RESUMO
Prion protein (PRNP) gene mutations have recently been associated with clinical pictures resembling Frontotemporal dementia (FTD). We describe a novel seven extra-repeat insertional mutation in the PRNP gene in a family affected by early-onset autosomal dominant FTD previously reported as caused by a PSEN1 mutation in which there was inconsistency between clinical picture and genotype. Both mutations were pathogenic and showed a variable penetrance when present separately; when occurring together, the onset was very early, within the third decade of life. Genetic screening of the PRNP gene becomes of major importance in early onset autosomal dominant dementia.
Assuntos
Saúde da Família , Demência Frontotemporal/genética , Mutação/genética , Presenilina-1/genética , Príons/genética , Adulto , Idade de Início , Idoso de 80 Anos ou mais , Feminino , Testes Genéticos , Humanos , Masculino , Pessoa de Meia-Idade , Fenótipo , Proteínas PriônicasRESUMO
BACKGROUND: Frontotemporal dementia is a clinically and genetically heterogeneous syndrome. Mutations in two genes, Microtubule Associated Protein Tau (MAPT) and Progranulin (PGRN), and rarely Presenilin mutations, have been causally linked to this disorder. OBJECTIVE: To investigate the presence of PGRN, PSEN1, PSEN2 and APP mutations in a group of familial early-onset frontotemporal dementia (f-EOFTD) patients negative for MAPT gene mutations. SUBJECTS AND METHODS: We prospectively studied 17 unrelated subjects diagnosed with f-EOFTD (one case neuropathologically confirmed as FTD-Ub+). Among these subjects eight belonged to eight autosomal dominant families unrelated to each other, and nine had at least one first degree relative affected by dementia. RESULTS: We identified two novel heterozygous mutations in two unrelated patients, Cys139Arg in the PGRN gene and Val412Ile in the PSEN1 gene. CONCLUSIONS: Early-onset f-FTD remains a heterogeneous disorder from a genetic point of view. PGRN mutation frequency was low in our sample. The presence of a novel PSEN1 mutation suggests that presenilin molecular studies should be performed when screening for MAPT and PGRN genes is negative.
Assuntos
Saúde da Família , Demência Frontotemporal/genética , Predisposição Genética para Doença , Peptídeos e Proteínas de Sinalização Intercelular/genética , Mutação/genética , Presenilina-1/genética , Adulto , Arginina/genética , Cisteína/genética , Análise Mutacional de DNA , Feminino , Fluordesoxiglucose F18 , Demência Frontotemporal/diagnóstico por imagem , Humanos , Masculino , Proteínas Associadas aos Microtúbulos/genética , Pessoa de Meia-Idade , Progranulinas , CintilografiaRESUMO
Aim of the study was to assess the added diagnostic value of neuropsychologic tests and structural neuroimaging (computed tomography or magnetic resonance) in the routine clinical assessment of demented patients in Italian expert centers. Nine centers were involved, located across the whole country (3 in Northern, 3 in Central, and 3 in Southern Italy). Diagnostic pathways were tracked for 474 patients with an expert diagnosis of neurodegenerative or vascular dementia (age 76+/-8; 62% females; Mini-Mental State Examination 17.70+/-5.7). The contribution of neuropsychology and structural neuroimaging to diagnosis was estimated as "number needed to test" (NNT), denoting the number of patients who need to undergo such procedures to improve expert diagnosis of 1 unit. Expert physicians reached their diagnosis without resorting to structural imaging examinations and neuropsychologic tests in 93% of Alzheimer disease (AD) and 76% of non-AD dementias. The completion of the extended assessment led to improvement of diagnostic accuracy in both cases: the NNT was 15.3 (95% confidence interval: 10.4-29.1) and 4.1 (3.0 to 6.5) for AD and non-AD diagnoses. The added value of structural imaging and neuropsychologic testing in the routine clinical assessment of demented patients is substantial in both AD and non-AD cases.
