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Ask the Expert: Questions about Genome Interpretation

Posted By Laura Elayne Firetag, ND, Monday, April 6, 2015
I just received my genome interpretation and I have hundreds of questions. Right now, I’m most concerned that I’m double positive for all BCMO SNPs. What is this BCMO gene and are these positives something about which I should be concerned?

Great question!
Since there are readers who might not be familiar with SNPs, I will begin with a very brief explanation of single nucleotide polymorphisms (SNPs). SNPs are the most common type of genetic variation among people and are found in DNA (deoxyribonucleic acid). DNA holds the biological instructions necessary to create every cell, tissue and organ in our bodies and it is passed along from generation to generation. While many SNPs have no impact on health or may even reduce the risk of disease, physicians who use genetics to recommend clinical interventions will hone in on the SNPs that could lead to the development of imbalance or disease and then offer recommendations to optimize health.

Now, to answer your question - yes, if you are homozygous positive for all of the reported BCMO SNPs, there is a reason for concern. The BCMO gene is the gene that codes for the enzyme known as beta,beta-carotene 15,15'-monooxygenase. Research in the field of precision medicine (also referred to as nutrigenomics), or medicine based on your unique genome, is just beginning and while we do know a lot, there is MUCH more to be learned. For now, we know this enzyme is responsible for the conversion of dietary carotenoids (provitamin A carotenoids) from foods such as carrots and pumpkin into Vitamin A. Vitamin A is necessary to maintain healthy skin and the tissue that lines your respiratory, digestive and genitourinary tracts. Vitamin A also plays a significant role in immune function, embryonic development, antioxidant activity, DNA expression, visual function and the formation of sperm. There is speculation that the presence of BCMO SNPs could contribute to an increased risk of developing age-related macular degeneration. Fortunately, even with the presence of BCMO SNPs, true vitamin A deficiency is very rare in the United States.

The fact that you are homozygous positive for all of the clinically relevant SNPs, though, means that if anyone has a tendency towards deficiency, it is you. Vitamin A is stored in the liver and blood levels remain relatively constant as the liver releases what is necessary. One research study concluded that blood levels of retinol (Vitamin A) are similar in people with and without the BCMO SNPs but researchers have yet to assess liver stores of vitamin A based on genome. I have had a few friends who “turn orange” when they consume foods high in carotenoids on a daily basis. While I have not asked them about their genome, I suspect they might be homozygous positive for many BCMO SNPs.

For you, supplementation with a physician-recommended dose of Vitamin A would most likely be beneficial. High and/or long-term doses of Vitamin A can be toxic so it is best to seek the advice of a licensed naturopathic physician for optimal dosing and monitoring. Serum calcium, triglycerides and liver enzymes should be periodically assessed when supplementing with Vitamin A. While Vitamin A toxicity is not likely in your future, especially if under the supervision of a physician, early signs of vitamin A toxicity include joint pain, muscle aches, dry skin, bone pain, headaches and fatigue so please seek medical attention if you experience any of these symptoms while supplementing with Vitamin A. Also, for women of child-bearing age, vitamin A supplementation can cause birth defects. Until you consult with a physician, dietary sources of Vitamin A include fish oil, fish liver oil, dairy products, eggs and foods fortified with Vitamin A. Fish liver oils such as cod liver oil can have a rather high amount of Vitamin A so if you do begin to supplement with cod liver oil, be sure to mention the amount you are consuming to your physician. Women of child bearing age must be extra cautious when supplementing with cod liver oil.

As a silver lining, the fact that you have the BCMO SNPs could be beneficial as long as your intake of Vitamin A is adequate. A recent study, published in 2015, concluded that carotenoids, in the absence of the BCMO enzyme, appear to inhibit atherosclerosis while the retinoids (Vitamin A) produced from carotenoids in the presence of the BCMO enzyme appear to contribute to the development of atherosclerosis in mice. This is only one study performed on mice, not humans, so don’t jump to a concrete conclusion just yet about the relationship between BCMO SNPs, Vitamin A and atherosclerosis! As more people have their genomes sequenced and new research studies are performed, we will know more. In the meantime, consider consulting with a physician who specializes in precision medicine or nutrigenomics.

• Sources:
o Meyers KJ, Mares JA, Igo RP Jr, et al. Genetic evidence for role of carotenoids in age-related macular degeneration in the Carotenoids in Age-Related Eye Disease Study (CAREDS). Invest Ophthalmol Vis Sci. 2014;55:587–599.
o Zolberg Relevy N, Bechor S, Harari A, Ben-Amotz A, Kamari Y, Harats D, et al. (2015) The Inhibition of Macrophage Foam Cell Formation by 9- Cis β-Carotene Is Driven by BCMO1 Activity. PLoS ONE 10(1): e0115272.
o Hendrickson, S. J., A. Hazra, C. Chen, A. H. Eliassen, P. Kraft, B. A. Rosner, and W. C. Willett. B-Carotene 15,15'-monooxygenase 1 Single Nucleotide Polymorphisms in Relation to Plasma Carotenoid and Retinol Concentrations in Women of European Descent. American Journal of Clinical Nutrition (2012): 1379-389. Web. 14 Mar. 2015. .
o Gaby, Alan. Nutritional Medicine. Concord, N.H: Fritz Perlberg, 2011. 125-9. Print.
o Groff, James L., Sareen S. Gropper, and Jack L. Smith. Advanced Nutrition and Human Metabolism. 4th ed. Belmont, CA: Thomson Wadsworth, 2005. 361-7. Print.

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