Loose anagen hair as a cause of hereditary hair loss in children.

BACKGROUND AND DESIGN: The loose anagen hair syndrome is a recently described disorder with enhanced hair loss in which anagen hairs can be painlessly pulled from the scalp.

RESULTS: In three families, we have observed an autosomal dominant form of inheritance. We have confirmed that the extracted bulbs consist only of cortical cells and that the hair shafts have an abnormal shape. Using routine light and electron microscopy, we observed disadhesion between all layers of the follicle and within some layers and premature keratinization of the inner root sheath of the follicle. In addition, abnormal maturation of the various layers was observed at the electron microscopic level, including regions of the cortex that contained decreased numbers of filaments. The disorder appears to be cyclic, since relatively normal and markedly affected regions of the shaft can be observed within a single follicle.

CONCLUSIONS: Possible mechanisms responsible for the disease include abnormal intercellular signaling and disturbances of desmosomal components and/or cadherins.