Black-white differences in glaucoma

Glaucoma is a progressive condition caused by a combination of genetic and environmental factors and is the leading cause of irreversible blindness worldwide. Primary open-angle glaucoma (POAG) is the most common form of glaucoma and is often associated with elevated intraocular pressure (IOP).

The additive heritability of POAG ranges from 24 to 42%. This new study analyzes data on 4,986 POAG cases and 58,426 controls from 4 race/ethnicity groups. The authors found 24 loci linked to POAG.

The authors found more than double the prevalence of POAG among African-Americans compared to whites--16.1% vs. 7.4%. (The prevalence for East Asians was 9.9%; for Hispanics, it was 7.9%). The figures below shows the relationship between genetic ancestry and POAG. 

Hold it--I thought, as Jonathan Marks instructs us, that race is a cultural and political phenomenon, not a biological one?