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Robyn Guymer

Publications and source records attributed to Robyn Guymer.

9 recordsLinked to original sources
PubMed2006

Characterization of the peripheral retinopathy in X-linked and autosomal recessive Alport syndrome.

BACKGROUND: Alport syndrome is an inherited disease resulting in kidney failure, hearing loss and ocular abnormalities. Alport syndrome is however often unrecognized, and the aim of this study was to characterize the associated but rarely described peripheral retinopathy and determine whether its demonstration was diagnostically helpful. METHODS: Index cases were diagnosed with Alport syndrome on renal biopsy in themselves or a family member. Inheritance and affected status were determined using microsatellite markers at the COL4A5 and COL4A3/COL4A4 loci, respectively. Participants' eyes were dilated, and examined with direct and indirect ophthalmoscopy, and slit lamp biomicroscopy by an expert ophthalmologist who was unaware of the patients' disease status. RESULTS: Ten males and nine females with X-linked Alport syndrome and seven with autosomal recessive disease were studied. Of the 26 patients, 16 had central retinopathy (62%), and 19 patients had peripheral retinopathy (74%). The peripheral changes occurred in both males and females with X-linked and autosomal recessive Alport syndrome, and were more common when renal failure, hearing loss, lenticonus and the central changes were present, but were also noted in 3 X-linked carriers with normal renal function. CONCLUSIONS: The peripheral retinopathy occurs in X-linked and autosomal recessive Alport syndrome even when the central retinopathy is absent. Careful retinal examination and photography that includes the periphery is a safe and inexpensive method that may help in the diagnosis of Alport syndrome especially in carriers of X-linked disease.

Adolescent↗
PubMed2006

Analysis of the Y402H variant of the complement factor H gene in age-related macular degeneration.

PURPOSE: Recent studies in U.S. populations have indicated that the Y402H variant of the complement factor H (CFH) gene contains a major risk susceptibility allele for age-related macular degeneration (AMD). This study was conducted to ascertain whether this is also true in a non-U.S. population and also whether the at-risk allele is associated with the clinical phenotype of disease and the age at diagnosis. METHODS: Two hundred thirty-six unrelated individuals with AMD and 144 unrelated but ethnically matched control subjects were recruited and examined. All subjects completed a standard questionnaire, were given a fundus examination, and provided a blood sample for DNA extraction. Alleles of Y402H in the CFH gene were determined by use of a MALDI-TOF-based approach followed by statistical analysis. RESULTS: Individuals with AMD who had at least one copy of the C allele of Y402H had an increased risk of disease (odds ratio [OR] 2.98; 95% confidence interval [CI] 1.81-4.93) compared with cases with the T allele. On subgroup analysis, this risk was found to be most significant in individuals with neovascular disease (OR 4.34; 95% CI 1.94, 9.71). In addition, individuals with neovascular disease who were homozygous CC presented with a significant 7.0-year earlier age at diagnosis relative to those individuals who were homozygous TT. The population-attributable risk for the C allele ranged between 47% to 69%, depending on the AMD disease subtype. CONCLUSIONS: The C allele of Y402H represents a significant risk factor in individuals with AMD, and this effect is most pronounced in individuals with neovascular disease.

Aged↗
PubMed2005

Exposure to Chlamydia pneumoniae infection and progression of age-related macular degeneration.

Recent studies have found an association between exposure to Chlamydia pneumoniae infection and risk of age-related macular degeneration (AMD). To assess a potential risk of AMD progression posed by exposure to C. pneumoniae, the authors reexamined Australian residents in 2001-2002 who were aged 51-89 years with early AMD at baseline (1992-1995). Examination included macular photography and an enzyme-linked immunosorbent assay to determine antibody titers to the elementary bodies from C. pneumoniae AR39. AMD progression was assessed quantitatively, using both coarse and fine progression steps following an international classification for AMD grading, and also qualitatively, by side-by-side comparison of baseline and follow-up macular photographs. Serologic data were available for 246 of 254 (97%) subjects. AMD progression was associated with a higher antibody titer. After adjustment for age, smoking, family history of AMD, history of cardiovascular diseases, and source study, the subjects in the upper tertiles of antibody titers were 2.1 (95% confidence interval: 0.92, 4.69), 2.6 (95% confidence interval: 1.24, 5.41), and 3.0 (95% confidence interval: 1.46, 6.37) times more at risk of progression than those in the lowest tertile, using three definitions of progression, respectively. The fact that seroreactivity to C. pneumoniae was independently associated with the risk of AMD progression suggests that C. pneumoniae infection may be an additional risk factor for AMD progression.

Aged↗
PubMed2004

Association of the M55L and Q192R paraoxonase gene polymorphisms with age-related macular degeneration.

PURPOSE: To investigate the reported association of the two single-nucleotide polymorphisms (SNPs) of the paraoxonase gene (PON1), Met-Leu 55 (M55L) and Gln-Arg 192 (Q192R), in individuals of Anglo-Celtic descent who have age-related macular degeneration (AMD). DESIGN: Case-control association study. METHODS: Sixty-two individuals with late (end-stage) AMD and 115 control subjects (without AMD) were included in this study. The M55L and Q192R SNPs were amplified by polymerase chain reaction and genotyped, and statistical analysis was undertaken. RESULTS: No association of either SNP was detected in persons of Anglo-Celtic descent who had AMD, although there was a significant difference in SNP allele frequency between Anglo-Celtic and Japanese individuals. CONCLUSION: The M55L and Q192R SNPs of the PON1 gene do not appear to be associated with late AMD in individuals of Anglo-Celtic descent.

Aged↗
PubMed2003

Visual impairment caused by retinal abnormalities in mesangiocapillary (membranoproliferative) glomerulonephritis type II ("dense deposit disease").

Patients with mesangiocapillary glomerulonephritis (MCGN) type II usually present by early adulthood with hematuria, proteinuria, and renal impairment, and these features often are accompanied by a partial lipodystrophy and an autoantibody for the alternative complement pathway convertase (C3NeF). The diagnosis of MCGN type II depends on the demonstration of "dense deposits" in the glomerular basement membrane (GBM). Most patients also have multiple subretinal white spots or drusen that are histopathologically identical with the GBM deposits and evident ophthalmoscopically by the time renal failure develops. Initially visual acuity and visual fields are preserved, but fluorescein angiography and specialized tests of retinal function, such as dark adaptation, electroretinography, and electrooculography, may be abnormal and will worsen progressively. Over the next 20 years, vision often deteriorates because of retinal atrophy, and sometimes because of subretinal neovascular membranes, macular detachment, and central serous retinopathy. The authors describe a patient with MCGN type II who presented with renal failure and impaired vision at the age of 59. He already had widespread retinal atrophy, and subsequently a subretinal membrane developed. The drusen seen in MCGN type II, like the partial lipodystrophy, are a helpful clinical pointer to the diagnosis of this condition. All patients with MCGN type II should be warned of the risk of retinal complications and reviewed by an ophthalmologist at presentation and regularly after about 10 years to minimize the loss of visual acuity from complications of the retinopathy.

Atrophy↗
PubMed2001

The genetics of age-related macular degeneration.

AIM: To review the genetics of age-related macular degeneration (AMD). The pathogenesis of AMD, the leading cause of severe visual disability and blindness in our community, remains unknown. However, AMD is regarded as a genetic disease where family history of AMD is a significant risk factor for the disease. Understanding the genetic factors associated with AMD offers the greatest chance for understanding the underlying disease processes. METHODS: Through a review of the literature and the use of original research findings, the current knowledge of the genetics of AMD is explored. CONCLUSION: AMD is increasing in prevalence and remains a major challenge for eye heath providers. Finding the genes that are associated with AMD offers the greatest chance for the development of preventative strategies and treatments.

Journal Article↗
PubMedDate not supplied

Unraveling a complex genetic disease: age-related macular degeneration.

In most of the Western world, age-related macular degeneration (AMD) remains the largest single cause of severe visual impairment, and its prevalence continues to increase. It is considered to be a complex disease, in which multiple genes and environment play a role in pathogenesis. Several environmental insults are implicated with smoking, serum cholesterol, hypertension, sunlight exposure, and many other factors being variously associated with disease pathogenesis. Until recently, there have been relatively few breakthroughs to further our understanding of the genetics of AMD, despite remarkable progress in molecular genetic techniques over the last 20 years, and the fact that many rare inherited macular diseases have had their causative genes mapped. Development of new tools such as high-density single-nucleotide polymorphism chips and microarrays have changed the face of genetic research, but have yet to directly translate into improved clinical outcomes in ophthalmology. However with the recent finding of the Tyr402His polymorphism in the complement factor H gene being implicated in AMD, we are about to witness a new wave of research in this disease. Not only does the identification of a biologically plausible gene identify a new pathway, but it also identifies new biological mechanisms for disease, avenues to pursue treatment, and a better understanding of how the environment interacts with the genetic background to create disease. This article aims to review the process of gene discovery in complex disease, why the search for genes remains difficult, how to translate laboratory findings to a clinical setting, and how these findings will impact on disease treatment and public health issues.

Genetic Variation↗