A Brief History of APOL1: A Gene Evolving

APOL1 kidney risk variants lead to high rates of kidney disease in people of recent African ancestry. These risk variants are very common and confer a large increase in risk of kidney disease. This unusual combination of high frequency and large effect size occurs because the risk variants also appear to have beneficial properties. The risk variants show enhanced protective effects against certain pathogens, particularly the trypanosomes that cause African sleeping sickness. Here, we consider the origins and evolution of the primate-only APOL1 gene. Human genetics, mouse models, biochemistry, and comparative genomics suggest that APOL1 is an innate immunity gene and that the risk variants have the potential for heightened immunity that comes at the cost of toxicity to the kidneys. A better understanding of the evolution of APOL1 may help illuminate how APOL1 causes kidney disease in individuals who harbor the high-risk variants. (C) 2017 Published by Elsevier Inc.