Unraveling the genetic landscape of undiagnosed cerebellar ataxia in Brazilian patients.

INTRODUCTION: Hereditary ataxias (HAs) encompass a diverse and genetically intricate group of rare neurodegenerative disorders, presenting diagnostic challenges. Whole-exome sequencing (WES) has significantly improved diagnostic success. This study aimed to elucidate genetic causes of cerebellar ataxia within a diverse Brazilian cohort. METHODS: Biological samples were collected from individuals with sporadic or familial cerebellar ataxia, spanning various ages and phenotypes, excluding common SCAs and Friedreich ataxia. RFC1 biallelic AAGGG repeat expansion was screened in all patients. For AAGGG-negative cases, WES targeting 441 ataxia-related genes was performed, followed by ExpansionHunter analysis for repeat expansions, including the recently described GGC-ZFHX3. Variant classification adhered to ClinGen guidelines, yielding definitive or probable diagnoses. RESULTS: The study involved 76 diverse Brazilian families. 16 % received definitive diagnoses, and another 16 % received probable ones. RFC1-related ataxia was predominant, with two definitive cases, followed by KIF1A (one definitive and one probable) and SYNE-1 (two probable). Early-onset cases exhibited higher diagnostic rates. ExpansionHunter improved diagnosis by 4 %.We did not detected GGC-ZFHX3 repeat expansion in this cohort. CONCLUSION: This study highlights diagnostic complexities in cerebellar ataxia, even with advanced genetic methods. RFC1, KIF1A, and SYNE1 emerged as prevalent mutations. ZFHX3 repeat expansion seem to be rare in Brazilian population. Early-onset cases showed higher diagnostic success. WES coupled with ExpansionHunter holds promise as a primary diagnostic tool, emphasizing the need for broader NGS accessibility in Brazil.

Frequency of GAA-FGF14 Ataxia in a Large Cohort of Brazilian Patients With Unsolved Adult-Onset Cerebellar Ataxia.

Objectives: Intronic FGF14 GAA repeat expansions have recently been found to be a common cause of hereditary ataxia (GAA-FGF14 ataxia; SCA27B). The global epidemiology and regional prevalence of this newly reported disorder remain to be established. In this study, we investigated the frequency of GAA-FGF14 ataxia in a large cohort of Brazilian patients with unsolved adult-onset ataxia. Methods: We recruited 93 index patients with genetically unsolved adult-onset ataxia despite extensive genetic investigation and genotyped the FGF14 repeat locus. Patients were recruited across 4 different regions of Brazil. Results: Of the 93 index patients, 8 (9%) carried an FGF14 (GAA)≥250 expansion. The expansion was also identified in 1 affected relative. Seven patients were of European descent, 1 was of African descent, and 1was of admixed American ancestry. One patient carrying a (GAA)376 expansion developed ataxia at age 28 years, confirming that GAA-FGF14 ataxia can occur before the age of 30 years. One patient displayed episodic symptoms, while none had downbeat nystagmus. Cerebellar atrophy was observed on brain MRI in 7 of 8 patients (87%). Discussion: Our results suggest that GAA-FGF14 ataxia is a common cause of adult-onset ataxia in the Brazilian population, although larger studies are needed to fully define its epidemiology.

Professor Faustino Esposel: Neurology, football and spiritualism / Professor Faustino Esposel: Neurologia, futebol e espiritismo

ABSTRACT Faustino Monteiro Esposel was a renowned neurologist from Rio de Janeiro, born on October 24, 1888. Together with his mentor, Professor Antônio Austregésilo Rodrigues Lima - the founder of modern Brazilian Neurology -, Professor Esposel described one of the rival signs of the Babinski sign, known as the Austregésilo-Esposel sign, in a study published in the renowned journal L'Encéphale in 1912. This article aims to summarize the life story of this illustrious neurologist as well as to highlight his achievements "beyond medicine".

RESUMO Faustino Monteiro Esposel foi um renomado neurologista do Rio de Janeiro, nascido em 24 de outubro de 1888. Junto de seu mentor, o Professor Antônio Austregésilo Rodrigues Lima, considerado o pai da Neurologia brasileira moderna, descreveu um dos sinais sucedâneos do sinal de Babinski, conhecido como sinal de Austregésilo-Esposel, publicado no renomado periódico L'Encéphale em 1912. Este artigo tem como objetivo trazer a história deste ilustre neurologista, destacando também seus feitos "além da medicina".

The history behind ALS type 8: from the first phenotype description to the discovery of VAPB mutation / A história por detrás da ELA tipo 8: da primeira descrição do fenótipo à descoberta da mutação VAPB

ABSTRACT Over the past 68 years, the Finkel type late-onset adult autosomal dominant spinal muscular atrophy (SMA) that is allelic with amyotrophic lateral sclerosis-8 (ALS8) gained a genotype-phenotype correlation among the motor neuron diseases through the work of groups led by Zatz and Marques Jr.

RESUMO Nos últimos 68 anos, a atrofia muscular espinhal (AME), autossômica dominante, de início tardio, em adultos, conhecida como doença de Finkel, que é alélica com esclerose lateral amiotrófica tipo 8 (ELA8), ganhou uma correlação fenotípica e genotípica dentre as doenças do neurônio motor, a partir da colaboração dos grupos de Zatz e Marques Jr.

The history behind ALS type 8: from the first phenotype description to the discovery of VAPB mutation.

Over the past 68 years, the Finkel type late-onset adult autosomal dominant spinal muscular atrophy (SMA) that is allelic with amyotrophic lateral sclerosis-8 (ALS8) gained a genotype-phenotype correlation among the motor neuron diseases through the work of groups led by Zatz and Marques Jr.

Professor Faustino Esposel: Neurology, football and spiritualism.

Faustino Monteiro Esposel was a renowned neurologist from Rio de Janeiro, born on October 24, 1888. Together with his mentor, Professor Antônio Austregésilo Rodrigues Lima - the founder of modern Brazilian Neurology -, Professor Esposel described one of the rival signs of the Babinski sign, known as the Austregésilo-Esposel sign, in a study published in the renowned journal L'Encéphale in 1912. This article aims to summarize the life story of this illustrious neurologist as well as to highlight his achievements "beyond medicine".

Evidence and practices of the use of next generation sequencing in patients with undiagnosed autosomal dominant cerebellar ataxias: a review / Evidências e práticas do uso do sequenciamento de nova geração em pacientes com ataxias cerebelares autossômicas dominantes não diagnosticadas: uma revisão

ABSTRACT Autosomal dominant cerebellar ataxias (ADCA) are heterogeneous diseases with a highly variable phenotype and genotype. They can be divided into episodic ataxia and spinocerebellar ataxia (SCA); the latter is considered the prototype of the ADCA. Most of the ADCA are caused by polyglutamine expansions, mainly SCA 1, 2, 3, 6, 7, 17 and Dentatorubral-pallidoluysian atrophy (DRPLA). However, 30% of patients remain undiagnosed after testing for these most common SCA. Recently, several studies have demonstrated that the new generation of sequencing methods are useful for the diagnose of these patients. This review focus on searching evidence on the literature, its usefulness in clinical practice and future perspectives.

RESUMO As ataxias cerebelares autossômicas dominantes (ACAD) são doenças heterogêneas com fenótipo e genótipo altamente variáveis. Podem ser divididas em ataxia episódica e ataxia espinocerebelar (SCA), sendo este último considerado o protótipo do ACAD. A maior parte das ACAD são causadas por expansões de poliglutaminas, principalmente SCA 1, 2, 3, 6, 7, 17 e atrofia dentatorubro-palidoluisiana (DRPLA). No entanto, 30% dos pacientes permanecem sem diagnóstico após o teste para essas SCA mais comuns. Recentemente, vários estudos têm demonstrado que a nova geração de métodos de sequenciamento são ferramentas úteis para o diagnóstico desses pacientes. Esta é uma revisão sistemática da literatura, com foco em sua utilidade na prática clínica e em perspectivas futuras.

Evidence and practices of the use of next generation sequencing in patients with undiagnosed autosomal dominant cerebellar ataxias: a review.

Autosomal dominant cerebellar ataxias (ADCA) are heterogeneous diseases with a highly variable phenotype and genotype. They can be divided into episodic ataxia and spinocerebellar ataxia (SCA); the latter is considered the prototype of the ADCA. Most of the ADCA are caused by polyglutamine expansions, mainly SCA 1, 2, 3, 6, 7, 17 and Dentatorubral-pallidoluysian atrophy (DRPLA). However, 30% of patients remain undiagnosed after testing for these most common SCA. Recently, several studies have demonstrated that the new generation of sequencing methods are useful for the diagnose of these patients. This review focus on searching evidence on the literature, its usefulness in clinical practice and future perspectives.