Nance–Horan syndrome is a rare X linked syndrome characterized by congenital cataract leading to profound vision loss, characteristic dysmorphic features and dental anomalies. Microcornea, microphthalmia and mild or moderate mental retardation may accompany these features. Heterozygous females often manifest similarly but with less severe features than affected males.
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Genetics
This syndrome is due to mutations in the Nance Horan gene (NHS) which is located on the short arm of the X chromosome (Xp22.13).
Clinical features
Dental features:
Facial features:
Ophthalmic features:
These lead to severe visual impairment in affected males.
Other:
30% of patients also have some degree of intellectual impairment: of these 80% are mildly to moderately affected: the other 20% may have developmental delays and behavior problems.
Carrier females display milder variable symptoms of disease. Ocular signs are present in 90% of heterozygous females. These are typically lens opacities often involving the posterior Y sutures. More rarely dental anomalies and the characteristic facial features may also occur.
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.