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Joan E Bailey-Wilson, Anthony Musolf, Claire L Simpson, Bilal A. Moiz, Kyle A. Long, Deyana D. Lewis, Candace D. Middlebrooks, Laura Portas, Federico Murgia, Dwight Stambolian; Han Chinese families show significant linkage for myopia on 10q26 and suggestive linkage on 9q33.. Invest. Ophthalmol. Vis. Sci. 2017;58(8):1223. doi: https://doi.org/.
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© ARVO (1962-2015); The Authors (2016-present)
Myopia is caused by an overgrowth of the eye which causes light to focus in front of the retina, leading to blurry vision. Myopia has reached epidemic proportions in Southeast Asia, with about 80% of the population affected. The genetic underpinnings that drive myopia are still murky however. This study uses Han Chinese families (living in the U.S.) with a history of myopia to search for linkage between genomic variants and the disease.
The sample data consisted of 34 Han Chinese families with a history of myopia. Subjects were genotyped on an Illumina Exome Array. We had refractive error measurements on the subjects and these were converted to either affected (≤ -1D), unaffected (≥ 0 D) or unknown (< 0D, > -1 D). Three types of parametric linkage analyses were performed: standard single variant two-point linkage, multipoint linkage, and collapsed haplotype pattern variant linkage (CHP). CHP creates a multi-allelic pseudomarker that corresponds to a genomic region from multiple single variants. This serves to raise information content. Standard two-point linkage analysis is then run on the CHP marker. Family-based association analyses are currently underway, including a family-based test using both rare and common variants and a rare variant version of TDT.
CHP linkage analysis identified a genome-wide significant locus at 10q26.13, centered around TACC2. This pseudomarker consisted of several rare exonic SNPs from the TACC2 gene. CHP analysis also found 6 more suggestive signals in 10q24.2-26.2. Single variant two-point identified 34 suggestive loci on 10q24-26, while multipoint identified 8 suggestive loci in 10q26.11-13. Many of the suggestive markers in both analyses were found in HTRA1, a known age-related macular degeneration gene. Several other promising candidate genes, such as BAG3 and DOCK1, are also present in the region. Multipoint analysis also identified a highly suggestive region at 9q33.1. This region includes TLR4, a gene known to interact with alpha-crystallin in the retina.
This study identified a genome-wide significant signal on 10q26 and a suggestive signal on 9q33 in Han Chinese families. Both regions contain strong candidate genes. Targeted sequencing and laboratory confirmation for both regions is planned to elucidate the causal variants.
This is an abstract that was submitted for the 2017 ARVO Annual Meeting, held in Baltimore, MD, May 7-11, 2017.
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