An imbalance in the Firmicutes/Bacteroidetes ratio is reported to link to conditions like obesity, IBD, and metabolic dysfunction.31 An increase in Firmicutes has been observed in conditions like rheumatoid arthritis.32 To date, no gut microbiota data are published on people with MPO deficiency. This evidence concerns the gene MPO and hyperinsulinemic hypoglycemia, familial, 4.