Trichothiodystrophy Overview Trichothiodystrophy (TTD) is a rare inherited, genetic disease characterized by a broad spectrum of abnormalities. Patients with different symptoms are linked together by the common feature of short, dry, brittle, sulfur-deficient hair which has a characteristic “tiger tail” pattern (alternating light and dark bands) under polarizing microscopy. The signs and symptoms vary widely between patients. Typically, patients are born preterm and with low birth weight. Maternal pregnancy complications are common. Infants may be born with a shiny parchment-like covering on the skin that peels off over several days to weeks (collodion membrane). Through childhood they may have developmental delay or intellectual disability, short stature with poor weight gain, dry, scaly skin (ichthyosis), eye abnormalities (the most common being congenital cataracts), recurrent infections and bone abnormalities. Nearly half (42%) of patients with TTD have extreme sensitivity to ultra...