Nance–Horan syndrome
Nance–Horan syndrome is a rare X linked syndrome characterized by congenital cataract leading to profound vision loss, characteristic dysmorphic features and dental anomalies.[1][2] 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.
Presentation[edit | edit source]
Dental features:
- small teeth in males
- pointed (screwdriver shaped or conical) incisors (sometimes called Hutchinson teeth)
- incisors with an irregulal incisal edge
- canines: enlarged and globular; may be dome or bud shaped with trilobed edge
- premolars and molars: small, round and globular; may have supernumary lobes (mulberry or lotus flower shape)
- widely separated teeth (diastemma)
- hypoplastic enamel
- dental agenesis
- presence of mesiodents (median incisor behind normal upper incisors)
- pulp chamber anomalies
Facial features:
- anteverted pinnae
- long face
- prominent nasal bridge and nose
- prognathism occasionally
Ophthalmic features:
- bilateral congenital nuclear opacities (100%)
- severe amblyopia
- nystagmus (93%)
- strabismus (43%)
- microcornea (96%)
- congenital glaucoma
- scleral staphylomas
- retinal cystoid degeneration
- microphthalmia
These lead to severe visual impairment in affected males.
Other:
- The fourth metacarpal may be shortened
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.
Genetics[edit | edit source]
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).[3]
Diagnosis[edit | edit source]
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Management[edit | edit source]
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[edit | edit source]
This syndrome was first described by Margaret B. Horan and Walter Elmore Nance in 1974.[4][5]
References[edit | edit source]
External links[edit | edit source]
Classification | |
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External resources |
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- Blindness
- Disorders of lens
- Rare syndromes
- Congenital disorders of eyes
- Genetic syndromes
- Syndromes affecting teeth
- Syndromes affecting the eyes
- Syndromes with craniofacial abnormalities
Contributors: Prab R. Tumpati, MD