April 2014
Volume 55, Issue 13
Free
ARVO Annual Meeting Abstract  |   April 2014
Rare Genetic Variants are Associated with POAG in Populations of African Ancestry
Author Affiliations & Notes
  • Michael A Hauser
    Medicine, Duke Univ Medical Center, Durham, NC
    Ophthalmology, Duke University Medical Center, Durham, NC
  • Allison E Ashley-Koch
    Medicine, Duke Univ Medical Center, Durham, NC
  • Xuejun Qin
    Medicine, Duke Univ Medical Center, Durham, NC
  • Shelby Strickland
    Medicine, Duke Univ Medical Center, Durham, NC
  • Yutao Liu
    Medicine, Duke Univ Medical Center, Durham, NC
    Ophthalmology, Duke University Medical Center, Durham, NC
  • Christopher A Girkin
    Ophthalmology, Univ Alabama Birmingham, Birmingham, AL
  • Donald L Budenz
    Ophthalmology, Univ of North Carolina, Chapel Hill, NC
  • Stephen Akafo
    Unit of Ophthalmology, University of Ghana Medical School, Accra, Ghana
  • R. Rand Allingham
    Ophthalmology, Duke University Medical Center, Durham, NC
  • Footnotes
    Commercial Relationships Michael Hauser, None; Allison Ashley-Koch, None; Xuejun Qin, None; Shelby Strickland, None; Yutao Liu, None; Christopher Girkin, None; Donald Budenz, None; Stephen Akafo, None; R. Allingham, None
  • Footnotes
    Support None
Investigative Ophthalmology & Visual Science April 2014, Vol.55, 3807. doi:
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      Michael A Hauser, Allison E Ashley-Koch, Xuejun Qin, Shelby Strickland, Yutao Liu, Christopher A Girkin, Donald L Budenz, Stephen Akafo, R. Rand Allingham, ; Rare Genetic Variants are Associated with POAG in Populations of African Ancestry. Invest. Ophthalmol. Vis. Sci. 2014;55(13):3807.

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      © ARVO (1962-2015); The Authors (2016-present)

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Abstract

Purpose: Individuals of African Ancestry are 4-5 times more likely to develop primary open angle glaucoma (POAG) than Caucasians, but little is known about their genetic risk factors. We evaluate the association of rare genetic variants to POAG in African Americans and a population from Ghana, West Africa.

Methods: The Illumina HumanExome BeadChip containing over 250,000 variants was used to genotype 2834 individuals of African Ancestry: African Americans (666 POAG cases and 668 controls) and Ghanaians (750 POAG cases, 750 controls). Principle component analysis (PCA) of 1800 ancestry informative markers on the BeadChip was used to identify population stratification. Rare variants were analyzed for association with POAG, using both single variant and gene collapsing tests implemented in Plink-Seq

Results: PCA indicated that African Americans in this dataset are genetically derived from admixture between the parental West African (Ghanaian) and Caucasian populations. A variant in the TMCO4 gene was found to be associated in African Americans with both Fisher’s Exact Test (p=3.6x10-5; OR=0.43) and the c alpha test (p=9x10-6). The role of TMCO4 is unknown; but a closely-related gene, TMCO1, has been associated with POAG in Caucasians. Fisher’s Exact Test also shows that a variant in TMCO4 is associated in the Ghanaian dataset (p= 7.7x10-3). Two more genes among the 10 strongest associations in the African American exome chip analysis were replicated in the Ghanaian dataset. ACSL5 is associated in African Americans (p=8x10-5; OR=0.33), and this gene replicates in the Ghanaian dataset (p=0.01; OR=0.11); and intergenic SNPs near THSD7B are associated in both African Americans (p=1x10-4; OR=0.62) and Ghanaians (p=0.01; OR=0.18). Both of these genes are expressed in the retina. Full meta-analysis of all 2834 samples in both datasets will be presented.

Conclusions: We have identified multiple genes associated with POAG pathogenesis in both African Americans and Ghanaians. TMCO4 is closely related to TMCO1, which has previously been associated with POAG in Caucasians, and may affect apoptotic cell death. THSD7B belongs to a large family of genes containing thrombospondin type 1 domains, including ADMSTS10, a gene responsible for glaucoma in dogs, as well as a syndromic form of glaucoma in a Lebanese family. Future directions include sequencing of selected candidate genes and functional analysis of the variants identified.

Keywords: 539 genetics  
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