In the letter of Dr Carbone it is stated that all cells of the same person have the same DNA.

That’s a surprise! The human body has trillions of cells and, with a few exceptions like cells that produce antibodies, scientists have believed that essentially all cells from an individual contain identical sets of DNA. But recent studies [2] [3] suggest that somatic changes in the DNA—those changes not inherited from the parents—might arise in cells naturally and could, under the right circumstances, trigger disease. Now, researchers using MIDAS can search for even more subtle differences between the genomes of two cells from the same tissue or organ of an individual. These differences could provide insights into the evolution of neurodegenerative diseases, and also of cancers—which are known for being a genetically heterogeneous collection of cells.