Morphological Analyses in Fragility of Pili Torti with Björnstad Syndrome

The study investigated the morphological features responsible for the fragility of pili torti in a patient with Björnstad syndrome using transmission electron microscopy. Pili torti is characterized by twisted, flattened, and thin hair shafts that are easily broken. The research found that the tensile strength of pili torti was 2.1 times lower than that of normal hair, attributed to a smaller cross-sectional area and lower Young's modulus. The cuticle layers of pili torti had wavy shapes with varying thicknesses, and the cortex exhibited loose keratin intermediate filaments. These abnormalities, occurring below the infundibulum, suggested that the fragility was due to loose intermediate filaments caused by dysformation of disulfide bonds.