Whole Exome Sequencing and Segregation Analysis Confirms That a Mutation in COL17A1 Is the Cause of Epithelial Recurrent Erosion Dystrophy in a Large Dominant Pedigree Previously Mapped to Chromosome 10q23-q24.

To report identification of a COL17A1 mutation in a family with a corneal dystrophy previously mapped to chromosome 10q23-q24.Whole-exome sequencing was performed on DNA samples from five affected family members and two unrelated, unaffected individuals. Identified variants were filtered for those that were: located in the linked interval on chromosome 10q23-q24; novel or rare (minor allele frequency ≤0.01); heterozygous; present in all affected individuals and not in controls; and present in genes that encode proteins expressed in human corneal epithelial cells (reads per kilobase per million ≥1). Sanger sequencing of identified variants (SNVs) was performed in additional family members. In silico analysis was used to predict the functional impact of non-synonymous variants.Three SNVs located in two genes were identified that met the filtering criteria: one rare synonymous c.3156C>T variant in the collagen, type XVII, alpha I (COL17A1) gene; and two rare variants, one synonymous and one missense, in the dynamin binding protein (DNMBP) gene. Sanger sequencing of additional family members determined that only the COL17A1 variant segregates with the affected phenotype. In silico analysis predicts that the missense variant in DNMBP would be tolerated.The corneal dystrophy mapped to chromosome 10q23-q24 is associated with the c.3156C>T variant in COL17A1. As this variant has recently been identified in five other families with early onset recurrent corneal erosions, and has been shown in vitro to introduce a cryptic splice donor site, this dystrophy is likely caused by aberrant splicing of COL17A1 and should be classified as epithelial recurrent erosion dystrophy

Differing roles for TCF4 and COL8A2 in central corneal thickness and fuchs endothelial corneal dystrophy.

Fuchs endothelial corneal dystrophy (FECD) is the most common late-onset, vision-threatening corneal dystrophy in the United States, affecting about 4% of the population. Advanced FECD involves a thickening of the cornea from stromal edema and changes in Descemet membrane. To understand the relationship between FECD and central corneal thickness (CCT), we characterized common genetic variation in COL8A2 and TCF4, genes previously implicated in CCT and/or FECD. Other genes previously associated with FECD (PITX2, ZEB1, SLC4A11), and genes only known to affect CCT (COL5A1, FOXO1, AVGR8, ZNF469) were also interrogated. FECD probands, relatives and controls were recruited from 32 clinical sites; a total of 532 cases and 204 controls were genotyped and tested for association of FECD case/control status, a 7-step FECD severity scale and CCT, adjusting for age and sex. Association of FECD grade with TCF4 was highly significant (OR= 6.01 at rs613872; p = 4.8×10(-25)), and remained significant when adjusted for changes in CCT (OR= 4.84; p = 2.2×10(-16)). Association of CCT with TCF4 was also significant (p = 6.1×10(-7)), but was abolished with adjustment for FECD grade (p = 0.92). After adjusting for FECD grade, markers in other genes examined were modestly associated (p ∼ 0.001) with FECD and/or CCT. Thus, common variants in TCF4 appear to influence FECD directly, and CCT secondarily via FECD. Additionally, changes in corneal thickness due to the effect of other loci may modify disease severity, age-at-onset, or other biomechanical characteristics

Pedigree of a family with chromosome 10q23-q24 linked dystrophy.

<p>Females are represented by circles, males by squares, and individuals of unknown gender by diamonds. Affected individuals are shown with filled symbols and unaffected individuals are shown with open symbols. Individuals of unknown affected status are shown with a question mark. The arrow head indicates the proband. An asterisk (*) indicates individuals that underwent WES. A dagger (†) indicates individuals that underwent Sanger sequencing for identified candidate variants in <i>COL17A1</i> and <i>DNMBP</i>.</p

Sanger sequencing results of filtered candidate variants for the corneal dystrophy linked to chromosome 10q23-q24.

<p>Sanger sequencing results of filtered candidate variants for the corneal dystrophy linked to chromosome 10q23-q24.</p

Clinical features of chromosome 10q23-q24 linked dystrophy.

<p>A. Affected individual V-2 (28 years old) demonstrates a clear cornea in the right eye. B. Three months later, she developed a corneal erosion (arrows). C. Affected individual V-3 (24 years old) also demonstrated clear corneas prior to the development of a corneal erosion, the location of which can be identified by the opacification of the corneal epithelium (arrows). D. Affected individual IV-1 (72 years old) demonstrates diffuse subepithelial opacification secondary to chronic recurrent corneal erosions seen with slit and diffuse illumination in the right (D and E) and left (F) eyes.</p

Filtered coding region variants in positional candidate genes for the corneal dystrophy linked to chromosome 10q23-q24.

<p>Filtered coding region variants in positional candidate genes for the corneal dystrophy linked to chromosome 10q23-q24.</p

Relationship between Oxidation Level and Optical Properties of Secondary Organic Aerosol

Brown carbon (BrC), which may include secondary organic aerosol (SOA), can be a significant climate-forcing agent via its optical absorption properties. However, the overall contribution of SOA to BrC remains poorly understood. Here, correlations between oxidation level and optical properties of SOA are examined. SOA was generated in a flow reactor in the absence of NO_<i>x</i> by OH oxidation of gas-phase precursors used as surrogates for anthropogenic (naphthalene, tricyclo­[5.2.1.0^2,6]­decane), biomass burning (guaiacol), and biogenic (α-pinene) emissions. SOA chemical composition was characterized with a time-of-flight aerosol mass spectrometer. SOA mass-specific absorption cross sections (MAC) and refractive indices were calculated from real-time cavity ring-down photoacoustic spectrometry measurements at 405 and 532 nm and from UV–vis spectrometry measurements of methanol extracts of filter-collected particles (300 to 600 nm). At 405 nm, SOA MAC values and imaginary refractive indices increased with increasing oxidation level and decreased with increasing wavelength, leading to negligible absorption at 532 nm. Real refractive indices of SOA decreased with increasing oxidation level. Comparison with literature studies suggests that under typical polluted conditions the effect of NO_<i>x</i> on SOA absorption is small. SOA may contribute significantly to atmospheric BrC, with the magnitude dependent on both precursor type and oxidation level

Summary of genotyped samples.

<p>Unless otherwise indicated, statistics are shown as mean ± SD.</p>a<p>Total includes 87 individuals with FECD grade of 1–3 in worse eye, not classified as FECD cases or controls.</p>b<p>Average of two eyes, when available.</p

Meta-analysis for association of <i>TCF4</i> SNP rs613872 with FECD case/control status.

<p>Horizontal lines denote the 95% CI for the OR for each G allele at rs613872. The width of the squares indicating estimates of OR is proportional to the sample size in each study.</p