Nance-Horan syndrome

Nance-Horan syndrome is a rare inherited condition that affects the eyes, the teeth and, in some people, the face and the mind. It is carried on the X chromosome, so males are affected more severely than females. The central sign is a congenital cataract in the lens of the eye, usually present from birth, which reduces sharpness of sight, and it often comes with an abnormally small eye or cornea, a squint and involuntary eye movements. The teeth are also unusual: the cusps of the back teeth may be tapered, extra teeth can appear, the front teeth may be shaped like screwdrivers and gaps can open between them. Some people have a long narrow face, a prominent nose and ears that turn forward, and about three in ten affected males have an intellectual disability. Female carriers usually show a milder picture, such as small lens opacities with little or no loss of vision. The syndrome is caused by changes in the NHS gene on the short arm of the X chromosome. It has no cure; care consists of eye surgery, dental treatment where needed, and genetic counselling for relatives. It was first described in 1974 by Margaret B. Horan and Walter Elmore Nance. The Wikipedia article is the source for this entry, which records what is known and is not medical advice.