The paper by Kendler et al. (2007) that the above Letter to the Editor comments upon was incorrectly cited in the list of References.

The correct version of the reference is given below:Kendler KS, Gardner CO, Gatz M, Pedersen NL (2007). The sources of co-morbidity between major depression and generalized anxiety disorder in a Swedish national twin sample. Psychological Medicine 37, 453–462.