Vitamin A (BCMO1)

BCMO1 · rs7501331 + rs12934922

Plant-based beta-carotene is only provitamin A and must first be cleaved into retinal. The enzyme BCMO1 catalyses this step, and common variants make many people weak converters. Carriers of several unfavourable alleles cover their vitamin A needs less well from purely plant sources.

The markers

BCMO1 (beta-carotene-15,15′-monooxygenase, also BCO1) splits beta-carotene into two molecules of retinal. Two common missense variants lower activity: rs12934922 (R267S) and rs7501331 (A379V). In vitro the combination of both reduces catalytic activity by about 57 percent; carriers of both alleles produce roughly 69 percent less retinol from a standard dose and have about 240 percent higher fasting beta-carotene (Leung 2009). The regulatory marker rs6564851 near the gene was the strongest GWAS hit for circulating beta-carotene (Lietz 2012).

What it means

An unfavourable BCMO1 profile does not mean deficiency but a poorer yield from plant provitamin A. With a mixed diet containing some preformed retinol (liver, egg, dairy, fortified foods) supply is usually secured. The genotype matters mainly with a purely plant-based diet or raised demand.

Context

The BCMO1 effects are well documented functionally and are among the better-understood vitamin genotypes. They describe a predisposition, not a disease. Genome shows the three markers as technical evidence; they are in the built-in panel 'Vitamins A–E'.

What Genome measures. The genotypes at the BCMO1 markers rs12934922 (R267S), rs7501331 (A379V) and the regulatory rs6564851.

Related topics

rsIDs, microarray and SNP lookupVitamin D (synthesis, transport, receptor)Disease associations

Sources

  1. 1Leung et al., 2009 Two common SNPs in BCMO1 alter beta-carotene metabolism in female volunteers. FASEB Journal 23:1041–1053. doi.org/10.1096/fj.08-121962
  2. 2Lietz et al., 2012 SNPs upstream from BCMO1 influence provitamin A conversion efficiency. Journal of Nutrition 142:161S–165S. doi.org/10.3945/jn.111.140756