CHCHD10 Pro34Ser is not a highly penetrant pathogenic variant for amyotrophic lateral sclerosis and frontotemporal dementia

Meta-analysis of the association between CHCHD10 Pro34Ser variant and the risk of amyotrophic lateral sclerosis

BACKGROUND

Amyotrophic lateral sclerosis (ALS), one of the motor neuron diseases, appears to be caused by genetic and environmental risk factors. However, the influence of Pro34Ser variant of CHCHD10 gene in increasing risk of ALS remains indeterminate. This study conducted a meta-analysis to establish the association between Pro34Ser variant of CHCHD10 gene and risk of ALS.

METHODS

PubMed, Web of Science, and Embase databases were systematically searched for genome-wide association studies or case-control studies published up to March 28, 2020, on the association between Pro34Ser variant and risk of ALS. Data from eligible studies were extracted and analyzed.

RESULTS

Twelve case-control studies involving 7442 patients with sporadic ALS and 75,371 controls were analyzed. The Pro34Ser variant was not associated with increased risk of ALS disease based on fixed-effects meta-analysis (Pro34Ser-positive vs Pro34Ser-negative: OR 1.23, 95% CI 0.90 to 1.69, P = 0.201).

CONCLUSION

Existing evidence suggests that Pro34Ser variant in CHCHD10 is not associated with risk of ALS, particularly in Caucasian participants. However, our results ought to be validated using large, well-designed studies, especially in Asian and African populations.

CHCHD10 variants in amyotrophic lateral sclerosis: Where is the evidence?

OBJECTIVE

After the initial report of a CHCHD10 mutation in mitochondrial disease with features resembling amyotrophic lateral sclerosis (ALS), CHCHD10 mutations have been considered to be a frequent cause for ALS. However, the exact pathogenicity and clinical significance of these mutations remain unclear. Here, we aimed to determine the role of CHCHD10 mutations in ALS.

METHODS

We analyzed 4,365 whole genome sequenced ALS patients and 1,832 controls from 7 different countries and examined all nonsynonymous single nucleotide variants in CHCHD10. These were tested for association with ALS, independently and in aggregate using several genetic burden tests (including sequence kernel association test [SKAT], optimal unified test [SKAT-O], and Firth logistic regression).

RESULTS

We identified 3 new variants in cases, but only 1 was ALS-specific. Also, 1 control-specific mutation was identified. There was no increased burden of rare coding mutations among ALS patients compared to controls (p = 0.86, p = 0.86, and p = 0.88 for SKAT, SKAT-O, and Firth, respectively). The few carriers with potential pathogenic CHCHD10 mutations exhibited a slowly progressive ALS-like phenotype with atypical features such as myopathy and deafness.

INTERPRETATION

CHCHD10 mutations seem to be a far less prevalent cause of pure ALS than previously suggested, and instead appear related to more complex phenotypes. There appears to be insufficient evidence for the pathogenicity of most previously reported variants in pure ALS. This study shows that routine testing for CHCHD10 mutations in pure ALS is not recommended and illustrates the importance of sufficient genetic and functional evidence in establishing pathogenicity of genetic variants. Ann Neurol 2018;83:110-116.

New ALS-Related Genes Expand the Spectrum Paradigm of Amyotrophic Lateral Sclerosis

Amyotrophic Lateral Sclerosis (ALS) is characterized by the degeneration of upper and lower motor neurons. Clinical heterogeneity is a well-recognized feature of the disease as age of onset, site of onset and the duration of the disease can vary greatly among patients. A number of genes have been identified and associated to familial and sporadic forms of ALS but the majority of cases remains still unexplained. Recent breakthrough discoveries have demonstrated that clinical manifestations associated with ALS-related genes are not circumscribed to motor neurons involvement. In this view, ALS appears to be linked to different conditions over a continuum or spectrum in which overlapping phenotypes may be identified. In this review, we aim to examine the increasing number of spectra, including ALS/Frontotemporal Dementia and ALS/Myopathies spectra. Considering all these neurodegenerative disorders as different phenotypes of the same spectrum can help to identify common pathological pathways and consequently new therapeutic targets in these incurable diseases.

ALS: Recent Developments from Genetics Studies

Amyotrophic lateral sclerosis (ALS) is a fatal disorder that is characterized by a progressive degeneration of the upper and lower motor neurons. Most cases appear to be sporadic, but 5-10 % of cases have a family history of the disease. High-throughput DNA sequencing and related genomic capture tools are methodological advances which have rapidly contributed to an acceleration in the discovery of genetic risk factors for both familial and sporadic ALS. It is interesting to note that as the number of ALS genes grows, many of the proteins they encode are in shared intracellular processes. This review will summarize some of the recent advances and gene discovery made in ALS.

Identification of CHCHD10 Mutation in Chinese Patients with Alzheimer Disease

CHCHD10 gene has been identified to be associated with frontotemporal dementia (FTD) and amyotrophic lateral sclerosis (ALS). Considering the clinical phenotype and pathology characterization were overlapped between FTD and Alzheimer disease (AD), and so far, no systematic analysis of CHCHD10 mutation was conducted in patients with AD in Asian population. Therefore, we screened of all exons in CHCHD10 in a cohort of 484 AD patients (60 with family history) from Mainland China. A heterozygous variant p.A35D (c.104C>A), previously reported in a patient with FTD in Italian population, was identified in a female patient with sporadic LOAD. The age at onset of mutation carrier was 86, presented as typical amnestic dementia. The mutation was found to be deleterious according to in silico predictions and excluded in 500 ethnically and geographically matched controls. Our finding revealed the clinical manifestations of variant p.A35D (c.104C>A) in a LOAD case and indicated that CHCHD10 mutation was presented in different types of dementia.