Nature Medicine 12, 1259–1268 (2006); published online 22 October 2006.

In page 1264 of this article, it is stated that “The donor cells were dispersed over an average radius of 1.6 ± 0.6 mm, and the mean number of HNA+ nuclei/mm3 within each was 136,726 ± 23,515”. The authors wish to clarify that they used the word “radius” in the non-geometric sense, as in this definition of the American Heritage Dictionary: “A bounded range of effective activity or influence”. At the same time, they want to remark that the numbers, figures and scale bars shown in the paper are correct.