A genome-wide association study of central corneal thickness in Latinos

PURPOSE. Central corneal thickness (CCT) is a clinically important risk factor for primary openangle glaucoma and keratoconus. Genetic factors controlling CCT in Latinos, the most populous minority population in the United States, are unclear. Here we describe the first genome-wide association study (GWAS) report of CCT in Latinos. METHODS. We performed a GWAS for CCT on 1768 Latinos recruited in the Los Angeles Latino Eye Study (LALES) using Illumina's HumanOmniExpress BeadChip (~730K markers). To discover additional associated single-nucleotide polymorphisms (SNPs), we imputed SNPs based on the 1000 Genomes Project reference panels. All subjects were 40 years of age and older. We used linear regression with adjustment for age, sex, and principal components of genetic ancestry. RESULTS. We replicated the involvement of several previously reported loci, such as RXRACOL5A1, FOXO1, and ZNF469, for CCT in Latinos (P < 0.002). Moreover, we discovered novel SNPs, rs3118515, rs943423, rs3118594, and rs3132307, that reached GWAS significance (P < 5 * 10^-8) in the uncharacterized LOC100506532 (gene type: miscRNA) for CCT in Latinos. By conditional analysis, we demonstrate that rs3118515 in this gene is responsible for the GWAS signal in the chromosome 9 RXRA-COL5A1 region in Latinos. Moreover, multiple sources of ENCODE evidence suggest that rs3118515 is in a regulatory region. Reverse-transcription PCR products indicated that transcripts of LOC100506532 surrounding rs3118515 were expressed in human corneas. CONCLUSIONS. We discovered novel SNPs for CCT in Latinos and provided the first reported evidence of the corneal expression of LOC100506532. These results help to further increase our understanding of the genetic architecture of CCT.