After backcrossing onto C3H/HeH for three generations to allow comparison with OtpR108W/+ mice, Otp+/tm1Asim animals showed a modest obesity phenotype (Appendix B Supplementary Figure 1b,c,e,f) and other similarities to OtpR108W/+ mice (Appendix B Supplementary Figure 1h,i,k,l,n,o,q,r). This evidence concerns the gene OTP and obesity due to melanocortin 4 receptor deficiency.