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The C9ORF72 repeat expansion alters neurodevelopment.

ABSTRACT: Genetic mutations that cause adult-onset neurodegenerative diseases are often expressed during embryonic stages, but it is unclear whether they alter neurodevelopment and how this might influence disease onset. Here, we show that the most common cause of frontotemporal dementia (FTD) and amyotrophic lateral sclerosis (ALS), a repeat expansion in C9ORF72, restricts neural stem cell proliferation and reduces cortical and thalamic size in utero. Surprisingly, a repeat expansion-derived dipeptide repeat protein (DPR) not known to reduce neuronal viability plays a key role in impairing neurodevelopment. Pharmacologically mimicking the effects of the repeat expansion on neurodevelopment increases susceptibility of C9ORF72 mice to motor defects. Thus, the C9ORF72 repeat expansion stunts development of the brain regions prominently affected in C9ORF72 FTD/ALS patients.

SUBMITTER: Hendricks E

PROVIDER: S-EPMC10757587 | biostudies-literature | 2023 Aug

REPOSITORIES: biostudies-literature

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The C9ORF72 repeat expansion alters neurodevelopment.

Hendricks Eric E Quihuis Alicia M AM Hung Shu-Ting ST Chang Jonathan J Dorjsuren Nomongo N Der Balint B Staats Kim A KA Shi Yingxiao Y Sta Maria Naomi S NS Jacobs Russell E RE Ichida Justin K JK

Cell reports 20230816 8

Genetic mutations that cause adult-onset neurodegenerative diseases are often expressed during embryonic stages, but it is unclear whether they alter neurodevelopment and how this might influence disease onset. Here, we show that the most common cause of frontotemporal dementia (FTD) and amyotrophic lateral sclerosis (ALS), a repeat expansion in C9ORF72, restricts neural stem cell proliferation and reduces cortical and thalamic size in utero. Surprisingly, a repeat expansion-derived dipeptide re ...[more]

PMID: 37590144

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The C9ORF72 Repeat Epansion Impairs Neurodevelopment

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2023-08-12 | GSE238005 | GEO

Screening for C9ORF72 repeat expansion in FTLD.

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The C9orf72 repeat expansion disrupts nucleocytoplasmic transport.

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The C9ORF72 Repeat Epansion Impairs Neurodevelopment

Project description:The C9ORF72 Repeat Epansion Impairs Neurodevelopment

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Hippocampal sclerosis dementia with the C9ORF72 hexanucleotide repeat expansion.

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| S-EPMC4087047 | biostudies-literature

C9ORF72 repeat expansion in clinical and neuropathologic frontotemporal dementia cohorts.

Project description:ObjectiveTo determine the frequency of a hexanucleotide repeat expansion in C9ORF72, a gene of unknown function implicated in frontotemporal dementia (FTD) and amyotrophic lateral sclerosis (ALS), in Australian FTD patient cohorts and to examine the clinical and neuropathologic phenotypes associated with this expansion.MethodsWe examined a clinically ascertained FTD cohort (n = 89) and a neuropathologically ascertained cohort of frontotemporal lobar degeneration cases with TDP-43 pathology (FTLD-TDP) (n = 22) for the C9ORF72 hexanucleotide repeat expansion using a repeat primed PCR assay. All expansion-positive patients were genotyped for rs3849942, a surrogate marker for the chromosome 9p21 risk haplotype previously associated with FTD and ALS.ResultsThe C9ORF72 repeat expansion was detected in 10% of patients in the clinically diagnosed cohort, rising to 29% in those with a positive family history of early-onset dementia or ALS. The prevalence of psychotic features was significantly higher in expansion-positive cases (56% vs 14%). In the pathology cohort, 41% of TDP-43-positive cases harbored the repeat expansion, and all exhibited type B pathology. One of the 17 expansion-positive probands was homozygous for the "nonrisk" G allele of rs3849942.ConclusionsThe C9ORF72 repeat expansion is a relatively common cause of FTD in Australian populations, and is especially common in those with FTD-ALS, psychotic features, and a strong family history. Detection of a repeat expansion on the 9p21 putative "nonrisk" haplotype suggests that not all mutation carriers are necessarily descended from a common founder and indicates that the expansion may have occurred on multiple haplotype backgrounds.

| S-EPMC3430710 | biostudies-literature

Homozygosity for the C9orf72 GGGGCC repeat expansion in frontotemporal dementia.

Project description:An expanded hexanucleotide repeat in the C9orf72 gene is the most common genetic cause of frontotemporal dementia and amyotrophic lateral sclerosis (c9FTD/ALS). We now report the first description of a homozygous patient and compare it to a series of heterozygous cases. The patient developed early-onset frontotemporal dementia without additional features. Neuropathological analysis showed c9FTD/ALS characteristics, with abundant p62-positive inclusions in the frontal and temporal cortices, hippocampus and cerebellum, as well as less abundant TDP-43-positive inclusions. Overall, the clinical and pathological features were severe, but did not fall outside the usual disease spectrum. Quantification of C9orf72 transcript levels in post-mortem brain demonstrated expression of all known C9orf72 transcript variants, but at a reduced level. The pathogenic mechanisms by which the hexanucleotide repeat expansion causes disease are unclear and both gain- and loss-of-function mechanisms may play a role. Our data support a gain-of-function mechanism as pure homozygous loss of function would be expected to lead to a more severe, or completely different clinical phenotype to the one described here, which falls within the usual range. Our findings have implications for genetic counselling, highlighting the need to use genetic tests that distinguish C9orf72 homozygosity.

| S-EPMC3753468 | biostudies-literature

C9ORF72 repeat expansion in Australian and Spanish frontotemporal dementia patients.

Project description:A hexanucleotide repeat expansion in C9ORF72 has been established as a common cause of frontotemporal dementia (FTD). However, the minimum repeat number necessary for disease pathogenesis is not known. The aims of our study were to determine the frequency of the C9ORF72 repeat expansion in two FTD patient collections (one Australian and one Spanish, combined n?=?190), to examine C9ORF72 expansion allele length in a subset of FTD patients, and to examine C9ORF72 allele length in 'non-expansion' patients (those with <30 repeats). The C9ORF72 repeat expansion was detected in 5-17% of patients (21-41% of familial FTD patients). For one family, the expansion was present in the proband but absent in the mother, who was diagnosed with dementia at age 68. No association was found between C9ORF72 non-expanded allele length and age of onset and in the Spanish sample mean allele length was shorter in cases than in controls. Southern blotting analysis revealed that one of the nine 'expansion-positive' patients examined, who had neuropathologically confirmed frontotemporal lobar degeneration with TDP-43 pathology, harboured an 'intermediate' allele with a mean size of only ?65 repeats. Our study indicates that the C9ORF72 repeat expansion accounts for a significant proportion of Australian and Spanish FTD cases. However, C9ORF72 allele length does not influence the age at onset of 'non-expansion' FTD patients in the series examined. Expansion of the C9ORF72 allele to as little as ?65 repeats may be sufficient to cause disease.

| S-EPMC3577667 | biostudies-literature

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