Clinical Evidence of Disease Anticipation in Families Segregating a C9orf72 Repeat Expansion.

Importance: Patients carrying a C9orf72 repeat expansion leading to frontotemporal dementia and/or amyotrophic lateral sclerosis have highly variable ages at onset of disease, suggesting the presence of modifying factors.

Objective: To provide clinical-based evidence for disease anticipation in families carrying a C9orf72 repeat expansion by analyzing age at onset, disease duration, and age at death in successive generations.

Design, Setting, And Participants: This cohort study was performed from June 16, 2000, to June 1, 2016, in 36 extended Belgian families in which a C9orf72 repeat expansion was segregating.

Mutations in glucocerebrosidase are a major genetic risk factor for Parkinson's disease and increase susceptibility to dementia in a Flanders-Belgian cohort.

Objective: To investigate the frequency of glucocerebrosidase (GBA) mutations in a Flanders-Belgian Parkinson's disease (PD) patient cohort and to assess genotype-phenotype correlations.

Methods: We performed an in-depth sequencing of all coding exons of GBA in 266 clinically well-characterized PD patients and 536 healthy control individuals.

Results: We identified rare, heterozygous GBA mutations in 12 PD patients (4.

Phenotypic characteristics of Alzheimer patients carrying an ABCA7 mutation.

Objective: To generate a clinical and pathologic phenotype of patients carrying rare loss-of-function mutations in ABCA7, identified in a Belgian Alzheimer patient cohort and in an autosomal dominant family.

Methods: We performed a retrospective review of available data records, medical records, results of CSF analyses and neuroimaging studies, and neuropathology data.

Results: The mean onset age of the mutation carriers (n = 22) was 73.

Clinical features of TBK1 carriers compared with C9orf72, GRN and non-mutation carriers in a Belgian cohort.

We identified in a cohort of patients with frontotemporal dementia (n = 481) or amyotrophic lateral sclerosis (n = 147), 10 index patients carrying a TBK1 loss of function mutation reducing TBK1 expression by 50%. Here, we describe the clinical and pathological characteristics of the 10 index patients and six of their affected relatives carrying a TBK1 mutation. Six TBK1 carriers were diagnosed with frontotemporal dementia, seven with amyotrophic lateral sclerosis, one with both clinical phenotypes and two with dementia unspecified.

Loss of TBK1 is a frequent cause of frontotemporal dementia in a Belgian cohort.

Objective: To assess the genetic contribution of TBK1, a gene implicated in amyotrophic lateral sclerosis (ALS), frontotemporal dementia (FTD), and FTD-ALS, in Belgian FTD and ALS patient cohorts containing a significant part of genetically unresolved patients.

Methods: We sequenced TBK1 in a hospital-based cohort of 482 unrelated patients with FTD and FTD-ALS and 147 patients with ALS and an extended Belgian FTD-ALS family DR158. We followed up mutation carriers by segregation studies, transcript and protein expression analysis, and immunohistochemistry.