Phenotypic and genotypic features of patients diagnosed with ALS in the city of Sakarya, Turkey

TBK1 variants in Chinese patients with amyotrophic lateral sclerosis: Genetic analysis and clinical features

BACKGROUND AND PURPOSE

Haploinsufficiency of TANK-binding kinase 1 (TBK1) loss-of-function (LoF) variants has been shown to be pathogenic in amyotrophic lateral sclerosis (ALS) and frontotemporal dementia (FTD). However, the genetic spectrum of TBK1 and clinical features of ALS patients with TBK1 variants remain largely unknown in Asians.

METHODS

Genetic analysis was performed on 2011 Chinese ALS patients. Software was used to predict the deleteriousness of missense variants in TBK1. In addition, PubMed, Embase and Web of Science were searched for related literature.

RESULTS

Twenty-six TBK1 variants were identified in 33 of 2011 ALS patients, including six novel LoF variants (0.3%) and 20 rare missense variants, 12 of which were predicted to be deleterious (0.6%). In addition to TBK1 variants, 11 patients had other ALS-related gene variants. Forty-two previous studies found that the frequency of TBK1 variants was 1.81% in ALS/FTD patients. The frequency of TBK1 LoF variants in ALS was 0.5% (Asians 0.4%; Caucasian 0.6%) and that of missense variants was 0.8% (Asians 1.0%; Caucasian 0.8%). ALS patients with TBK1 LoF variants affecting the kinase domain had a significantly younger age of onset than patients carrying LoF variants affecting the coiled coil domains CCD1 and CCD2. FTD has a frequency of 10% in Caucasian ALS patients with TBK1 LoF variants, which was not found in our cohort.

CONCLUSION

Our study expanded the genotypic spectrum of ALS patients with TBK1 variants and found that the clinical manifestations of TBK1 carriers are diverse.

Multisystem Proteinopathy Due to VCP Mutations: A Review of Clinical Heterogeneity and Genetic Diagnosis

In this work, we review clinical features and genetic diagnosis of diseases caused by mutations in the gene encoding valosin-containing protein (VCP/p97), the functionally diverse AAA-ATPase. VCP is crucial to a multitude of cellular functions including protein quality control, stress granule formation and clearance, and genomic integrity functions, among others. Pathogenic mutations in VCP cause multisystem proteinopathy (VCP-MSP), an autosomal dominant, adult-onset disorder causing dysfunction in several tissue types. It can result in complex neurodegenerative conditions including inclusion body myopathy, frontotemporal dementia, amyotrophic lateral sclerosis, or combinations of these. There is also an association with other neurodegenerative phenotypes such as Alzheimer-type dementia and Parkinsonism. Non-neurological presentations include Paget disease of bone and may also include cardiac dysfunction. We provide a detailed discussion of genotype-phenotype correlations, recommendations for genetic diagnosis, and genetic counselling implications of VCP-MSP.

Phenotype of VCP Mutations in Chinese Amyotrophic Lateral Sclerosis Patients

Mutations in the valosin-containing protein (VCP) gene have been linked to amyotrophic lateral sclerosis (ALS) in the Caucasian populations. However, the phenotype of VCP mutations in Chinese patients with (ALS) remains unclear. Targeted next-generation sequencing covered 28 ALS-related genes including the VCP gene was undertaken to screen in a Chinese cohort of 275 sporadic ALS cases and 15 familial ALS pedigrees. An extensive literature review was performed to identify all patients with ALS carrying VCP mutations previously reported. The clinical characteristics and genetic features of ALS patients with VCP mutations were reviewed. One known p.R155C mutation in the VCP gene was detected in two siblings from a familial ALS pedigree and two sporadic individuals. In addition, the same VCP p.R155C mutation was detected in an additional patient with ALS referred in 2021. Three patients with VCP p.R155C mutation presented with muscular weakness starting from proximal extremities to distal extremities. The other patient developed a phenotype of Paget's disease of bone in addition to the progressive muscular atrophy. We reported the first VCP mutation carrier manifesting ALS with Paget's disease of bone in the Chinese population. Our findings expand the phenotypic spectrum of the VCP mutations in Chinese patients with ALS and suggest that ALS patients with VCP p.R155C mutations tend to present with relatively young onset, symmetrical involvement of proximal muscles weakness of arms or legs, and then progressed to distal muscles of limbs.

An autopsy report of a familial amyotrophic lateral sclerosis case carrying VCP Arg487His mutation with a unique TDP-43 proteinopathy

We here report an autopsy case of familial amyotrophic lateral sclerosis (ALS) with p.Arg487His mutation in the valosin-containing protein (VCP) gene (VCP), in which upper motor neurons (UMNs) were predominantly involved. Moreover, our patient developed symptoms of frontotemporal dementia later in life and pathologically exhibited numerous phosphorylated transactivation response DNA-binding protein of 43 kDa (p-TDP-43)-positive neuronal cytoplasmic inclusions and short dystrophic neurites with a few lentiform neuronal intranuclear inclusions, sharing the features of frontotemporal lobar degeneration with TDP-43 pathology type A pattern. A review of previous reports of ALS with VCP mutations suggests that our case is unique in terms of its UMN-predominant lesion pattern and distribution of p-TDP-43 pathology. Thus, this case report effectively expands the clinical and pathological phenotype of ALS in patients with a VCP mutation.