The trichothiodystrophies (TTD) are characterised by brittle, sulphur deficient hair that has an unusual tiger-tail banding pattern under polarising light microscopy. People affected by TTD can experience a range of symptoms including dry skin, short stature, intellectual disability and susceptibility to infection. About half of the patients have an inability to properly repair DNA damage following exposure to ultra-violet (UV) light and this feature categorizes photosensitive and non-photosensitive forms of the disease. Initially described as a DNA repair syndrome, photosensitive TTD is now regarded as a transcription and repair syndrome. In contrast, very little is known about non-photosensitive TTD. We identified a mutation that affects the X-linked, RNF113A gene in two male cousins with TTD that do not have any problems with UV induced DNA repair. A new gene implicated in non-photosensitive TTD! The function of RNF113A is as yet unknown though similar proteins found in fish, flies and flat worms direct the formation of the brain and central nervous system suggesting a conserved role for this protein. (By Dr. Mark Corbett, http://jmg.bmj.com/content/early/2015/01/22/jmedgenet-2014-102418 )