WHAT DEFECTS HAVE BEEN OBSERVED IN CLONED ANIMALS?
A wide array of abnormalities and defects have been observed in reproductively cloned animals, both before and after birth [4; 6; 8-10; 13; 16; 20; 23; 24; 29; 32; 38-45]. However, these abnormalities have not always been studied in detail, possibly because most reproductive animal cloning has been done for commercial purposes and there is less interest in the failures than in the successes. The panel was told that funding for studies to catalog and understand the basis of the abnormalities is sorely needed [39]. The reported defects in cloned animals are summarized in Table 1 and detailed in Table 2. The most notable defects are increased birth size, placental defects, and lung, kidney, and cardiovascular problems [39; 46]. Other problems have included liver, joint, and brain defects, immune dysfunction, and postnatal weight gain. Thus, a wide variety of tissues and organs can fail to develop properly in cloned animals, and some of the reported defects (such as aberrant growth and dev
