Sex and Weight Affect the Genetic Influence on MPOD in Children

Kara Zehr¹, Simmer Beniwal¹, Ruyu Liu², Naiman A. Khan²

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¹Division of Molecular and Cellular Biology, ²Division of Nutritional Sciences

This work was supported by the National Institutes of Health (HD069381); Abbott Nutrition through the Center for Nutrition, Learning, and Memory (CNLM) (2012-04608) and Department of Kinesiology and Community Health at the University of Illinois at Urbana – Champaign

METHODS

RESULTS

CONCLUSION

Aims and Hypothesis

Aim: This study aimed to examine the genetic influence of BCO1 and CD36 on MPOD, and how this influence is affected by sex and weight status in children aged from 7-12 years.

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Hypothesis: We hypothesized that SNPs near the BCO1 gene (rs7501331, rs12934922, rs6420424) and near the CD36 gene (rs3173798, rs10499859, rs1527483) influence MPOD differently based on sex and weight status.

Macular Pigment Optical Density

MPOD was assessed using Customized Heterochromatic Flicker Photometry (cHFP).

DNA Collection and Genotyping

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DNA was obtained via saliva samples (Oragene DNA self-collection kit. DNA Genotek Inc., Ottawa, Ontario, Canada) and then manually extracted. Samples were then genotyped for 6 SNPs (BCO1: rs7501331, rs12934922, rs6420424) (CD36: rs3173798, rs10499859, rs1527483) at the Functional Genomics Unit of the W.M. Keck Center at the University of Illinois using the Fluidigm® SNP genotyping platform.

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BACKGROUND

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• Lutein and zeaxanthin are dietary carotenoids. This class of molecules are responsible for the bright colors seen in many vegetables. Carotenoids are fat soluble and cannot be synthesized de novo in the body.
• Lutein, zeaxanthin, and meso-zeaxanthin, are deposited in the macular region of the retina. Carotenoids can protect our eyes from blue light damage by acting as antioxidants.
• Macular Pigment Optical Density (MPOD) is a measure of absorption of blue light by macular pigment, which is linearly related to retinal carotenoid levels. High MPOD scores have been linked to increased cognitive function, and reduced risk of macular degeneration.
• Some factors known to influence MPOD levels include weight status, sex, smoking status, diet, and genetic variation. Currently there is minimal research on the influence of sex, weight status, and genetic variation on MPOD levels in pediatric populations.
• BCO1 and CD36 where chosen for this project due to the large body of research on their influences on MPOD. The exact mechanisms behind how these genes affect MPOD is unknown.

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• Single Nucleotide Polymorphism (SNP) - Is a substitution of a single nucleotide at a specific region of the genome. They are the most common mutation in DNA, occuring once every 1000 base pairs in an individual's genome.
• Beta-carotene 15,15’ Monooxygenase (BCO1) - is an enzyme primarily active in the small intestines of humans. Here it catalyzes the oxidative cleavage of provitamin A (beta-carotene) into in two molecules of vitamin A (retinal).
• Cluster Determinant 36 (CD36) - is an integral membrane protein which imports fatty acids into the cell. It is a member of the class B scavenger receptor family of cell surface proteins. Research as suggested a link to CD36 in fatty acid uptake in the intestines and fatty acid metabolism.

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DEFINITIONS

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Anthropometric Measures

Participants height and weight were measured without shoes, using a stadiometer and a digital scale, respectively. Each measurement was taken three times and the average was used for analyses.

Statistical Analysis

All statistical analyses were performed using SPSS Statistics version 24 (IBM, Armonk, New York). Independent T tests were used to compare the difference in MPOD between groups.

• The T allele on rs3173798 in male subjects was associated with lower MPOD. However, this relationship was not detected in female subjects.
• The T, T, and C alleles on rs7501331, rs3173798, and rs1527483, respectively, were associated with lower MPOD in subjects with BMI percentile less than the 85th percentile. In subjects with BMI over the 85th percentile, no difference in MPOD levels was detected based on genotypes on the aforementioned SNPs.
• More research, focusing on sex and weight status, is necessary to understand the underlying processes that lead to these observed relationships in younger populations.

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Table 1: Subject demographics MPOD and BMI statistics

Table 3: Effect of Sex on the relationship between SNPs and MPOD

Table 4: Effect of BMI percentile on the relationship between SNPs and MPOD

Table 2: SNP Information

Figures 1 & 2: Sample Distributions of Sex and Weight Status

ACKNOWLEDGEMENTS:

DIVISION OF NUTRITIONAL SCIENCES

College of Agricultural, Consumer and Environmental Sciences

Sex and Weight Affect the Genetic Influence on MPOD in Children

Kara Zehr¹, Simmer Beniwal¹, Ruyu Liu², Naiman A. Khan²

​

​

Background

¹Division of Molecular and Cellular Biology, ²Division of Nutritional Sciences

• Lutein and zeaxanthin are dietary carotenoids. This class of molecules are responsible for the bright colors seen in many vegetables. Carotenoids are fat soluble and cannot be synthesized de novo in the body.
• Lutein, zeaxanthin, and meso-zeaxanthin, are deposited in the macular region of the retina. Carotenoids can protect our eyes from blue light damage by acting as antioxidants.

​

​

​

​

​

​

​

​

​

• Macular Pigment Optical Density (MPOD) is a measure of absorption of blue light by macular pigment, which is linearly related to retinal carotenoid levels. High MPOD scores have been linked to increased cognitive function, and reduced risk of macular degeneration.
• Some factors known to influence MPOD levels include weight status, sex, smoking status, diet, and genetic variation. Currently there is minimal research on the influence of sex, weight status, and genetic variation on MPOD levels in pediatric populations.
• BCO1 and CD36 where chosen for this project due to the large body of research on their influences on MPOD. The exact mechanisms behind how these genes affect MPOD is unknown.

​

DIVISION OF NUTRITIONAL SCIENCES

College of Agricultural, Consumer and Environmental Sciences

Sex and Weight Affect the Genetic Influence on MPOD in Children

Kara Zehr¹, Simmer Beniwal¹, Ruyu Liu², Naiman A. Khan²

​

​

Methods

¹Division of Molecular and Cellular Biology, ²Division of Nutritional Sciences

Macular Pigment Optical Density

MPOD was assessed using Customized Heterochromatic Flicker Photometry (cHFP).

DNA Collection and Genotyping

DNA was obtained via saliva samples (Oragene DNA self-collection kit. DNA Genotek Inc., Ottawa, Ontario, Canada) and then manually extracted. Samples were then genotyped for 6 SNPs (BCO1: rs7501331, rs12934922, rs6420424) (CD36: rs3173798, rs10499859, rs1527483) at the Functional Genomics Unit of the W.M. Keck Center at the University of Illinois using the Fluidigm® SNP genotyping platform.

​

Anthropometric Measures

Participants height and weight were measured without shoes, using a stadiometer and a digital scale, respectively. Each measurement was taken three times and the average was used for analyses.

Statistical Analysis

All statistical analyses were performed using SPSS Statistics version 24 (IBM, Armonk, New York). Independent T tests were used to compare the difference in MPOD between groups.

DIVISION OF NUTRITIONAL SCIENCES

College of Agricultural, Consumer and Environmental Sciences

Sex and Weight Affect the Genetic Influence on MPOD in Children

Kara Zehr¹, Simmer Beniwal¹, Ruyu Liu², Naiman A. Khan²

​

​

Aims and Hypothesis

¹Division of Molecular and Cellular Biology, ²Division of Nutritional Sciences

Aim: This study aimed to examine the genetic influence of BCO1 and CD36 on MPOD, and how this influence is affected by sex and weight status in children aged from 7-12 years.

​

​

​

​

Hypothesis: We hypothesized that SNPs near the BCO1 gene (rs7501331, rs12934922, rs6420424) and near the CD36 gene (rs3173798, rs10499859, rs1527483) influence MPOD differently based on sex and weight status.

DIVISION OF NUTRITIONAL SCIENCES

College of Agricultural, Consumer and Environmental Sciences

Sex and Weight Affect the Genetic Influence on MPOD in Children

Kara Zehr¹, Simmer Beniwal¹, Ruyu Liu², Naiman A. Khan²

​

​

Results

¹Division of Molecular and Cellular Biology, ²Division of Nutritional Sciences

Table 1: Subject demographics MPOD and BMI statistics

Table 2: SNP Information

Table 4: Effect of BMI percentile on the relationship between SNPs and MPOD

Table 3: Effect of Sex on the relationship between SNPs and MPOD

Figures 1 & 2: Sample Distributions of Sex and Weight Status

DIVISION OF NUTRITIONAL SCIENCES

College of Agricultural, Consumer and Environmental Sciences

Sex and Weight Affect the Genetic Influence on MPOD in Children

Kara Zehr¹, Simmer Beniwal¹, Ruyu Liu², Naiman A. Khan²

​

​

Conclusion

¹Division of Molecular and Cellular Biology, ²Division of Nutritional Sciences

• The T allele on rs3173798 in male subjects was associated with lower MPOD. However, this relationship was not detected in female subjects.

​

• The T, T, and C alleles on rs7501331, rs3173798, and rs1527483, respectively, were associated with lower MPOD in subjects with BMI percentile less than the 85th percentile. In subjects with BMI over the 85th percentile, no difference in MPOD levels was detected based on genotypes on the aforementioned SNPs. 

​

• More research, focusing on sex and weight status, is necessary to understand the underlying processes that lead to these observed relationships in younger populations.

​

DIVISION OF NUTRITIONAL SCIENCES

College of Agricultural, Consumer and Environmental Sciences