bioRxiv Science⌕ Search

Biology subjects

Seddon, J. M.

Publications and source records attributed to Seddon, J. M..

2 recordsLinked to original sources

Association between Drusen Burden Determined by OCT and Genetic Risk in Early and Intermediate Age-Related Macular Degeneration

PURPOSETo determine associations between macular drusen parameters derived from an automatic optical coherence tomography (OCT) algorithm, age-related macular degeneration (AMD) stage and genetic variants.\n\nMETHODSEyes classified as early or intermediate AMD with OCT imaging and genetic data were selected (n=239 eyes). Drusen area and volume measurements were estimated using the Zeiss Cirrus advanced retinal pigment epithelium (RPE) analysis algorithm in a 5mm diameter (perifoveal) zone centered on the fovea. Associations between drusen measurements and common genetic variants in the complement and high density lipoprotein (HDL) lipid pathways and the ARMS2 variant were calculated using generalized estimating equations and linear mixed models adjusting for age, sex, smoking, BMI, and education.\n\nRESULTSWhen compared to eyes with no measurable drusen, drusen area [≥] the median was independently associated with a higher number of risk alleles for CFH risk score, risk variants in C3 and ARMS2/HTRA1. Similar results were obtained for drusen volume. When all genes were analyzed in the same model, only CFH score and ARMS2/HTRA1 were associated with drusen measurements. HDL pathway genes were not significantly related to drusen parameters. Early and intermediate AMD stages were associated with OCT derived drusen area and volume.\n\nCONCLUSIONGenetic variants in CFH and ARMS2/HTRA1, commonly associated with advanced AMD, were independently associated with higher drusen burden determined by OCT in eyes with early and intermediate AMD. The automatic RPE algorithm using OCT provides a quantitative classification of non-advanced AMD. Drusen morphology and other OCT-derived sub-phenotypes are biomarkers that could provide early anatomic endpoints for clinical trials.

genetics↗

Identification of stable reference genes for quantitative PCR in koalas

To better understand host and immune response to diseases, gene expression studies require identification of reference genes with stable expression for accurate normalisation. This study describes the selection and testing of reference genes with stable expression profiles in koala lymph node tissues across two genetically distinct koala populations. From the 25 most stable genes identified in transcriptome analysis, 11 genes were selected for verification using reverse transcription quantitative PCR, in addition to the commonly used ACTB and GAPDH genes. The expression data were analysed using stable genes statistical software - geNorm, BestKeeper, NormFinder, the comparative {Delta}Ct method and RefFinder. All 13 genes showed relative stability in expression in koala lymph node tissues, however Tmem97 and Hmg20a were identified as the most stable genes across the two koala populations.

molecular biology↗