Trichoglyphics, namely the direction put on by the hair, as well as dermatoglyphics are influenced by genetic and environmental factors acting between the 10th and 17th week of fetal life. Most subjects with smooth hair present a hair whorl in the parietal region, in front of the posterior fontanelle, on the median line or laterally on the right or, less frequently, on the left. In the hair whorl the hair usually rotate clockwise in most cases, but counterclockwise in 11.1% of cases. The latter rotation is more frequent in left-handed subjects (1). A minority of subjects presents a frontal hair whorl (2). The latter, although possibly present in normal subjects, is more frequent in some inherited skin disorders (3). This is why a frontal hair whorl may be an additional sign to confirm the suspicion of inherited disorders, particularly those associated with mental retardation.
How to cite:Eur. J. Pediat. Dermatol. 15, 185, 2005