Differences in gene expression between very curly and straight human hair

Hair shape is defined in the follicle: large hair follicles produce ‘terminal’ hairs, small follicles produce fine ‘vellus’ hairs, curved follicles produce curly hair in all ethnicities, according to the available literature. In order to understand better how shape is determined in the follicle and complement the publically available knowledge on hair shape genetics, our research group undertook a global high-throughput approach to compare the levels of gene expression among straight and very curly hair. The microarray was the methodology chosen. A list of the transcripts differently expressed that pass the statistical two independent groups test including correction for multiple testing (Bonferroni-Hochberg with 0.05 cut-off) was obtained. From 85 genes that were significantly different 68 genes were more expressed in very curly hair follicles and 17 genes were more expressed in straight hair follicles. The team collected 50 hair follicles from each volunteer: 6 donors with extremely curly hair and 5 donors with straight hair, all non-bald adult males with ages between 19-40 years old. The isolated RNA was processed and used on Affymetrix GeneChip HuGene 1.0 ST Arrays (Affymetrix Core Facility at Instituto Gulbenkian de Ciencia, Oeiras, Portugal)