Filaggrin genotyping/stratification
As a proxy for FLG genotyping, NMF was measured in vivo , non-invasively, at a depth of 25 µm in the stratum corneum of the thenar eminence by Near-Infrared Raman spectroscopy (NMF-scan, RiverD International B.V., Rotterdam, The Netherlands), a method that has previously been shown to be an excellent proxy for FLG genotyping17–19. Formal FLG genetic testing as performed as follows: buccal swabs were collected using Isohelix SK-3S swabs and BFX/S1/05/50 buccal fix tubes (Cell Projects ltd). Filaggrin genotyping was performed at the A*STAR Skin Research Labs using Microfluidics PCR for full coverage of FLG repeat alleles using a method described previously20.