Short anagen hair with persistent synchronized pattern of scalp hair growth.

Unlike other mammals that molt hair seasonally, human beings have scalp hair follicles that exhibit an asynchronized pattern of cycling, with the growth and subsequent shedding of each hair being independent of others around it. This mosaic cycling behavior is established early and continues throughout life. We describe a boy who continues to have a synchronized pattern of hair growth and shedding, and a short anagen duration at 4 years of age. He appears to never have established the expected asynchronized pattern of hair growth.