For example, Sod1 harbors an intron variant that diverges between the two strains and has previously been associated with both the ratio of Firmicutes to Bacteroidetes as well as obesity, providing direct evidence for variants in Sod1 regulating microbial diversity and a possible link to metabolic traits like obesity47,48. Here, SOD1 is linked to obesity due to melanocortin 4 receptor deficiency.