from earliest to prefinal disease stages.

Saccade velocity is reduced in presymptomatic spinocerebellar ataxia type 2

A characteristic feature of spinocerebellar ataxia type 2 (SCA2) is saccadic slowing at early disease stages. We sought to determine whether this sign is detectable before clinical manifestation and quantifies the disease progression throughout life in linear fashion. In a specialized ataxia clinic, 54 presymptomatic carriers of SCA2 polyglutamine expansions and 56 relatives without mutation were documented with regard to their maximal saccade velocit Spinocerebellar ataxia type 2 Among the control individuals, a significant effect of aging on MSV was observed. After elimination of this age influence through a matched-pair approach, a presymptomatic decrease of MSV could be shown. The MSV reduction was stronger in carriers of large expansions. In the years before calculated disease manifestation, the MSV impairment advanced insidiously.Saccade velocity is a sensitive SCA2 endophenotype that reflects early pontine degenerationPolyglutamine expansion and may be a useful diagnostic parameter before the onset of ataxia. Significance: Future neuroprotective therapies of polyglutamine neurodegeneration may be assessed by MSV from earliest to prefinal disease stages...(AU)

Antigliadin antibodies in Cuban patients with spinocerebellar ataxia type 2.

OBJECTIVE: To evaluate the significance of antigliadin antibodies (AGA) levels for spinocerebellar ataxia type 2. METHODS: We determined AGA levels in 64 patients with spinocerebellar ataxia type 2 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% of the ataxia patients and 9.09% of the controls. Statistical comparison using chi2 test with Yates's correction reveals significant differences between these two groups (chi2 = 3.94; p = 0.047). The same was obtained for strongly positive AGA (chi2 = 4.62; p = 0.032). There were no 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. CONCLUSIONS: These results demonstrate 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.

Estudio del fenotipo electrofisiológico y su correlación con variables clínicas y moleculares / Spinocerebellar ataxia type 2 in Cuba. a study of the electrophysiological phenotipe and its correlation with clinical and molecular variables

Introducción. La ataxia espinocerebelosa tipo 2 tiene la mayor prevalencia del mundo en la provincia de Holguín (Cuba). Es causada por la expansión de una secuencia de CAG contenida en el gen SCA2, y se caracteriza por una gran variabilidad en su expresión clínica y electrofisiológica, aun intrafamiliarmente. La identificación de factores que expliquen esta variabilidad podría conducir al descubrimiento de vías terapéuticas que retarden el comienzo de la enfermedad. Objetivo. Con el propósito de contribuir al conocimiento de dicha variabilidad fenotípica hemos desarrollado esta investigación. Pacientes y métodos. Primero determinamos el número exacto de repeticiones de CAG en una muestra de 52 pacientes SCA2, y luego practicamos estudios electrofisiológicos (estudios de conducción nerviosa periférica y sensitiva, PESS de nervio mediano y tibial posterior así como reflejo H). Resultados. Se identificaron dos grupos bien diferenciados entre sí. El primero incluyó a los pacientes con expansiones mayores de 41 unidades de CAG, y se caracterizó por el bloqueo total de la conducción aferente y el predominio de una lesión de tipo axonal. El segundo grupo incluyó a enfermos con expansiones iguales o menores a 41 unidades de CAG, y mostró una gran variabilidad en su comportamiento electrofisiológico además de una lesión predominantemente mielínica. También demostramos la existencia de correlaciones estadísticamente significativas entre las variables electrofisiológicas y las clínicas y moleculares consideradas. Conclusiones. Estos hallazgos sugieren que para expansiones menores o iguales a 41 unidades de CAG deben estar influyendo otros factores genéticos o ambientales que provoquen la variabilidad observada y que no son significativos para las manifestaciones clínicas y electrofisiológicas en individuos con expansiones mayores de 41 unidades de CAG (AU)

Ataxia espinocerebelosa tipo 2 en Cuba: estudio del fenotipo electrofisiológico y su correlacióncon variables clínicas y moleculares / Spinocerebelar ataxia Type 2 in Cuba: a study of the electrophysicological phenotype

The spinocerebellar ataxia type 2 has a prevalence of 43 per 100,000 inhabitants in Holguín province,which is the highest one reported worldwide. It is due to an intergenerational CAG repeat expansion contained in the first exonof diseasecausinggene, and it is characterized by a high variability in its clinical and electrophysiological presentation, evenintrafamiliarly. Objective. Factors identification, which explains this variability, could lead to the findings of therapeuticalways that may retard the disease onset. Patients and methods. We have done this research in order to contribute to thisphenotypic variability knowledge of the different structures and functions of the nervous system. Results. By means of molecularand electrophysiological studies we have found two groups well differentiated in a 52patientsample. The first one wascharacterized by CAG repeat expansions above 41 units and by the total blockade of the afferent conduction that is, basicelectrophysiological alteration with axonal damage predominance. The second one was characterized by CAG repeat expansionslower or equal to 41 units and showed a high variability in its electrophysiological behavior with myelinic damage predominance.We realized of the existence of statistical significance correlations between the electrophysiological, clinical and molecularvariables considered. Conclusions. These findings suggest that for by CAG repeat expansions lower or equal to 41 unitsshould be affecting other genetics and/or environmental factors that explain the variability found in this group which arenot significant for clinical and electrophysiological presentation in individuals with CAG repeat expansions...(AU)

Ataxia espinocerebelosa tipo 2 en Cuba: Estudio del fenotipo electrofisiológico y su correlación con variables clínicas y moleculares / Spinocerebellar ataxia type 2 in Cuba. A study of the electrophysiological phenotype and its correlation with clinical and molecular variables

Introducción: la ataxia espinocerebelosa tipo 2 tiene la mayor prevalencia del mundo en la provincia de Holguín (Cuba). Es causada por la expansión de una secuencia de CAG contenida en el gen SCA2, y se caracteriza por una gran variabilidad en su expresión clínica y electrofisiológica, aun intrafamiliarmente. La identificación de factores que expliquen esta variabilidad podría conducir al descubrimiento de vías terapéuticas que retarden el comienzo de la enfermedad. Objetivo: con el propósito de contribuir al conocimiento de dicha variabilidad fenotípica hemos desarrollado esta investigación. Pacientes y métodos: primero determinamos el número exacto de repeticiones de CAG en una muestra de 52 pacientes SCA2, y luego practicamos estudios electrofisiológicos (estudios de conducción nerviosa periférica y sensitiva, PESS de nervio mediano y tibial posterior así como reflejo H). Resultados: Se identificaron dos grupos bien diferenciados entre sí. El primero incluyó a los pacientes con expansiones mayores de 41 unidades de CAG, y se caracterizó por el bloqueo total de la conducción aferente y el predominio de una lesión tipo axonal. El segundo grupo incluyó a enfermos con expansiones iguales o menores a 41 unidades de CAG, y mostró una gran variabilidad en su comportamiento electrofisiológico además de una lesión predominantemente mielínica. También demostramos la existencia de correlaciones estadísticamente significativas entre las variables electrofisiológicas y las clínicas y moleculares consideradas. Conclusiones: estos hallazgos sugieren que para expansiones menores o iguales a 41 unidades de CAG deben estar influyendo otros factores genéticos o ambientales que provoquen la variabilidad observada y que no son significativos para las manifestaciones clínicas y electrofisiológicas en individuos con expansiones mayores de 41 unidades de CAG(AU)

Introduction: the spinocerebellar ataxia type 2 has a prevalence of 43 per 100,000 inhabitants in Holguín province, which is the highest one reported worldwide. It is due to an intergenerational CAG repeat expansion contained in the first exon of disease causing gene, and it is characterized by a high variability in its clinical and electrophysiological presentation, even intrafamiliarly. Objetive: factors identification, which explains this variability, could lead to the findings of therapeutical ways that may retard the disease onset. Patients and Methods: we have done this research in order to contribute to this phenotypic variability knowledge of the different structures and functions of the nervous system. Results: by means of molecular and electrophysiological studies we have found two groups well differentiated in a 52-patient sample. The first one was characterized by CAG repeat expansions above 41 units and by the total blockade of the afferent conduction that is, basic electrophysiological alteration with axonal damage predominance. The second one was characterized by CAG repeat expansions lower or equal to 41 units and showed a high variability in it s electrophysiological behavior with myelinic damage predominance. We realized of the existence of statistical significance correlations between the electrophysiological, clinical and molecular variables considered. Conclusions: these findings suggest that for by CAG repeat expansions lower or equal to 41 units should be affecting other genetics and/or environmental factors that explain the variability found in this group which are not significant for clinical and electrophysiological presentation in individuals with CAG repeat expansions above 41 units(AU)

[Type 2 spinocerebellar ataxia: acceptance of prenatal diagnosis in descendents at risk]. / Ataxia espinocerebelosa tipo 2: aceptación del diagnóstico prenatal en descendientes en riesgo.

INTRODUCTION: Type 2 spinocerebellar ataxia is a hereditary degenerative disorder of the nervous system. Advances in molecular genetics have made it possible to carry out presymptomatic and prenatal studies. A programme to define the strategies and principles for doing this has been devised. OBJECTIVE: To find the level of acceptance of prenatal diagnosis in couples at risk, and to determine the effect of different variables on this acceptance. PATIENTS AND METHODS: We made a descriptive type study of a series of cases. The study group included 226 persons. Forty of these were couples of descendents and the remainder were asymptomatic descendents. We applied a questionnaire, after prior information as to the aims of the study and obtaining the consent of the participants. RESULTS: Regarding acceptance of prenatal diagnosis by couples of descendents, we found that most (77.5%) accepted this and only 2.5% did not. Prenatal diagnosis was accepted by 67.74% of the descendents themselves. CONCLUSIONS: In general there was a high level of acceptance. 159 of the 226 questioned claimed that they would like to have more children and 98.7% of these accepted the test, whilst only 0.01% refused it. The main reasons given were the hope of having healthy children and that the disease would not occur in future generations.

[Spinocerebellar ataxia type 2 in Cuba. A study of the electrophysiological phenotype and its correlation with clinical and molecular variables]. / Ataxia espinocerebelosa tipo 2 en cuba. Estudio del fenotipo electrofisiológico y su correlación con variables clínicas y moleculares.

INTRODUCTION: The spinocerebellar ataxia type 2 has a prevalence of 43 per 100,000 inhabitants in Holguín province, which is the highest one reported worldwide. It is due to an intergenerational CAG repeat expansion contained in the first exon of disease causing gene, and it is characterized by a high variability in its clinical and electrophysiological presentation, even intrafamiliarly. OBJECTIVE: Factors identification, which explains this variability, could lead to the findings of therapeutical ways that may retard the disease onset. PATIENTS AND METHODS: We have done this research in order to contribute to this phenotypic variability knowledge of the different structures and functions of the nervous system. RESULTS: By means of molecular and electrophysiological studies we have found two groups well differentiated in a 52-patient sample. The first one was characterized by CAG repeat expansions above 41 units and by the total blockade of the afferent conduction that is, basic electrophysiological alteration with axonal damage predominance. The second one was characterized by CAG repeat expansions lower or equal to 41 units and showed a high variability in it s electrophysiological behavior with myelinic damage predominance. We realized of the existence of statistical significance correlations between the electrophysiological, clinical and molecular variables considered. CONCLUSIONS: These findings suggest that for by CAG repeat expansions lower or equal to 41 units should be affecting other genetics and/or environmental factors that explain the variability found in this group which are not significant for clinical and electrophysiological presentation in individuals with CAG repeat expansions above 41 units.