"Isabella's received transfusions and hasn't noticed any effect over about seven years," says Linya. "But it's possible she simply wouldn't have noticed; I'm younger than she is and I can expect to look younger than a non-engineered person of the same age for my entire life, and our alt didn't share our face and was also shy of four years old. Perhaps she's aging much slower than she otherwise would. We don't have any better data. Bar can tell whether substances are safe for possible recipients that she has available to look at, and we have one full dose left - I don't need it to try to duplicate the effect at home; I have his genome sequenced."