Machado Joseph-Disease Is Rare in the Peruvian Population.

Spinocerebellar ataxia type 3 or Machado-Joseph disease (MJD/SCA3) is the most prevalent autosomal dominant cerebellar ataxia worldwide, but its frequency varies by geographic region. We describe MJD/SCA3 patients diagnosed in a tertiary healthcare institution in Peru. In a cohort of 341 individuals (253 probands) with clinical ataxia diagnosis, seven MJD/SCA3 probands were identified and their pedigrees extended, detecting a total of 18 MJD/SCA3 cases. Out of 506 alleles from all probands from this cohort, the 23-CAG repeat was the most common ATXN3 allele (31.8%), followed by the 14-CAG repeat allele (26.1%). Normal alleles ranged from 12 to 38 repeats while pathogenic alleles ranged from 64 to 75 repeats. We identified 80 large normal (LN) alleles (15.8%). Five out of seven families declared an affected family member traced back to foreign countries (England, Japan, China, and Trinidad and Tobago). MJD/SCA3 patients showed ataxia, accompanied by pyramidal signs, dysarthria, and dysphagia as well as abnormal oculomotor movements. In conclusion, ATXN3 allelic distribution in non-MJD/SCA3 patients with ataxia is similar to the distribution in normal individuals around the world, whereas LN allele frequency reinforces no correlation with the frequency of MJD/SCA3. Evidence of any atypical MJD/SCA3 phenotype was not found. Furthermore, haplotypes are required to confirm the foreign origin of MJD/SCA3 in the Peruvian population.

Huntington juvenil y fenocopia intrafamiliar a propósito de dos casos / Juvenile Huntington and intrafamily phenocopy, about two cases

RESUMEN La enfermedad de Huntington (EH) es una enfermedad neurodegenerativa hereditaria de progresión irremediablemente fatal. Existen otros trastornos con síntomas semejantes a los de esta enfermedad y que son llamados fenocopias. En nuestro reporte, se presentan los casos de dos hermanos con fenotipo compatible con EH, uno ellos con una fenocopia intrafamiliar, caracterizada por un síndrome coreico y cambios del comportamiento, con estudio genético negativo para EH. El caso índice cursa con una forma parkinsoniana de EH de inicio juvenil, con evolución lentamente progresiva que, además, presenta síntomas neuropsiquiátricos, con respuesta mínima a tratamiento sintomático con psicofármacos. El hermano mayor, caso de fenocopia intrafamiliar, cursó con movimientos discinéticos cervicofaciales y faciales severos, psicosis y cognición conservada. En conclusión, las fenocopias de EH pueden presentarse incluso dentro de una familia con EH genéticamente confirmada. Se recomienda una detallada evaluación neurológica y un estudio genético apropiado en todos los casos en que se tenga sospecha clínica de EH, incluso en familiares directos de pacientes diagnosticados con la enfermedad.

ABSTRACT Huntington's disease (HD) is an inherited neurodegenerative disorder with an always fatal outcome. Other disorders resemble the symptoms of this disease and are called phenocopies. The cases of two brothers in a family affected with a phenotype compatible with HD, are presented, one of them an intrafamilial phenocopy, characterized by choreic syndrome, abnormal behavior, and negative HD genetic testing. The index case evolves with a juvenile-onset slowly progressive parkinsonian form of HD that, in addition, presents neuropsychiatric symptoms with minimal response to symptomatic treatment with dopamine antagonists. The older brother, the intrafamilial phenocopy, experienced severe facial cervicofacial and cervical dyskinetic movements, psychosis, and preserved cognition. In conclusion, the HD phenocopies might occur even within a known, genetically confirmed HD family. It is recommended to perform a detailed neurological examination together with appropriate genetic testing in all cases with clinical suspicious of HD, including direct family members of HD affected individuals.