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Acta Neuropathologica

, Volume 130, Issue 6, pp 863–876 | Cite as

Novel clinical associations with specific C9ORF72 transcripts in patients with repeat expansions in C9ORF72

  • Marka van Blitterswijk
  • Tania F. Gendron
  • Matthew C. Baker
  • Mariely DeJesus-Hernandez
  • NiCole A. Finch
  • Patricia H. Brown
  • Lillian M. Daughrity
  • Melissa E. Murray
  • Michael G. Heckman
  • Jie Jiang
  • Clotilde Lagier-Tourenne
  • Dieter Edbauer
  • Don W. Cleveland
  • Keith A. Josephs
  • Joseph E. Parisi
  • David S. Knopman
  • Ronald C. Petersen
  • Leonard Petrucelli
  • Bradley F. Boeve
  • Neill R. Graff-Radford
  • Kevin B. Boylan
  • Dennis W. Dickson
  • Rosa RademakersEmail author
Original Paper

Abstract

The loss of chromosome 9 open reading frame 72 (C9ORF72) expression, associated with C9ORF72 repeat expansions, has not been examined systematically. Three C9ORF72 transcript variants have been described thus far; the GGGGCC repeat is located between two non-coding exons (exon 1a and exon 1b) in the promoter region of transcript variant 2 (NM_018325.4) or in the first intron of variant 1 (NM_145005.6) and variant 3 (NM_001256054.2). We studied C9ORF72 expression in expansion carriers (n = 56) for whom cerebellum and/or frontal cortex was available. Using quantitative real-time PCR and digital molecular barcoding techniques, we assessed total C9ORF72 transcripts, variant 1, variant 2, variant 3, and intron containing transcripts [upstream of the expansion (intron 1a) and downstream of the expansion (intron 1b)]; the latter were correlated with levels of poly(GP) and poly(GA) proteins aberrantly translated from the expansion as measured by immunoassay (n = 50). We detected a decrease in expansion carriers as compared to controls for total C9ORF72 transcripts, variant 1, and variant 2: the strongest association was observed for variant 2 (quantitative real-time PCR cerebellum: median 43 %, p = 1.26e-06, and frontal cortex: median 58 %, p = 1.11e-05; digital molecular barcoding cerebellum: median 31 %, p = 5.23e-10, and frontal cortex: median 53 %, p = 5.07e-10). Importantly, we revealed that variant 1 levels greater than the 25th percentile conferred a survival advantage [digital molecular barcoding cerebellum: hazard ratio (HR) 0.31, p = 0.003, and frontal cortex: HR 0.23, p = 0.0001]. When focusing on intron containing transcripts, analysis of the frontal cortex revealed an increase of potentially truncated transcripts in expansion carriers as compared to controls [digital molecular barcoding frontal cortex (intron 1a): median 272 %, p = 0.003], with the highest levels in patients pathologically diagnosed with frontotemporal lobar degeneration. In the cerebellum, our analysis suggested that transcripts were less likely to be truncated and, excitingly, we discovered that intron containing transcripts were associated with poly(GP) levels [digital molecular barcoding cerebellum (intron 1a): r = 0.33, p = 0.02, and (intron 1b): r = 0.49, p = 0.0004] and poly(GA) levels [digital molecular barcoding cerebellum (intron 1a): r = 0.34, p = 0.02, and (intron 1b): r = 0.38, p = 0.007]. In summary, we report decreased expression of specific C9ORF72 transcripts and provide support for the presence of truncated transcripts as well as pre-mRNAs that may serve as templates for RAN translation. We further show that higher C9ORF72 levels may have beneficial effects, which warrants caution in the development of new therapeutic approaches.

Keywords

C9ORF72 Frontotemporal dementia Frontotemporal lobar degeneration Motor neuron disease Amyotrophic lateral sclerosis Disease modifier 

Notes

Acknowledgments

The research leading to these results has received funding by NIH grants R01 NS080882, P50 AG016574, P01 NS084974, R21 NS089979, the ALS Association, and the ALS Therapy Alliance. Dr. Van Blitterswijk is supported by the Milton Safenowitz Post Doctoral Fellowship for ALS research from the ALS Association, and the Clinical Research in ALS and Related Disorders for Therapeutic Development (CReATe) Clinical Research Fellowship (U54 NS092091).

Compliance with ethical standards

Conflicts of interest

MDJ and RR hold a patent on methods to screen for the hexanucleotide repeat expansion in the C9ORF72 gene. All other authors declare that they have no conflicts of interest.

Supplementary material

401_2015_1480_MOESM1_ESM.pdf (482 kb)
Supplementary material 1 (PDF 481 kb)

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Copyright information

© Springer-Verlag Berlin Heidelberg 2015

Authors and Affiliations

  • Marka van Blitterswijk
    • 1
  • Tania F. Gendron
    • 1
  • Matthew C. Baker
    • 1
  • Mariely DeJesus-Hernandez
    • 1
  • NiCole A. Finch
    • 1
  • Patricia H. Brown
    • 1
  • Lillian M. Daughrity
    • 1
  • Melissa E. Murray
    • 1
  • Michael G. Heckman
    • 2
  • Jie Jiang
    • 3
  • Clotilde Lagier-Tourenne
    • 3
    • 4
  • Dieter Edbauer
    • 5
    • 6
    • 7
  • Don W. Cleveland
    • 3
    • 8
  • Keith A. Josephs
    • 9
  • Joseph E. Parisi
    • 9
  • David S. Knopman
    • 9
  • Ronald C. Petersen
    • 9
  • Leonard Petrucelli
    • 1
  • Bradley F. Boeve
    • 9
  • Neill R. Graff-Radford
    • 10
  • Kevin B. Boylan
    • 10
  • Dennis W. Dickson
    • 1
  • Rosa Rademakers
    • 1
    Email author
  1. 1.Department of NeuroscienceMayo ClinicJacksonvilleUSA
  2. 2.Division of Biomedical Statistics and InformaticsMayo ClinicJacksonvilleUSA
  3. 3.Ludwig InstituteUniversity of California at San DiegoLa JollaUSA
  4. 4.Department of NeurosciencesUniversity of California at San DiegoLa JollaUSA
  5. 5.German Center for Neurodegenerative Diseases (DZNE)MunichGermany
  6. 6.Institute for Metabolic BiochemistryLudwig-Maximilians University MunichMunichGermany
  7. 7.Munich Cluster of Systems Neurology (SyNergy)MunichGermany
  8. 8.Department of Cellular and Molecular MedicineUniversity of California at San DiegoLa JollaUSA
  9. 9.Department of NeurologyMayo ClinicRochesterUSA
  10. 10.Department of NeurologyMayo ClinicJacksonvilleUSA

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