Pili torti is a rare condition in which the hair shaft grows irregularly. It causes the hair to twist in an unusual 180-degree pattern. This causes flattening at various points along the shaft, causing the hair to break off easily. Pili torti is established in a number of rare syndromes or diseases, such as Bjornstad syndrome, Crandall syndrome, Bazex syndrome and Menkes kinky-hair disease. The most common form is genetic.