Rare X-linked dominant condition
Medical condition
Nance–Horan syndrome, also known as X-linked congenital cataracts and microcornea, X-linked cataract–dental syndrome, cataracts-oto-dental syndrome, cataract–dental syndrome, and mesiodens–cataract syndrome, is a rare X-linked syndrome characterized by eye and teeth abnormalities, intellectual disability, and facial deformities.
Signs and symptoms.
The main ocular sign of Nance–Horan syndrome is a congenital nuclear cataract which results in reduced visual acuity. Other ocular features include microphthalmia, microcornea, strabismus, and nystagmus. Dental features include tapered premolar/molar cusps, supernumerary teeth, screwdriver-shaped incisors, and diastema. Abnormal facial features include anteverted pinnae, prominent and bulbous nose, and long narrow face. 30% of males with Nance–Horan syndrome have intellectual disabilities. Carrier females exhibit less severe clinical symptoms, including lens opacities at the posterior Y-sutures with minimal or no loss of vision, modest face dysmorphism, and dental abnormalities.
Genetics.
This syndrome is caused by mutations in the Nance Horan gene (NHS) which is located on the short arm of the X chromosome (Xp22.13).
Management.
There is no known cure for this syndrome. Patients usually need ophthalmic surgery and may also need dental surgery. Genetic counseling and screening of the mother's relatives is recommended.
History.
This syndrome was first described by Margaret B. Horan and Walter Elmore Nance in 1974.
References.
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