Among in vivo models of ileitis, the SAMP1/YitFC (SAMP) mice have the unique feature of spontaneously developing early ileitis (starting at 10 weeks of age) without genetic or immunologic manipulations, which reaches 100% penetrance by 20 weeks of age, with progressively worse disease up to 60 weeks [11,12]. This evidence concerns the gene TMEM201 and Crohn ileitis.