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Objective:To investigate the clinical characteristics, genetic characteristics and diagnosis of spinocerebellar ataxia type 2 (SCA2) patients with childhood onset.Methods:The clinical data of a SCA2 pedigree who diagnosed at Neurogenetic Metabolic Disease Clinic of Children′s Hospital Affiliated to Zhengzhou University in July 2019 were collected, and the reported cases of childhood-onset SCA2 were reviewed. The CAG repeat of ATXN2 gene was detected by polymerase chain reaction, capillary gel electrophoresis and Sanger sequencing techniques.Results:A total of 9 people in 4 generations of the family were affected, showing an autosomal dominant inheritance. The proband was a 3 years and 4 months old boy, who showed abnormal symptoms at 9 months which manifested as developmental retardation. At 1 year old, he developed progressive regression which represented neither to be amused, recognize others, stand and walk alone, nor had language development. Meanwhile, he had difficulty swallowing, long-term constipation, and a history of convulsions. His sister and mother were not yet sick. His grandmother could not walk, had slurred speech accompanied by nystagmus, and magnetic resonance imaging showed cerebellar atrophy. His granduncles and grandaunts had unstable walking and dysarthria. His great-grandfather required wheelchair to walk. This pedigree showed an autosomal dominant inheritance. One of the ATXN2 gene alleles of the proband, his sister, mother and grandmother all showed abnormal amplification with 99, 55, 44, and 43 times respectively and no inserting CAA sequence. A total of 14 literatures reported 20 cases of childhood-onset SCA2 patients who were genetically diagnosed. The majorities had onset in infancy, and few can develop into school age. The main clinical manifestations were developmental delay, dystonia or insufficiency, myoclonus or infantile spasms, motor retardation, abnormal eye movement, retinitis pigmentosa and dysphagia, while the classic cerebellar syndrome was only partially present. Abnormal rhythm was found on electroencephalogram, cerebellar atrophy on magnetic resonance imaging or CT of the head.Conclusions:This case is the youngest genetically-confirmed SCA2 patient reported in China. Reported patients usually have onset in infancy with excessive repeat sequence expansion. Their clinical characteristics are different from the classic patients and could only be diagnosed by dynamic mutation detection.
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Objective:To explore the phenotype and molecular genetic features of spinocerebellar ataxia type 2 (SCA2) cases with ATXN2 intermediate-length CAG-repeat expansion.Methods:Fragment analysis by capillary electrophoresis was performed to detect the dynamic mutations in the samples of the probands in 1 383 pedigrees with autosomal dominant inherited ataxia in Research Center for Motor Disorders and Neurogenetic Diseases, Department of Neurology, China-Japan Friendship Hospital from 2005 to 2018. The clinical and genetic features of individuals carrying the ATXN2 intermediate-length CAG-repeat expansion were carefully analyzed.Results:Two hundred and three individuals (including the probands and members of their families) in 163 families carried the expanded CAG repeats in ATXN2 gene, among which 107 individuals in 93 families carried the intermediate-length CAG-repeats. Within 20 parent-child pairs, the CAG repeats increased 0-28 copies in 16 pairs with paternal inheritance, and 0-4 copies in 4 pairs with maternal inheritance.Conclusions:For suspected SCA2 cases, ATXN2 gene testing should be performed on the parental members and adult offspring members in the family. Dynamic mutations testing is essential to identify the individuals with ATXN2 intermediate-length repeat expansion, which is very important for genetic counseling.
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@#In recent years, considerable progress has been made in the study of glaucoma, especially primary open angle glaucoma(POAG). A series of POAG genes has been identified through genetic linkage analysis and genome-wide association studies(GWAS), which significantly advanced the study of glaucoma genetics. The latest perspective suggests that glaucoma is a disease of the central nervous system(CNS). A large number of basic clinical studies have demonstrated the close association between CNS disease and glaucoma. Among these studies, discoveries related to genetics are of prominence.
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La ataxia espinocerebelosa tipo 2 (SCA2) es una enfermedad neurodegenerativa causada por la expansión del trinucleótido CAG en el exón 1 del gen Ataxina-2 (ATXN2), situado en la región cromosómica 12q23-24. Este es el primer reporte de diagnóstico molecular realizado en Ecuador para esta enfermedad. Presentación de los casos Dos pacientes ecuatorianos de género masculino de 39 y 46 años de edad fueron remitidos al Servicio de Genética Médica del Hospital de Especialidades de las Fuerzas Armadas Nº1 para identifcar el tipo de ataxia espinocerebelosa presente en cada caso. Para ambos pacientes, la evaluación clínica evidenció síntomas compatibles con una SCA2, el análisis genealógico mostró un patrón de herencia autosómico dominante y el diagnóstico molecular confrmó que la ataxia espinocerebelosa presente era de tipo 2. Conclusión El diagnóstico específco de las ataxias espinocerebelosas debe basarse principalmente en una correlación fenotípica-genotípica, la cual involucra evaluaciones clínicas, análisis genealógico y estudios genéticos moleculares para cada caso. La SCA2 constituye un tipo de enfermedad cuyo diagnóstico implica complejidades clínicas y genéticas, concluyendo que este proceso debe efectuarse con la inclusión del asesoramiento genético familiar, siendo el comienzo del manejo integral de esta enfermedad