aDivision of Genetics and Genomic Medicine, Department of Pediatrics

bDivision of Dermatology, Departments of Medicine and Pediatrics, Washington University School of Medicine in St. Louis, St. Louis, Missouri, USA

Correspondence to Carrie C. Coughlin, MD, MPHS, Division of Dermatology, MSC 8123-29-10014, 660 S. Euclid Ave, St. Louis, MO 63110, USA. Tel: +1 314 454 2714; fax: +1 314 454 4232; e-mail: [email protected]