Therefore, the clinical course of episodes of this anaemia varies, and the range of severity will not be the same with all variants that are in class B. The episodes of acute haemolytic anaemia may tend to be more common and more severe for variants with a lower mean activity (such as G6PD Coimbra and G6PD Mediterranean variants) than with a higher mean activity (such as G6PD Seattle and G6PD Kalyan-Kerala variants). This evidence concerns the gene G6PD and anemia.