It was found that the gene linked with leukemia ETV6-RUNX1 that was generated in the womb was similar in both the pairs of twins. There were 22 similar gene mutations in both pairs, which were not significant in development of leukemia.
A mutation, called NF1, appeared in one pair of twins. This gene was inherited from their parents. The mutation predisposed the twins to neurofibromatosis, a condition that is considered a risk factor for leukemia.
The findings are published in the journal Proceedings of the National Academy of Sciences.