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Familial frontotemporal dementia with amyotrophic lateral sclerosis and a shared haplotype on chromosome 9p.

ABSTRACT: Families with autosomal dominant frontotemporal dementia and amyotrophic lateral sclerosis (FTD/ALS) have previously been linked to a locus on chromosome 9p21. We describe the clinical phenotype and pathology of a large family with autosomal dominant FTD/ALS with nine affected members originating from Gwent in South Wales, UK. We also further refine the locus on chromosome 9p21 using a haplotype sharing approach and assess heterogeneity in 9p21 linked families. Within this family, affected individuals present with either FTD or ALS or both diseases simultaneously. In addition there was marked phenotypic variation including ataxia, Parkinsonism, psychosis and visuo-spatial cognitive deficits. The pathological features of the three cases described were consistent with type 2 FTD pathology, as previously reported in similar families. However, we also report distinctive cerebellar and glial pathology and a significant proportion of TDP-43 negative inclusions. No mutations in known genes for FTD or ALS were found. We identified a large 4.8-megabase haplotype on chromosome 9p21, which was shared by all affected family members. This haplotype overlaps and limits the previously reported FTD/ALS linkage region on chromosome 9p21. Sequencing of this region did not identify any evidence of a pathogenic exonic mutation. This suggests that the pathogenic change affects non-coding DNA and that the disease is caused by variation in gene or protein expression.

SUBMITTER: Pearson JP

PROVIDER: S-EPMC4696389 | biostudies-literature | 2011 Apr

REPOSITORIES: biostudies-literature

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Familial frontotemporal dementia with amyotrophic lateral sclerosis and a shared haplotype on chromosome 9p.

Pearson Justin P JP Williams Nigel M NM Majounie Elisa E Waite Adrian A Stott Jennifer J Newsway Victoria V Murray Alex A Hernandez Dena D Guerreiro Rita R Singleton Andrew B AB Neal James J Morris Huw R HR

Journal of neurology 20101112 4

Families with autosomal dominant frontotemporal dementia and amyotrophic lateral sclerosis (FTD/ALS) have previously been linked to a locus on chromosome 9p21. We describe the clinical phenotype and pathology of a large family with autosomal dominant FTD/ALS with nine affected members originating from Gwent in South Wales, UK. We also further refine the locus on chromosome 9p21 using a haplotype sharing approach and assess heterogeneity in 9p21 linked families. Within this family, affected indiv ...[more]

PMID: 21072532

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Project description:Amyotrophic lateral sclerosis and frontotemporal dementia are two progressive, adult onset neurodegenerative diseases, caused by the cell death of motor neurons in the motor cortex and spinal cord and cortical neurons in the frontal and temporal lobes, respectively. Whilst these have previously appeared to be quite distinct disorders, in terms of areas affected and clinical symptoms, identification of cognitive dysfunction as a component of amyotrophic lateral sclerosis (ALS), with some patients presenting with both ALS and FTD, overlapping features of neuropathology and the ongoing discoveries that a significant proportion of the genes underlying the familial forms of the disease are the same, has led to ALS and FTD being described as a disease spectrum. Many of these genes encode proteins in common biological pathways including RNA processing, autophagy, ubiquitin proteasome system, unfolded protein response and intracellular trafficking. This article provides an overview of the ALS-FTD genes before summarizing other known ALS and FTD causing genes where mutations have been found primarily in patients of one disease and rarely in the other. In discussing these genes, the review highlights the similarity of biological pathways in which the encoded proteins function and the interactions that occur between these proteins, whilst recognizing the distinctions of MAPT-related FTD and SOD1-related ALS. However, mutations in all of these genes result in similar pathology including protein aggregation and neuroinflammation, highlighting that multiple different mechanisms lead to common downstream effects and neuronal loss. Next generation sequencing has had a significant impact on the identification of genes associated with both diseases, and has also highlighted the widening clinical phenotypes associated with variants in these ALS and FTD genes. It is hoped that the large sequencing initiatives currently underway in ALS and FTD will begin to uncover why different diseases are associated with mutations within a single gene, especially as a personalized medicine approach to therapy, based on a patient's genetics, approaches the clinic.

Project description:Frontotemporal dementia and amyotrophic lateral sclerosis are closely related clinical syndromes with overlapping molecular pathogenesis. Several families have been reported with members affected by frontotemporal dementia, amyotrophic lateral sclerosis or both, which show genetic linkage to a region on chromosome 9p21. Recently, two studies identified the FTD/ALS gene defect on chromosome 9p as an expanded GGGGCC hexanucleotide repeat in a non-coding region of the chromosome 9 open reading frame 72 gene (C9ORF72). In the present study, we provide detailed analysis of the clinical features and neuropathology for 16 unrelated families with frontotemporal dementia caused by the C9ORF72 mutation. All had an autosomal dominant pattern of inheritance. Eight families had a combination of frontotemporal dementia and amyotrophic lateral sclerosis while the other eight had a pure frontotemporal dementia phenotype. Clinical information was available for 30 affected members of the 16 families. There was wide variation in age of onset (mean = 54.3, range = 34-74 years) and disease duration (mean = 5.3, range = 1-16 years). Early diagnoses included behavioural variant frontotemporal dementia (n = 15), progressive non-fluent aphasia (n = 5), amyotrophic lateral sclerosis (n = 9) and progressive non-fluent aphasia-amyotrophic lateral sclerosis (n = 1). Heterogeneity in clinical presentation was also common within families. However, there was a tendency for the phenotypes to converge with disease progression; seven subjects had final clinical diagnoses of both frontotemporal dementia and amyotrophic lateral sclerosis and all of those with an initial progressive non-fluent aphasia diagnosis subsequently developed significant behavioural abnormalities. Twenty-one affected family members came to autopsy and all were found to have transactive response DNA binding protein with M(r) 43 kD (TDP-43) pathology in a wide neuroanatomical distribution. All had involvement of the extramotor neocortex and hippocampus (frontotemporal lobar degeneration-TDP) and all but one case (clinically pure frontotemporal dementia) had involvement of lower motor neurons, characteristic of amyotrophic lateral sclerosis. In addition, a consistent and relatively specific pathological finding was the presence of neuronal inclusions in the cerebellar cortex that were ubiquitin/p62-positive but TDP-43-negative. Our findings indicate that the C9ORF72 mutation is a major cause of familial frontotemporal dementia with TDP-43 pathology, that likely accounts for the majority of families with combined frontotemporal dementia/amyotrophic lateral sclerosis presentation, and further support the concept that frontotemporal dementia and amyotrophic lateral sclerosis represent a clinicopathological spectrum of disease with overlapping molecular pathogenesis.

Dataset Information

Familial frontotemporal dementia with amyotrophic lateral sclerosis and a shared haplotype on chromosome 9p.

Publications

Familial frontotemporal dementia with amyotrophic lateral sclerosis and a shared haplotype on chromosome 9p.

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