ABSTRACT
BACKGROUND: Different loss-of-function mutations were identified underlying PGRN haploinsufficiency in patients with frontotemporal lobar degeneration. PGRN mutations were also identified in other neurodegenerative brain diseases such as amyotrophic lateral sclerosis and Alzheimer disease, though their biologic contribution to these diseases remains elusive. Because of its apparent role in neuronal survival, we argued that PGRN might also contribute to Parkinson disease (PD) pathogenesis. METHODS: We screened PGRN exons for mutations in 255 patients with PD and 459 control individuals by direct genomic sequencing. Genetic association of PGRN with risk for PD was assessed using single nucleotide polymorphisms (SNPs) across the gene. RESULTS: In patients we identified four missense mutations of which p.Asp33Glu and p.Arg514Met were absent in control individuals. Single SNP and haplotype analyses did not detect significant associations with PD. CONCLUSIONS: Our results do not support a major role for PGRN in the genetic etiology of Parkinson disease (PD). At this stage and in the absence of functional data, it remains unclear whether p.Asp33Glu and p.Arg514Met are biologically relevant to PD pathogenesis in the mutation carriers.
Subject(s)
Genetic Variation , Intercellular Signaling Peptides and Proteins/genetics , Mutation, Missense , Parkinson Disease/genetics , Polymorphism, Single Nucleotide , Aged , Amino Acid Sequence , Female , Genetic Predisposition to Disease/epidemiology , Humans , Male , Middle Aged , Molecular Sequence Data , Parkinson Disease/epidemiology , Progranulins , Retrospective Studies , Risk FactorsABSTRACT
OBJECTIVE: Leucine-rich repeat kinase 2 (LRRK2) mutations are the most common cause of Parkinson disease (PD). Several dominantly inherited pathogenic substitutions have been identified in different domains of the Lrrk2 protein. Herein, we characterize the clinical and genetic features associated with Lrrk2 p.R1441C. METHODS: We identified 33 affected and 15 unaffected LRRK2 c.4321C>T (p.R1441C) mutation carriers through an international consortium originating from three continents. The age-specific cumulative incidence of PD was calculated by Kaplan-Meier analysis. RESULTS: The clinical presentation of Lrrk2 p.R1441C carriers was similar to sporadic PD and Lrrk2 p.G2019S parkinsonism. The mean age at onset for parkinsonism was 60 years, range 30-79 years; fewer than 20% of the patients had symptoms before the age 50 years, while by 75 years >90% of them had developed symptoms. Haplotype analysis suggests four independent founders for the p.R1441C mutation. CONCLUSIONS: The distribution in age at onset and clinical features in Lrrk2 p.R1441C patients are similar to idiopathic and Lrrk2 p.G2019S parkinsonism. Several independent founders of the p.R1441C substitution suggest this site is prone to recurrent mutagenesis.
