It has come to our attention that there may be some confusion about the relationship of the data in two of our NKX2-5 papers. Therefore, this correspondence aims to address the following issues: firstly, the relationship and the differences between our two NKX2-5 papers^1,2 and secondly, the research need for congenital heart disease (CHD) on the basis of somatic mutations.

The confusion about the relationship between the two publications may have originated because both papers are based on the analysis of 68 specimens of malformed hearts that had been conserved in formalin in Leipzig, and both papers report 35 nonsynonymous mutations in NKX2-5 in the diseased but not in the healthy part of the heart. Our oversight of not citing the Am J Pathol (AJP) paper¹ in the J Med Genet (JMG) paper² may also have contributed to this confusion. Although it was not our intention to avoid citing the AJP paper in our JMG short report, different timelines in the submission and revision process of both papers prior to acceptance resulted in this oversight. We deeply regret this. It is, however, of considerable importance that in further publications on NKX2-5 or submitted manuscripts on other cardiac specific transcription factors of the Leipzig collection of malformed hearts, both the AJP and JMG papers cited together, or the pertinent paper in appropriate situations.^3–6 It is of equal importance that workers in the field cite both papers together.⁷

Herein, we wish to discuss the differences between both papers in their focal emphasis, to prevent ongoing confusion. Specifically, the sequence information of the 35 nonsynonymous mutations is reported in both papers, but there is a simple rationale behind this. In the JMG paper, we reported on the multiple haplotypes associated with the 35 nonsynonymous mutations and …