No GGGGCC-hexanucleotide repeat expansion in C9ORF72 in parkinsonism patients in Sweden

Abstract

An intronic GGGGCC-hexanucleotide repeat expansion in C9ORF72 was recently identified as a major cause of amyotrophic lateral sclerosis and frontotemporal dementia. Some amyotrophic lateral sclerosis patients have signs of parkinsonism, and many parkinsonism patients develop dementia. In this study we examined if the hexanucleotide repeat expansion was present in parkinsonism patients, to clarify if there could be a relationship between the repeat expansion and disease. We studied the size of the hexanucleotide repeat expansion in a well defined population-based cohort of 135 Parkinson's disease patients and 39 patients with atypical parkinsonism and compared with 645 Swedish control subjects. We found no correlation between Parkinson's disease or atypical parkinsonism and the size of the GGGGCC repeat expansion in C9ORF72. In conclusion, this GGGGCC-repeat expansion in C9ORF72 is not a cause of parkinsonism in the Swedish population.

Key words::

• C9ORF72
• Parkinson's
• disease (PD)
• multiple system atrophy (MSA)
• progressive supranuclear palsy (PSP)
• hexanucleotide repeat expansion

Acknowledgement

We are indebted to the patients and their families for their participation in this project.

This study was supported by the Swedish Brain Research Foundation, Hållsten's Research Foundation, Kempe Foundation, the Swedish Science Council, the Swedish Brain Power Consortium, the Erling-Persson Family Foundation, the Torsten Söderberg Foundation, and the Swedish Association for the Neurologically Disabled.

Declaration of interest: The authors report no conflicts of interest. The authors alone are responsible for the content and writing of the paper.