Benzene rings
=============

* David Maxwell

I am most grateful to Dr. Atkinson for pointing out my error. He is, of course, absolutely correct. The error crept in when I tried to replicate my hand-drawn diagram, using a word-processing program to draw the chemical structure. As noted,1 the chemical structures of homogentisic acid and hydroquinone are strikingly similar.

## Reference

1.  1. Maxwell D. Alkaptonuria and photography: a patient's urine tells the story. CMAJ 2005;172(8):1002-3.
    
    [FREE Full Text](http://www.cmaj.ca/lookup/ijlink/YTozOntzOjQ6InBhdGgiO3M6MTQ6Ii9sb29rdXAvaWpsaW5rIjtzOjU6InF1ZXJ5IjthOjQ6e3M6ODoibGlua1R5cGUiO3M6NDoiRlVMTCI7czoxMToiam91cm5hbENvZGUiO3M6NDoiY21haiI7czo1OiJyZXNpZCI7czoxMDoiMTcyLzgvMTAwMiI7czo0OiJhdG9tIjtzOjIyOiIvY21hai8xNzMvNC8zNDUuMi5hdG9tIjt9czo4OiJmcmFnbWVudCI7czowOiIiO30=)