CHCHD10 Mutations Research Articles

Mutational analysis of TBK1 in Taiwanese patients with amyotrophic lateral sclerosis

Mutations in the TBK1 gene were just recently identified to cause amyotrophic lateral sclerosis (ALS), and their role in ALS in various populations remains unclear. The aim of this study was to determine the frequency and spectrum of mutations in TBK1 in a Taiwanese ALS cohort of Han Chinese origin. Mutational analyses of TBK1 were carried out by direct nucleotide sequencing in a cohort of 207 unrelated patients with ALS. Among them, the genetic diagnoses of 168 patients remained elusive after mutations in SOD1, C9ORF72, TARDBP, FUS, ATXN2, OPTN, VCP, UBQLN2, SQSTM1, PFN1, HNRNPA1, HNRNPA2B1, MATR3, CHCHD10, and TUBA4A had been excluded. We identified one nonsense mutation, p.R444X (c.1330C>T), in one patient with apparently sporadic ALS-frontotemporal dementia. In vitro functional study demonstrated the p.R444X mutation resulting in a truncated TANK-binding kinase 1 (TBK1) protein product, low protein expression, and loss of kinase function and interaction with optineurin. The frequency of TBK1 mutations in ALS patients in Taiwan is, therefore, approximately 0.5% (1/207). This study reports a novel TBK1 mutation and stresses on the importance to consider TBK1 mutation as a possible etiology of ALS.

CHCHD10 mutations promote loss of mitochondrial cristae junctions with impaired mitochondrial genome maintenance and inhibition of apoptosis.

CHCHD10-related diseases include mitochondrial DNA instability disorder, frontotemporal dementia-amyotrophic lateral sclerosis (FTD-ALS) clinical spectrum, late-onset spinal motor neuropathy (SMAJ), and Charcot-Marie-Tooth disease type 2 (CMT2). Here, we show that CHCHD10 resides with mitofilin, CHCHD3 and CHCHD6 within the "mitochondrial contact site and cristae organizing system" (MICOS) complex. CHCHD10 mutations lead to MICOS complex disassembly and loss of mitochondrial cristae with a decrease in nucleoid number and nucleoid disorganization. Repair of the mitochondrial genome after oxidative stress is impaired in CHCHD10 mutant fibroblasts and this likely explains the accumulation of deleted mtDNA molecules in patient muscle. CHCHD10 mutant fibroblasts are not defective in the delivery of mitochondria to lysosomes suggesting that impaired mitophagy does not contribute to mtDNA instability. Interestingly, the expression of CHCHD10 mutant alleles inhibits apoptosis by preventing cytochromec release.

Lack of CHCHD2 mutations in Parkinson's disease in a Taiwanese population

A recent study identified a missense mutation in coiled-coil-helix-coiled-coil-helix domain–containing 2 (CHCHD2) gene, p.Thr61Ile, in a Japanese multigenerational family with autosomal dominant Parkinson's disease (PD). Subsequent analyses identified several genetic variants in this gene that contributed to increased risk of sporadic PD, making CHCHD2 a novel candidate gene associated with PD. However, independent studies are warranted to confirm the role of CHCHD2 in PD. Among 1433 participated subjects, we sequenced all exons and exon-intron boundaries of CHCHD2 from 137 probands with familial PD and 129 age/sex-matched controls. An additional 586 sporadic PD patients and another 581 independent controls were later screened to validate possible risk substitutions. We found no CHCHD2 mutations, but we observed 5 genetic variants, including p.Pro2Leu (rs142444896), a risk variant for sporadic PD in Japanese populations. However, we did not find any significant associations between p.Pro2Leu (rs142444896) and risk of PD in our study cohort (0.86% vs. 1.20%, p = 0.20). Our data suggest that genetic variants of CHCHD2 do not play a major role in our Taiwanese PD population.

CHCHD2 gene mutations in familial and sporadic Parkinson's disease

Mutations in CHCHD2 gene have been reported in autosomal dominant Parkinson's disease (ADPD). However, there is still lack of evidence supported CHCHD2 mutations lead to ADPD in other populations. We performed whole exome sequencing, positron emission tomography (PET), and haplotype analyses in an ADPD pedigree and then comprehensively screened for CHCHD2 gene mutations in additional 18 familial parkinsonism pedigrees, 364 sporadic PD patients, and 384 healthy controls to assess the frequencies of known and novel rare nonsynonymous CHCHD2 mutations. We identified a heterozygous variant (c.182C>T; p.Thr61Ile) in the CHCHD2 gene in the ADPD pedigree. PET revealed a significant reduction in dopamine transporter binding in the putamen and caudate nucleus of the proband, similar to idiopathic PD. The single nucleotide variant 5C>T (Pro2Leu) in CHCHD2 was confirmed to have a significantly higher frequency among sporadic PD patients than controls. Our results confirm that ADPD can be caused by CHCHD2 mutations and show that the Pro2Leu variant in CHCHD2 may be a risk factor for sporadic PD in Chinese populations.

Mutation analysis of CHCHD2 in Canadian patients with familial Parkinson's disease

Recently, several CHCHD2 mutations were reported to be associated with autosomal dominant Parkinson's disease (PD) in a Japanese population. However, an association between CHCHD2 and PD was not observed in 2 Caucasian data sets. The present study searched for CHCHD2 coding variants in Canadian PD patients. Sanger sequencing of all CHCHD2 exons revealed no coding mutations in 155 familial cases. Moreover, 3 coding CHCHD2 polymorphisms available on the NeuroX array (Pro2Leu, Pro14Ser, and Ile118Met) were homozygous for the major allele in an additional 85 PD patients. Our study suggests that CHCHD2 mutations may not account for PD in Canadian patients.

G.P.128 - Occurrence of CHCHD10 mutations in Finnish patients with motor neuron disorder

G.P.128 - Occurrence of CHCHD10 mutations in Finnish patients with motor neuron disorder

Mutation analysis of CHCHD2 gene in Chinese familial Parkinson's disease

Funayama et al. recently identified mutations in the CHCHD2 gene in Japanese families with autosomal dominant Parkinson's disease, increasing our knowledge about the monogenic cause of this disorder. However, there is no report regarding the association between CHCHD2 and Parkinson's disease (PD) in the Chinese Han population. The aim of this study was to obtain the prevalence of CHCHD2 mutations in Chinese familial PD. Genetic analysis of mutations in CHCHD2 gene was conducted in a cohort of 92 families with autosomal dominant Parkinson's disease from mainland China. No mutations in CHCHD2 gene were identified, suggesting that CHCHD2 mutations might not be a common cause of PD in Chinese familial cases.

The CHCHD10 P34S variant is not associated with ALS in a UK cohort of familial and sporadic patients

Mutations in CHCHD10 have recently been reported as a cause of amyotrophic lateral sclerosis (ALS) and frontotemporal dementia. To address the genetic contribution of CHCHD10 to ALS, we have screened a cohort of 425 UK ALS ± frontotemporal dementia patients and 576 local controls in all coding exons of CHCHD10 by Sanger sequencing. We identified a previously reported p.P34S variant that is also present in neurologically healthy controls (p = 0.58). Our results suggest that CHCHD10 is not a primary cause of ALS in UK cases.

A new gene for Parkinson's disease: should we care?

Over the past two decades, several genetic causes of and risk factors for Parkinson's disease have emerged. In The Lancet Neurology, Manabu Funayama and colleagues 1 Funayama M Ohe K Amo T et al. CHCHD2 mutations in autosomal dominant late-onset Parkinson's disease: a genome-wide linkage and sequencing study. Lancet Neurol. 2015; 14: 274-282 Summary Full Text Full Text PDF PubMed Scopus (207) Google Scholar describe a series of experiments that they argue nominate CHCHD2 mutations as a novel cause of Parkinson's disease. They studied a large multigenerational family with an apparent autosomal dominant form of Parkinson's disease. Through the use of linkage and a combination of whole-exome and whole-genome sequencing, they nominated a mutation (Thr61Ile) within CHCHD2 as the cause of disease. After this initial finding, Funayama and colleagues then screened a large series of patients with familial (n=341) or sporadic (n=517) Parkinson's disease, and a series of controls (n=559). They identified three additional families with CHCHD2 mutations: a family with the same Thr61Ile mutation, a family with an Arg145Gln mutation, and a family with a splice-site mutation (300+5G>A). The two families with the same mutation seem to be unrelated, and the initial genetic evidence suggests that this mutation arose independently in each family.

CHCHD2 mutations in autosomal dominant late-onset Parkinson's disease: a genome-wide linkage and sequencing study

Identification of causative genes in mendelian forms of Parkinson's disease is valuable for understanding the cause of the disease. We did genetic studies in a Japanese family with autosomal dominant Parkinson's disease to identify novel causative genes. We did a genome-wide linkage analysis on eight affected and five unaffected individuals from a family with autosomal dominant Parkinson's disease (family A). Subsequently, we did exome sequencing on three patients and whole-genome sequencing on one patient in family A. Variants were validated by Sanger sequencing in samples from patients with autosomal dominant Parkinson's disease, patients with sporadic Parkinson's disease, and controls. Participants were identified from the DNA bank of the Comprehensive Genetic Study on Parkinson's Disease and Related Disorders (Juntendo University School of Medicine, Tokyo, Japan) and were classified according to clinical information obtained by neurologists. Splicing abnormalities of CHCHD2 mutants were analysed in SH-SY5Y cells. We used the Fisher's exact test to calculate the significance of allele frequencies between patients with sporadic Parkinson's disease and unaffected controls, and we calculated odds ratios and 95% CIs of minor alleles. We identified a missense mutation (CHCHD2, 182C>T, Thr61Ile) in family A by next-generation sequencing. We obtained samples from a further 340 index patients with autosomal dominant Parkinson's disease, 517 patients with sporadic Parkinson's disease, and 559 controls. Three CHCHD2 mutations in four of 341 index cases from independent families with autosomal dominant Parkinson's disease were detected by CHCHD2 mutation screening: 182C>T (Thr61Ile), 434G>A (Arg145Gln), and 300+5G>A. Two single nucleotide variants (-9T>G and 5C>T) in CHCHD2 were confirmed to have different frequencies between sporadic Parkinson's disease and controls, with odds ratios of 2·51 (95% CI 1·48-4·24; p=0·0004) and 4·69 (1·59-13·83, p=0·0025), respectively. One single nucleotide polymorphism (rs816411) was found in CHCHD2 from a previously reported genome-wide association study; however, there was no significant difference in its frequency between patients with Parkinson's disease and controls in a previously reported genome-wide association study (odds ratio 1·17, 95% CI 0·96-1·19; p=0·22). In SH-SY5Y cells, the 300+5G>A mutation but not the other two mutations caused exon 2 skipping. CHCHD2 mutations are associated with, and might be a cause of, autosomal dominant Parkinson's disease. Further genetic studies in other populations are needed to confirm the pathogenicity of CHCHD2 mutations in autosomal dominant Parkinson's disease and susceptibility for sporadic Parkinson's disease, and further functional studies are needed to understand how mutant CHCHD2 might play a part in the pathophysiology of Parkinson's disease. Japan Society for the Promotion of Science; Japanese Ministry of Education, Culture, Sports, Science and Technology; Japanese Ministry of Health, Labour and Welfare; Takeda Scientific Foundation; Cell Science Research Foundation; and Nakajima Foundation.

CHCH10 mutations in an Italian cohort of familial and sporadic amyotrophic lateral sclerosis patients

Mutations in CHCHD10 have recently been described as a cause of frontotemporal dementia (FTD) comorbid with amyotrophic lateral sclerosis (ALS). The aim of this study was to assess the frequency and clinical characteristics of CHCHD10 mutations in Italian patients diagnosed with familial (n = 64) and apparently sporadic ALS (n = 224). Three apparently sporadic patients were found to carry c.100C>T (p.Pro34Ser) heterozygous variant in the exon 2 of CHCHD10. This mutation had been previously described in 2 unrelated French patients with FTD-ALS. However, our patients had a typical ALS, without evidence of FTD, cerebellar or extrapyramidal signs, or sensorineural deficits. We confirm that CHCHD10 mutations account for ∼1% of Italian ALS patients and are a cause of disease in subjects without dementia or other atypical clinical signs.

Mutation in the novel nuclear-encoded mitochondrial protein CHCHD10 in a family with autosomal dominant mitochondrial myopathy.

Mitochondrial myopathies belong to a larger group of systemic diseases caused by morphological or biochemical abnormalities of mitochondria. Mitochondrial disorders can be caused by mutations in either the mitochondrial or nuclear genome. Only 5% of all mitochondrial disorders are autosomal dominant. We analyzed DNA from members of the previously reported Puerto Rican kindred with an autosomal dominant mitochondrial myopathy (Heimann-Patterson et al. 1997). Linkage analysis suggested a putative locus on the pericentric region of the long arm of chromosome 22 (22q11). Using the tools of integrative genomics, we established chromosome 22 open reading frame 16 (C22orf16) (later designated as CHCHD10) as the only high-scoring mitochondrial candidate gene in our minimal candidate region. Sequence analysis revealed a double-missense mutation (R15S and G58R) in cis in CHCHD10 which encodes a coiled coil-helix-coiled coil-helix protein of unknown function. These two mutations completely co-segregated with the disease phenotype and were absent in 1,481 Caucasian and 80 Hispanic (including 32 Puerto Rican) controls. Expression profiling showed that CHCHD10 is enriched in skeletal muscle. Mitochondrial localization of the CHCHD10 protein was confirmed using immunofluorescence in cells expressing either wild-type or mutant CHCHD10. We found that the expression of the G58R, but not the R15S, mutation induced mitochondrial fragmentation. Our findings identify a novel gene causing mitochondrial myopathy, thereby expanding the spectrum of mitochondrial myopathies caused by nuclear genes. Our findings also suggest a role for CHCHD10 in the morphologic remodeling of the mitochondria.

Screening of CHCHD10 in a French cohort confirms the involvement of this gene in frontotemporal dementia with amyotrophic lateral sclerosis patients

Mutations in the CHCHD10 gene have been recently identified in a large family with a complex phenotype variably associating frontotemporal dementia (FTD) with amyotrophic lateral sclerosis (ALS), cerebellar ataxia, myopathy, and hearing impairment. CHCHD10 encodes a protein located in the mitochondrial intermembrane space and is likely involved in mitochondrial genome stability and maintenance of cristae junctions. However, the exact contribution of CHCHD10 in FTD and ALS diseases spectrum remains unknown. In this study, we evaluated the frequency of CHCHD10 mutations in 115 patients with FTD and FTD-ALS phenotypes. We identified 2 heterozygous variants in 3 unrelated probands presenting FTD and ALS, characterized by early and predominant bulbar symptoms. This study demonstrates the implication of CHCHD10 in FTD and ALS spectrum. Although the frequency of mutations is low in this series (2.6%), our work suggests that CHCHD10 mutations should be searched particularly when bulbar symptoms are present at onset.