Expansión anormal de hexanucleótido en gen C9orf72 en una familia con demencia frontotemporal y cuadros asociados / Abnormal expansion of C9orf72 gene in familial frontotemporal dementia

Frontotemporal Dementia (FTD) and Motor Neuron Disease (MND) may share similar pathogenic mechanisms. An abnormal hexanucleotide expansion in C9orf72 gene is the most common genetic abnormality of these conditions and explains their concurrence in the same family. We report a 77-year-old female presenting with non-fluent aphasia leading to mutism and a mild Parkinsonism. A magnetic resonance imaging showed a severe atrophy of frontal and temporal lobes. Several family members of the patient suffered of atypical Parkinsonism, lateral amyotrophic sclerosis and dementia. We identified an abnormal hexanucleotide expansion in the C9orf72 gene in the proband. To the extent of our knowledge, this is the first time that this diagnosis is confirmed in our country. The knowledge of the genetic basis of neuro degenerative disorders improves diagnosis and opens expectatives for future treatments of these disabling conditions.

Revisão dos principais genes e proteínas associadas à demência frontotemporal tau-positiva / Review of main genes and proteins associated with tau-positive frontotemporal dementia

O objetivo desta revisão foi apresentar os genes APOE e MAPT e as proteínas ApoE e tau como marcadores genéticos que vêm sendo estudados na demência frontotemporal com inclusões tau-positivas, os quais poderão, futuramente, auxiliar no diagnóstico diferencial. A demência frontotemporal é um transtorno neurocognitivo marcado por disfunção dos lobos frontais e temporais, geralmente associada à atrofia dessas estruturas e relativa preservação das regiões cerebrais posteriores. Clinicamente, manifesta-se por volta dos 57 anos de idade, com igual incidência entre homens e mulheres. A demência frontotemporal tem início insidioso e caráter progressivo, com discreto comprometimento da memória episódica, mas com importantes alterações comportamentais, de personalidade e na linguagem. Devido às semelhanças possíveis entre as manifestações clínicas das demências inclusive a doença de Alzheimer, há grande dificuldade no diagnóstico diferencial, sendo necessário um exame clínico e neuropsicológico detalhado do indivíduo acometido, além de exames bioquímicos e de neuroimagem. O gene MAPT codifica a proteína tau e sua função principal é estabilizar os microtúbulos. Em células nervosas sadias, a proteína tau é normalmente encontrada nos axônios, ao contrário dos achados descritos nos transtornos neurocognitivos, em que a proteína se encontra distribuída no corpo celular e nos dendritos. A apolipoproteína E ApoE é uma glicoproteína polimórfica, codificada pelo gene APOE, que tem importante papel na absorção, transporte e redistribuição de colesterol, necessário ao reparo e manutenção do tecido nervoso. Com o aumento da expectativa de vida e controle da natalidade, o envelhecimento populacional tornou-se fato, trazendo consigo maior prevalência de doenças crônico-degenerativas, de modo que é de extrema importância conhecer melhor essas doenças, no sentido de buscar novas formas de tratamento, visto que as demências não dispõem ainda de cura...

This review aimed to present the APOE and MAPT gene and ApoE and tau proteins as genetic markers that have been studied in frontotemporal dementia, which may in future help in the differential diagnosis. Frontotemporal dementia is a neurocognitive disorder characterized by frontal and temporal lobes dysfunction, often associated with atrophy of these structures and relative preservation of posterior brain regions. Clinically, it manifests around 57 years-old, with same incidence in men and women. Frontotemporal dementia has an insidious and progressive onset, with a mild impairment of episodic memory, but with significant behavioral, personality and language changes. Due to possible similarities between the clinical manifestations of dementia including Alzheimer's disease there is a great difficulty in the differential diagnosis, which needs detailed clinical and neuropsychological examination of individuals affected, further biochemical and neuroimaging exams. MAPT gene encodes tau protein, its main function is to stabilize microtubules. In healthy nerve cells, tau protein is usually found in the axons, in contrast to the findings described in neurocognitive disorders in which protein is distributed in the cell body and dendrites. The apolipoprotein E ApoE is a polymorphic glycoprotein, encoded by the APOE gene, which plays an important role in absorption, transport and redistribution of cholesterol, necessary for the repair and maintenance of nervous tissue. Because of increasing life expectancy and birth control, population aging has become fact, bringing a higher prevalence of chronic diseases, so it is extremely important to know more about these dis eases, in order to seek new ways of treating dementias seen that do not have a cure...

Manifestaciones neuropsiquiátricas y cognitivas en demencia frontotemporal y esclerosis lateral amiotrófica: dos polos de una entidad común / Overlapping features of frontotemporal dementia and amyotrophic lateral sclerosis

Recent genetic and neuropathologic advances support the concept that frontotemporal dementia (FTD) and amyotrophic lateral sclerosis (ALS) are overlapping multisystem disorders. While 10-15% of ALS patients fulfil criteria for FTD, features of motor neuron disease appear in approximately 15% of FTD patients, during the evolution of the disease. This overlap has been reinforced by the discovery of Transactive Response DNA Binding Protein 43 kDa (TDP43) inclusions as the main neuropathologic finding in the majority of ALS cases and almost a half of FTD cases. Also, an expansion in the intron of C9ORF72 (chromosome 9p21) has been identified in families affected by ALS, ALS-FTD and FTD. This review provides an update on the recent genetic and neuropathologic findings of ALS and FTD and a characterization of their clinical presentation forms, based on the current diagnostic criteria. Finally it underscores the importance of having a national registry of patients with ALS and FTD, to provide an earlier diagnosis and a multidisciplinary care.

A Brazilian family with hereditary inclusion body myopathy associated with Paget disease of bone and frontotemporal dementia

Inclusion body myopathy associated with Paget disease and frontotemporal dementia (IBMPFD) is a progressive and usually misdiagnosed autosomal dominant disorder. It is clinically characterized by a triad of features: proximal and distal myopathy, early onset Paget disease of bone (PDB), and frontotemporal dementia (FTD). It is caused by missense mutations in the valosin-containing protein (VCP) gene. We describe here the clinical and molecular findings of the first Brazilian family identified with IBMPFD. Progressive myopathy affecting the limb girdles was detected by clinical examination followed by muscle biopsy and creatine kinase measurement. PDB was suggested after anatomopathological bone examination and FTD was diagnosed by clinical, neuropsychological and language evaluations. Brain magnetic resonance revealed severe atrophy of the anterior temporal lobes, including the hippocampi. A R93C mutation in VCP was detected by direct sequencing screening in subject W (age 62) and in his mother. Four more individuals diagnosed with "dementia" were reported in this family. We also present a comprehensive genotype-phenotype correlation analysis of mutations in VCP in 182 patients from 29 families described in the literature and show that while IBM is a conspicuously penetrant symptom, PDB has a lower penetrance when associated with mutations in the AAAD1 domain and FTD has a lower penetrance when associated with mutations in the Junction (L1-D1) domain. Furthermore, the R93C mutation is likely to be associated with the penetrance of all the clinical symptoms of the triad.