Human Molecular Genetics 2009 18:15; pp. 2825–38; doi:10.1093/hmg/ddp218.

Ms Seema Dhindaw was omitted from the list of authors and should have appeared as the third author of this article. Ms Dhindaw made a significant contribution to the data collection, analysis and interpretation; and initial drafts of this article. Her contact details are as follows:

E-mail: [email protected]

Correspondence Address: 1728 Quarry Ridge Place NW, #225, Rochester, MN 55901, USA.