Embryonic stem cell 
A study of twin four year old girls has identified a rogue cell as a culprit in childhood leukemia.
Both twins were found to have the “pre-leukemic” cells in their bone marrow, although, to date, only one has developed leukemia. Researchers found they both have “pre-leukemic stem cells” containing a mutated gene, which forms when the DNA is broken and rejoined at another point. The pre-leukemic cells are transferred from one twin to the other in the womb through their shared blood supply. UK researchers reported in Science that a second genetic mutation is needed for full-blown disease to develop. …read more