Skin biopsies (approx. 3mm3) were collected respectively from the inside of the skin in fibroblast culture media (DMEM high glucose, FBS, L-glutamine, N.E. amino acids, Pen/Strep; all Invitrogen). Fibroblasts attached, proliferated and were passaged twice before DNA was extracted (DNeasy Blood and Tissue Kit; Qiagen according to manufacturer recommendations).