The Heritability of the Ring-Like Distribution of Macular Pigment Assessed in a Twin Study

Tariq, Ambreen; Mahroo, Omar A.; Williams, Katie; Liew, Shiao Hui Melissa; Beatty, Stephen; Gilbert, Clare; Kuijk, Frederik J. van; Hammond, Christopher J.

doi:10.1167/iovs.13-13829

Cited by 11 publications

(27 citation statements)

References 23 publications

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“…Nonetheless, among the 314 twin participants, prevalence of the ring‐like profile (29%) determined objectively compares well with the 26% reported in the original study (Tariq et al. 2014). This suggests that ring‐like MP structures can be identified by objective classification based on the limited eccentricities used in our analysis.…”

Section: Discussionmentioning

confidence: 99%

“…Case‐wise concordance for the presence of a ring‐like or central dip profile was calculated separately for MZ and DZ twins as 2 C /(2 C + D ), where C is the number of twin pairs concordant and D the number discordant (Tariq et al. 2014). Heritability calculation for pigment profiles was performed as described previously (Tariq et al.…”

Section: Methodsmentioning

confidence: 99%

“…Heritability calculation for pigment profiles was performed as described previously (Tariq et al. 2014) with maximum likelihood structural equation twin modelling, using the OpenMx package (http://openmx.psyc.virginia.edu) in R (http://www.r-project.org). …”

Section: Methodsmentioning

confidence: 99%

“…2011; Tariq et al. 2014). However, the classification of spatial profile phenotypes varies across the literature and there is currently no universal consensus on a single classification system.…”

Section: Introductionmentioning

confidence: 99%

“…2003), as has subjective visual assessment of two‐wavelength FAF scan images (Tariq et al. 2014). As well as inconsistencies with nomenclature, classification of a ring‐like spatial profile may be affected by measurement error, noise in the data or a product of an artefact of the MPOD measurement method (Delori 2004).…”

Section: Introductionmentioning

confidence: 99%

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Repeatability of the macular pigment spatial profile: A comparison of objective versus subjective classification

Ctori

Mahroo

Williams

et al. 2018

Acta Ophthalmologica

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PurposeClassification of macular pigment (MP) spatial profile phenotypes varies and is often based on subjective visualisation. We investigated repeatability of MP optical density (MPOD) comparing an objective versus subjective profiling system.MethodsThe coefficient of repeatability (CoR) was calculated for point MPOD values (0–3.8°) obtained by dual‐wavelength fundus autofluorescence (FAF) from two scans obtained in a single visit of 40 healthy individuals (39 ± 9 years). For each individual's dataset, the MP profile was classified as exponential, ring‐like or central dip using an objective method (based on deviations away from an exponential fit), as well as by subjective visual profiling. Existing FAF images of 88 monozygotic (MZ) and 69 dizygotic (DZ) twin pairs were reanalysed using the objective profiling method and concordance and heritability of ring‐like profiles determined.ResultsThe CoR was 0.23 at 0° and 0.06 at 0.8°. Agreement of objective profiling between scans was excellent (κ = 0.85, 95% CI 0.69 to 1.00; p < 0.0005). Subjective profiling showed moderate agreement between scans (κ = 0.48, 95% CI 0.23 to 0.73; p < 0.0005). Agreement between objective and subjective classification was low (κ = 0.23, 95% CI 0.04 to 0.42; p = 0.02). Concordance for the ring‐like profile using objective profiling was 0.74 for MZ compared to 0.36 for DZ twins. Heritability was calculated as 81.5% (95% confidence interval 61.1–93.1%).ConclusionCompared to visual assessment, objective MP profiling is a more reliable method and should be considered in future observational and interventional studies. In addition, MP profile phenotypes showed high heritability.

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Section: Discussionmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Repeatability of the macular pigment spatial profile: A comparison of objective versus subjective classification

Ctori

Mahroo

Williams

et al. 2018

Acta Ophthalmologica

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Relative Genetic and Environmental Contributions to Variations in Human Retinal Electrical Responses Quantified in a Twin Study

et al. 2017

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PurposeTo estimate heritability of parameters of human retinal electrophysiology and to explore which parameters change with age.DesignProspective, classic twin study.ParticipantsAdult monozygotic and dizygotic twin pairs recruited from the TwinsUK cohort.MethodsElectroretinogram responses were recorded using conductive fiber electrodes in response to stimuli incorporating standards set by the International Society for the Clinical Electrophysiology of Vision. These parameters were extracted; in addition, photopic negative-response (PhNR; originating from retinal ganglion cells) and i-wave components were extracted from responses to the photopic single flash. Parameter values were averaged from both eyes.Main Outcome MeasuresMean values were calculated for the cohort. Correlation coefficients with age were calculated (averaging parameters from both twins from each pair). Coefficients of intrapair correlation were calculated for monozygotic and dizygotic twins. Age-adjusted heritability estimates were derived using standard maximum likelihood structural equation twin modeling.ResultsResponses were recorded from 210 participants in total (59 monozygotic and 46 dizygotic twin pairs). Ninety-three percent were women. Mean age for the cohort was 62.4 years (standard deviation, 11.4 years). In general, response amplitudes correlated negatively, and implicit times positively, with age. Correlations were statistically significant (P < 0.05) and moderate or strong (coefficient, >0.35) for the following parameters: scotopic standard and bright-flash a-wave implicit times, photopic 30-Hz flicker and single-flash b-wave implicit times, and PhNR and i-wave implicit times. Intrapair correlations were higher for monozygotic than dizygotic twins, suggesting important genetic influences. Age-adjusted estimates of heritability were significant for all parameters (except scotopic dim-flash b-wave implicit time), ranging from 0.34 to 0.85. Highest estimates were for photopic single-flash a-wave and b-wave amplitudes (0.84 and 0.85, respectively).ConclusionsThis study explored heritability of retinal electrophysiologic parameters and included measurements reflecting ganglion cell function. Most parameters showed significant heritability, indicating that genetic factors are important, determining up to 85% of the variance in some cone system response parameters. Scotopic responses tended to show lower heritability (possibly relating to greater rod system susceptibility to environmental factors). Future studies can explore the identity of these genetic factors, improving our understanding of how they shape retinal function.

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Macular and Plasma Xanthophylls Are Higher in Age-related Macular Degeneration than in Normal Aging

McGwin

Kar

Berlin

et al. 2023

Ophthalmology Science

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The Heritability of the Ring-Like Distribution of Macular Pigment Assessed in a Twin Study

Cited by 11 publications

References 23 publications

Repeatability of the macular pigment spatial profile: A comparison of objective versus subjective classification

Repeatability of the macular pigment spatial profile: A comparison of objective versus subjective classification

Relative Genetic and Environmental Contributions to Variations in Human Retinal Electrical Responses Quantified in a Twin Study

Macular and Plasma Xanthophylls Are Higher in Age-related Macular Degeneration than in Normal Aging

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