In-utero epigenetic factors are associated with early-onset myopia in young children
PLOS ONE
Authors: Seow, Wei Jie; Ngo, Cheryl S.; Pan, Hong; Barath, Veluchamy Amutha; Tompson, Stuart W.; Whisenhunt, Kristina N.; Vithana, Eranga; Chong, Yap-Seng; Juo, Suh-Hang H.; Hysi, Pirro; Young, Terri L.; Karnani, Neerja; Saw, Seang Mei
Abstract
Objectives To assess whether epigenetic mechanisms affecting gene expression may be involved in the pathogenesis of early-onset myopia, we performed genome-wide DNA methylation analyses of umbilical cord tissues, and assessed any associations between CpG site-specific methylation and the development of the disorder when the children were 3 years old. Methods Genome-wide DNA methylation profiling of umbilical cord samples from 519 Singaporean infants involved in a prospective birth cohort 'Growing Up in Singapore Towards healthy Outcomes' (GUSTO) was performed using the Illumina Infinium HumanMethylation450K chip microarray. Multivariable logistic regression models were used to assess any associations between site-specific CpG methylation of umbilical cord tissue at birth and myopia risk in 3 year old children, adjusting for potential confounders. Gene expression of genes located near CpG sites that demonstrated statistically significant associations were measured in relevant ocular tissues using human and mouse fetal and adult eye samples. Results We identified statistically significant associations between DNA methylation levels at five CpG sites and early-onset myopia risk after correcting for multiple comparisons using a false discovery rate of 5%. Two statistically significant CpG sites were identified in intergenic regions: 8p23(p = 1.70x10(-7)) and 12q23.2(p = 2.53x10(-7)). The remaining 3 statistically significant CpG sites were identified within the following genes: FGB (4q28, p = 3.60x10(-7)), PQLC1 (18q23, p = 8.9x10(-7)) and KRT12 (17q21.2, p = 1.2x10(-6)). Both PQLC1 and KRT12 were found to be significantly expressed in fetal and adult cornea and sclera tissues in both human and mouse. Conclusions We identified five CpG methylation sites that demonstrate a statistically significant association with increased risk of developing early-onset myopia. These findings suggest that variability in the neonatal cord epigenome may influence early-onset myopia risk in children. Further studies of the epigenetic influences on myopia risk in larger study populations, and the associations with adulthood myopia risk are warranted.
A novel mutation of the Keratin 12 gene responsible for a severe phenotype of Meesmann's corneal dystrophy
MOLECULAR VISION
Authors: Sullivan, Lori S.; Baylin, Eric B.; Font, Ramon; Daiger, Stephen P.; Pepose, Jay S.; Clinch, Thomas E.; Nakamura, Hisashi; Zhao, Xinping C.; Yee, Richard W.
Abstract
Purpose: To determine if a mutation within the coding region of the keratin 12 gene (KRT12) is responsible for a severe form of Meesmann's corneal dystrophy. Methods: A family with clinically identified Meesmann's corneal dystrophy was recruited and studied. Electron microscopy was performed on scrapings of corneal epithelial cells from the proband. Mutations in the KRT12 gene were sought using direct genomic sequencing of leukocyte DNA from two affected and two unaffected family members. Subsequently, the observed mutation was screened in all available family members using polymerase chain reaction and direct sequencing. Results: A heterozygous missense mutation (Arg430Pro) was found in exon 6 of KRT12 in all 14 affected individuals studied. Unaffected family members and 100 normal controls were negative for this mutation. Conclusions: We have identified a novel mutation in the KRT12 gene that is associated with a symptomatic phenotype of Meesmann's corneal dystrophy. This mutation results in a substitution of proline for arginine in the helix termination motif that may disrupt the normal helix, leading to a dramatic structural change of the keratin 12 protein.