ABCG2 Gene Function

Since I have been stuck the last few days talking about gout, what about this ABCG2 gene?  What does it do?  According to GeneCards the ABCG2 gene encodes for a protein involved in transporting molecules.  It is a xenobiotic transporter.  It likely serves as a cellular defense mechanism against mitoxantrone and anthracyclines.  It is a high capacity urate exporter, hence the association with hyperuricemia and gout.  Interestingly, the protein plays a role in porphyrin homeostatsis, by the "export of protoporphyrin IX (PPIX) both from mitochondria to cytosol and from cytosol to extracellular space, and cellular export of hemin, and heme" (see ABCG2).  I wonder if the PPIX function somehow has something to do with why only a small portion of people with hyperuricemia develop gout.  I also suspect there's a significant environmental component to developing the disease.  We also do not know all there is to know about the ABCG2 gene, so more functions are likely to be discovered.

There are some things worth mentioning when it comes to living with gout.  First, an excessive intake to high fructose corn syrup seems to cause some twinges in my big toe.  Maybe this is due to SLC2A9 being involved with fructose, glucose, and uric acid transport.  The ABCG2 gene may also be involved in transporting sugars.  Second, taking iron supplements seemed to be the cause of twinges and almost a full blown gout attack after a month of taking the supplements.  Perhaps my ABCG2 "transport protein" was getting overloaded by the extra iron I was taking.  I also note that my FECH gene codes for an enzyme that converts protoporphyrin IX into heme.  But a mutation (rs2272783) reduces the enzymes activity to about 70% of normal.  No issues with photosensitivity here but interesting nonetheless.