Journal Article

REEP1 mutation spectrum and genotype/phenotype correlation in hereditary spastic paraplegia type 31

Christian Beetz, Rebecca Schüle, Tine Deconinck, Khanh-Nhat Tran-Viet, Hui Zhu, Berry P.H. Kremer, Suzanna G.M. Frints, Wendy A.G. van Zelst-Stams, Paula Byrne, Susanne Otto, Anders O.H. Nygren, Jonathan Baets, Katrien Smets, Berten Ceulemans, Bernard Dan, Narasimhan Nagan, Jan Kassubek, Sven Klimpe, Thomas Klopstock, Henning Stolze, Hubert J.M. Smeets, Constance T.R.M. Schrander-Stumpel, Michael Hutchinson, Bart P. van de Warrenburg, Corey Braastad, Thomas Deufel, Margaret Pericak-Vance, Ludger Schöls, Peter de Jonghe and Stephan Züchner

in Brain

Published on behalf of The Guarantors of Brain

Volume 131, issue 4, pages 1078-1086
Published in print April 2008 | ISSN: 0006-8950
Published online March 2008 | e-ISSN: 1460-2156 | DOI: http://dx.doi.org/10.1093/brain/awn026
REEP1 mutation spectrum and genotype/phenotype correlation in hereditary spastic paraplegia type 31

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Mutations in the receptor expression enhancing protein 1 (REEP1) have recently been reported to cause autosomal dominant hereditary spastic paraplegia (HSP) type SPG31. In a large collaborative effort, we screened a sample of 535 unrelated HSP patients for REEP1 mutations and copy number variations. We identified 13 novel and 2 known REEP1 mutations in 16 familial and sporadic patients by direct sequencing analysis. Twelve out of 16 mutations were small insertions, deletions or splice site mutations. These changes would result in shifts of the open-reading-frame followed by premature termination of translation and haploinsufficiency. Interestingly, we identified two disease associated variations in the 3′-UTR of REEP1 that fell into highly conserved micro RNA binding sites. Copy number variation analysis in a subset of 133 HSP index patients revealed a large duplication of REEP1 that involved exons 2–7 in an Irish family. Clinically most SPG31 patients present with a pure spastic paraplegia; rare complicating features were restricted to symptoms or signs of peripheral nerve involvement. Interestingly, the distribution of age at onset suggested a bimodal pattern with the appearance of initial symptoms of disease either before the age of 20 years or after the age of 30 years. The overall mutation rate in our clinically heterogeneous sample was 3.0%; however, in the sub-sample of pure HSP REEP1 mutations accounted for 8.2% of all patients. These results firmly establish REEP1 as a relatively frequent autosomal dominant HSP gene for which genetic testing is warranted. We also establish haploinsufficiency as the main molecular genetic mechanism in SPG31, which should initiate and guide functional studies on REEP1 with a focus on loss-of-function mechanisms. Our results should be valid as a reference for mutation frequency, spectrum of REEP1 mutations, and clinical phenotypes associated with SPG31.

Keywords: hereditary spastic paraplegia; SPG31; REEP1; haploinsufficiency; micro RNA

Journal Article.  4527 words.  Illustrated.

Subjects: Neurology ; Neuroscience

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