Trichothiodystrophy Hair Shafts Display Distinct Ultrastructural Features

The study examined hair shafts from three patients with trichothiodystrophy (TTD), a rare disorder, using transmission electron microscopy. The patients had mutations in the ERCC2 (XPD) gene, which is part of the DNA repair/transcription pathway. The hair shafts were relaxed using partial disulphide bond reduction and sodium dodecyl sulphate for better visualization. Compared to normal hair shafts, TTD cuticle cells showed abnormal marginal bands and exocuticle layers. There were also clusters of cells that stained differently in the cortex of the aberrant shafts, and the keratin macrofibrils in the cytoplasm appeared much shorter. The results suggest not only a lack of high sulphur components like keratin-associated proteins, but also a significant imbalance in protein content and organization.