ABSTRACT
A hexanucleotide expansion in chromosome 9 open-reading frame 72 (C9ORF72) has been found to be a major cause of frontotemporal lobar degeneration (FTLD). We describe a 20-year follow-up of a unique case with very slowly progressive FTLD caused by the C9ORF72 repeat expansion. In serial neuropsychological examinations, the patient's cognitive decline was exceptionally slow and after 20 years the patient still was mainly independent in activities of daily living. Our case indicates that there is great individual variation in the progression and duration of C9ORF72-associated FTLD, and also language variants or mixed phenotypes may be present.
Subject(s)
Frontotemporal Lobar Degeneration/genetics , Proteins/genetics , C9orf72 Protein , DNA Repeat Expansion , Disease Progression , Fluorodeoxyglucose F18 , Follow-Up Studies , Frontotemporal Lobar Degeneration/diagnostic imaging , Frontotemporal Lobar Degeneration/pathology , Humans , Magnetic Resonance Imaging , Male , Middle Aged , Positron-Emission TomographyABSTRACT
BACKGROUND: Frontotemporal lobar degeneration (FTLD) is a genetically complex disorder. The majority of mutations linked to FTLD families are found in the microtubule-associated protein tau (MAPT) and progranulin (PGRN) genes. Mutations in the chromatin-modifying protein 2B gene (CHMP2B) have been identified in a few families. However, CHMP2B has been showed to be a rare cause of FTLD. Our aim was to determine the frequency of CHMP2B mutations in a clinical series of patients with FTLD in Northern Finland. PATIENTS AND METHODS: We examined 72 (36 men) Finnish patients with FTLD. The mean age at onset was 58.9 (range 4380). Symptoms of motor neuron disease (FTLDMND) were present in 12 patients (17%). Positive family history was detected in 28% of the patients. Mutations in MAPT and PGRN were excluded from these patients. All exons and exonintron boundaries of the CHMP2B gene were sequenced. RESULTS: No pathogenic CHMP2B mutations were found. A rare polymorphism in the non-coding region of exon 1 (rs36098294) and three other previously reported polymorphisms were detected. CONCLUSIONS: Our results confirm that mutations in CHMP2B are not a common cause of FTLD. MAPT and PGRN mutations are also rare in Finnish population, suggesting that other, still unknown genetic factors may play a role in the pathogenesis of FTLD in Finnish population.
Subject(s)
Endosomal Sorting Complexes Required for Transport/genetics , Frontotemporal Lobar Degeneration/etiology , Frontotemporal Lobar Degeneration/genetics , Mutation/genetics , Nerve Tissue Proteins/genetics , Adult , Aged , Aged, 80 and over , Case-Control Studies , DNA Mutational Analysis/methods , Female , Finland , Humans , Male , Middle Aged , Polymorphism, Genetic/geneticsABSTRACT
BACKGROUND AND PURPOSE: Mutations in the progranulin (PGRN) gene have recently been associated with frontotemporal lobar degeneration (FTLD). The frequency of these mutations varies between populations. The aim of this study was to determine mutations and genetic variations of the PGRN gene in Finnish patients with FTLD and FTLD with associated motor neuron disease (FTLD-MND). SUBJECTS AND METHODS: All exons of the PGRN gene were sequenced from 69 Finnish patients with FTLD. The FTLD-MND phenotype was present in 13 of the 69 patients. RESULTS: No pathogenic PGRN mutations were identified in the cohort. Eleven sequence variations were detected, of which IVS8 + 15C>T, IVS4-51_-52insAGTC and IVS11 + 25G>A have not been reported previously. At least one single-nucleotide polymorphism (SNP) of PGRN was detected in 83% of patients. CONCLUSIONS: We conclude that mutations in PGRN are rare among Finnish patients with FTLD and FTLD-MND. However, SNPs were frequent suggesting high genetic variability of the PGRN gene.
