Loose Anagen Hair Syndrome
Loose anagen hair syndrome (LAHS) is a condition that occurs predominantly in young children with blonde or light brown hair. It is slightly more common in girls. The condition is characterized by the painless extraction of increased numbers of anagen growing hairs on a pull test. The affected child’s hair is often described as not growing and may demonstrate hairs of varying lengths. The condition usually improves with age but may persist into adulthood. Most cases of LAHS occur sporadically, however, it has also shown an autosomal dominant inheritance pattern in some families.
Pathophysiology of LAHS
The affected hairs in LAHS are anagen (growing) hairs that may lack an inner and outer root sheath on a pull test. The anagen bulbs are often dysmorphic and the hairs may demonstrate longitudinal grooves and ruffled cuticles. Poor cohesion of outer root sheath cells has been described in LAHS. The underlying cellular defect or defects allows the easy and painless extraction of these growing anagen hairs from follicular epithelium.