Exploring Genetic Factors Involved in Huntington Disease Age of Onset: E2F2 as a New Potential Modifier Gene

PLoS One. 2015 Jul 6;10(7):e0131573. doi: 10.1371/journal.pone.0131573. eCollection 2015.

Abstract

Age of onset (AO) of Huntington disease (HD) is mainly determined by the length of the CAG repeat expansion (CAGexp) in exon 1 of the HTT gene. Additional genetic variation has been suggested to contribute to AO, although the mechanism by which it could affect AO is presently unknown. The aim of this study is to explore the contribution of candidate genetic factors to HD AO in order to gain insight into the pathogenic mechanisms underlying this disorder. For that purpose, two AO definitions were used: the earliest age with unequivocal signs of HD (earliest AO or eAO), and the first motor symptoms age (motor AO or mAO). Multiple linear regression analyses were performed between genetic variation within 20 candidate genes and eAO or mAO, using DNA and clinical information of 253 HD patients from REGISTRY project. Gene expression analyses were carried out by RT-qPCR with an independent sample of 35 HD patients from Basque Country Hospitals. We found suggestive association signals between HD eAO and/or mAO and genetic variation within the E2F2, ATF7IP, GRIN2A, GRIN2B, LINC01559, HIP1 and GRIK2 genes. Among them, the most significant was the association between eAO and rs2742976, mapping to the promoter region of E2F2 transcription factor. Furthermore, rs2742976 T allele patient carriers exhibited significantly lower lymphocyte E2F2 gene expression, suggesting a possible implication of E2F2-dependent transcriptional activity in HD pathogenesis. Thus, E2F2 emerges as a new potential HD AO modifier factor.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adult
  • Age of Onset
  • Aged
  • Alleles
  • Exons / genetics
  • Female
  • Genes, Modifier / genetics*
  • Genotype
  • Humans
  • Huntington Disease / genetics*
  • Male
  • Middle Aged
  • Polymorphism, Single Nucleotide / genetics*
  • Trinucleotide Repeats / genetics
  • Young Adult

Grant support

This work was supported by Basque Government grants (PE08UN78,09+UEGV096/C01 and IT634-13) received by AA and by University of the Basque Country (UPV/EHU) grant (UFI 11/20) received by AMZ. The European Huntington’s Disease Network is funded by CHDI Foundation, Inc. (http://chdifoundation.org/). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.