IFITM1 and obesity due to melanocortin 4 receptor deficiency: Since an obesity phenotype has not been described for single Ifitm gene deletions (Ifitm3 deficient or Ifitm1 deficient)[16,53] nor have any brain anomalies such as the deficiency in microglia as shown in this report been described for any of these single Ifitm gene deletion strains, this will require further investigation.