Lymphoid hypoplasia and somatic cloning

Background Adult somatic cloning by nuclear transfer is associated with high rate of perinatal mortality but there is still no evidence that nuclear transfer itself is responsible for these failures. We report on a longlasting defect linked to somatic cloning. Methods Skin cells grown from an ear biopsy specimen from a 15-day-old calf were used as a source of nuclei. The donor animal was a clone of three females obtained from embryonic cells. Clinical examination, haematological, and biochemical profiles, and echocardiography of the somatic clone were done from birth to death. Findings After 6 weeks of normal development, the somatic cloned calf had a sudden and rapid fall in lymphocyte count and a decrease in haemoglobin. The calf died on day 51 from severe anaemia. Necropsy revealed no abnormality except thymic atrophy and lymphoid hypoplasia. Interpretation Somatic cloning may be the cause of long-lasting deleterious effects. Our observation should be taken into account in debates on reproductive cloning in human beings.