Our findings also indicate that permanent engraftment of B. uniformis in the distal gut is not strictly required for its immune and metabolic effects in either wt or Rag1-/- mice, although we cannot rule out that the bacterium uses upper regions as ecological niches, and that this contributes to some of the effects in diet-induced obesity. The gene discussed is RAG1; the disease is obesity due to melanocortin 4 receptor deficiency.